SEDIMENTOLOGI dan STRATIGRAFI(1)

PRINSIP DASAR

Hadi NugrohoPS TEKNIK GEOLOGI

UNIVERSITAS DIPONEGOROSEMARANG

2009

Sedimentology• the study of sedimentary rocks

and the processes by which its formed, origin, classification and

interpretation ◦ origin

◦ burial◦ deposition

◦ dispersal, distributionof natural sediment grains

Sedimentology

• Descriptive Approach: - Traditional Petrology & Petrography

- Facies Analysis

• Quantitative Approach:- Physical and Chemical Sciences

Stratigraphy

• Is the science of rock strata.

• It is concerned with all aspect of the study of sedimentary rocks,

interpreted to apply to all stratified rocks, including layered metamorphic

and igneous rocks.

• It is concerned withall characters and attributes of rocks

as strata; and their interpretation in termsof mode of origin and

geologic history

STRATIGRAPHY :• the science of rock strata

What is strata ?

Strata (plural of stratum) :

A layer of sedimentary rocks, visually separable from other layers above and below; a bed.

Strata due to different color or minerals composition

Strata due to sedimentary structure (cross bedded)

Kolom Stratigrafi

STRATIGRAPHIC RECORDSingkapan

Dynamic of Sedimentation and

Sequence Stratigraphy

• How sedimentary rock is accumulated• Factors controlling process

Stratigraphic Record and its pattern

Sedimentologi & Stratigrafi

ROCKS CYCLE

MAGMA

IGNEOUS ROCKSMETAMOPHICROCKS

SEDIMENTARYROCKS

SEDIMENTS

meltingcrystallization

metamorphism

denudation processes

metamorphism

weatheringerosiontransportationdeposition

Diagenesis processes :compactiondesiccationcementationre-crystalizationlithification

ROCK CYCLE AS IT RELATES TO THE PLATE TECTONICS MODEL

THE ORIGIN OF SEDIMENTARY ROCKS

Fine Detritus

SiltstoneClaystone

Marl

Evaporite

GypsumAnhidrite

Salt

Coarse Detritus

BrecciasConglomerate

Sandstone

Coal

PeatBituminousAnthracite

Carbonate Rocks

MECHANICAL SEDIMENTATION

CHEM

ICAL SEDIMENTATIO

N ORG

ANIC

SED

IMEN

TATI

ON

CrystallineLimestone

ReefalLimestone

Wackstone, Packstone, Grainstone , etc.

Oolitic Limestone

Dolomite

Diatoms Earth

ChertFertirite

Silica sediment

Grouping of Sedimentary Rocks and Its Processes( PETROGENESIS )

Accommodation Space

DYNAMICS OF SEDIMENTATION

SEISMIC CENTRAL SUMATRA BASIN

Proses Deposisi dari

Formasi Pematang

Riau

CONCEPTS in

STRATIGRAPHY

CONCEPTS IN STRATIGRAPHY

STENO’S PRINCIPLES (1669)Superposition of Strata

Original Lateral Continuity of StrataOriginal Horizontality of Strata

Collorary: Vertical Accumulation of Strata

CROSS-CUTTING PRINCIPLE veins, dykes etc were known to cut across the

country rock: the rocks cutting across a country rock are younger than the country.

LAW OF SUPERPOSITION (STENO, 1669)

• Law of Superposition:• “The youngest strata are at top in an

undisturbed sequence” (Anthony, 1955, p. 83).

HORIZONTAL LATERAL CONTINUITY (STENO, 1669)

• Law of Original Continuity: • “The original continuity of water-laid

sedimentary strata is terminated only by pinching out against the basin of deposition, at the time of their deposition”

• (Anthony, loc.op.cit, p.83).

ORIGINAL HORIZONTALITY (STENO, 1669)

• Statement of Principle: Dipping beds were once horizontal (Woodford, 1935, p.3)

• Modified Statement: • Law of horizontality: • “Sedimentary strata are laid down nearly

horizontally and essentially parallel to the surface upon which they accumulate” (Anthony, loc op cit., p.83).

• Statement of principle: A mid all the revolutions of the globe, the economy of nature has been uniform ... and her laws are the only things that have resisted the general movement. The rivers and the rocks, the seas and the continents have been changed in all their parts; but the laws which direct these changes, and the rules to which they are subject, have remained invariably the same. (Playfair, Illustrations of Huttonian Theory of the Earth, 1802, p.421, quoted by Woodford, op.cit., p.6).

• Modified Statement: ‘The present is the key to the past’.

UNIFORMITARIANISM (HUTTON, 1785)

PRINCIPAL OF CROSS-CUTTING RELATIONSHIP

Fault cross throughout a succession of rocks is youngerthan the youngest rocks crossed by the fault

A folding process on a succession of sedimentary rocks occurred after the deposition of the youngest folded strata

Intrusion of igneous rocks into a succession of rocksoccurred after the intruded youngest rocks

Examples ………

CROSS CUTTING RELATIONSHIP

PRINCIPLE OF CROSS-CUTTING RELATIONSHIP

LAW OF FAUNAL SUCCESSION (ABBE GIRAUD-SOULAVIE, 1777)

Statement of principle:Fossil differs according to their geologic ages (stratigraphic position); fossils in lower formations are unlike those in higher beds. Fossil floras and faunas succeed one another in a definite and determinable order (Anthony, 1955, p.89)

Modified Statement: Strata can be distinguished by their characteristic fossils (Woodford, 1935, op.cit, p.5-6; Schenk, 1940, p. 1754-1755)

STRATA IDENTIFIED BY FOSSILS (SMITH, 1816)

LAW OF FAUNAL SUCCESSION STRATA IDENTIFIED BY FOSSILS

PRINCIPLE OFBIOSTRATIGRAPHIC CORRELATION

PRINCIPLE OF UNIFORMITARIANISM

“THE PRESENT IS THE KEY TO THE PAST”

The same external and internal processeswe recognize in action today have been operating

throughout the Earth’s history

APPLICATION OF STRATIGRAPHIC CONCEPTS

THREE BASIC TYPES OF UNCONFORMITIES

CONCEPTSAPPLICATION :

What’sHappened

?