petrogenesis of high-k, calc-alkaline and shoshonitic intrusive ......dabie-sulu orogenic belt...

78

Petrogenesis of high-K, calc-alkaline and shoshonitic intrusive rocks in the Tongling area, Anhui Province

(eastern China), and their tectonic implications

Cailai Wu1,†, Shuwen Dong2, Paul T. Robinson1, B. Ronald Frost3, Yuanhong Gao1, Min Lei1, Qilong Chen1, and Haipeng Qin11State Key Laboratory of Continental Tectonics and Dynamics, Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China2Chinese Academy of Geological Sciences (CAGS), Beijing 100037, China3Department of Geology and Geophysics, University of Wyoming, Laramie, Wyoming 82072, USA

ABSTRACT

The Mesozoic intermediate-silicic intru-sive rocks in the Tongling area, Anhui Prov-ince, eastern China, include a high-K, calc-alkaline series and a shoshonitic series . Rocks of the calc- alkaline series comprise more than 90% of the total and consist chiefl y of gabbro-diorite , granodiorite, quartz monzo-diorite, and porphyritic quartz monzodiorite. These rocks are associated with important skarn-type copper-iron deposits. They con-tain three types of enclaves: mica-rich vari-eties that appear to be residues of partially melted pelitic rock, mafi c quartz monzo-diorite, and microdiorite. The shoshonitic series consists of pyrox ene monzodiorite, monzonite, and quartz monzonite, which are commonly asso ciated with skarn-type gold deposits. Enclaves in these rocks are typi-cally pyroxene-rich or amphibole-rich vari-eties or amphibole gabbros. Zircon sensitive high-resolution ion micro probe (SHRIMP) U-Pb age data suggest that the granodiorites, quartz monzo diorites, and gabbro-diorites of the calc-alkaline series were generated at ca. 146–142, 143, and 140 Ma, respectively. The shoshonitic rocks range in age from 143 to 136 Ma. Although there is some overlap in reported ages of the two series, contact rela-tions indicate that the shoshonitic rocks post-date the calc-alkaline varieties. On the basis of the geochemistry of the two series and the character of their enclaves, the shoshonitic series is thought to have formed primarily by differentiation of a mantle-derived, weakly contaminated, alkali basalt magma, whereas the high-K, calc-alkaline series refl ects mix-

ing of differentiated mantle and crustal melts, followed by assimilation–fraction crystalliza-tion (AFC) processes. The magmatic activity may have been related to reactivation of the Tongling-Deijiahui structural zone in re-sponse to rapid, highly oblique subduction of the paleo–Pacifi c plate beneath South China.

INTRODUCTION

The Tongling district, which is situated in the eastern part of the Yangtze River basin in Anhui Province, is an ancient copper capital of China and one of the most important metal-bearing districts in the country (Fig. 1A). The polymetallic district is ~40 km long in an E-W direction and 20 km wide, with a total area of ~800 km2 (Fig. 1B). Within the district, there are 76 intermediate-silicic intrusive bodies and 54 known ore deposits (Wu et al., 2010a). The intrusive rocks are mostly intermediate dio-rites, monzonites, and quartz monzonites that form an early high-K, calc-alkaline series and a slightly later shoshonitic series. The ore depos-its are predominantly skarn type with copper, iron, and gold mineralization, accompanied by minor strata-bound types in the host carbon-ates (Zhao et al., 1999; Zhai et al., 1992). Some porphyry-type mineralization is also present, but it generally occurs only in the deeper parts of the intrusions (Pan and Dong, 1999). The total reserves in this district have been esti-mated to be 500 Mt copper and 150 t gold (Wu et al., 2010a).

Because of their associated copper and gold deposits, the intrusive rocks have been studied for many years (e.g., Chang and Liu, 1983; Tang et al., 1998; Xing and Xu, 1995, 1996; Zhou et al., 1993; Wu et al., 1996, 2000, 2003), but there is no agreement regard-

ing the petro genesis of the two series. Several processes have been proposed for the origin of these rocks: (1) assimilation of country rock by alkaline basaltic magma (Mao, 1990), (2) fractional crystallization of lower-crustal melts (Wu, 1986), (3) assimilation of lower-crustal material by alkaline basaltic magma followed by fractional crystallization (Xing and Xu, 1995), (4) partial melting of basaltic lower crust to form tonalitic intrusive rocks (Zhang et al., 2001), and (5) mixing of mantle-derived magmas with those formed by partial melting of basaltic lower crust (Wang et al., 2003). In this paper, we reexamine the origin of these granitoids using new sensitive high-reso lution ion microprobe (SHRIMP) U-Pb ages, whole-rock geochemistry, and the com-positions of the various enclaves hosted in the gran itoids. We review all of the recent data on the ages of the rocks and their enclaves (X.S. Xu et al., 2004; Du et al., 2004, 2007; Yang et al., 2007; Zhang et al., 2006; Wu et al., 2001; Wang et al., 2004a, 2004b, 2004c; X.C. Xu et al., 2008), but the validity of some ages is uncertain, because different dating techniques have yielded different ages for the same intru-sive body (Zhou et al., 1987;Wu et al., 1996). For example, 40Ar-39Ar dating of biotite from some of the Tongling rocks has yielded ages of 140–137 Ma for granodiorite, 137–136 Ma for quartz monzodiorite, 138–137 Ma for pyroxene monzodiorite, and 134 Ma for gabbro-diorite (Wu et al., 1996, 2001), but these ages only record the time at which the intrusive bod-ies cooled through ~300 °C, the Ar-Ar clo-sure temperature of biotite (Cliff, 1985). A few zircon SHRIMP U-Pb ages have recently become available (Yang et al., 2008; X.C. Xu et al., 2008), but these studies all focused on individual bodies . Here, we report new zircon

For permission to copy, contact [email protected]© 2013 Geological Society of America

GSA Bulletin; January/February 2014; v. 126; no. 1/2; p. 78–102; doi: 10.1130/B30613.1; 12 fi gures; 10 tables.

†E-mail: [email protected]

Petrogenesis of intermediate-acid intrusive rocks and zircon SHRIMP U-Pb dating in the Tongling area, Anhui Province (eastern China)

Geological Society of America Bulletin, January/February 2014 79

A

B

Figure 1. Geological sketch map of Tongling area, Anhui, China. R—Tertiary system; K2, K1—Upper and Lower Cretaceous system; J3—Upper Jurassic system; J1–2—Middle and Lower Jurassic system; T22-T23—Middle Triassic system; D3-T21—Upper Devonian system–Middle and Lower Triassic system; S—Silurian system; «—dating sample locations.

Wu et al.

80 Geological Society of America Bulletin, January/February 2014

SHRIMP ages for four plutons and discuss the petrogenesis of the intrusive rocks and their enclaves, as well as the tectonic environment in which they formed.

GEOLOGICAL SETTING

The continental core of China is composed of the South China block and the North China craton, which were welded together along the Dabie-Sulu orogenic belt between ca. 250 and 220 Ma. The South China block was formed by collision and amalgamation of the Yangtze and Cathaysian blocks at ca. 880 Ma. The Tongling area lies in the Yangtze polymetal-lic belt located in the northeastern part of the Yangtze block (Chang et al., 1991; S. Xu et al., 1992; Pan and Dong, 1999) (Fig. 1A). It is nearly perpendicular to the Tan-Lu fault, a major left-lateral, strike-slip fault that offsets the Dabie ultrahigh-pressure (UHP) metamor-phic belt several hundred kilometers to the northeast (Fig. 1A). The exact age of initiation of the Tan-Lu fault is uncertain, but 40Ar-39Ar dating of amphibole in ductile shear zones in the southern part of the fault suggests it was activated no later than 143 Ma, in response to rapid, highly oblique subduction of the paleo–Pacifi c plate beneath southeast China (Zhu et al., 2005). Gravity and aeromagnetic data suggest that the Tongling district is underlain by a regional, deep-seated, structural feature, the Tongling-Deijiahui structural zone (E-W dashed line in Fig. 1B; Chang et al., 1991, 1996; Lu et al., 2003). This feature is consid-ered by Wang and Cong (1998) to be an east-ward extension of the Xiaotian-Mozitan deep fault, which separates the Huaiyang arc fl ysch belt from the Dabie arc complex west of the Tan-Lu fault. We suggest that the magmatism and mineralization in the Tongling district may have been initiated during reactivation of this feature by transtensional movement on the Tan-Lu fault. Such reactivation may have caused crustal thinning and mantle upwelling, leading to partial melting of the upper mantle and lower crust, ultimately producing exten-sive intermediate-silicic magmatism in the region. Subduction of the paleo–Pacifi c plate also triggered extensive Jurassic and Creta-ceous magmatic activity elsewhere in south-east China and reactivated many preexisting faults and fracture zones (Wong et al., 2009).

Very few basement outcrops occur in the Yangtze block, and the Tongling area is domi-nated by a sequence of Paleozoic and Trias-sic marine carbonate, clastic, and siliceous sedimentary rocks, locally overlain by Cre-taceous to Middle Tertiary continental clastic and volcanic rocks (Xu and Zhou, 2001). The

Paleozoic and Triassic sedimentary rocks form a series of complex, NE-trending folds with thrust faults along their limbs (Zhai et al., 1996), many of which are cut by NW-trending brittle faults (Fig. 1B). Several possible base-ment faults, including the major Tongling-Deijiahui structural zone, have been identifi ed from geophysical data, and their intersections are thought to partially control the location of the Mesozoic intrusions (Ren et al., 1992; Zhai et al., 1996; Chang et al., 1996; Tang et al., 2004).

