Stratigraphy. The part of geology that deals with the formation, composition, sequence, and correlation of rocks, especially stratified rocks

Transcription

1 Stratigraphy The part of geology that deals with the formation, composition, sequence, and correlation of rocks, especially stratified rocks Limestone Sandstone Shale 1

2 Stratigraphy The part of geology that deals with the formation, composition, sequence, and correlation of rocks, especially stratified rocks underpins all of geology Limestone Sandstone Shale 1

3 Stratigraphy The part of geology that deals with the formation, composition, sequence, and correlation of rocks, especially stratified rocks underpins all of geology deals especially with time element Limestone Sandstone Shale 1

4 Stratigraphy The part of geology that deals with the formation, composition, sequence, and correlation of rocks, especially stratified rocks underpins all of geology deals especially with time element supplies 4th dimension for localizing geological material Limestone Sandstone Shale 1

5 Stratigraphy The part of geology that deals with the formation, composition, sequence, and correlation of rocks, especially stratified rocks underpins all of geology deals especially with time element supplies 4th dimension for localizing geological material essential for studies on evolution and environmental change through time Limestone Sandstone Shale 1

6 Main activities Lithostratigraphy: establishing the geometrical shape and spatial relationship of rock bodies Establishing a formal (relative) time framework - chronostratigraphy Determining numerical ages for units, i.e. geochronology Correlating successions with one another and with the chronostatigraphical standard: often by using biostratigraphy 2

7 Lithostratigraphy The part of stratigraphy dealing with the lithology of strata and with their organization into units based on lithological character. 3

8 Lithostratigraphy The part of stratigraphy dealing with the lithology of strata and with their organization into units based on lithological character. Biostratigraphy The part of stratigraphy dealing with the fossil content of strata and with their organization into units based on the distribution of fossils. 3

9 Lithostratigraphy The part of stratigraphy dealing with the lithology of strata and with their organization into units based on lithological character. Biostratigraphy The part of stratigraphy dealing with the fossil content of strata and with their organization into units based on the distribution of fossils. Chronostratigraphy The part of stratigraphy dealing with the recognition of named units corresponding to intervals of geological time to serve as a reference system for recording events in geological history. 3

10 Formation- Member-Beds: lithostratigraphic units Salvador (1994) 4

11 Different biostratigraphical units: biozones Salvador (1994) 5

12 Geophysical units Salvador (1994) 6

13 Salvador (1994) 7

14 Lithostratigraphy The part of stratigraphy dealing with the organization of rocks into units based on their lithological character. Formation C Formation B Formation A 8

15 Strata are continuous and of the same thickness over long distances F E D C B A 9

16 Diachrony - age of lithological units varies laterally

17 Biostratigraphy 11

18 Biostratigraphy The part of stratigraphy dealing with the distribution of fossils in the stratigraphical record and the organization of strata into units based on the basis of their contained fossils 11

19 Biostratigraphy The part of stratigraphy dealing with the distribution of fossils in the stratigraphical record and the organization of strata into units based on the basis of their contained fossils Biostratigraphical units are termed biozones, e.g. Globigerina brevis Biozone (note capital B in Biozone) 11

20 Biostratigraphy The part of stratigraphy dealing with the distribution of fossils in the stratigraphical record and the organization of strata into units based on the basis of their contained fossils Biostratigraphical units are termed biozones, e.g. Globigerina brevis Biozone (note capital B in Biozone) Hierarchy of Superbiozones (Superzones), Biozones (Zones), Subbiozones (Subzones) 11

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25 Correlation of strata by their contained fossils independent of lithology: Biostratigraphy species biozone 13

26 Correlation of strata by their contained fossils independent of lithology: Biostratigraphy species biozone 13

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28 SBZ 3 14

29 P4c P4a, b SBZ 3 14

30 Biozones may be diachronous Envelope of species distribution A B C D E time later disappearance Time later first appearance Geographic range Space 15

