cq t.leach report 1992

7/23/2019 CQ T.leach Report 1992

1/81

CMS

l.{ew

Zealand

Lrd

Exploation

Geologiss,

Petrologists

and

Consultants

Petrological

Eualuation

of

the

High

$ulphidation

$gstems

in

the

Ia

Paua

and

f erro

Quema

prospect

fireas,

panama

FOR

CYPRUS

GOLD

COMPANY

Prepared

by Terry

M.

Leach

June

1992

CMS

report

# 473

(

reference

5002,12

)

Phone: (6+-9)3766533,

Fax

(

64-9

)

360

1010

Street

Ad.dress:

11

Blake

st

Mailing

Address:

po

Box

47zgs

Ponsonby

Ponsonby

Auckland,

NZ

Auckland,

NZ

Auckland,

NZ

CMS

New

kaland

Ltd.


2/81

CMS

New

Zealand

Ltd

Exploration

Geologists,

Petrologists

and

Consuitants

Petrological

Eualuation

of

the High

Sulphidation

Sgstems

in

the La

Paua

and

Cerro

0uema

Prospect

Hreas, Panama

FOR

CYPRUS

GOLD

COMPANY

Prepared

by Terry M. Leach

June

1992

CMS

report

#

473

(

reference

800212

)

Phone: (64-9)3766533

Fax

(

64-9

)

360

1010

Auckland,

NZ

Street Address:

11 Blake St

Mailing Address:

PO Box

47295

Ponsonby

Auckland,

NZ

Ponsonby

Auckland, NZ

CMS New

kaland Ltd.


3/81

I

SUMMARY

1'

Petrological

analyses,

and

subsequent

interpretation

of

data,

was

carried

out

on

a

suite

of

sixty-

one

(61)

surface,

drillcore

and

rock chip

samples

collected

from

Cyprus

Gold,s

La

pava

and

Cerro

Quema

prospect

areas,

south-west

panama.

2.

Gold

mineralisation

in

the

two

prospects

are

hosted

by

andesites

which

are

overlain

by

pyroclastic

units

intercarated

a

sequence

of

porphyritic

dacites

to

with

minor

porphyritic

flows.

3.

At

La

Pava

a

deep

narrow

zone

of

quartz_sulphide_barite/alunite

alteration

mushrooms

at

shallow

levels

into

east-west

elongate,

concentric

alteration

zones

grading

from

an

inner

quartz-

pyrite

zone, then

progressively

outward to

quartz-kaolinite, quartz-kaolinite-interlayered clay

and

then

peripheral

quartz-smectite

alteration

assemblages.

The

zonations

in

alteration

indicate

that

moderately

hot

acidic

fluids

upflowed

within

fractured

and

brecciated

zone

to

the

north

of

the

main

mineraiised

zone,

and

mushroomed

out

at

shallow

levels

within

the

permeable

pyroclastic

units.

4'

Two

phases

of

acid

fluids

are postulated

for

the

La

Pava

hydrothermal

system:

an

early

event

which

caused

intense

acid

leaching

and

silicification;

and

a later

event

which

locally

brecciated

the

siiicified

zones

and

deposited

sulphates

and

sulphides

into

fractures

and

open

vughs.

This

later

event

is

postulated

to

be

the

gold

*

copper

mineralising

event.

supergene

oxidation

of

sulphideshas

resulted

in

a

50-100m

thick

leached

zone,

with

oxide

grades

reflecting

primary

sulphide

grades,

with

only

minimal

supergene

enrichment.

5'

The

hydrothermal

system

at

La

Pava

is

characteristic

of

a

high

sulphidation

epithermal

gold

+

copper

prospect'

High

grade

porphyry

copper

deposits

have

been

encountered

in

close

proximity

to

a

number

of

similar

high

sulphidation

systems

in

the

west

pacific

region.

A

programme

is

recommended

to

evaluate

the potential

of

a high

grade

porphyry

immediately

to

the

noth

of

La

Pava.

"

6'

East-west

elongate,

zoned

hydrothermal

alteration

assemblages

were

also

encountered

within

fractured

porphyritic

rocks

and

overlying

pyroclastics

in

the

cerro

euema

prospecr

aea.

This

zonation

indicated

a

source

of

hot

acid

fluids

at

depth

in

the

euemita

area,

with

ouflows

eastward

to

the

cerro

Quema

area.

A

two-stage

hydrothermal

system

is

also

envisaged,

with

gold

and

copper-a$enic-sulphide

mineralisation

occurring

in

late

stage

fractures

and

hypogene

leached

wghs"

Any

potential

associated

porphyry

system

may

lie

at inaccessible

depths

beneath

euemita"

CMS

New

kaland

Ltd.


4/81

7'

Alteration

in

the

El

Domo

is

consistent

with

this

area

having

slumped

north

from

the

cerro

Quema

silicified/mineralised

zone.

Alteration

at

La

Mesita

imply

this

area

is

marginal

to

the

hydrothermal

system,

and

therefore

no

further

drilling

can

be

justified

in

that

direction.

CMS

New

kaland

Ltd.


5/81

II

INTRODUCTION

:

Cyprus

Gold's

La

Pava

and

Cerro

Quema

prospect

areas, in

south-west

Panama,

form

two

prominent

topographic highs, elongate 1-2km

in

an east-west

direction, approximately

3-4km

apan

(

Figure

1;

photo

I

&

2

).

The

La

Pava

prospect

is

located

at

an

elevation

of

around

450-

550m

asl,

whereas

the

Cerro

Quema

prospect (

incorporating

the

Quemita,

La

Mesita,

El

Domo

and

Cerro

Quema

areas

)

ranges

from

700-950m

asl.

Both

prospects

are

hosted

by

of

a suite

of

intermediate,

possibly

calc-alkaline,

porphyritic

to

fragmental

rocks

which

have

undergone

varying

intensities

of advanced

argillic,

argillic

and

peripheral

propylitic

alteration.

Five

days

of

field

investigations

of

the

Cerro

Quema

project

area were

carried

out

by

the

author,

in

April

1992,

in

order

to assess

the

geological

setting

of

the

La

Pava

and

Cerro

Quema prospects,

and

to

initiate

sampling

for

a

petrological

evaluation

of these

prospects.

The

Ceros

Sureste

area

was not

included

in

this

study.

Previous

petrological

work

(

S. Williams

1989-1991

)

on

samples from

La

Pava

and

euemita

indicated

that the rocks

had

undergone intense

hypogene

acid

leaching

and

very locallised gold

+

copper

mineralisation,

which

is

characteristic

of many high

sulphidation-style

epithermal

deposits

worldwide.

It

has

been recently

discovered

that

some

high

sulphidation

deposits in

the

west

Pacific

region

are

situated

at

the

periphera

of, and

at somewhat

higher

elevation

than,

blind

high

grade

porphyry

copper

deposits

(

eg

FSE-Lepanto,

Philippines;

Wafi-Raffertys, pNG; see

T.Leach

memo

to

Chris

Torrey,

Cyprus

Gold, Feb

1992

).

In

these

cases it

is

apparent

thar

rhe

mineralised

fluids

associated

with gold

*

copper

mineralisation

in

the

high

sulphidation

sysrems

have

sourced

from

the

region

of

the high

grade

porphyry

copper

system. Petrological

evaluations

have

been

beneficiai

in

understanding

the

controls

on alteration

and mineralisation

of

the

high

sulphidation

systems,

and in

indicating

the

likely

presence

and

direcrion

of

potenrial

high

grade

porphyry

systems

ar

depth.

The

scope

of

this

p@ological

evaluation therefore

is

:

i)

to

develop

an

understanding

of

the

distribution

in

hydrothermal

alteration

ar

La

pava

and

Cerro

Quema,

and

its

relationship

to

gold,

and

possibly

copper,

mineralisation.

ii)

to

determine

the

source

direction

of

the

hydrothermal

/

mineralising

fluids,

and

to

evaluate

the

potential

for

encountering

porphyry

copper

systems

in

the immediate

cinity.