Seventy-six individual intrusions have been identifi ed in the Tongling area (Fig. 1B). Most of these are small stocks and dikes, gener-ally with outcrop areas of 0.05–3 km2, locally accompanied by small sills, apophyses, and veins. They are hosted mostly in Silurian to Triassic carbonates and quartz sandstones, and less commonly in siliceous rocks. The intrusive rocks are divided into a high-K, calc-alkaline series and a shoshonitic series on the basis of their petrochemistry.

The high-K, calc-alkaline rocks occur as NE-trending stocks in Carboniferous dolomitic limestone and Permian to Triassic carbon-ate rocks. Mineralized skarns hosting copper deposits are well developed in the carbonates (Chang and Liu, 1983), and these may represent remobilization of stratiform sulfi de deposits (Xu and Zhou, 2001). Many of the stocks lie along, or near, the axes of anticlines, but some irregu-lar bodies appear to have been emplaced at fault intersections. The calc-alkaline bodies contain abundant enclaves, chiefl y composed of micro-diorite, mafi c quartz monzodiorite, and mica-ceous material. Based on fi eld relationships, these rocks predate the shoshonitic bodies and have 40Ar-39Ar cooling ages ranging from 140 to 137 Ma for granodiorite, 137–136 Ma for quartz monzodiorite, and 134 Ma for gabbro-diorite (Wu et al., 2000).

The shoshonitic intrusive bodies are pyrox-ene monzodiorites that occur as NW- to NE-trending dikes or stocks. They typically have sharp contacts with the host Triassic carbonates and exhibit a preferred orientation of tabular plagioclase grains aligned parallel to the intru-sive contacts. The host carbonates have locally been converted to marble, scapolite, and skarn. All of these intrusive bodies contain abundant enclaves, including spinel pyroxenite, horn-blendite, hornfels, marble, and skarn. Some of the shoshonitic bodies were intruded along contacts between the high-K, calc-alkaline bodies and the host country rocks. The shosho-nitic rocks are commonly associated with gold, silver, lead, and zinc deposits. Their 40Ar/39Ar cooling ages range from 137 to 136 Ma (Wu et al., 2000).

LITHOLOGY OF THE INTRUSIVE ROCKS AND THEIR ENCLAVES

The high-K, calc-alkaline series rocks range in composition from gabbro-diorite through quartz monzodiorite and granodiorite to aplitic granite. Most of these rocks have hypidiomor-phic granular textures, except for the gabbro-diorites, which have gabbroic-diabasic textures, and some granodiorites with porphyritic tex-tures. The rock-forming minerals are plagio-clase, quartz, amphibole, biotite, and potassium feldspar, most of which range from 1.2 mm to 2.2 mm in size. Some porphyritic granodiorites have plagioclase phenocrysts up to ~6 mm. Many of the plagioclase grains have diffuse cores crowded with opaque inclusions; others contain inclusions of apatite. Some alkali feld-spar phenocrysts are rimmed by plagioclase, suggesting magma mixing (cf. Hibbard, 1991). These rocks contain three types of enclaves, which are different from those in the shoshonitic series. Their main features are:

(1) Mica-rich enclaves: These enclaves occur mainly in the granodiorites. They are black, elliptical bodies that range from 4 to 8 cm in their long direction, and they consist chiefl y of biotite (>80 modal%) and plagioclase (15%), with minor cordierite and almandine garnet. Accessory minerals include magnetite, pyrite, chalcopyrite, and sphalerite. Texturally, the enclaves consist of plagioclase phenocrysts imbedded in a granular mosaic of biotite. These enclaves are interpreted as partially melted resi-dues of metamorphic country rock.

(2) Mafic quartz monzodiorite enclaves: These enclaves occur in granodiorites and quartz monzodiorites. They are light gray in color, angular in shape, and 8–30 cm across. They have sharp contacts with the host rocks and are generally concentrated along intrusive contacts, suggesting that they represent a chilled border phase. The mineralogy of these enclaves is similar to that of the host rocks, i.e., plagio-clase + amphibole + alkali feldspar + quartz + biotite, but they contain a higher percentage of dark minerals, such as amphibole and bio-tite. Typical specimens have hypidiomorphic-granular textures and consist of 50–60 modal% plagioclase, 15%–20% euhedral amphibole, and 5%–10% quartz, accompanied by minor potas-sium feldspar and biotite.

(3) Microdiorite enclaves: These enclaves occur chiefl y in granodiorites but are also pres-ent in some quartz monzodiorites and porphy-ritic granodiorites. They are dark gray in color and vary in shape from ellipsoidal or spherical to irregular, fl ame-like forms. These enclaves generally range from 20 to 50 cm in diameter, with the largest up to 140 cm. They are typically



distributed in the middle of the intrusive bodies, locally occurring in swarms or belts, and they have gradational contacts with the host rocks. These enclaves mostly contain the same miner-als as the host rocks, and some of the crystals have reaction rims, suggesting possible min-gling of magmas. Some enclaves are compos-ite features with dark central zones and lighter rims, probably also refl ecting magma mix-ing events. The minerals in these enclaves are plagio clase (40–50 modal%), amphibole (20%–30%), biotite (5%–8%), potassium feldspar (3%–7%), and quartz (3%–5%), with accessory apatite, titanite, zircon, magnetite, pyrite, and chalcopyrite. They have typical microgranular textures and locally contain plagioclase pheno-crysts with compositions similar to those of the groundmass grains. Some of the phenocrysts straddle the boundary between the enclave and host rock, and some have distinct, ellipsoidal cores with more calcic compositions than the rims. Plagioclase in the groundmass is typically reversely zoned and contains many inclusions of apatite. Some quartz contains abundant inclu-sions of fi brous amphibole. Such textures sug-gest that the enclave magma cooled rapidly in the host magma (Di et al., 2003).

The shoshonitic series includes pyroxene monzodiorite, monzonite, and quartz monzo-nite, all of which have idiomorphic-hypidiomor-phic granular textures. The main rock-forming minerals (which range from 1.5 to 2.2 mm in size) are clinopyroxene, plagioclase, potassium feldspar, and quartz, accompanied by subor-dinate biotite and amphibole. In addition, the rocks contain abundant, fi ne-grained (0.01–0.5 mm) accessory minerals such as magnetite, zircon, titanite, and apatite. Sulfi de minerals, including chalcopyrite, pyrite, sphalerite, and bornite, are also common.

Three types of enclaves also occur in these rocks: pyroxene-rich, amphibole-rich, and amphibole gabbro enclaves. The pyroxene- and amphibole-rich enclaves are coarser grained than the host rocks, but the minerals in the enclaves and host rock have the same compo-sitions. The amphibole gabbro enclaves are medium grained and have typical allotriomor-phic and hypidiomorphic textures, suggesting that they may have formed by mixing of mafi c and felsic magmas.

(1) Pyroxene-rich enclaves: These mainly occur in the pyroxene monzodiorites. They form black, irregular clots, 4–7 cm across, composed chiefl y of clinopyroxene (90–95 modal%), with subordinate spinel (2%–3%), amphibole (1%–2%), and accessory biotite, apatite, magnetite, and pyrite. Most of the enclaves have abundant, relatively large (3–5 mm), euhedral to rounded crystals of pyroxene in a matrix of the same

composition. All have sharp contacts with the host rock. We interpret these to be accumula-tions of early-formed pyroxene crystals that solidifi ed before they were dispersed by a new pulse of similar magma.

(2) Amphibole-rich enclaves: These occur in the monzonites and pyroxene monzodiorites. They are black, spherical or ellipsoidal, and 20–30 cm across. They consist chiefl y of amphi-bole (90–95 modal%) accompanied by minor clinopyroxene, biotite, and pyrite. Most of these enclaves have textures and grain sizes similar to those of pyroxene-rich varieties. Likewise, they all have sharp contacts with the host rocks, and they are typically marked by thin reaction rims of very fi ne-grained diopside. In some samples, tabular plagioclase in the host rock is oriented parallel to the enclave boundary. These enclaves are also interpreted as accumulations of amphi-bole dispersed by intrusion of a more mafi c magma as indicated by the pyroxene rims.

(3) Amphibole gabbro enclaves: These mainly occur in the monzonites and quartz monzonites. They are black, spherical clots ranging from 5 to 15 cm in diameter, composed of amphibole (60–70 modal%) with subordinate plagioclase (15%–27%), minor biotite (1%–3%), and traces of pyroxene and apatite. These enclaves have allotriomorphic to hypidiomorphic textures. On the basis of their textures and mineralogies, these enclaves most likely formed by mixing of mafi c and felsic magmas.

ANALYTICAL METHODS

Zircon SHRIMP U-Pb Dating

Four samples, HCJZK1, SYSZK3, FHS2, and YSZ3, each ~2 kg, were collected for zircon separation. The samples were crushed to 60–100 mesh, rinsed, and air-dried. Magnetic minerals were removed with a hand magnet, and the dense minerals were separated with heavy liquids. Zir-con grains were then handpicked under a binoc-ular microscope, mounted in epoxy along with zircon standard R33 (Black et al., 2004), and ground to about half their thickness. The zircon grains were photographed in refl ected light and imaged in cathodoluminescence mode (CL) to determine their internal structures and to select points for analysis. All of the analyses were carried out using the Stanford/U.S. Geological Survey (USGS) SHRIMP-RG (sensitive high-resolution ion microprobe, reverse geometry) facility. Age uncertainties are cited at the 95% confi dence level for the selected populations, and the internal precision for single analyses in tables and fi gures is 1σ. The age calculations were performed using the software Isoplot and Squid (Ludwig, 2001, 2003).