31 Index fossils Widely distributed Abundant in the fossil record Facies independent Evolve rapidly so that biozones are of short duration Easily identifiable 16

32 Index fossils Widely distributed Abundant in the fossil record Facies independent Evolve rapidly so that biozones are of short duration Easily identifiable Deep vs shallow marine 16

33 Chronostratigraphy The part of stratigraphy dealing with the relative time relationships and ages of rocks. 17

34 Chronostratigraphy The part of stratigraphy dealing with the relative time relationships and ages of rocks. Chronostratigraphical units are bodies of rock that were formed during a specified interval of geological time. 17

35 Chronostratigraphy The part of stratigraphy dealing with the relative time relationships and ages of rocks. Chronostratigraphical units are bodies of rock that were formed during a specified interval of geological time. The intervals of time during which chronostratigraphical units were formed are called geochronological units. 17

36 (Salvador 1994, pp ) 18

37 sand = chronostratigraphical unit (Salvador 1994, pp ) 18

38 sand = chronostratigraphical unit time taken for sand to pass through hourglass = geochronological unit (Salvador 1994, pp ) 18

39 Chronostratigraphy and Geochronology 19

40 Chronostratigraphy and Geochronology Stage (and Age) 19

41 Chronostratigraphy and Geochronology Stage (and Age) basic working unit of chronostratigraphy 19

42 Chronostratigraphy and Geochronology Stage (and Age) basic working unit of chronostratigraphy normally the lowest ranking unit that can be recognized on a global scale 19

43 Chronostratigraphy and Geochronology Stage (and Age) basic working unit of chronostratigraphy normally the lowest ranking unit that can be recognized on a global scale variable in time span, but most stages are 2-10 million years long 19

44 Chronostratigraphy and Geochronology 20

45 Chronostratigraphy and Geochronology Chronozones 20

46 Chronostratigraphy and Geochronology Chronozones chronostratigraphical units 20

47 Chronostratigraphy and Geochronology Chronozones chronostratigraphical units corresponding geochronological unit is the chron 20

48 Chronostratigraphy and Geochronology Chronozones chronostratigraphical units corresponding geochronological unit is the chron comprise the body of rocks formed anywhere during the time span of some designated stratigraphical unit (e.g. a biozone) or geological feature (e.g. Deccan Traps volcanism) 20

49 Chronostratigraphy and Geochronology Chronozones chronostratigraphical units corresponding geochronological unit is the chron comprise the body of rocks formed anywhere during the time span of some designated stratigraphical unit (e.g. a biozone) or geological feature (e.g. Deccan Traps volcanism) named according to the stratigraphical unit on which it is based, e.g. Exus albus Chronozone is based on Exus albus Range Zone 20

50 What is relevant to our work? 1) A fossil out of context is very difficult to place in a stratigraphical framework 2) Southeast Asia is tectonically highly active, often resulting in restricted lateral extension of facies 3) Current climate is favours rainforest development 4) Combined this makes lithostraitgraphical correlation difficult, and we need to get as much as possible out of those outcrops we have available 5) Most stratigraphical units that we are using are defined outside our region of interest. 21

51 Southeast Asian Letter classification Originally formulateed as chronostratigraphical units, but later often interpreted as Larger Benthic Foraminifera Biozones Epoch/Stage Biozone Tf3 Burdigalian- Serravallian Aquitanian Late Oligocene Early Oligocene Late Eocene Paleocene- Middle Eocene Tf1-2 Te5 Te 1-4 Td Tc Tb Ta 1) Improve correlation with less local stratigraphic schemes 2) In some way formalize this biostratigraphical zonation so that a. regional differences can be discussed b. Our findings can be placed in a global context 22

52 Regional stratigraphic schemes Stratigraphic schemes can not be horizontally relocated to other regions Stratigraphic ranges of species differ 23

53 Stratigraphy 24