Supergene

acid leaching

/

weathering

is

very

intense

in most

of

the

drillholes

at

both La

pava

and

Cerro

Quema,

and has

subsequently

changed

the

original hydrothermal

alteration

mineralogy.

Therefore

most

of

the

sampling

for

this

study

has concentrated

on collecting

unweathered

CMS

New

7aland

Ltd.


6/81

hydrothermaily

altered

samples.

Samples

have

also been collected

from

some weathered

intervals

in

order to

evaluate

how

the weathering

has

effected

the

hydrothermal alteration.

A

suite

of one

hundred

and three

core,

RC

rock

chip

and surface

grab

samples

were collected from

within

the

La

Pava and Cerro Quema prospect

areas.

Of

these

thirty

drillcore

and

RC

rock

chip

samples

were analysed from

fifteen drillholes in

the La

Pava

prospect

(

Figure

2) and

thirty-one

core,

RC

chip

and surface

samples

were

analysed from

fourteen

drillholes

in

the

the

Quemita-

Cerro

Quema-La

Mesita-El

Domo

areas

(

Figure

3

).

Brief

petrographic

analyses were

carried out on thirty-two

thin sections,

whereas

brief combined

petrographic-mineragraphic

analyses were

done on

eighteen

polished

thin

sections. X-ray

diffraction

(

XRD

)

analyses were carried

out on orientated clay separates

from

forty

of the

samples,

and

scannedat2-25

o

2,

A

summary

of the

petrological

data

is

given

in

Table I,

along with the

mineral

abbreviations

used

in

this

table

and

throughout

the

report.

The

petrographic

and

petrographic-mineragraphic

descriptions,

and

the

XRD

charts

are

included

in

the

Appendix

at the back

of

this report.

CMS

New

kaland Ltd.


7/81

tt)

lJ

,

F

U

tJ-t

o-

v,

o

.

o-

a

CL

f

o

z

=

J

f

a

o

u.

.

IIJ

U

t

o

o-

:

I

I

o-

.

o

o

o-

o

:

o

L

f

.9

u-

o

-

3o

O

lL

i 2500c.

At

34-35m

in

pRH-g1-07,

minor

kaolinite

is

detected

with pyrophyllite,

implying

slightly

lower

temperarures

(

>200-250"c

).

The

sericitic

mineral

described

by

williams

(

March

1991

)

at

33.6m

in

pDH-g0-04

and

66.5m

in

pDH-g1-5

is

probably

pyrophyllite.

Therefore

the

intense

acid

leaching

within

the

oxide

zone

ar

euemita

is

interpreted

to

be

a

weathered

equivalent

of

the

quartz-pyrophyllite

t

Kaolinite

+

illitic

clay

encountered

at

depth

in

the

sulphide

zone.

The quartz

-

iron

oxide

alteration

in

the

leached

silicified

zones

at

shallow

levels

in

cerro

Quema

PRH-91-16

&

17;

PRH-92-44

&

52

)

are probably

weathered

equivalents

of quartz-pyr-ite

alteration

zones

similar

to

those observed

in

La

pava.

z)

This

assemblage

is peripheral

to

the

pyrophyllite

*

kaolinite

assemblage

and

implies

cooling

(

temperatures

of


25/81

4)

This

assemblage

is

marginal

to

the

pyrophyllite

and

dickitelkaolinite

zones

and

suggests

further

neutralisation

(

to

pH

=

4-5

)

and iocal

cooiing

of the hypogene

fluid.

Carbonate,

commonly

as

siderite,

is

encountered

where

fluids

have

been

considerably

neutralised.

The

interlayered

clay

mineralogy

in

Cerro

Quema

indicates

increasing

higher

temperature

with

depth

in

the

hydrothermal

system.

The

amount

of

smectite

interlayering

in

illite-smectite

(

as

shown

by

the

increasing

d-spacing

of

the

001

reflection

from

XRD

analyses

)

increases

with

decreasing

temperature.

Cool

smectite-illite

(

smectite

>

25Vo;001

>

114

)

is

encountered

at

shallow

levels

in PRH-92-45

(

15-16m

)

and

in

PRH-53;

intermediare

amounrs

of

smectite

(

10-

25vo;

ffil

=

10.4-10.94

,

and

moderate

temperatures

of

alteration

are

encountered

at

shallow

levels

in

PRH-91-16

&PRH-92-44,51

&

52; whereas

low

smecrite

clays

/relatively

high

temperatures

occur

at

depth

in

PRH-91-16

(

which

correlates

with

the

occurrence

of

high

temperature

dickite

).

Although

it

is

apparent

that

temperatures

increased

with

depth

in

the

region

of

pRH-91

-16

and,92-

45;

it

is

however

unkely

that

the intense

acid

leaching

encountered

near

surface

at

Cerro

euema

(

PRH-91-16/17:

PRtr-92-44/52

)

could

have

derived

directly

from

depth,

since

the

alreration

mineralogy

at

deeper

levels

implies

relativeiy

neutral

conditions.

Fluids

of this pH

could

not

have

caused

the

leaching

&

silicification

encountered

at

shallow

levels.

It

is

therefore

interpreted

that

the

silicified

leached

zones

encountered

at

shallow

levels

at

Cerro

Quema

were

derived

from

a

horizontal

outflow

of

hot

acid

fluids

from

the

euemita

region

(

see

Figure

8

).

The

absence

of

silicification

between

PRH-91-10

and

pRH-g1-16

implies

that

some

block

faulting

(

either

up

or

down

)

may

have

taken place.

Quartz-pyrite

alteration

at

42-43min

the

El

Domo

drillhole

pRH-g2-57,

is probably

the

sulphide

equivalent

of

the

quartz-jarosite-limonite

alteration

within

the

oxide

zone

encountered

at

shallow

levels

in

PRH-91-16/17.It

is

therefore

interpreted

that

the

El

Domo

region

is

a

slumped

blocked

which

has

been displaced

northwad

from

the

cerro

euema

area.

The

appearance

of

chlorite

implies

near

neutral

fluid

pH,

and

smectite-illite

indicates

low

temperatures

(

200mf

at

1'5-

2'0

"/"

Cu

1090m

msl

(a)

Waf i

River High

Sutphidation

(

Leach+Erceg 1990;

Erceg

et

Gold -Porphyry Copper Oeposif

at

1991

)

Epithermat 6old

L panto

(High

Sutphidation)

J.s-mr

uPtloY

t

3.6

yo

Cu

of Hot

;tsi

t7--

Acd

Ftuids

FSt

(

Porphyry

Copper)

>200mt

al 1-2o/o

(u

6uinaon

(

P

orphyry

C

o

pp

ar

)

500

mt at 0'1"/o Cu

0.4

ppm

Alj

(bl

Mankayan

High

Sutphidaiion

Copper+

6old - Porphyry

Copper

Depositq

Phitippines

(Siltiloe

1983; 6arcia 1990

)

La

Pava

High

Sulph

i d rtion

Sys

te

m

500

{i'

m.s.t.

?

Buricd

Porphyry

C

opp

er

(c)

Postutated

Bured Porphyry Copper

System

atDepth,North

of

La

Pava

Figure

9

:

Retafionshps Between

lJigh

Sutphidation

and

Porphyry

Copper

Deposits


32/81

Exploration

for

a

potential

porphyry

system may

be

carried out by :

i)

geological

and alteration mapping

along

the

northern

slope

of La

Pava,

down to

Rio

QUema

ii)

geophysics;

particularly

electrical methods to

detect

pyrite

associated with

the

hypogene

acid event.

i) RC

drilling into

the

northern

slope

of La Pava

in

order

to define

the

extent

of

the

steeply,

northerly

dipping

upflow zone,

and

explore

for mineralisation associated

with

this upflow

zone.

