GEOL 440 Sedimentology and stratigraphy:

processes, environments and deposits

Jim Bestand

Bruce Fouke

MWF: LecturesF: Laboratory Class

Lecture 1: Scope, assessment and structure of course; Introduction to Sedimentologyand Basic Definitions: uses and applications of Sedimentology.

•What is this course about?• How do I get the most out of this

course?

The purpose of this course is to provide an integrated overview of the sciences of sedimentology and

stratigraphy. State-of-the-art analytical tools will be integrated with the latest theoretical concepts on

deposition and diagenesis to provide a comprehensive answer to the questions "What is the origin of a sedimentary rock?" and “How can the study of sedimentary processes help us better understand ancient environments and manage

modern environmental change”.

Course materials and textbooks

Handout -course outline

Handouts/lecture notes

Other texts and journal papers……

essential

Course materials and textbooks

Use Boggs for parts of course

Assessment•Types

•Deadlines•Curves

Questions?

Any previous knowledge of sedimentology?

THE KEY - PROCESSES

A general approach…..

1) Present is the key to the past (yes, but lets discuss!)2) Observe the ancient3) Do the inverse problem

techniques

interregional mappingseismic imaging

seismic imagingregional mappingwell correlation

local mappingoutcrop/core studiesfacies analysisthin sections

Types of Sedimentary Rocks

Siliciclastic

Biogenic, biochemical& organic

Chemicalsediments

conglomerates and breccias,sandstones and mudrocks

limestones (& dolomites),cherts,

phosphates & coals

evaporites,ironstones

ignimbrites, tuffs,debris flowsVolcaniclastic

Some examples of sedimentary environments & rocks

think about how we can best interpret the depositional environment

from the rock record

(i.e. what do we need to know as a sedimentary forensic scientist!)

Source

Sink

fluvial transport

landslides

glacialerosion

fjords

shoreline

Stratigraphy

shelf break

fans

abyssal plainsor basin floor

openslopes

deltaic & estuarinetrapping

tidewater

glacial runoffstreams

floodplainsprimary

productivity

Coral reefs

weathering

hillslopeerosion

shelf

Sedimentary environments: the framework

Source

Sink

Sedimentary environmentsLets take a tour around some modern

environments & their ancient equivalents.

Deserts

Algeria

Deserts

aeolian dunes

capped by basalt

TheNamib Desert

Rivers

Rakaia River, NZ

c.5 km

Rivers

• modern process• ancient product

The joining of thePadma & MeghnaRivers, Bangladesh.

c.3 km

Rivers

…. and fans

Rakaia River, NZ

Rivers … some deposits

• process• environment• geometry

Palaeo-Rakaia River deposit,Canterbury Plains,

NZ

Rudite/ conglomerate

Sandstone

Bedforms

Soft-sediment deformation

Deltas(& deserts)

The Nile Delta

190 km

Deltas –Mississippi

• process• environment• thickness• variability• porosity/perm• structural control• palaeoclimate

Deltas

The Ganges Delta

354 km

Deep Sea environmentsDelta front

Shelf

Canyons

Sinuous submarinechannels

Offshore SE Indonesia

• Mass movements• Drift deposits• Gravity flow deposits• Storm deposits

Salt lakes:Lake Eyre,Australia

20th December 1983

22nd February 1984

Salt lakes

4th March 1985

27th October 1984

Salt lakes … deposits

Evaporite

Differences between ‘clastics & carbonates

In carbonate environments, sediment is generally produced in-situ

In ‘clastic sediments thegrains & matrix are

usually the result of disintegration of the

parent rock, & transport into the depositional

environment

Carbonates

Carbonates - reefs

Brain corals

Modern carbonate sediments are mainly composed of two minerals: calcite and aragonite.

Carbonates

Carbonate formation may result in the following rocktypes:

limestone,chalk,dolomite.

Volcaniclastic

Resultant deposits: • pyroclastic flows• debris flows/lahars• ash beds

Mt. St. Helens

Volcaniclastic

Mt. St. Helens

So …what and where's this?

OpportunityMars Rover

OK…but you are asking…….why is Sedimentology important?

…… so name a few?

• oil, gas and coal (source, reservoir and seal)

• detrital sediments - heavy metals (e.g gold), diamonds etc

• industrial minerals - sandstones, clays, aggregates

• modern environments - management & planning (e.g. groundwater)

• input to environmental engineering

•deciphering ancient climates and climate change

Reading for this time: B&D Chapter 1 “Definitions, rationale…’ or Boggs Introductory few pages (xvii-

xix) and look at structure of B&D text (main chapter headings etc)

Next time: a very brief history of the subject and we’ll begin to look at weathering and sediment production……..