Whole-Rock Chemical Analysis

Thirty-six relatively fresh whole-rock and six enclave samples were selected for complete whole-rock chemical analysis at the Chinese Geological Experiment and Testing Center, Academy of Geological Sciences, Beijing. Major oxides and Sr, Ba, Zn, Rb, Nb, Zr, and Ga were determined by X-ray fl uorescence spec-trometry (XRF) on glass discs using National Standard GB/T 14506-1919. Total iron as Fe2O3 was determined by XRF, and FeO contents were determined by titration. Rare earth ele-ments (REE) and other trace elements, includ-ing Cu, Pb, Th, U, Hf, Ta, Sc, Cs, V, Co, Cr, and Ni, were determined by inductively coupled plasma–mass spectrometry (ICP-MS) with an Agilent 7500a system using National Standard LY/T 1253-1999. The analytical precision for the major oxides is better than 1%, whereas that for most trace elements is 5%.

Mineral Analysis

The compositions of plagioclase, potassium feldspar, amphibole, biotite, and pyroxene were determined on a Superprobe 733 at the Mineral-ogy Laboratory of the China University of Geo-sciences, Beijing, with an acceleration voltage of 15 kV and a beam current of 0.02 mA using natural and synthetic minerals for standards (Tables 3–7). The accuracy of the reported val-ues is 1%–5%, depending on the absolute ele-ment concentrations. Oxygen abundances in the silicate minerals are based upon stoichiometry (Deer et al., 1992).

ANALYTICAL RESULTS

Zircon SHRIMP U-Pb Dating

Each dated sample is described in this sec-tion, and the analytical results are presented in Table 1.

Sample HCJZK1Sample HCJZK1 is from a drill core (hole

ZK1) of the Huchengjian gabbro-diorite of the high-K, calc-alkaline series. The rock is dark gray in color and is characterized by abundant pyroxene and plagioclase phenocrysts of simi-lar size. The matrix has a diabasic texture and consists of tabular plagioclase with fi ne-grained interstitial pyroxene and magnetite (see Table 2 for a chemical analysis of this rock).

Zircon grains from this sample are prismatic, with length:width ratios generally between 1:1 and 2:1. CL images are uniformly gray with no evidence of zoning (Fig. 2A). Their U contents range from 524 to 1545 ppm, and Th ranges from 661 to 2752 ppm, yielding Th/U ratios of 1.3–2.7, indicating an igneous origin (Table 1).

Wu et al.


TAB

LE 1

. ZIR

CO

N S

EN

SIT

IVE

HIG

H-R

ES

OLU

TIO

N IO

N M

ICR

OP

RO

BE

(S

HR

IMP

) U

-Pb

ISO

TO

PIC

DA

TA F

OR

INT

RU

SIV

E R

OC

KS

OF

TO

NG

LIN

G, A

NH

UI P

RO

VIN

CE

, CH

INA

Spo

t nam

e

206 P

b C(%

)U

(ppm

)T

h(p

pm)

232 T

h/23

8 U

206 P

b R(p

pm)

Dis

c.(%

)To

tal 2

38U

/206

Pb

% e

rrTo

tal 2

07P

b/20

6 Pb

% e

rr20

6 Pb/

238 U

% e

rr20

7 Pb/

206 U

% e

rr

206 P

b/23

8 U a

ge

(Ma)

1σ e

rrH

CJZ

K1-

10.

2378

314

011.

8514

.7−2

545

.65

0.5

0.05

001.

90.

0219

0.5

0.04

812.

614

01

HC

JZK

1-2

0.03

812

1055

1.34

15.5

−50

45.0

00.

50.

0486

1.8

0.02

220.

50.

0474

2.2

142

1H

CJZ

K1-

30.

0110

5227

052.

6620

.2−6

944

.77

0.5

0.04

881.

60.

0223

0.5

0.04

692.

414

21

HC

JZK

1-4

0.10

1046

1716

1.69

20.4

−20

44.1

10.

40.

0497

1.5

0.02

260.

40.

0483

2.0

144

1H

CJZ

K1-

50.

0115

4527

521.

8430

.5−1

743

.53

0.4

0.04

911.

40.

0230

0.4

0.04

841.

614

61

HC

JZK

1-6

0.15

1207

2151

1.84

23.2

−744

.64

0.5

0.05

011.

50.

0224

0.5

0.04

872.

014

31

HC

JZK

1-7

0.03

1092

1673

1.58

21.1

−34

44.4

70.

40.

0492

1.5

0.02

250.

40.

0479

2.0

143

1H

CJZ

K1-

80.

0753

372

51.

4110

.120

45.1

90.

60.

0494

3.1

0.02

210.

60.

0494

3.1

141

1H

CJZ

K1-

90.

2252

466

11.

309.

9−1

445

.38

0.6

0.05

062.

20.

0220

0.7

0.04

843.

214

01

HC

JZK

1-10

0.01

887

1471

1.71

17.2

−24

44.2

10.

50.

0490

1.8

0.02

260.

50.

0482

2.0

144

1H

CJZ

K1-

110.

0385

112

881.

5616

.6−2

643

.95

0.5

0.04

921.

80.

0227

0.5

0.04

822.

114

51

SY

SZ

K03

-10.

2721

316

30.

794.

16

44.9

81.

00.

0510

3.4

0.02

221.

00.

0490

4.4

141

1S

YS

ZK

03-2

0.13

1086

1118

1.06

20.9

044

.68

0.4

0.04

991.

50.

0224

0.4

0.04

891.

814

31

SY

SZ

K03

-30.

1195

976

70.

8318

.827

43.9

00.

50.

0498

1.7

0.02

280.

50.

0498

1.7

145

1S

YS

ZK

03-4

0.47

503

529

1.09

9.4

−13

45.7

70.

60.

0525

2.2

0.02

170.

70.

0484

4.2

139

1S

YS

ZK

03-5

0.24

955

1705

1.84

18.3

−30

44.7

60.

50.

0508

1.7

0.02

230.

50.

0480

2.8

142

1S

YS

ZK

03-6

0.38

419

740

1.82

7.8

1746

.00

0.7

0.05

182.

50.

0217

0.7

0.04

933.

713

81

SY

SZ

K03

-70.

4328

427

91.

025.

4−9

244

.71

0.9

0.05

232.

90.

0222

0.9

0.04

637.

414

21

SY

SZ

K03

-80.

0165

966

11.

0412

.34

46.0

20.

60.

0489

2.0

0.02

170.

60.

0489

2.0

139

1S

YS

ZK

03-9

0.53

189

133

0.73

3.6

7045

.24

1.0

0.05

313.

50.

0220

1.0

0.05

104.

614

01

SY

SZ

K03

-10

0.24

367

461

1.30

7.2

−58

43.6

20.

80.

0508

2.9

0.02

280.

90.

0472

5.0

146

1S

YS

ZK

03-1

10.

0983

914

161.

7416

.2−8

344

.38

0.5

0.04

821.

80.

0225

0.5

0.04

652.

514

41

FH

S2-

10.

8330

479

0.27

22.6

4211

.54

0.5

0.06

481.

30.

0866

0.5

0.06

451.

453

13

FH

S2-

20.

0751

842

90.

8510

.0−1

5144

.48

0.6

0.04

952.

40.

0224

0.7

0.04

474.

614

31

FH

S2-

30.

6422

020

10.

9421

.519

8.78

0.6

0.06

771.

30.

1137

0.6

0.06

651.

669

14

FH

S2-

40.

2547

342

20.

929.

065

45.1

40.

70.

0508

2.3

0.02

220.

70.

0508

2.3

141

1F

HS

2-5

0.66

225

204

0.94

4.3

−20

45.2

41.

00.

0541

3.3

0.02

191.

00.

0483

7.0

140

1F

HS

2-6

0.22

540

361

0.69

10.6

−91

43.9

80.

60.

0507

2.1

0.02

260.

60.

0463

4.3

145

1F

HS

2-7

0.07

573

481

0.87

10.9

−75

45.0

50.

60.

0483

2.1

0.02

220.

60.

0467

2.7

142

1F

HS

2-8

0.05

515

452

0.91

9.9

−98

44.5

10.

60.

0493

2.2

0.02

240.

70.

0461

5.1

143

1F

HS

2-9

0.39

346

255

0.76

6.6

1144

.81

0.8

0.05

192.

70.

0222

0.8

0.04

924.

814

21

FH

S2-

100.

5823

111

50.

524.

4−2

744

.70

1.0

0.05

353.

30.

0222

1.0

0.04

816.

814

21

FH

S2-

111.

5223

311

00.

497.

513

426

.55

0.8

0.06

302.

40.

0375

0.8

0.05

874.

523

52

YS

Z3-

10.

3035

729

0.08

6.9

−134

44.2

50.

70.

0513

2.6

0.02

240.

80.

0451

6.0

144

1Y

SZ

3-2

0.79

242

240.

104.

8−9

143

.42

0.9

0.05

523.

10.

0228

1.0

0.04

638.

314

61

YS

Z3-

30.

1125

026

0.11

5.0

−50

43.1

11.

10.

0499

3.2

0.02

311.

10.

0475

4.2

148

2Y

SZ

3-4

0.39

294

180.