It

is recommended

that

a

petrological

evaluation

be made

of the

surface

mapping

and

RC

drilt

programme

in

order

to

further

refine

the above

conceptual model,

and

re-evaluate

the

potential

for

a buried

porphyry

copper

system

in

the immediate

aea.

ii)

Cerro

Quema

:

An

upflow

of

hypogene,

hot

(

>250'C

),

low pH

(

3-a

),

mineralised

fluids is interpreted

to

have

originated

at depths

beneath

the

Quemita

area,

and

outflowed horizontally

westward

within

shallow

pyroclastic

units"

High

temperature

conditions did prevail

under the

Cerro

Quema

region

but are

unlikely

to have

contributed

to the

silicification

and

mineralisation

encountered

at

shallow

depths in

the drillholes.

As

for

La

Pava,

a two

stage influx

of

hot

acid

fluids

is

postulated

for

Cerro

Quema.

The late

stage

acid

event has

been

accompanied

by

fracturing

and

brecciation

of

silicified

dacites/andesites

and

overlying pyroclastics,

with associated

deposition

of

sulphides

(

pyrite

+

Cu-As-sulphides

)

+

barite.

':l

The

alteration

at

El

Domo

is

consistent

with

this region

being

slumped

to

the

north

from

the region

of

PRH-91

-16

&

-17.

The

alteration

at La

Mesita

ind.icates

that

this area is

on

the

periphera

or

margins

of

the hydrothermal

system,

and does

therefore

not

justify

further

exploration

drilling.

Although

the

hottest

and

lowest

pH

conditions

were

present

at around

750m

asl

in

the

Quemita

area,

drilling

beneath

this

depth

(

eg

at

ll4-I16m

in

PRH-91-06

)

indicated

lower

temperature

&

higher

pH

conditions

were

present

below this

level.

This

temperature

reversal

shows

that

PRH-

9I-16

/

PDH-90-04

were

dilled

through

the

upflow,

which

was

probably

centered

slightly

to

the

CMS

New

kaland

Ltd.

26


33/81

north. However sampling

of

the

bluffs to the

north

(

LQ-4

)

indicated

that

the

upflow

was

close

to

the

PDH-90-04

region.

At

Cerro

Quema

alteration

within the

upflow

zone

is characterised

by

quartz-pyrophyllite-barite-

sulphides,

whereas as La

Pava

the

upflow

zone

contains quartz-barite/alunite-sulphides ( Figure

4). This difference

in

alteration

mineralogy

indicates

that

conditions

at

drilled depths

in Cerro

Quema

(

around

75Om asl

)

were

hotter, but

less

acidic,

an those

at

the

drilled

depths

(

450m

asl)

at

La

Pava,

at

300m

lower

elevation.

The

pressures within the

high

sulphidation system

were

probably

controlled by a

porphyry

system

at

depth,

rather than

by

a circuiating,

meteoric-

dominated

system.

It is

therefore

considered

that

it is

not necessary

to

invoke

faulting to

explain

the differences

in

temperature

of the

two

hydrothermal

systems.

The variation

in

styles

of

alteration

between

La

Pava

and Cerro

Quema

can

be

explained

by

different

rates

of

reaction

and

mixing

between the hypogene

acidic

fluid

and

the host

wallrock

and

circulating fluids.

A

mineralised

porphyry

system

may

also be

present

at depth beneath

the

Quemita

area,

however

this could be

less

accessible than the

one

postulated

beneath

La

Pava.

It is

therefore

recommended

that any

seach

for

a

porphyry

system associated

with

the

Quemita-Cerro

Quema

high

sulphidation

system,

should await the results of the

proposed

work at

La

Pava.

CMS

New

7aland Ltd.

27


34/81

PHOTOMICROGRAPHS

CMS

New

kaland Ltd.


35/81

$.J

3-'

i\

\

ir.\

r

microlaths

and

ion

oxides. Feldspars

(

probabiy

plagioclase

)

have

undergone

total replacement

to

kaoiinite. Free

quartz

is

absent,

indicative

of a

probable

andesitic composition.

PRH-92-44

:89-

90m.

Field

of

view

is

2.6mm.

Photo

4

:

Tuffaceous

textures

with

elongate

glass

fragments

replaced

by

kaolinite,

set

in

a

fine

grained

matrix

altered

to

quartz

+

dickite. Rock

has

undergone minor fracturing

and associated

suihide

deposition.

PDH-01-108.2n.

Field of

view

is

2.6mm.

CMS

New

kaland Ltd.

29


36/81

Photo

5:

Fragmental

/

breccia

sample with locally

abundant

quartz

crystal clasts, and

porphyritic

rock

clasts composed

of

plagioclase

altered

to

kaolinite

set

in

a

matrix

altered

to

granular

quartz.

The

clasts

are set

in

a

minor

matrix

of

pyrite-quartz-kaolinite.

PDH-01-90

:

89.6m.

Field

of view

is 2.6mm.

L

Framboidal

pyrite

indicative

of cool hydrothermal

conditions

and

temperature

reversals

at

depth

in

the

Quemita

area.

PRH-91-06

:

114m.

Field of ew is

1.3mm.

30

MS

New

Zealand Ltd.


37/81

f,

af-

e

i

/l'

\

t-

js

/

':.

i:r.

:tti

ffi.H.i;

Photo

7 :

Relatively

hard

brown

arsensulvanite

(

AsS

)

is

cut by

late

stage

vein

of

unidentified

grey-purple (

Ss

)

sulphide in

thin veinlets

at 99.4m

in PDH-04.

Field

of

view is

0.3mm

/''.

t

'^T,

Photo

8

: Chalcopydte

infilling

cavities

in pyrite

vein

ar

89.6m in

PDH-90-01.

Chalcopyrite has

been

overgrown

by,

and

partially

repiaced

by,

covellite. Field

of

view is

0.3mm

.

:,

ra

J

CMS

New

kalqnd

Ltd.

31


38/81

REFERENCES

:

Garcia

:J.

(

1990

)

: Geology and

mineralisation

characteristics

of

the

Mankayan

Mineral District,

Benguet, Philippines.

Geol.

Soc. Japan

pp 17-26

Leach T.M.

&

Erceg

M.

(

1990

)

The

Wafi

River high

sulphidation

epithermal

gold

deposit,

PNG.

Proc.

Pac-Rim'90

Congress.

pp

451-456

White N.

(

1990

)

High

sulphidation

epithermal

gold

deposits

: characteristics

and

model for

their

origin.

In

3rd

Syposium on

deep-crust fluids.

Geol Soc.

Japn.

pp

5-14

CMS

New

kaland

Ltd.

32


39/81

APPENDICES

: i) Brief

Petrographic

Descriptions

ii)

Brief

Petrographic-Mineragraphic

Descriptions

iii)

X-Ray

Diffraction

Charts

33

MS

New

Zealand

Ltd.


40/81

APPENDIX

I

:

BRIEF

PETROGRAPHIC

DESCRIPTIONS

LQ3:

Fine

grained

tan-brown

limonite

stained,

massive

sample.

ln

thin

section

porphyritic

to

rarely

glomeroporphyritic

feldspar

(

probably

plagiociase

)

totally

altered

to

Kaolin

clay;

and

rare mafic

(

interpreted

to

be

hornblende

)

phenocrysts,

altered

to

Kaoiin

+

Smectite

clay;

are

set

in a

fine

grained

felted

matrix

of

plagioclase

microlaths,

and

mafic

micolites,also

altered

to

Kaolin

c1ay.

Interstitial

chloritic-smectitic

clay

+

scattered

iron

oxide.

Alteration

is interpreted

to

be

all

supergene

weathering.

Mineral

abundances

:

kaolin

clay : 60-70Eo;

smectite

:2A-257o;

chloritic

clay

:

10-127o;

iron

oxide

:

5-6Vo

LQ6:

Andesite(Dacite)

In

hand

specimen

the sample

exhibits

weak

flow

lamination

with

subparallel

aligned,

abundant

dark

green-black

hornblende

and

white

plagioclase

phenocrysts

set

in a

very

fine

grained

pale

geen-gey matrix.

