Sedimentary Geology Exam #1 Material

Types of Strat. Columns

Standard straight-sided, profile, strip-log

Rudite

Conglomerate

Argillaceous

Clayey

Sedimentary petrology

Sed. Rocks (field, megascopic, microscopic)

Sedimentary Petrography

Description of classifications of sediments (micro)

Sedimentary Petrogenesis

Origin & Formation

Stratigraphy

Formation & distribution of sediments in space and time.

Scour

Where currents erode out basal sediments (increased energy env.)

Graded Bedding

Larger fragments at the bottom (increased energy) and smaller fragments on top (lower energy env.); likely deposited this way due to storms

Basal Sediment

Layer of debris, mud, rock, and organic matter found at the bottom of a glacier, ice sheet, or base of lake or ocean, resting on top of bedrock.

Tempest AKA Tempestite

Distinct sed. Bed or deposit created by a violent storm

Hardground

A hardened, lithified seafloor; forms when carbonate sediments are cemented together by minerals on the ocean floor during a prolonged pause in sediment accumulation; indicates a sharp boundary between two rock units

Sed. Rocks are Important because…

• most common rock

• 66 percent of the earth’s surface

• On avg. 1800 m thick

• Supply natural resources

• Most significant aquifers on the planet

Aquifer

Underground layer of water-bearing permeable rock, gravel, sand, or silt that stores and transmits groundwater

Watershed

An area of land where all rain and melting snow drain downhill into a single common body of water

What are sed. Rocks?

• sediments that accumulate in fluids

• They form at/near surface conditions

• They consist of chemical/biochemical precipitates or fragments of grains of rocks, minerals, or fossils

What are fluids?

• water, ice, air, and viscous fluids

Eolianite

Rock formations created by lithification of wind-blown sand dunes

Lithification

Turning into stone

Tillite

A hard sed. Rock formed when loose glacier debris is compressed and cemented together over millions of years

Sediments

Broken-up, eroded rocks

Carbonic acid…

Breaks down rocks

What are the 4 types of sed. Rocks?

Lithogenous, biogenous, hydrogenous, and cosmogenous

Lithogenous

Derived from weathering of rocks/lithics

Biogenous

Derived from organisms

Hydrogenous

Precipitated from water

Cosmogenous

Extra-terrestrial sed. Formed from meteoric debris

Viscous

Resistant to flow (ketchup)

Lahar

Volcanic debris flow

Volcanic Clastics

Wind and water laid stuff

Bentonite

Ash-layer

What are the characteristics of sed. Rocks?

1. Consolidation of loose sediments cemented together

2. Layering

3. Fossils

4. Sedimentary structures

5. Follow laws of superposition and original horizontality

Sedimentary structures

Bedding, ripple marks, mudcracks, bioturbation, fluid escape structures, etc.

Bioturbation

Disruption of sed. Layers by burrowing, tunneling, or feeding activities of living organisms

Geochronologic definition

Units in absolute time; lower>middle>late

Geochronologic units

Eons>eras>periods>epochs>ages

Chronostratigraphic def.

Time-rock units; time intervals in which a rock is deposited; lower>middle>upper

Chronostratigraphic units

Eonothem>erathem>system>series>stage

Tertiary-Quaternary Time

2.6 Million years

Paleozoic-Mesozoic time

252 million years

Paleozoic-Mesozoic time

252 million years

Precambrian-Cambrian time

541 million years

Archaen-Proterozoic time

2.5 billion years

Hadean-Archaen time

4 billion years

Thousands of years

Ka

Thousands of years

Ka

Millions of years

Ma

Billions of years

Ga

GSSP

Global Boundary Stratotype Section & Point “Golden Spike”

Defines the lower boundary of a geologic stage

GSSP

Global Boundary Stratotype Section & Point “Golden Spike”

Defines the lower boundary of a geologic stage

Lithostratigraphic Units

Units we map in the field; a defined body of sedimentary, extrusive igneous, meta sedimentary, or meta volcanic strata that is distinguished by lithic characteristics and stratigraphic position.

Lithostratigraphic Rules

1. Boundaries placed at positions of lithic change

2. Fundamental unit is formation, a mappable unit on the earth’s surface

3. Each unit has a binomial name derived from the type locality (ex: camp Nelson (1) formation (2))

4. Basic units: supergroup>group>formation>member>bed

Biostratigraphy

Focuses on correlating and assigning relative ages of rock strata by using the fossil assemblages contained within them.