065.

8−4

843

.68

0.8

0.05

212.

90.

0228

0.9

0.04

754.

914

51

YS

Z3-

51.

3826

077

0.31

99.0

42.

250.

50.

1617

0.4

0.44

340.

50.

1615

0.4

2330

12*

YS

Z3-

61.

2133

136

0.11

7.0

4940

.85

0.8

0.05

082.

90.

0245

0.8

0.05

082.

915

61

YS

Z3-

73.

3818

293

0.53

62.9

132.

480.

60.

1614

0.7

0.40

280.

60.

1612

0.7

2104

13*

YS

Z3-

80.

1833

623

0.07

6.7

842

.78

0.8

0.05

052.

80.

0233

0.8

0.04

933.

314

91

YS

Z3-

90.

4230

828

0.09

6.1

−65

43.2

40.

80.

0524

2.9

0.02

300.

90.

0470

6.5

147

1Y

SZ

3-10

0.24

357

370.

117.

0−7

443

.82

0.8

0.05

092.

70.

0227

0.8

0.04

684.

914

51

YS

Z3-

110.

2938

645

0.12

7.6

7243

.33

0.7

0.05

132.

60.

0231

0.7

0.05

132.

614

71

Not

e:20

6 Pb C

and

206

Pb R

are

com

mon

and

rad

ioge

nic

port

ions

, res

pect

ivel

y.*2

06P

b/20

7 Pb

age.



TAB

LE 2

. WH

OLE

-RO

CK

GE

OC

HE

MIC

AL

AN

ALY

SE

S O

F IN

TR

US

IVE

RO

CK

S A

ND

EN

CLA

VE

S O

F T

HE

TO

NG

LIN

G D

IST

RIC

T

Hig

h-K

, cal

c-al

kalin

e se

ries

Sam

ples

HC

JZK

1S

ML3

MJ1

JGS

2JG

S9

DT

S2

QS

J1D

GS

1JT

4D

BZ

3D

BZ

1T

EB

D1

TE

BD

2T

GS

1R

ocks

GB

DG

BD

QM

DP

QM

DQ

MD

QM

DQ

MD

QM

DQ

MD

QM

DQ

MD

QM

DQ

MD

QM

DS

iO2

52.6

454

.53

54.3

960

.21

61.8

863

.66

59.0

160

.86

60.1

059

.95

59.1

560

.29

61.7

262

.62

TiO

21.

150.

900.

820.

580.

550.

570.

720.

770.

640.

750.

750.

650.

670.

56A

l 2O3

17.3

217

.70

15.5

316

.11

16.2

815

.69

16.4

915

.75

16.1

516

.26

16.5

016

.44

16.5

216

.82

Fe 2

O3

3.59

2.72

3.81

1.50

2.32

1.82

2.54

2.16

3.13

2.74

2.23

0.72

2.07

1.32

FeO

5.36

5.73

2.48

2.50

2.62

4.07

3.12

3.44

2.84

2.75

2.19

3.46

3.83

1.95

MnO

0.18

0.18

0.12

0.07

0.07

0.12

0.11

0.12

0.06

0.06

0.06

0.13

0.13

0.07

MgO

3.45

3.06

2.09

1.29

1.36

1.43

2.40

2.12

1.34

2.69

2.53

1.73

1.77

1.47

CaO

8.09

6.72

6.75

5.58

4.63

4.06

5.69

5.81

4.92

6.42

6.36

7.66

5.15

5.86

Na 2

O3.

673.

773.

284.

074.

254.

034.

184.

384.

245.

005.

483.

964.

134.

97K

2O

2.17

2.18

2.80

3.39

3.23

3.01

3.01

2.82

2.99

2.70

1.96

3.38

2.79

2.94

P2O

50.

410.

390.

370.

240.

240.

230.

450.

330.

250.

310.

280.

290.

300.

27LO

I0.

571.

063.

231.

540.

980.

761.

840.

691.

290.

851.

130.

840.

680.

48S

0.12

0.09

0.01

0.10

0.02

0.21

0.67

0.16

0.52

0.27

0.27

0.02

0.07

0.01

CO

20.

220.

384.

992.

291.

020.

550.

560.

341.

080.

500.

900.

560.

200.

14To

tal

98.9

499

.41

100.

6799

.47

99.4

510

0.21

100.

7999

.75

99.5

510

1.25

99.7

910

0.13

100.

0399

.48

ALK

6.0

6.1

6.6

7.8

7.7

7.1

7.4

7.3

7.5

7.7

7.6

7.4

7.0

8.0

Na 2

O/K

2O

1.7

1.7

1.2

1.2

1.3

1.3

1.4

1.6

1.4

1.9

2.8

1.2

1.5

1.7

Fe*

0.71

0.72

0.74

0.74

0.77

0.79

0.69

0.71

0.81

0.66

0.62

0.69

0.76

0.68

Fe#

0.61

0.65

0.54

0.66

0.66

0.74

0.57

0.62

0.68

0.51

0.46

0.67

0.68

0.57

MA

LI–2

.26

–0.7

9–0

.72

1.97

2.93

3.02

1.54

1.42

2.39

1.28

1.11

−0.3

21.

792.

07A

SI

0.77

0.87

0.77

0.8

0.87

0.92

0.83

0.77

0.86

0.72

0.74

0.69

0.88

0.78

AI

0.14

0.14

0.14

0.13

0.13

0.12

0.13

0.12

0.13

0.11

0.1

0.13

0.13

0.12

An

43.9

43.9

41.1

31.3

30.5

31.7

3328

.831

.124

.824

33.8

34.4

26.2

Cr

48.6

38.3

2064

.162

.198

61.2

67.4

53.8

86.7

45.7

129.

171

.236

.9N

i12

.610

.411

.711

.310

.310

.913

.210

.38.

813

.911

.010

.910

.913

.4V

191

160

124

7068

6658

8682

112

9073

7859

Co

23.8

2115

.99.

99.

512

.311

.415

.310

.210

9.4

9.3

137.

8R

b66

6795

8786

8778

6295

4131

9270

74S

r70

372

356

689

390

276

311

9898

175

778

075

283

677

810

99Y

26.4

18.4

18.3

12.5

12.9

14.5

17.8

19.8

20.5

16.9

17.8

19.7

1913

.8Z

r21

215

673

192

132

245

262

171

178

226

256

186

181

184

Nb

19.2

13.3

17.7

15.9

16.3

16.9

15.9

15.5

15.8

14.7

15.5

17.1

16.9

16B

a63

965

160

891

411

3110

3692

892

388

110

4578

890

191

410

45H

f5.

213.

54.

124.

125.

175.

035.

284.

843.

784.

824.

165.

66.

15.

6Ta

0.92

0.36

0.68

0.71

0.79

1.05

0.97

0.86

0.67

0.91

0.85

0.77

0.97

0.72

(con

tinue

d)

Wu et al.


TAB

LE 2

. WH

OLE

-RO

CK

GE

OC

HE

MIC

AL

AN

ALY

SE

S O

F IN

TR

US

IVE

RO

CK

S A

ND

EN

CLA

VE

S O

F T

HE

TO

NG

LIN

G D

IST

RIC

T (c

ontin

ued

)

Hig

h-K

, cal

c-al

kalin

e se

ries

Sam

ples

HC

JZK

1S

ML3

MJ1

JGS

2JG

S9

DT

S2

QS

J1D

GS

1JT

4D

BZ

3D

BZ

1T

EB

D1

TE

BD

2T

GS

1R

ocks

GB

DG

BD

QM

DP

QM

DQ

MD

QM

DQ

MD

QM

DQ

MD

QM

DQ

MD

QM

DQ

MD

QM

DT

h6.

607.

5612

.06

9.73

10.1

711

.14

9.44

8.72

8.50

9.41

10.2

211

.66

9.82

8.93

U1.

322.

262.

102.

302.

702.

022.

832.

482.

402.

352.

872.

602.

601.

35C

u75

4128

7363

3690

122

221

43

1512

240

Zn

131

115

8644

5595

6876

6233

4087

9457

Pb

52.2

53.5

2421

.114

.819

34.3

21.8

41.5

11.6

16.6

27.1

25.3

10.8

Sc

0.28

12.2

39

5.23

5.14

5.89

5.36

8.34

6.12

9.63

9.2

7.35

7.66

5.56

Ag

0.2

0.29

0.1

0.1

0.1

0.1

0.2

0.2

0.3

0.2

0.1

0.3

0.1

0.3

As

33.2

10.3

2.8

3.6

24.

35.

67.

827

.82.

72.

94.

63.

32.

5B

i1.

60.

30.

20.

30.

20.

80.

40.

91.

70.

80.

70.

90.

30.

2S

b0.

200.

710.

240.

300.

300.

520.

380.

840.

210.

800.

740.

740.

420.

20G

a28

.417

18.6

1919

.622

.618

.216

.720

.517

15.7

19.2

18.4

22.2

Li31

.720

.825

.49.

510

.716

.89.

113

.68.

79.

79.

213

.816

.613

Be

1.9

1.94

2.51

2.15

2.18

2.13

2.26

2.18

1.9

1.88

1.96

2.39

2.19

2.28

Mo

2.4

1.6

1.0

1.4

1.2

2.5

1.6

1.2

2.2

0.8

1.0

2.5

1.0

1.5

La37

.928

.645

.335

.134

.734

.438

.439

.439

.734

.537

.841

.040

.739

.1C

e73

.055

.785

.365

.065

.564

.779

.278

.372

.265

.475

.180

.276

.876

.2P

r9.