In

thin

section

relatively

abundant

(10-I2Vo

of

the

rock

),

large unaltered

hornblende

phenocrysts,

locaily

poikilitically

enclosing plagioclase, are

only

locally

slightly to partially

weathered to

smectite

clay.

Plagioclase

phenocrysts

(

15-20 7o

of

the

section

)

are

mainly oligoclase

to

minor

andesine

in composition,

and

have undergone

varying

degrees

of

alteration

to

albite t

scattered

illitic

clay.

A

few

scattered,

trace,

rounded,

in

piaces

partially

absorbed

qtrartzphenocrysts

make

up

less than0.17o

of the

section.

The

phenocrysts

are

set

in a

fine

grained felted

matrix

of

plagioclase

microlaths,

which

have

undergone

slight

to

partial

alteration

to

iilitic

clay

+

late stage

smectite,

which

is

interpreted

to be a

product

of weathering.

Smectite

infills

interstitial

spaces

between

microlaths.

Minute

dusty

iron

oxides

and

rare honblende microlites

are scattered

throughout

the rock

matrix.

The rock

is

probably

andesitic

in

composition,

however

the

presence

of

free

quartz

phenocrysts

implies the composition

is

probably transitional

to dacite.

34

MS

New

Zealand

Ltd.


41/81

PDH-90-01

:

67.5m

-

Dacitic

Fragmental

/ Crystal

Tuff

core

sample

which

has

been

totally

altered

to

a

light

to

pale

grey

leached/porous

siliceous

rock

with

abundant

fractures

and

possible

breccia

zones

seaied

by red-brown

hematite

and

tan-brownlimonite.

Intensity

of

alteration

has

almost

totally

masked

primary

textures.

Rare,

locally

iarge

(

up

to

2-

3mm

in

diameter

),

subangular

quartz

phenocrysts

clasts

indicate

that

the

rock

is

a

fine grained

fragmental,

probably

a

crystal

tuff,

and

of

probable

dacitic

composition.

The

quaracrystal

clasts

are locally

shattered,

with

fragments

sealed

by very

fine

granular

e

+

iron

oxides.

The

quartz

clasts

are

set

in

a

matrix

which

has

been

totally

replaced

by

a

very

fine

grained

granular

mosaic

of

Quartz

+

trace

mutually

intergrown

Barite.

Scattered

iron

oxides (

mainly

Hematite,

some

Limonite)

appears

to

have

in places

pseudomorphed

subhedrai

to

pyritohedral

disseminated

Pyrite'

The

matrix

is

in

places

vughy/porous

with

vughs

exhibiting

a semi-tabular

habit

suggestive

of leached

feldspar

crystal

clasts.

The

core

is

cut

by

thin

late

stage

fractured

panially

to

completely

fi1led

by iron

oxides.

PDH-90-04

:

70.2m

: Dacitic

Fragmental

/ Crystal

Tuff

Light

tan-pale

grey

core

with

scattered

quartz

phenocrysts

/

crystal

fragments,

which

has

undergone

intense

leaching

to

a

highly silicified,

porous/vughy

rock.

Locally

vughs

have

been

partially

inlled

by

iron

oxides.

The

core

has

undergone

very

intense

acid

leaching

and

silicification.

Rare

scattered

subangular

to

sub-rounded,

locally

shattered,

qaartz

crystal

fragments

(

up

to

4-5mm

in

diameter

)

are

suggestive

of

a

fine

grained

pyroclastics

(

probably

a

crystal

tuff

),

and

of probable

dacitic

composition'

Elsewhere

the

rock

is

vughy/porous

with

tabular

habits

of

the

vughs

suggestive

of

feldspar

crystal

fragments.

The

quartz

crystal

clasts

are

set

in

a very

fine

grained

matrix

composed

of

granular

Quartz,

in

places

intergrown

with

locaily

abundant

hexagonal

grains

of

what

are

interpreted

to

be

hydrothermal

Apatite.

scattered

trace

iron

oxides

disseminated

in

the

rock matrix

appear

to

be

after

fjlrir".

vughs

are

often

lined

by

very

fine

grained

drusy

Quanz

crystals,

with

local

deposition

of

smectite

clay

overgrowing

quartz.

35

MS

New

kaland

Ltd.


42/81

PDH-90-05

: 13.0m

:

Dacitic

Fragmentat

/

Crystal

Tuff

Light

grey-tan

brown,

slightly

limonite-stained,

highly

silicified,

locally

vughy/porous,

leached

fine

grained

core.

In

thin

section

the

rock

is

composed

of

rare

scattered,

mainly

fine

grained,

locally

large

(

up

to

1-

3mm in

diameter

)

clasts

or

fragments

of

quartz phenocrysts

are indicative

of

a

fine

grained

pyroclastic

/

crystal

tuff,

of

probable

dacitic

composition.

In

places

rare

open

vughs

/

cavities have

a

psuedo-tabular

habit,

suggestive

of feldspar

crystal fragments.

The

interpreted

crystal fragments

are

set

in

a very

fine

grained

matrix

completely

altered

to an

interiocking

mosaic

of

quartz

+

abundant

hexagonal

low

birefringent

mineral

interpreted

to

be

hydrothermal

apatite.

Trace

iron

oxides

have

mainly

been

deposited

into

open

wghs.

PRH'9L-07

:

34-35m

:

Dacitic

Fragmental

/

Crystal

Tuff;

Local

Rebrecciation

Rock

chip

sample

which

range

from

white,

clay-rich,

to mortled

grey-white

rock

with

?clay

altered

crystal fragments

set in

a

fine

grained

matrix.

In

thin

section

the rock

is

a ne grained

fragmental

composed

of

abundant

feldspar

and

possible

lithic

clasts

(

up

to

1-2mm

in

diameter

)

completely

repiaced

by

Illiticfficaceous

clay

+

minor

Quartz

+

ra.re

Pyrite,

and

scattered,

locally

abundant,

angular

to rounded quartz

crystal fragments

(

mostly


43/81

Phenocryst phases

are

set in

a

very fine

grained

totally

silicified

matrix

replaced

by

granuiar

interlocking

Quartz

+

rare

?Apatite

+

abundant

Jarosite and/or

iron

oxides

after

pyrite.

The

rock has

been

cut

by thin, locally

discontinuous veinlets of

Quartz.

Elsewhere

Quartz

lines

and

in

places

infills

vughs.

Mineral

abundances

:

quartz

:80-90Vo:jarosite/iron

oxides

: lo-127o; ?apatite

:2-3Vo

PRH-91-13

: 54-55m

:

Dacite

&

Dacitic

Fragmental/Crystal

Tuff

Mainly

tan-brown

limonite

stained,

highly

silicified,

locally

porous

-

leached

rock

chips.

Some

chips

have

been

altered to white-grey

ciay.

In

thin section the

chips

exhibit

both

fragmental

and

porphyritic

textures.

In

some cases

quartz

are

euhedral

are

partially

resorbed

indicative

of a

porphyritic

rock,

whereas

elsewhere the

quartz

is

angular

implying

a

fragmentpyroclastic

habit.

The phenocrysts/clasts

lre

set

in

a

fine

grained

matrix altered to

a

mosaic of

granuiar

Quartz

+

minor

Dickite

/

Kaolin

clay

+

abundant dusty

Limonite

Trace Barite

infills

a

few

vughs

and

thin

fractures.

Mineral

abundance

:

quartz

:6O-707o;

iron

oxides

:20-25Vo;

Dickiteffuolinite

:

5-6Vo;

Barite:

trace

PRH-91-13

:

97-98m

:

Dacite and

Dacitic

Fragmental

I

Crystal

Tuff

Red-brown

hematite-stained,

to

light

grey-white,

highly

silicified,

massive

rock

chips

with

minimal

leached

vughs

/

cavities.

Both porphyritic

and

fragmental

textures

are evident in rock

chips.

Trace partially

resorbed

quartz

phenocrysts

are

evident

in

some

chips;

whereas

angular to subangular

quartz

clasts

are

encountered

in

others.

Trace

tabular

vughs

(

?after feldspar

crystal

fragments

)

are infilled

by

Quartz

and/of trace

Baite.

