7-8 PRINSIP DASAR STRATIGRAFI- Nicolas STENO- William SMITH

Stratum Strati : tingkat(an) Grafi / grafik : penggambaranMakna Stratigrafi secara harfiah : penggambaran tingkat(an) Dalam arti yang luas (makna dalam geologi) : Penggambaran hubungan (tingkatan) antar (lapisan) batuan vertikal maupun lateral dalam ruang dan waktu

STENOS PRINCIPLES (1669)Superposition of Strata Original Lateral Continuity of StrataOriginal Horizontality of StrataCollorary: Vertical Accumulation of Strata

LAW OF SUPERPOSITION (STENO, 1669)Modified statement: Law of Superposition:The youngest strata are at top in an undisturbed sequence (Anthony, 1955, p. 83

WRLitostratigrafiABCD A > B > C > D

CONCEPT OF STRATAStrata, stratum, beds, layerStratification/ bedding/ layeringStrata as a basic concept in geologyConcept of Strata is important in understanding correlation and time relationships Concept of Strata is important in understanding of reservoir rocks and seals

IDENTIFICATION OF STRATA AND STRATIFICATIONVertical change in lithologyCharacteristics vertical variations in lithology such as : Grain size, Color, Mineralogy, etcSome degree of lateral continuityVertical changes and variations in lithology varies from extremely thin, laminae, to very thick

THE NATURE OF VERTICAL BOUNDARIES OF BEDSGRADUAL OR TRANSITIONALABRUPT OF SHARPEROSIONALTRUNCATIONDISCONTINUITIES: gaps or breaks in deposition are quite common in stratal sequences.

CAUSES OF STRATIFICATIONStrata and stratification is caused by changes in the depositional regime, mechanical energy, chemical of biologicalChanges are caused by climate/weather, sea level change or tectonics/sediment supplyChanges may take place daily, annually or even in millions of years

BED AS BASIC LITHOLOGIC UNITGenerally a uniform unit of lithologyThickness varies from laminae to extremely thickVertical boundaries of strata are considered depositional interfaceLithology of a bed may change laterally but in an extremely gradual way

THE TIME SIGNIFICANCE OF STRATAStenos Law of Superposition implies that stratal or depositional surfaces are isochronous time surfacesA stratum or a packet of strata represents of time period of deposition or contemporaneous depositionSeismic reflection surfaces are stratal surfaces and being former bedding surfaces they are geologic time surfaces and are essentially synchronous (Vail et al, 1977)

STRATA IDENTIFIED BY FOSSILS (SMITH, 1816)Modified Statement: Strata can be distinguished by their characteristic fossils (Woodford, 1935, op.cit, p.5-6; Schenk, 1940, p. 1754-1755)

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)

LAW OF FAUNAL SUCCESSIONIn a succession of strata units can be identified by the specific assemblage of the fauna of its fossil content top The fauna of the fossil content resembles closer to the modern fauna as one goes toward the topA geologic time scale can be established based on the faunal succession.

WREvolusiBiostratigrafiPaleontologi > >

WRLitostratigrafiABCD A > B > C > D

WREvolusiBiostratigrafiPaleontologi > > A > B > C > D

WRABCD A > B > C > DEF12 E () > F ()BAGAIMANA GABUNGAN/KORELASI 1 DAN 2 ??Lito vs Biostratigrafi

WRABCD A > B > C > DEF12 E () > F ()(A>B) = E () > { C () > D () } =F [(- ) > ]Lito vs Biostratigrafi

WREvolusiLitostratigrafiBiostratigrafiPaleontologi

HORIZONTAL LATERAL CONTINUITY Steno, 1669)Modified statement: 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)

STRATAL CONTINUITY AND CORRELATIONStenos Law of Stratal Continuity established that strata or bed can be traced laterally indefinitely(?)William Smiths Law established that a bed (ls, ss, sh etc) can be identified in different sections by its fossil content Correlation by fossil Correlation is essentially lateral tracing of beds Stratal Continuity = time continuityAs bedding planes or stratal interface are isochronous, correlation is interpreted as establishing time relationships of strata

LATERAL CONTINUITY VS LATERAL TERMINATIONStenos Law of Lateral Contintuity of strata: Strata continues laterally except at the edge of the depositional basin or being truncatedSequence Stratigraphy Lateral Termination of Strata: All strata terminates laterally by lapping out towards the base as well towards the top of the sequence boundary.

LATERAL TERMINATION OF STRATABase-lappingDown-lapping towards the open seaOn-lapping toward landTop-lappingOff-lapping

LATERAL TERMINATION OF STRATA

STRATAL PATTERN OF LATERAL ACCUMULATION

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)

GREZZLYS CONCEPT OF FACIES

CLINOFORM DEPOSITION

VERTICAL VS LATERAL ACCUMULATION OF STRATA

STRATAL PATTERN OF PROGRADATION, RETROGRADATION AND AGRADATION

TUGAS 2

BAGAIMANA PANDANGAN SAINS TERHADAP PENCIPTAAN, DAN APAKAH PENCIPTAAN ITU SAINS ?

TERIMA KASIH

ELCAPITAN FACIES CHANGES