86.

69.

67.

37.

47.

39.

38.

68.

97.

58.

99.

18.

78.

8N

d34

.70

25.2

033

.60

25.7

025

.90

26.4

031

.40

33.4

030

.70

27.2

031

.90

31.9

031

.10

31.4

0S

m7.

935.

256.

484.

865.

005.

026.

246.

336.

455.

446.

216.

346.

066.

05E

u1.

861.

441.

581.

251.

271.

322.

111.

691.

431.

451.

581.

621.

531.

54G

d5.

933.

974.

503.

333.

413.

428.

245.

254.

483.

934.

314.

614.

384.

04T

b1.

150.

630.

660.

530.

610.

630.

990.

690.

840.

610.

740.

720.

760.

67D

y5.

333.

713.

682.

612.

642.

964.

563.

803.

993.

413.

653.

953.

832.

92H

o1.

070.

670.

690.

440.

470.

530.

940.

700.

800.

610.

680.

750.

680.

51E

r3.

141.

831.

811.

101.

111.

332.

451.

952.

311.

711.

791.

842.

051.

15T

m0.

480.

290.

370.

260.

210.

290.

310.

270.

390.

360.

390.

340.

230.

27Y

b2.

301.

802.

672.

101.

861.

502.

091.

910.

811.

751.

691.

160.

721.

71Lu

0.35

0.28

0.41

0.32

0.30

0.25

0.27

0.28

0.12

0.27

0.27

0.19

0.11

0.27

Σ RE

E18

513

619

715

015

015

018

718

317

315

417

518

417

817

5E

u*/E

u0.

800.

940.

860.

910.

900.

930.

910.

880.

780.

920.

890.

880.

870.

91R

b/S

r0.

090.

090.

170.

100.

090.

110.

060.

060.

130.

050.

040.

110.

090.

07B

a/R

b9.

89.

76.

410

.513

.212

.011

.914

.89.

325

.525

.49.

813

.114

.2S

r/Y

26.6

39.3

30.9

71.4

69.9

52.6

67.3

49.5

36.9

46.2

42.2

42.4

40.9

79.6

(con

tinue

d)



TAB

LE 2

. WH

OLE

-RO

CK

GE

OC

HE

MIC

AL

AN

ALY

SE

S O

F IN

TR

US

IVE

RO

CK

S A

ND

EN

CLA

VE

S O

F T

HE

TO

NG

LIN

G D

IST

RIC

T (c

ontin

ued

)

Hig

h-K

, cal

c-al

kalin

e se

ries

(HA

C)

Enc

lave

s (H

AC

)

Sam

ples

TG

S2

FH

S2

FH

S1

NH

C1

ST

J3S

TJ5

QT

Y1

QT

Y2

SJD

LC1

XQ

T4

YS

Z3

TG

S3

FH

SB

4T

EB

DB

6R

ocks

QM

DG

DG

DG

DG

DG

DG

DP

GD

PG

DP

GD

PG

DP

GV

MD

EM

QM

ES

iO2

62.7

463

.12

63.5

862

.85

64.2

364

.33

61.1

661

.72

63.7

763

.59

58.1

975

.37

59.5

854

.50

TiO

20.

550.

560.

570.

600.

500.

480.

520.

420.

490.

320.

470.

110.

930.

90A

l 2O3

16.7

315

.48

16.2

616

.13

16.3

816

.40

16.3

416

.08

15.5

314

.49

15.1

412

.69

16.3

515

.09

Fe 2

O3

2.52

2.12

2.12

1.72

1.87

1.53

1.25

0.55

2.23

1.05

2.11

0.51

4.13

3.19

FeO

2.42

3.06

2.90

1.55

2.58

2.74

2.68

2.09

2.94

2.18

2.76

0.97

3.29

5.14

MnO

0.11

0.08

0.09

0.07

0.08

0.07

0.03

0.05

0.07

0.10

0.11

0.04

0.09

0.20

MgO

1.44

1.22

1.46

1.44

1.22

1.23

1.06

0.73

1.33

0.89

1.38

0.16

2.65

4.69

CaO

4.72

3.94

4.18

5.03

3.60

3.94

3.96

4.48

4.14

4.36

6.46

1.64

3.44

7.42

Na 2

O4.

813.

934.

754.

685.

065.

094.

565.

124.

111.

411.

463.

873.

853.

82K

2O

2.72

3.23

3.01

3.33

2.53

2.70

2.78

3.41

3.10

3.88

2.71

3.96

2.51

2.33

P2O

50.

280.

250.

250.

230.

210.

210.

230.

180.

220.

170.

220.

030.

430.

24LO

I0.

581.

310.

622.

200.

750.

662.

862.

160.

923.

103.

520.

241.

770.

76S

0.01

0.16

0.02

0.34

0.09

0.36

0.65

0.21

0.33

0.33

0.03

0.04

0.96

0.82

CO

20.

271.

810.

360.

260.

950.

952.

203.

080.

824.

275.

690.

160.

100.

57To

tal

99.9

010

0.27

100.

1710

0.43

100.

0510

0.69

100.

2810

0.28

100.

0010

0.14

100.

2599

.79

100.

0899

.67

ALK

7.6

7.4

7.8

8.2

7.7

7.9

7.8

9.0

7.4

5.7

4.6

7.9

6.5

6.3

Na 2

O/K

2O

1.8

1.2

1.6

1.4

2.0

1.9

1.6

1.5

1.3

0.4

0.5

1.0

1.5

1.6

Fe*

0.77

0.8

0.76

0.68

0.77

0.76

0.78

0.77

0.79

0.77

0.77

0.9

0.73

0.62

Fe#

0.63

0.71

0.67

0.52

0.68

0.69

0.72

0.74

0.69

0.71

0.67

0.86

0.55

0.52

MA

LI2.

843.

323.

613.

054.

063.

93.

574.

273.

131.

01−2

.52

6.23

3−1

.3A

SI

0.88

0.92

0.88

0.8

0.94

0.9

0.94

0.8

0.89

1.02

0.9

0.93

1.11

0.69

AI

0.12

0.13

0.12

0.12

0.11

0.11

0.12

0.12

0.12

0.17

0.17

0.1

0.13

0.11

An

28.3

31.2

26.1

2525

.33

24.4

529

.21

2029

.83

63.2

667

.52

17.4

21.6

747

.92

Cr

57.3

122.

258

79.3

129.

410

4.1

74.5

51.6

74.3

23.1

19.2

25.2

16.2

83.9

Ni

11.1

9.9

10.0

12.6

13.0

12.0

14.8

12.1

10.1

5.8

6.9

9.1

6.2

17.9

V61

6672

5759

5465

5463

3554

1713

220

7C

o11

9.4

8.4

11.3

9.8

10.7

10.4

1310

.66.

38.

76.

615

.124

Rb

7213

411

475

7270

7885

112

167

105

6511

576

Sr

1040

699

809

961

1188

1019

705

703

697

204

448

292

690

593

Y15

.516

.117

.413

.211

.911

.88.

28.

614

.713

16.5

7.2

27.6

13.7

Zr

189

187

187

196

175

172

122

118

162

161

4312

113

618

4N

b16

.917

.517

.713

18.8

17.9

16.1

15.3

16.8

18.2

13.5

12.6

145

Ba

1098

819

898

941

1056

951

681

803

898

726

489

695

797

829

Hf

5.9

6.13

6.78

3.98

54.

54.

215.

274.

75.

15.

43.

9n.

d.n.

d.Ta

0.85

0.88

1.26

0.82

0.67

0.56

0.75

0.81

0.76

0.82

0.61

0.67

n.d.

n.d.

(con

tinue

d)

Wu et al.


TAB

LE 2

. WH

OLE

-RO

CK

GE

OC

HE

MIC

AL

AN

ALY

SE

S O

F IN

TR

US

IVE

RO

CK

S A

ND

EN

CLA

VE

S O

F T

HE

TO

NG

LIN

G D

IST

RIC

T (c

ontin

ued

)

Hig

h-K

, cal

c-al

kalin

e se

ries

(HA

C)

Enc

lave

s (H

AC

)

Sam

ples

TG

S2

FH

S2

FH

S1

NH

C1

ST

J3S

TJ5

QT

Y1

QT

Y2

SJD

LC1

XQ

T4

YS

Z3

TG

S3

FH

SB

4T

EB

DB

6R

ocks

QM

DG

DG

DG

DG

DG

DG

DP

GD

PG

DP

GD

PG

DP

GV

MD

EM

QM

ET

h9.

3711

.35

9.95

7.81

11.6

911

.42

9.59

10.2

611

.69

16.4

48.

4116

.08

15.0

09.

00U

1.12

2.67

2.25

2.57

2.15

2.19

2.60

2.80

2.56

1.38

1.50

2.42

n.d.

n.d.

Cu

1327

514

038

2568

9344

85

712

760

420

2Z

n91

4258

6771

4317

764

3859

7398

7114

8P

b20

.819

.718

.131

.217

7.3

16.3

31.1

24.1

15.7

19.4

60.8

109

12.5

12.7

Sc

5.4

6.13

6.4

4.21

4.7

4.58

5.65

4.86

6.12

2.21

6.41

1.51

n.d.

n.d.

Ag

0.1

0.5

0.3

0.1

0.09

0.1

0.4

0.19

0.12

0.12

0.13

0.23

0.63

0.56

As

1.4

3.3

3.6

2.5

2.9

12.7

516.