The quartz phenocrysts

& chips

are

set

in

a very fine

grained

silicified

matrix

composed

o$minute granular Quartz + rare ?Apatite

+

trace scattered

Barite.

Trace

iron

oxide

after

sulphides.

One

chip

cut by

saccharoidal

Quartz

vein.

Elsewhere

Jarosite after Pyrite

occurs in

thin

discontinuous

veinlets.

Limonite

lines

open

vughs.

Mineral

abundance

:

quartz

80-x)vo;jarosite/iron

oxide :5-7vo; barite :


44/81

PRH-91-15

:

69-70m

:

Andesite

(?Dacite

)

Mostly

dark

grey

fine grained

chips

with

minor

white

?clay altered feldspar

?phenocrysrs

/

crystal

clasts.

Feldspar-phyric

porphyritic

sample

composed

of abundant

fine grained

?plagioclase

phenocrysts,

totally

altered

to

Kaolin

clay,

minor

mafic/?hornblende

phenocrysts

also

altered

to

Kaolin

clay,

and

trace

quartz

phenocrysts

iron

oxide

phenocrysts

replaced

by

Pyrite

+

Kaolin

clay.

The phenocryst

phases

are

set

in

a very fine grained

felted

matrix

of feldspar

microlaths

replaced

by

Kaolin

clay

+

Quarrz,

with

abundant

interstitial

euanz.

Rock

has

been

cut

by

med

grained

quartz

veins,

with

Q

locally

exhibiting

ribboned

texture

suggestive

of

porphyry

origin.

Quartz

veining

has

subsequently

undergone

fracturing

and

local

brecciation

with

associated

deposition

of kaolin

clay.

PRH-91-16

: 17-18m

: Hydrothermal

Breccia

of

euartz

veined

Dacitic

crvstal

Tuff

Red-brown

hematite-stained

highly

silicifi

ed,

locally porous/leached

vughy

sample.

In

thin

section

the

chip

is

a

polymict

breccia

with

rare

subrounded

clasts

of

:

i)

rare

very fine

grained

rock

replaced

by minute

granular euartz

ii)

abundant

quartz

crystal

vein

clasts

iii)

rare

granular

quartz

vein

clasts

Set

in

a

very

fine

grained

breccia

matrix

of

granular

Quartz

+

minor

to locally

abundant

?Apatite

+

minor

disseminated

dusty

to

subhedral

/pyritohedral

Jarosite

and

iron

oxides

after

?pyrite.

It

is

interpreted

that

the

rock

is

a hydrothermal

breccia

of a

quartz

veined

dacite/crystal

tuff,

which

has

been

sealed

by

euarrz-pyrite-?Apatite.

Mineral

abundance

:

quartz

:80-90vo;

?apatite

:

g-lavo;Jarositefiron

oxide

:

g_lyvo

4"

PRH-91-16

:

6l-62m

: Dacite

Pale

grey

to

mottled

light

grey

fine grained

?porphyritic

chips.

In

thin

section

the rock

is

porphyritic

with

abundant

feldspar (

?plagioclase

)

phenocrysts

totally

replaced

by

Illitic

clay

+

minor

Kaolin

clay +

rare

Quartz

+

pyrite/Sulpides,

minor

maficlhornblende

phenocrysts

altered

to

Kaolin

clay

+

minor

Pyrite/Sulphides

+

rare

euartz,

and

rare,

in places

large (up

to

1-3mm

wide

),

locally

partially

resorbed

quanz

phenocrysts.

38

MS

New

kaland

Ltd.


45/81

The

phenocryst

phases

re

set

in

a

very

fine

grained

matrix

completely

replaced

by

Quartz

+ Illitic

Clay

+

Kaolin

Clay

+

minor

disseminated

anhedral

to

euhedral

Pynte

(

cubic

>

pyritohedral

)

Rock

is cut

by

very thin

(


46/81

incative

of

porphyritic

texture.

Minor

number

of

leached

vughs

are

present

and

these

typically

exhibit

psuedo-tabula

habits,

suggesdve

of

feldspar

crystal

fragments'

The

crystal

clasts

afe

set

in

a

very

fine

grained,

totally

silicified

matrix

composed

of

granuiar

quafiz

+

scattered rare

iron

oxide,

commonly

with

cubic

or

pyritohedral

habits

after

Pyrite'

A

few

chips

are

composed

of

fine

grained

saccharoidal Quartz'

possibly

vein

clasts'

PRH-91-23

:

15'16m

:

Dacitic

Fragmental

/

Crystal

Tuff

Palegrey-whitetotan-birown,monite-stained,silicifiedintenselyporous-leachedrockchips

ln thin

section

the

chips

contain

rare

to

minor

quartz

crystal

fragments

indicative

of

a

fragmentai

origin.

a

few

semi-tabular

to

tabular

leached

vughs

are

suggestive

of

the

presence

of

minor

ferdspar

crystal

crasts.

Some

of

the reached

feldspar

ciasts have been

infined by

a

dusty kaolin

clay.

These

ciasts

are

set

in a

very

fine

grained

silicifred

matrix

composed

of

a

mosaic

of

granular

quartz

+

scattered,

locally

relatively

abundant

(

up

to

8-10Vo

of

the

rock

)

leached

cubic

vughs

after

Pyrite.

Some

vughs

ae

lined

to

partially

infilled

by

limonite'

Mineral

abundance

:

quartz

:80-907o;iron

oxideAimonite

:6-8To;Kaolin

clay

:4-57o

PRH.91.23

:

53.54

:

Dacitic

Crystat

Lithic Tuff

/

Fragmental

Grey

very

fine

grained,

silicifred

pyritic

chips;

with

commonly

weathering

to

tan-brown

limonite

saining.

In thin

section

the

rock

chips

are

fragmental

with

minor

rounded

rithic

clasts

(

up

to

2-3mm

in

d.iameter

)

totally

altered

to

gtanular

Quartz

+

scattered

disseminated

pyrite;

and

rare

subangular

quartz crystal

fragments.

The

rock

clasts

are

set

in

a

very

fine

grained

matrix

completely

silicified

to

granular

quartz

+

locally relatively

abundan disseminated

anhedral

to

commonly

pyritohedral

Pyrite'

A

few

clasts

are

cut

by

thin

Quartz

veinlets'

Minerar

abundances

:

(

in

unweathered

chips

)

quartz

:80-9ovo;

pyrite

:

1o-127o

PRH.91-26:35.36m:DaciticFragmental/CrystalVitricTuff

white

to

very

pale tan-bnown

(

sght

limonite

stained

)

highly

silicified

massive

rock

chips'

with

only

trace

leached

vughs.

40

CMS

New

kaland

Ltd.


47/81

In thin section

the

rock

is

a

fragmental

as

evidence

by

the

presence

of rare

quartz

crystal

fragments.

A

few

ieached

tabular

vughs

incated

that

trace

feldspar

crystal

clasts

were also

present.

The

crystal

fragments

are

set

in

a

very

fine

grained

matrix

completely

altered

to

a

mosaic

of

interlockin

g

qlartz"

with

trace

stubby

Rutile

crystals

and

scattered

iron

oxide.

In

a

few

chips

relatively

abundant

(

8-10Va

)

cubic/pyritohedral

vughs

after

leached

pyrite, have

been

partially

infilled

by

iron oxide

/

Limonite.

cut by

very

thin

(


48/81

PRH-91-28

:

11-12m

:

Dacitic Fragmental

/

Crystat

Vitric

to

Lithic

Tuff

Li_eht

grey-white,

to

red-brown

hematite-stained,

porous/vughy

locally

intensely

leached rock

chips.

ln

thin

section

e chips

are

fragmental with

rare subangular

quartz

crystal

fragments

being set

in

a

very

fine

grained

matrix locally exhibiting

weak

flow

lamination.

The

matrix

has undergone

complete

alteration

to a

very

fine

grained

mosaic of

granuiar

Quartz

+

scattered

iron

oxides

+

trace

very

locallised

hexagonal ?Apatite.

