Chapter 2 Sedimentary paleogeography- 4 2.1 concepts and law 2.2 sedimentary-facies indicators 2.3 sedimentary environments
Chapter 2 Sedimentary paleogeography-4 2.1 concepts and law 2.2 sedimentary-facies indicators 2.3 sedimentary environments
How to reconstruct paleoenvironments Fossils Lithofacies Geochemistry Taxonomic uniformitarianism: Actualism: comparison Interpretation of chemical comparison with nearest living with products of signatures: comparison with relatives and communities present-day processes present-day signatures and known controls Determination of physical Determination of physical Determination of chemical and biological aspects of aspects of environment spects of environment environment Palaeoenvironmental model Figure 16.1 The palaeoenvironmental model: determination of palaeoenvironments fron fossils, lithofacies and geochemistry
How to reconstruct paleoenvironments
Fluvial Braided stream Meandering stream Sand dune Desert Alluvial f: Continental Playa lakes environments Ice deposition moraines) Glacial Fluvial deposition Outwash) Glacial lakes Stream dominated Delta Wave dominated Tide dominated Transitional environments Beach Beach Barrier island Sand dune Lag detrital Continental deposition shelf deposition Carbonate Marine platform environments Continental Submarine fansⅵ slope and rise (turbidities) Deep-ocean Oozes basi Pelagic clay Evaporite nvironme
Classifications of Sed. Environments - I
sediments
Fluvial sediments
Active only at Braided and meandering stream flood stage heart bar In-channe a Mud deposited in abandoned channels (b) Point bar N Point bar belt Channel deposits Floodplain deposits (d) FIGURE 4.13 (a)A braided stream near Chester, California. (b)Facies model for a braided stream system. Braided streams deposit mostly sand and gravel with subordinate mud.(c)A meandering stream, otter Creek in Yellowstone National Park, Wyoming. Point bars are well developed on the inside banks of each meander. (d) Facies model for a meandering stream system. Meandering stream deposits are shoestring sands sur- rounded by mudstones
(b) (a) Point bar (d) Point bar heart bar (C) Braided and meandering stream