24.

42.

811

.747

.81.

85.

2B

i0.

27.

30.

40.

40.

30.

41.

41.

10.

40.

30.

13.

10.

30.

1S

b0.

240.

460.

401.

381.

300.

301.

200.

470.

530.

430.

5410

.50

0.40

0.61

Ga

24.4

20.9

20.9

21.1

23.2

2220

.822

.519

.718

.517

25.2

19.7

15.9

Li24

.910

.98.

415

.216

.714

.818

.515

.810

.19.

826

10.9

20.5

37.2

Be

2.39

2.39

2.46

2.23

2.43

2.27

2.14

1.98

2.2

2.58

1.84

3.07

1.5

0.96

Mo

0.9

3.3

2.1

1.2

1.4

2.2

3.1

1.3

1.6

1.8

0.6

1.2

2.1

3.6

La40

.538

.239

.937

.341

.443

.332

.429

.533

.836

.426

.317

.057

.026

.3C

e78

.871

.375

.768

.280

.984

.562

.258

.264

.262

.651

.727

.811

3.9

47.2

Pr

9.1

8.2

8.6

7.4

9.3

9.6

7.0

6.6

7.4

6.6

6.2

3.0

12.8

5.2

Nd

32.7

028

.90

30.7

025

.90

32.7

033

.60

24.6

023

.20

25.9

021

.10

23.0

09.

5046

.40

20.7

0S

m6.

375.

445.

844.

445.

905.

984.

504.

324.

943.

754.

531.

908.

204.

30E

u1.

621.

341.

391.

391.

381.

411.

091.

021.

200.

901.

250.

541.

601.

20G

d4.

313.

653.

874.

203.

513.

552.

782.

713.

342.

433.

361.

417.

604.

90T

b0.

680.

550.

630.

490.

490.

490.

470.

470.

600.

400.

520.

211.

200.

60D

y3.

283.

223.

502.

532.

572.

531.

811.

862.

932.

373.

221.

216.

003.

50H

o0.

590.

580.

630.

490.

410.

400.

300.

310.

530.

470.

580.

241.

200.

60E

r1.

371.

541.

671.

351.

060.

990.

620.

691.

381.

351.

650.

672.

901.

40T

m0.

210.

310.

330.

190.

130.

110.

150.

110.

190.

320.

290.

110.

480.

26Y

b1.

211.

401.

611.

151.

451.

001.

161.

301.

301.

741.

951.

342.

701.

20Lu

0.20

0.22

0.26

0.14

0.23

0.16

0.25

0.21

0.21

0.27

0.30

0.22

0.40

0.20

ΣRE

E18

116

517

515

518

118

813

913

014

814

112

565

262

118

Eu*

/Eu

0.90

0.88

0.85

0.98

0.86

0.87

0.88

0.86

0.86

0.86

0.95

0.98

0.61

0.80

Rb/

Sr

0.07

0.19

0.14

0.08

0.06

0.07

0.11

0.12

0.16

0.82

0.23

0.22

0.17

0.13

Ba/

Rb

15.3

6.1

7.9

12.5

14.7

13.7

8.8

9.5

8.0

4.3

4.7

10.7

6.9

10.9

Sr/

Y67

.143

.446

.572

.899

.886

.486

.081

.747

.415

.727

.240

.625

.043

.3(c

ontin

ued

)



TAB

LE 2

. WH

OLE

-RO

CK

GE

OC

HE

MIC

AL

AN

ALY

SE

S O

F IN

TR

US

IVE

RO

CK

S A

ND

EN

CLA

VE

S O

F T

HE

TO

NG

LIN

G D

IST

RIC

T (c

ontin

ued

)

)O

HS(

sevalcnE

)O

HS(

seirescitinohso h

S)

AC

H(s ev alcn

E

Sam

ples

FH

SB

7JG

6X

QT

3C

S1

DS

8D

S4

XS

1X

S5

SJC

1S

A1

SM

LM

BS

6B

MS

2C

SB

1R

ocks

MR

EP

MD

PM

DM

zQ

MQ

MQ

MQ

MD

QM

QM

QM

PC

EH

CE

HG

ES

iO2

42.0

750

.81

55.5

257

.32

56.3

261

.69

58.8

561

.58

59.3

557

.46

62.3

041

.96

34.8

240

.94

TiO

21.

881.

210.

871.

050.

990.

650.

710.

680.

790.

700.

480.

402.

452.

45A

l 2O3

20.4

417

.16

16.6

016

.67

16.4

115

.59

16.1

615

.83

15.6

815

.99

16.0

212

.13

13.1

411

.98

Fe 2

O3

5.91

2.71

3.84

0.97

2.96

0.82

1.97

1.36

2.25

3.42

1.00

2.79

7.15

9.20

FeO

9.47

5.55

3.32

4.54

5.07

3.98

2.47

2.93

3.91

3.02

2.80

3.97

9.16

8.34

MnO

0.24

0.14

0.18

0.08

0.16

0.08

0.10

0.09

0.11

0.12

0.10

0.28

0.18

0.20

MgO

6.04

3.26

1.91

1.73

2.55

2.09

1.89

2.24

2.49

1.05

0.99

11.4

78.

576.

86C

aO3.

909.

636.

896.

275.

843.

906.

474.

655.

666.

002.

2118

.41

13.4

810

.88

Na 2

O2.

593.

734.

494.

704.

413.

904.

353.

764.

274.

460.

971.

881.

912.

51K

2O

5.06

3.10

3.11

3.36

2.93

5.10

4.75

4.72

3.77

3.19

10.1

21.

160.

952.

05P

2O

50.

160.

560.

450.

350.

340.

210.

310.

220.

310.

290.

191.

851.

721.

90LO

I1.

310.

761.

100.

501.

011.

060.

701.

130.

991.

321.

692.

682.

870.

84S

0.03

1.30

0.04

0.84

0.83

1.02

0.86

0.45

0.20

0.21

1.08

0.37

0.52

1.09

CO

20.

140.

341.

512.

550.

050.

230.

200.

500.

382.

620.

800.

492.

550.

84To

tal

99.2

410

0.26

99.8

310

0.93

99.8

710

0.32

99.7

910

0.14

100.

1699

.85

100.

7599

.84

99.4

710

0.08

ALK

7.8

7.0

7.8

8.3

7.5

9.2

9.3

8.7

8.2

8.0

11.4

1.7

3.1

4.7

Na 2

O/K

2O

0.5

1.2

1.4

1.4

1.5

0.8

0.9

0.8

1.1

1.4

0.1

0.7

2.0

1.2

Fe*

0.7

0.7

0.78

0.75

0.75

0.68

0.69

0.64

0.7

0.85

0.78

0.36

0.64

0.71

Fe#

0.61

0.63

0.63

0.72

0.67

0.66

0.57

0.57

0.61

0.74

0.74

0.26

0.52

0.55

MA

LI3.

84−2

.86

0.73

1.84

1.53

5.2

2.68

3.91

2.41

1.72

9.14

−17.

3−1

1.4

−6.4

9A

SI

1.23

0.65

0.73

0.75

0.8

0.83

0.68

0.81

0.75

0.75

0.98

0.36

0.49

0.5

AI

0.22

0.14

0.13

0.13

0.12

0.15

0.14

0.15

0.13

0.12

0.26

0.12

0.12

0.1

An

40.8

339

.929

.626

.730

.523

.222

.328

25.7

27.3

53.6

7268

.349

.03

Cr

180.

724

.531

.818

.493

.820

9.6

115.

116

3.2

46.6

55.1

47.5

24.4

22.2

18.2

Ni

79.5

14.4

9.9

12.5

13.4

14.3

11.4

12.4

13.2

11.9

7.1

9.0

9.2

8.5

V30

717

812

812

814

373

8582

100

106

5262

5753

5C

o37

.529

.413

.69.

821

.214

.711

.214

.516

.610

.18.

88.

212

.646

.7R

b32

193

107

6087

162

104

130

8710

22.

7950

6277

Sr

669

1116

1109

952

720

665

940

719

1031

903

638

300

773

682

Y25

.924

.923

.320

.918

.513

.817

.615

.121

2016

.97.

620

.628

.5Z

r20

226

919

420

115

915

919

017

217

820

118

224

6977

Nb

2321

.118

.615

.717

.917

.118

.917

17.5

1816

.96

86

Ba

1684

752

944

788

789

966

944

972

916

943

1055

280

322

373

Hf

n.d.

6.23

5.7

5.19

4.71

5.74

5.2

5.6

4.2

4.9

5.5

n.d.

n.d.

n.d.

Tan.

d.0.

940.

720.

880.

951.

210.

750.

830.

540.

860.

86n.

d.n.

d.n.

d.(c

ontin

ued

)

Wu et al.


TAB

LE 2

. WH

OLE

-RO

CK

GE

OC

HE

MIC

AL

AN

ALY

SE

S O

F IN

TR

US

IVE

RO

CK

S A

ND

EN

CLA

VE

S O

F T

HE

TO

NG

LIN

G D

IST

RIC

T (c

ontin

ued

)

)O

HS(

sevalcnE

)O

HS(

seirescitinohs oh

S)

AC

H(sevalcn

E

Sam

ples

FH

SB

7JG

6X

QT

3C

S1

DS

8D

S4

XS

1X

S5

SJC

1S

A1

SM

LM

BS

6B

MS

2C

SB

1R

ocks

MR

EP

MD

PM

DM

zQ

MQ

MQ

MQ

MD

QM

QM

QM

PC

EH

CE

HG

ET

h35

.00

11.0

111

.14

9.20

11.6

311

.54

10.7

410

.50

11.2

29.