Eisewhere

the chips

appear

brecciated

with

rounded fine

grained

totally

silicified

lithic

clasts

set

in

a

fine

grained

matrix

of

Quartz

+

iron oxide

-

possibly

a

liic

tuff.

\fineral

abundances

:

qualtz

:9\957o;iron

oxide :5-77o;

?apatite

:

trace

(


49/81

PRH-92-44

z

29-30m: Dacitic

Fragmental

/

Lithic Tuff

Light

grey-white

highly

silicified rock chips,

with

local

grey

?clasts set in

a

fine

grained

porous/vughy

matrix.

In

thin

section

the

rock

chips are

polymict

breccias

with

clasts

of

:

i)

porphyritic

rock

with

partially

resorbed

quartz

phenocrysts,

and trace tabular vughs

after

feldspars,

set

in

a

very fine

grained

matrix totally replaced by

granular

Quartz

+

scattered dusty

iron

oxides

ii)

quartz

crystal fragments

iii)

totally silicified

lithic

clasts

These

clasts

arc set

in

a breccia matrix

of

fine

granular

mosaic

of

Quartz

+

scatttered

iron

oxides,

in

places

replacing

disseminated

cubic

to

pyritohedral

Pyrite.

Mineral

abundances

:

quartz

:90-957o:

iron

oxides

: 6-8Vo

PRH-92-44

: 89-90m

:

Andesite

Fine

grained,locally white clay

altered,

predominantly

red-brown,

hematite-stained

rock

chips.

Porphyritic

sample

composed

of

rare

feldspar

(

?plagioclase

)

phenocrysts,

totally

altered

to

Kaolin

clay,

and

trace

possible

mahc

(

?homblende

)

phenocrysts

also replaced

by Kaolin

clay.

The phenocryst

phases

are

set

in

a

fine

grained

felted

matrix

of

plagioclase

microlaths

altered

to

Kaolin

clay

+

minor

Quartz,

rare

mafic microlites

altered

to Kaolin

clay

+

iron

oxide

*

Quartz,

with

abundant

interstitial

Hematite,

after

primary

iron

oxides and/or

pyrite.

One

chip

cut

by

a

thin

(


50/81

chips semi-tabular

feldspar

phenocrysts

/

crystal frag are

altered

to

illitic

clay.

Rounded lithic

clasts

repiaced

by

Illitic

clay

+

Quartz

are set

in

a

matrix

also

of

Illitic

clay

+

Q

with abundant

Fe-O.

PRH-92

-

45

:

45-46m

:

Dacite

/

(?Andesite

)

Light

to

pale grey,

slightly

pyritic

and silicified,

in

places

mottled

?porphyritic

rock

chips.

A few

clasts

of

large

quartz

?phenocrysts

/

crystal

clasts.

In

thin

section the rock chips exhibit

porphyritic

textures with abundant

feldspar,

minor

mafic/hornblende

phenocrysts

altered

to

Dik/K

*

trace

Py/sulphides,

and trace

quartz phenocrysts.

A

few rock

chips are

quartz phenocryst

fragments. The

phenocrysts

are

set

in

a

fine

grained

matrix

altered

to

granular

Q

+

minor

Dik/I(

+

rare

disseminated

anhedral to

commonly subhedral

(

pyritohedral

>

cubic

)

Py.

One

porphyritic rock

chip is cut by

thin veinlet of

Dik

+ Py/sulphides.

PRH-92-53

: 35-36

:

Andesite

/

Dacite

Pale

to dark

grey-green

porphyritic

rock

chips.

In

thin section

the

rock

chips

are

porphyritic

with abundant

feldspar

/

plagioclase

phenocrysts

altered

to

illitic

clay

with

local

overprinting

by Sm

+

iron

oxide, moderately abundant hornblende

phenocrysts also

totally

replaced

by

illitic

clay

+

smectite

+ carbonate/siderite;

and trace

locally

partially

resorbed

quartz

phenocrysts.

The

phenocrysts

are

set

in

a fine

grained

felted matrix of

plagioclase

microlaths

and

hornblende

microlites

altered

to

illitic +

smectitic

clay,

with

abundant

interstitial

Quartz

+

scattered

disseminated Pyrite.

Mineral

abundance

:

quartz

4A-5A7o;

illitic

clay

:2A-25Vo:

smectite

:

L5-20Vo;

siderite

:8-lAVo;

ion

oxide

:3-5Vo

PRH-92-60

:

51-52m

Pale

to

dark

grey,

locally

limonite

stained

?porphyritic

sample with large

phenocrysts,

set

in

a

fine

grained

matrix.

In

tttin

section

the

rock

chips

are

porphyritic

and composed of abundant

feldspar

(

?plagiociase

)

phenocrysts

totally

altered

to

Ch

+

Sid

+

?kaolin

clay;

minor hornblende

phenocrysts

also

altered

to Ch

+

Sid

+

Q

+

Fe-O;

and a

few

race

partially

resorbed

quarrz phenocrysts.

The phenocrysts

are set in

a very fine

grained

matrix

completely altered

to

Ch

+

Q

+

scattered

disseminated

Pyrite +

Sid. The

alteration has

completely

masked

all

primary

textures in

the

matrix.

Mineal

abundance

:

quartz

: 25-3O7o;

chlorite

:

25-307o;

siderite

: 30-4OVo;

iron oxide

:

l2-157o

CMS

New

kaland Ltd.

44


51/81

PRH-92-73

:

80-81m

:

Dacite

/

Andesite

Light

tan-brown,

limonite-stained

to

red-brown,

hematite

stained, fine

grained

silicified,

leached

porous/vughy rock

chips.

Porphyritic

sample

composed

of abundant

leached

tabular feldspar

/

piagioclase

phenocrysrs,

infilled

by

Kaolin

clay

+

iron

oxides,

or open

and

lined

by iron

oxides;

possibie

mafic

(

?hornblende

)

phenocrysts

also leached

and

infilled

by

a

kaolin

clay;

and

trace rounded,

locally

partially

resorbed

quartz

phenocrysts.

The

feldspar

and

quartz

phenocrysts

Lre

set

in

a very

fine

grained

matrix

which

has

undergone

complete

replacement

to

granuiar

interlocking

Quartz

+

minor

scattered

dusty

iron

oxides

+

trace

Baite.

Mineral

abundance

:

quartz

70-8A7o;

kaolin clay

:

10-15

7o;

konoxide

: 6-8Va;

barite

-


52/81

Pm.H-92-86

:

60-6Lm

Dacite

/

Dacitic Fragmental

Irue grey

to

hematitic-limonitic

stained,

highly silicified,

locally

leached

porous/vughy rock

chips;

cuartr1'

with ?crystal

fragments replaced by

iron oxide.

lkps

exhibit both

fragmental

/

pyroclastic

and

porphyritic

textures.

Rare

quartz

is

both

rounded to

r.nnally

resorbed

in porphyritic

samples,

to

subangular

in

fragmental chips.

In

some

chips

:eusoas

have

been totally

leached

and

infilled by

kaolin clay

+ iron

oxides.

The

ciasts

/

phenocrysts

are set

in

a

very

fine

grained

matrix

of

gtanular

quartz

+

interstitial

kaon

llq,

-

scattered

iron

oxides.

rlffineral

abundance

:

quartz

:8O-907o:

kaolin clay

:

10-157a;kon

oxide

:6-87o

PWH-92-86

:

140-141m :

Dacite

lh}jte

to

grey-white

highly

leached

vughy/porous

silicified

rock

chips.

&rmhgitic

sample

composed

of

minor

leached

feldspar

phenocrysts which

have been

infilled

by

:xrK

+

Al,

and trace

partially

resorbed

quartz

phenocrysts. These

phases

are set

in a

fine

grained

mmrr

rctally

altered

to

granular

Quanz

+ minor

Alunite

lhffinlrral

abundance :

quartz

:

80-X)7o; alunite

: 8-I0Vo;

Kaolinite/dicKte

:2-3Vo

flilS

-\-erv

kaland Ltd.

