6/17/2013

1

L6 - ROCKSSEDIMENTARY

CIVE 430 ENGINEERING GEOLOGY

SUMMER 2013

Grand Canyon-Arizona

6/17/2013

2

Layered Sandstones

TRANSPORT AGENTS

Water (streams, rivers, sea currents)

Wind and Glaciers Mass Wasting Gravity

GLACIER

6/17/2013

3

TRANSPORT AGENTS

GLACIER

Depositional EnvironmentsContinental

Dominated by Water ActionFluvial-->Rivers Lacustrine-->Lakes Glacial-->Glaciers

Dominated by Wind Action (Eolian)Deserts

Alluvial Fan

6/17/2013

4

Sediment Types

CLASTIC or DETRITAL = Fragments of Older Rocks

CHEMICAL= Dissolved, Transported & Precipitated Chemically

CLASTIC

CHEMICAL

CLASTIC SEDIMENTS

6/17/2013

5

CLASTIC SEDIMENTARY ROCKS

CLASTIC SEDIMENTARY ROCKS

6/17/2013

6

CONGLOMERATE

Gravel and Conglomerate(Texture)

Sandy Conglomerate Muddy Conglomerate

6/17/2013

7

SANDSTONE

SANDSTONE

6/17/2013

8

A very large number of different minerals may occur in sands and in sandstone. The most common minerals are:

Sands and Sandstone(Detrital Mineral Grains)

(1) Quartz

(2) Feldspar

(3) Mica

Quartz: is a very common mineral that is found as grains in sandstone.

It is a very stable mineral that is resistant to chemical breakdown at the earths surface.

Grains of quartz may be broken and abraded during transport, but with a hardness of 7 on the Mohs Scale, quartz grains remain intact over long distances and long periods of transport.

Sands and Sandstone(Detrital Mineral Grains)

6/17/2013

9

Feldspar: Very common in igneous rocks and is usually the product of weathering of igneous rocks.

Feldspar is susceptible to chemical alteration during weathering, and being softer than quartz, tends to be abraded and broken up during transport.

Feldspar are thus commonly found only in places where the chemical weathering of rocks has not been so intense and the transport distance is short.

Sands and Sandstone(Detrital Mineral Grains)

Mica: The two most common mica minerals, muscovite and biotite, are relatively abundant as detrital grains in sandstone Mica grains have a platy shape that distinguish them in

hand specimens and under the microscope.

Muscovite

Biotite

Sands and Sandstone(Detrital Mineral Grains)

6/17/2013

10

Lithification of Clay

CLAY

SHALE

Lithification

SHALE (ANCIENT MUDSTONE)

6/17/2013

11

WIND TRANSPORTED

SAND DUNES

6/17/2013

12

SAND DUNES - SANDSTONES

DEPOSITIONAL ENVIRONMENTS

6/17/2013

13

Marine EnvironmentThe deep seas which cover most of the globe are floored by oceanic crust. On average the water depth is about 4000 meters.

DEPOSITIONAL FEATURES

6/17/2013

14

EFFECT OF TRANSPORT

CARBONATE SEDIMENTS

Skeletal fragments: in carbonate sediments are whole or broken pieces of the hard body parts of organisms which have calcium carbonate minerals as part of their structure.

Corals: some of the largest biogenic calcium carbonate structures are built by corals.

Algae: and microbial organisms are an important source of biogenic carbonate and are the most important contributors of fine-grained sediment in many carbonate environments.

6/17/2013

15

Biogenic Carbonates(Skeletal Remains)

Crinoid ForamineferaMolluscs

Carbonate Sands

6/17/2013

16

Carbonate Sands

Carbonate Sands

6/17/2013

17

DEPOSITIONAL FEATURESCORAL REEFS

Biogenic Carbonates(Corals)

6/17/2013

18

Biogenic Carbonates(Corals)

Biogenic Carbonates(Corals)

6/17/2013

19

CHEMICAL AND BIOLOGICALSEDIMENTS

Calcareous sediment

LIMESTONE

6/17/2013

20

LIMESTONE

Evaporites

6/17/2013

21

Evaporites