409.

666.

007.

0011

.00

Un.

d.3.

362.

182.

622.

542.

962.

322.

162.

422.

052.

21n.

d.n.

d.n.

d.C

u83

356

1412

697

192

7314

195

137

2891

133

289

Zn

335

7415

187

9653

5857

101

9810

930

321

212

1P

b12

.226

.536

.632

.823

29.9

22.3

23.3

47.3

61.5

93.6

13.4

11.2

12.8

.d.n.d.n

.d.n87.5

53.0185.7

30.753.6

57.982.8

33. 799.0 1

. d.nc

S Ag

0.11

0.42

0.15

0.7

0.3

0.4

0.7

10.

20.

30.

50.

160.

320.

27A

s0.

54.

92.

54.

49.

87.

77.

37.

220

42.7

18.5

3.9

3.2

19.9

Bi

0.1

0.6

0.4

0.5

1.6

1.0

4.2

4.5

0.3

9.0

0.8

0.2

0.2

0.3

Sb

0.05

0.84

0.30

0.72

1.20

0.90

1.50

2.60

0.85

2.00

1.30

0.78

0.62

0.78

Ga

27.9

18.9

22.6

19.6

18.4

23.8

21.3

23.5

18.2

24.7

28.3

10.4

12.2

15.1

Li76

.334

18.6

22.5

16.3

12.7

13.9

15.2

14.8

11.3

21.8

160

132

55.2

Be

3.37

2.5

2.61

2.21

2.26

2.2

2.21

2.19

2.08

2.3

1.6

1.42

1.22

3.65

Mo

3.5

1.6

2.6

2.1

1.9

2.8

2.7

15.9

3.2

6.5

1.0

3.9

3.2

3.8

La10

2.6

51.0

47.8

42.4

38.8

35.8

36.1

35.2

39.7

48.8

36.1

12.6

25.8

36.4

Ce

194.

010

0.9

92.0

72.5

72.8

67.2

71.9

67.5

74.0

88.8

70.5

28.6

58.4

74.5

Pr

18.7

11.9

10.9

11.4

8.3

7.6

8.3

7.8

8.7

11.0

8.1

3.3

8.9

9.7

Nd

75.3

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39.7

040

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30.8

027

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29.9

028

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31.4

036

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28.7

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37.6

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Sm

13.3

08.

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596.

965.

995.

105.

805.

546.

277.

295.

342.

508.

008.

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502.

261.

951.

761.

621.

221.

481.

411.

551.

601.

390.

602.

402.

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6.32

5.28

4.76

4.35

3.46

4.06

3.81

4.52

4.73

3.69

1.90

6.70

10.5

0T

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301.

120.

820.

750.

630.

560.

620.

610.

700.

780.

630.

301.

101.

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405.

174.

664.

183.

872.

903.

573.

164.

193.

943.

351.

504.

707.

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930.

841.

140.

650.

500.

640.

550.

770.

780.

630.

300.

901.

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702.

252.

322.

181.

791.

361.

651.

381.

992.

081.

610.

802.

202.

90T

m0.

310.

250.

360.

310.

270.

220.

320.

160.

310.

360.

250.

120.

350.

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102.

301.

861.

932.

351.

451.

710.

661.

761.

791.

200.

701.

702.

30Lu

0.40

0.35

0.30

0.31

0.37

0.23

0.28

0.11

0.28

0.25

0.19

0.10

0.30

0.30

Σ RE

E43

023

721

619

117

215

516

615

617

620

816

267

159

199

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/Eu

0.38

0.89

0.90

0.89

0.94

0.85

0.89

0.90

0.86

0.79

0.92

0.82

0.98

0.70

Rb/

Sr

0.48

0.08

0.10

0.06

0.12

0.24

0.11

0.18

0.08

0.11

0.44

0.17

0.00

0.11

Ba/

Rb

5.2

8.1

8.8

13.2

9.1

6.0

9.1

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10.5

9.2

3.8

5.6

5.2

4.8

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Y25

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.645

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.237

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ote:

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l/(C

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ecul

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hole

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k no

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rare

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lem

ent.

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k na

mes

: GB

D—

gabb

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MD

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mon

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orite

; QM

DP

—po

rphy

ritic

qua

rtz

mon

zodi

orite

; GD

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anod

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DP

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ritic

gra

nodi

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; GV

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anite

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Eleven grains have ages ranging from 140 ± 1 Ma to 146 ± 1 Ma. After excluding grain 5, which has very high Th and U, the remaining 10 analyses yield a weighted average age of 143 ± 1 Ma (n = 10, mean square of weighted deviates [MSWD] = 2.9; Fig. 3A).

Sample SYSZK03Sample SYSZK03 is a core sample of the

Shujiadian pyroxene monzodiorite of the sho-shonitic series taken from hole ZK03. The rock body occurs as a NE-trending stock with an irregular shape. It is hosted in Silurian silt-stone with veinlet and disseminated gold min-eralization. A large garnet skarn with an area of 2500 m2 occurs in the middle of the stock. The monzodiorite is dark gray, has a hypidio-morphic-granular texture, and consists mainly of plagioclase (An45–55) (60–70 modal%) and diopside (10%–15%), with subordinate biotite, potassium feldspar, and quartz (for a chemical analysis of this rock, see Wu et al., 1996).

Zircon grains from this sample are prismatic, with length:width ratios between 1:1 and 2:1, similar to those of the Huchengjian gabbro-diorite. Most of the grains are uniformly gray in their CL images, although a few display oscilla-tory zoning (such as grain 6) or a banded struc-ture (such as grains 7 and 11; Fig. 2B), which is typical of magmatic zircon (Pidgeon et al., 1998). The grains have U contents ranging from 189 to 1086 ppm and Th ranging from 133 to 1705 ppm, giving Th/U ratios of 0.73–1.84, consistent with an igneous origin (Table 1). Eleven analyzed spots from this sample yielded a cluster of U-Pb ages ranging from 138 ± 1 Ma to 146 ± 1 Ma, with a weighted average age of 142 ± 2 Ma (n = 11, MSWD = 4.1) that is regarded as the crystallization age (Fig. 3B).

Sample FHS2Sample FHS2 is from the Fenghuangshan

granodiorite of the high-K, calc-alkaline series, the largest intrusive body in the area. This body forms a stock with an irregular circular outcrop area of ~10 km2. The rock is light colored and consists chiefl y of plagioclase (45–55 modal%), quartz (15%–20%), and alkali feldspar (10%–15%), accompanied by minor amphibole and biotite. An analysis of this rock is given in Table 2.

Zircon grains in this sample are prismatic, with length:width ratios of 2:1–3:1, and they show good oscillatory zoning in CL images (Fig. 2C). The analyzed grains have U contents ranging from 225 to 573 ppm and Th ranging from 79 to 481 ppm, giving Th/U ratios ranging from 0.59 to 1.13, except for grain 1, which has a ratio of 0.27, still within the range of igne-ous zircon (>0.2). Eleven analyzed grains yield

A

B

C

DFigure 2. Cathodoluminescence (CL) images of zircon from the intrusive rocks in the Tongling district.

Wu et al.


206Pb/208U ages ranging from 140 ± 1 Ma to 691 ± 4 Ma. If grains 1, 3, and 11, which con-tain inherited cores (531 ± 3 Ma, 691 ± 4 Ma, and 235 ± 2 Ma, respectively; Fig. 2C), are rejected, the remaining grains yield a weighted average age of 142 ± 1 Ma (n = 8, MSWD = 1.1; Fig. 3C).

Sample YSZ3Sample YSZ3 is from the Yaoshan porphy-

ritic granodiorite of the high-K, calc-alkaline series, which crops out west of the Fenghuang-shan intrusion (Fig. 1B). It forms a sill with an outcrop area of 3 km2 that is connected to the Xingqiao porphyritic granodiorite in the north-east. The rock is characterized by phenocrysts of plagioclase and quartz, ranging up to 2 cm across, which are set in a fi ne-grained, felsic matrix. A chemical analysis of this sample is given in Table 2.

Zircon grains from this sample are elongate, euhedral prisms with length:width ratios of 2:1–4:1. CL images show that the grains have excel-lent oscillatory zoning, indicating an igneous origin (Fig. 2D). Eleven analyzed points on nine

grains have relatively low contents of U and Th (242–386 ppm and 18–93 ppm, respectively), yielding Th/U ratios of 0.06–0.53, which are considerable lower than zircons from the other samples (Table 1). These low ratios are due pri-marily to very low Th contents (18–93 ppm). Grains 5 and 7, which have inherited cores, have the highest Th values and highest Th/U ratios. The inherited cores in these two grains (with three analyses) yielded 207Pb/206Pb ages of 2330 ± 12 Ma and 2104 ± 13 Ma, respectively, and were discarded. The remaining eight ana-lyzed spots on seven grains yielded 206Pb/238U ages ranging from 144 ± 1 Ma to 149 ± 1 Ma, with a weighted average age of 146 ± 1 Ma (n = 8, MSWD = 0.8), which is considered the age of zircon crystallization (Fig. 3D).