46


53/81

APPENIDIX

II

:

BRIEF

PETROGRAPHIC-MINERAGRAPHIC

DESCRIPTIONS

LQ-4

:

Brecciated

Dacite

4m

wide,

apparently

near

vertical

zone

of

intense

quartz-pyrite

altered,

silicified

?porphyritic

rock

with

clay-pyrite

on

wallrock.

In

thin section

the

sampie

is

a

fragmentaVbreccia

rock

with

:

i)

subrounded

porphyritic

clasts

with feldspar

phenocrysts

totally replaced

by

Dik/K

+

rare

Pylsulphides;

and

a

few

clasts

with

large, parrially

resorbed

quartz

phenocrysts.

the

phenocrysts

phases

ate set in

a

fine grained

matrix

altered to

granular

Quartz

+

rare

disseminated

Pyt

DildKaoiin

ciay

)

quartz

crystal fragments

The

clasts are

set

in

a

very

fine

grained

matrix

altered to

K/Dik

+

Q

t

trace Micaceous

clay

+

moderately

abundant

Py/sulphides,

with

local

Pylsulphide

flooding.

Elsewhere

KlDik

has flooded

the

matrix

forming

elongate

clay

rich

zones.

Py

(2-4Vo

)

>>

Po

=

Rt

Py

occurs

as

mainly

anhedral,

rarely

subhedrpyritohedral

grains

predominantly

disseminated

in

the

breccia

matrix,

rarely

disseminated

in porphyritic

clasts,

and

as

trace

grains

replacing

phenocryst

phases.

Some Py

contain

minute

ovoid

Po,

and

irregular

Rt

inclusions.

PDH-01

-

89.6m

:

Dacitic

Fragmental

/

Breccia

Grey

silicified,

pyritic,

porphyritic

sample;

fractured

and

brecciated

by

pyrite-dickite

veining.

I-ocal

secondary

malachite

stainin g.

Foorly

sorted,

mainly

clast

supported

fragmental/breccia

sample

composed

of angular

porphyritic

:iasts

containing

feldspar

phenocrysts

totally

altered

to

Kaolin

clay,

set

in

a

fine

grained.

matrix

=piaced

by

granular

Quartz

+

Kaolin

clay

+

rare

disseminated

PylSulphides.

The

clasts

are

set in

a

rinor

matrix

containing

locally

shattered

quartz

crystal

fragments

within

a

very

fine grained

:reccia

groundmass

altered

to

euartz

+

pyrite/sulphide

+

Kaolin clay

4'

t

3-sEo

)

>>

co

t

Cpy

{'occurs

as

anhedral

to pyritohedral

grains

mainly

intergrown

with

e-K

in

breccia

marrix,

a

*'iinor

grains

disseminated

in porphyritic

clast

matrix,

and as

trace grains

replacing

phenocryst

nases.

Py

is

overgrown

by

trace

Cpy

in

zones

of Py flooding

of

breccia

matrix.

The

Cpy is

:c'ergrown

and

commonly

replaced

by Co.

Elsewhere

Co is

deposited

in

open vughs

in

breccia

natrix.

47

}dS

.\'ele

kaland

Ltd.


54/81

PDH-01

-

108.2m

:

Dacitic

Crystat

Tuff

Grey

sulphidic

porphyritic

rock,

cur

by

Dik

lined

fractures

In

thin

section

it

appears

that

the

rock

is

a

fragmental

with

subangular

quartz

crystal

fragments,

sub-tabular

feldspars

totally

leached

and

infilled

by Diffi,

and

angular

glass

& lithic

clasts

also

replaced/infilled

by

Dik1K.

the

clasts

are

set

in

a

weakly

foliated

matrix

altered

to

granular

euartz

+

DildK

+

disseminated

pylSulphides

The

rock

has

undergone

local

fracturing

and

in

situ

brecciation,

with

associated

deposition

of

PVlsulphides

in

fractures

and

in

breccia

matrix.

Py

(

4-6Vo

)

>>

Rt

Py

is

encountered

as

anhedrai

to rarely

pyritohedral

grains

mainly

disseminated

in

the

tuff

matrix,

and

as

minute

grains

infilling

fractures

and

breccia

zones.

The

py locaily

exhibits

etched

growth

zones'

especially

in

the

cores

of

Py

crystals.

Trace

Rt

is

scattered

in

the

rock

matrix.

PDH-04

-

99.4m

: Dacite (

?Dacitic

Tuff

)

Highly

leached/vughy,

pyritic,

fragmental

sample

composed

of

angular

crystal/iithic

clasts

ser

in

a

fine

grained

silicified

matrix.

Interpreted

to

be

a

porphyritic

rock

composed

of

tabular

leached

feldspar

phenocrysts,

with

vughs

partially

to

totally

infilled

by

Micaceous clay

/

?Pyr

+

pyrite

+ Barite

*

euartz,

and elsewhere

tabular

vughs,

probably

after

feldspar

are

completely

infilled

by

drusy

Barite;

moderately

abundant

euhedral

prismatic

hornblende

phenocrysts

replaced

by

Micaceous

clay

/

pyr

+euartz

+

pyrite,

and

minor

rounded,

locally

partially

resorbed

quartz

phenocrysts.

In

places

the quartz

are

angular,

and

have

the

appearance

of

being

crystal

fragments.

Elsewhere

quarrzphenocrysts

have

been

fractured

and

shattered

with

local

recrystailisation

to

fine

grained

euartz"

Phenocrysts

/

?crystal

fragments

are

set in

a very

fine

grained

matrix

completely

altered

to

a mosaic

of granular

Quartz

+

abundant

disseminated

Pyrite/sulphides;

with

feldspar

and

hornblende

microlires

altered

to

pyr

+

py.

The

rock

is cut by

network

of

thin

S/sulphide

veins

which

are

commonly

infilled

by

Barite.

Py (

10-1570

)

>

brown

isotropic

mineral

)

gey-purple

anisotropic

mineral

;

cu-suiphi

des

>

Rt

Py

occurs

as mainly

anhedral

to

rarely pyritohedral

grains

disseminated

in

the

tuff

matrix

and

infilling

thin

fractures.

The

Py

commonly

exhibit

etched

growth

zones,

mostly

in

the

cores

of

gains.

Trace

Rt

are

observed

as

inclusions

in

Py,

and

as

trace scattered grains

in

the

rock matrix.

PRH-O6-114m

:

Dacite

/

Dacitic

Fragmental/Tuff

Rock

chips

range

from

very

fine

grained

grey

silicified

pyntic

rocks,

to

momled

grey-white

?clay-

silica-pyite

altered

?porphyntic

rocks.

Rock

chips

range

from

porphyritic

rock

with

abundant

feldspar

phenocrysts

altered

to

mainly

Kaolin

clay

*

Pylsulphides,

locaily

with illitic

clay,

and rare

to

rrace

large paniay

resorbed

quarrz

phenocrysts;

set

in

a

matrix completely

replaced

by

fine

grained granular

euartz

+

Kaolin

clay

+

rare

illitic

clay.

Elsewhere

chips

are fragmental

with

feldspar

and quartz

crystal

fragments

also

set

in

a

matrix

of

granular

Q

+

Kaolin

clay

+

Py.

In

some

chips

the

rock

is

sheared

and

brecciated

with

rounded

silicified

rock

clasts/crystal

fragments

and quartz

crystal

clasts

set

in

a

foliatesheared

pyritic

matrix.

Py

(

4-6Vo

)

>>

Rt

Py

is

encountered

mainly

as

anhedal

to

rarely

subhedraVpyritohedral

grains

disseminated

in

the

matrix

mainly

of

the

fragmental

chips,

and

in

minor

amounts

in

the

porphyritic

chips,

and

replacing

feldspar

phenocrysts/clasts

with

kaolin/illitic

clay. l,ocally

the

py

is framboidal

in

a

few

fragmental chips.

Rt

occurs

as

trace

irregular

inclusions

in

a

few

py

grains.

PRH-91-10

-

94m

:

Dacite

/

Dacitic

Fragmental/Tuff

Pale

grey-green,

rock

chips;

in

places

cur

by

white

thin

veinlets.

In

thin

section

both

porphyritic

and

fragmental

chips

are

evident.

with

some polphyritic

clasts

containing

abundant

feldspar

phenocrysts

altered

to kaolin

clay

+*

Carb

+

illitic

clay,

set

in

a fine

grained

matrix

altered

to

Quartz

+

Kaolinite

+

Illitic

clay +

rare

disseminated

pylsulphides.

49

MS

New

kaland

Ltd.


56/81

Elsewhere

feldspar

(

altered

to

K

+

Illitic

clay

)

and quartz

crystal

fragments

are

set

in

a fine

grained

Q

+

Carb +

K

+

Illitic

clay

matrix.

some

clasts

are

cut

by

Carb

veining,

with

late

stage

Chalcedony

grading

out

to

e

in

open

cavities.

Py (3-4Vo

)

Py

is

encountered

mainly

as

anhedral,

locally

subhedraVpyritohedral,

grains

disseminated

in

the

matrix

of

both

porphyritic

and

fragmental

rock

chips,

rarely

replacing

feldspar

phenocrysts/clasts;

and

locally

intergrown

with

Carb

+

Q

in

veinlets,

where

it

commonly

lines

the

vein

fractures.

PRH'91'11

'

74m

:

Brecciated

Dacite

Fragmentar/Tuff

Fine

grained

light

grey

silicified

chips;

mostly

oxidised

to

tan

-brown

Lm-stained.

Polymict,

poorly

sorted

fragmental

/breccia sample

composed

of

rounded

rock

clasts

totally

replaced

by

fine

grained granular

Quartz,

and

abundant

quartz

crystal

fragments.

the

clasts

are

set

in

a

fine

grained

matrix

of

euartz

+

Barite

+

pylsulphides.

Py

(3-5Vo

)

>>

Co

>

Cpy

Py

is

encountered

as

anhedral

to

pyritohedral

grains,

mainly

intergrown

with

euar"tz-Barite

in

breccia

marix,

and

rarely

disseminated

in

clast

matrix.

Trace

ovoid

cpy

inclusions

are

encountered

in

some

Py grains.

co

is

observed

infiiling

open

cavities

in

breccia

matrix,

and

as

ovoid

inclusions,

interpreted

to

be

after

Cpy,

in

some

py

grains.

PRH-91-13

-

97m

:

Dacitic Crystat

Vitric

Tuff

Light

grey-white,

commonly

slight

tan-b,rown,

Lm-stained

silicified

rock

chips;

in places

leached

-

vughy

In

thin

section

trace

small

angular

quartz

crystal

fragments,

and rare

totally

leached

feldspar

crystal

fragments'

in

places

infilled

by

Barite;

are

set

in

a

very

fine grained

matrix

completely

altered

to

granular

Quanz

+

rare

Barite

+

scattered

iron

oxides,

after

pyrite.

All

samples

have

undergone

oxidation,

with

trace

hematite

replacing

disseminated

pyrite.

PRH-91-1S-69m:

Dacite

Pale

grey

to

mottled

light

grey,

slightly

pyntic

rock

chips.

Porphyritic

rock

chips

composed

of

abundant

feldspar

phenocrysts,

replaced

by

either

Kaolin

clay'

or

in

some

chips

Illitic

clay;

and

trace

quartz

phenocrysts.

The

phenocryst

phases

are

set in

a

fine grained

matrix

completely

altered

to

fine

granular

Q

+

minor

Kaolin

clay +

rare

disseminated

Pylsulphides

+

local

Iltic

clay.

Some

of

the

rock

chips

are

cut

by

thin

veinrets

of

chalcedonic

euartz.

Py (2-3Vo )

50

MS

New

Zealand

Ltd.


57/81

Pyrite

is

the

only

opaque

encountered

in

the

section

occurring

mainry

as

subhedravpyritohedral

grains

disseminated

in

the

rock

matrix,

and

locally

phenocrysts.

In

places

the

py

exhibits

framboidal

habits.

anhedral,

to

rarely

replacing

feldspar

PRH-91-16

-

89-90m

:

Dacite

Pale

grey,

sght

pyritic

and

silicified,

mortled

light

grey

?porphyritic

sampie.

In

thin

section

the

rock

chips

are porphyritic

with

abundant

feldspar

/?plagioclase

phenocrysts,

in

places

leached

and

infilled

by

Kaolin

clay

and/or

illitic

ciay,

elsewhere

replaced

by

Kaolin

+

illitic

clay;

minor

hornblende

phenocrysts

generally

altered

to kaolin

clay;

and

rare,

locally

panially

resorbed,

quartz

phenocrysts.

The phenocryst

phases are set

in

a

fine

to medium

grained

matrix,

with

vague

outlines

of

minor,

locally

interlocking,

feldspar

microlaths.

The

matrix

has

ben

completely

replaced

by

granular

e

+

rare

disseminated

Pylsulphides

t

rare

to

minor

kaolin

clay

*

illitic

clay.

The

locally

coarser

grained

:Y":^*d

interlocking

nature

of

some

maricies,

suggests

that

the

rock

may

be

a

porphyry

rntrustve-

Py

(

5-7Vo

)

>>

Rt

Py

is

ubiquitous

in

all

chips,

occurring

mainly

as

anhedral

to

commonly

subhedral

(

pyritohedral

.

cubic

)

grains

disseminated

in

the

porphyry

matrix;

as

trace

discontinuous

py

veinlets;

and

as

trace

gains

replacing

phenocrysts

phases.

A

few

Py

contain minute

irregular Rt

inclusions.

PRH'91'17

'

44-45m:

Dacite

/

Dacitic

Fragmentat

-

Crystat/Lithic

Tuff

Light

grey

to

mottle

/veined

white

?kaolin

clay,

slight

silicified

rock

chips.

In

thin

section

the

rock

chips

are

porphyritic

to fragmental.

Some

chips

are

composed

of

tabular

feldspar

phenocrysts,

altered

to

Kaolin

+

Illitic

clay,

and

resorbed

rounded

quartz

phenocrysts,

set

in

a

fine

grained

matrix

altered

to

granular

euartz

+

Kaorin

clay

+

Illitic

clay

+

rare disseminated

Pylsulphides'

Elsewhere

chips

are

composed

of

abundant

large

quartz

crystal

fragments

set

in

a

fine

grained

Q

+

Kaolin

clay

+

trace

Py

matrix.

It

is

interpreted

that

the

rock

is

a fragmental

containing

porphyritic

lithic

clasts.

In

places

the

quartz

crystal

fragments

have

undergone

shattering

and

recrystallisation

to granular

euarz.

Py (

2-4Vo

)

occurs

in

rare

amounts

as

minute

(

up

to

30p

),

mainly

anhedal

to

subhedral

(

pyritohedral

)

grains

disseminated

in

the

rock

crystal

/

phenocryst

phases.

matrix,

and infilling

thin

fractures

cutting

quartz

CMS

New

kaland

Ltd.

51


58/81

PRH-91-21

-

t06m

:

Dacire

Fine

grained

massive

grey

pyritic,

to

motded

white-grey

?porphyritic

rock

chips;

some

chips

xhibit

red-brown

hematite_staining.

In

thin

section the

rock

chips

are porphyritic

with

minor

to

moderate

ferdspar

phenocrysts

are

ither

leached

and

infilled

by,

or

altered

to,

Kaolin

clay

+

pylsulphides,

with

scattered

rare,

anially

resorbed'

quartz

phenocrysts.

The

phenocryst

phases

are

set

in

a fin,

commonly

dusty,

ine

grained

matix

completely

altered

to

mainry

granular

euartz

+

minor

disseminated

Pflsulphides

+

rare

local

Kaolin

clay.

some

chips

have

been

cur

by

thin

fracrures

infiiled

cq t.leach report 1992

Documents