The wide range in Th/U ratios for the zircons both within and between individual samples is puzzling. For example, the analyzed zircons from sample SYSZK have Th/U ratios ranging from 0.73 to 1.84, but they all have very simi-lar ages and all appear to be magmatic in form and internal texture. In contrast, all zircons from sample YSZ3 have low U (182–386 ppm) and

very low Th (18–45 ppm), except for two grains with 93 and 77 ppm Th that are clearly xeno-crysts. Except for these obviously xenocrystic grains, the zircons all appear to be magmatic in origin and are believed to date the time of crys-tallization of the various Tongling bodies.

Geochemistry

Intrusive RocksMost of the analyzed intrusive rocks from the

Tongling district are fresh, with loss on ignition (LOI) < 2 wt% (Table 2). Two samples from the calc- alkaline series (XQT4 and YSZ2) have LOI >3 wt% and are depleted in Na2O, indi-cating moderate alteration. All but these two samples have relatively high total alkalis, with enrichment in K2O, placing them in the shosho-nitic fi eld and upper parts of the calc-alkaline fi eld in the SiO2 versus (Na2O + K2O) diagram (Fig. 4) (Middlemost, 1994; Irvine and Baragar, 1971). On the SiO2 versus K2O diagram (Pec-cerillo and Taylor, 1976) (Fig. 5), they plot in the high-K, calc-alkaline and shoshonite fi elds, respectively. Most of the intrusive rocks (>90%)

A

C D

B

Figure 3. Zircon 238U/206Pb-207Pb/206Pb concordia diagrams for the intrusive rocks in Tongling. MSWD—mean square of weighted deviates.



belong to the high-K, calc-alkaline series and range in composition from mafi c to intermedi-ate, with SiO2 contents between 52.6 and 64.3 wt%, and K2O contents between 2 and 4 wt%; one sample of granite has 75.4 wt% SiO2 and 4 wt% K2O (Table 2). Although rocks of the sho-shonitic series have similar SiO2 contents (50.8–65.2 wt%), they have much higher total alkalis (7.4–11.4 wt%), with K2O contents generally between 3 and 5 wt%. One sample (SML2) has 10 wt% K2O with very low Na2O and slightly elevated LOI (Table 2), suggesting some altera-tion. Rocks from both series are mostly mag-nesian, with only a few ferroan samples (Frost et al., 2001; Frost and Frost, 2008). Both series are alkali-calcic to calc-alkaline on the basis of the modifi ed alkali lime index (MALI) (Frost et al., 2001) (Fig. 6). All of the rocks have ASI values (= Al/[Ca – 1.67P + Na + K]) 0

(Table 2), indicating they are metaluminous (Frost et al., 2001).

In the Harker diagrams, TiO2, Al2O3, Fe2O3, FeO, MgO, CaO, and P2O5 all show relatively systematic decreases in concentration with increasing SiO2, as expected for granitoid mag-mas undergoing fractionation (Fig. 7). However, the granite sample (TGS3) with 75.4 wt% SiO2 is completely separated from the other calc-alkaline rocks (Fig. 7), and its origin is unclear. Except for three samples, Na2O contents range between 3.3 and 5.5 wt% and show no system-atic variation with SiO2; in contrast, K2O shows a positive correlation with SiO2 in both the calc-alkaline and shoshonitic series (Table 2; Fig. 7).

The large ion lithophile elements show con-siderable scatter on the Harker diagrams but generally increase with increasing SiO2 (Fig. 8). An increase in Rb with increasing SiO2 in the shoshonitic series, coupled with nearly constant

Ba, results in a rapid decrease in the Ba/Rb ratio for these rocks. Zirconium shows a broad scatter of values in the calc-alkaline rocks but decreases regularly in the shoshonitic series (Fig. 8), whereas Y decreases systematically as SiO2 increases, resulting in generally posi-tive correlations between Sr/Y ratios and SiO2 contents, particularly in the calc-alkaline series. One anomalous geochemical feature of these rocks is their relatively high Cr contents (up to 129 ppm in the calc-alkaline series and 210 ppm in the shoshonitic series; Table 2). Not only do the rocks have high Cr contents, but there is a crude positive correlation between Cr and SiO2 (Fig. 8). This trend is particularly puzzling because the other transition metals (Ni, Co, V, and Sc) all decrease systematically with increas-ing SiO2. It may refl ect injection of more mafi c melts into the magma chamber.

Rocks of the high-K, calc-alkaline series have ΣREE of 65–197 ppm, with most samples in the range of 140–180 ppm, and they show no systematic change with SiO2 (Table 2). Chon-drite-normalized REE patterns of these rocks are quite uniform, with nearly fl at heavy (H) REE segments and signifi cant light (L) REE enrichment (LREE/HREE = 8.4–19.3; aver-age = 12.5). They have negligible to very weak negative Eu anomalies (Eu*/Eu = 0.78–0.98; Figs. 9A–9B). These patterns are similar to those of average upper-crustal rocks (Taylor and McClennan, 1985).

The ΣREE values in the shoshonitic series range from 155 to 237 ppm, i.e., slightly higher on average than in the high-K, calc-alkaline

Figure 4. Diagram of SiO2-(Na2O + K2O) for the rocks in Tongling (after Middlemost, 1994; Irvine and Baragar, 1971); the dashed line represents that the plot fi eld of more than 400 collected analyses of the intrusive rocks in Tongling. Circles—intrusive rocks of the high-K, calc-alkaline series. Squares—intrusive rocks of shoshonitic series.

Figure 5. Diagram of SiO2-K2O for the Tongling rocks (after Peccerillo and Taylor, 1976). Symbols are the same as those in Figure 4. K—potassium.

Figure 6. Diagram of SiO2 vs. modified alkali lime index (MALI) for the Tongling rocks (after Frost et al., 2001; Frost and Frost, 2008). Symbols are the same as those in Figure 4. A—alkaline series, AC—alkali-calcic series, CA—calc-alkaline series, C—calcic series.

Wu et al.


series, and they show a systematic decrease with increasing SiO2, although the range of SiO2 is quite narrow (50.8–62.3 wt%; Table 2). We inter-pret this trend as possibly refl ecting early crystal-lization of titanite, one of the major carriers of REEs in these rocks. Experiments by Prowatke and Klemme (2006) and measured mineral/glass data (Bachmann et al., 2005; Colombini et al., 2011) demonstrate that distribution coeffi cients for the middle REEs in titanite are very high and hence should lead to noticeable depletion in these elements. We calculated middle (M) REE depletion factors (2Gdn/[Lan × Lun]) for the sho-shonitic rocks, which range from 0.64 to 0.23, compatible with some titanite fractionation. Chondrite-normalized REE patterns for the sho-shonitic rocks are indistinguishable from those of the calc-alkaline series, showing the same fl at HREE portion and LREE enrichment (LREE/

HREE = 11.1–13.9; average = 12.3; Fig. 9C). Likewise, they also have very weak negative Eu anomalies (Eu*/Eu = 0.79–0.92; Table 2).

In the primitive mantle–normalized trace-element diagram, rocks of the high-K, calc-alkaline series show strong enrichment in large ion lithophile elements (LILEs; Rb, Ba, Th, K), marked negative anomalies in Nb and Ti, and weak negative anomalies in P and Nd. The negative Nb suggests a subduction component in the source area, as does the enrichment in LILEs. Most samples also show weak enrich-ment in Sr and Zr (Figs. 10A–10B). Rocks of the shoshonitic series generally have trace-element compositions comparable to the calc-alkaline rocks, except for somewhat higher values for some of the transition elements, par-ticularly Cr, V, and Co, and somewhat lower values of Sr and Ba, refl ecting their more mafi c

character. Despite the higher K2O contents of these rocks, their Rb concentrations overlap those of the calc-alkaline series (Table 2). The primitive mantle–normalized trace-element patterns of the two series are very similar (Fig. 10C).

Figure 7. Harker diagrams for the major elements (wt%). Data are from Table 2. Symbols are the same as those in Figure 4.

Figure 8. Harker diagrams for selected trace elements (ppm). Data are from Table 2. Symbols are the same as those in Figure 4.



EnclavesThe various enclaves range widely in chemi-

cal composition because of their different ori-gins. The microdiorite and quartz monzodiorite enclaves in the high-K, calc-alkaline series have

similar major-oxide compositions, generally close to those of their host rocks, but somewhat enriched in FeOt and MgO (Table 2). The mica-rich enclave is characterized by signifi cantly lower SiO2 and Na2O but higher TiO2, Al2O3,

FeOt, MgO, and K2O than the others. The ΣREEs are quite variable in the calc-alkaline enclaves, being highest in the mica-rich variety; however, all of the enclaves in the calc-alkaline series, except for the mica-rich samples, have similar chondrite-normalized patterns with strong LREE enrichment and very weak nega-tive Eu anomalies (Fig. 9D). These enclaves have rather variable mantle-normalized trace-element patterns but generally show strong enrichment in LILEs and marked negative Nb anomalies, but they lack the positive P anoma-lies of the enclaves in the shoshonitic series (Fig. 10D). The mafi c quartz monzodiorite enclave is similar in composition to its host rock but with higher FeOt and MgO and correspond-ing decreases in most other oxides. On the other hand, the mica-rich enclave contains relatively high contents of transition metals, particularly Cr, Ni, V, and Co, suggesting that it is refractory crustal material that is a relict of crustal partial melting. No metasedimentary rocks of this com-position are currently known in the sedimentary sequence overlying the basement; however, the presence

petrogenesis of high-k, calc-alkaline and shoshonitic intrusive ......dabie-sulu orogenic belt...

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