mesozoic geology

1: Mesozoic Geology

2: Introduction The Mesozoic began 248 mya and ended 65 mya Three periods - Triassic, Jurassic, Cretaceous breakup of Pangaea was the major geologic event tectonism and sedimentation are used to classify the Mesozoic in N. America Note the overlap in three styles of Cordilleran Orogeny

3: Tectonism and Sedimentation

4: 1. The Breakup of Pangaea The movement of continents during and after the breakup affected global climate and oceanic regimes as well as that of individual continents ocean basins were created or closed before new mountain ranges were built sea-level changes

5: Pangaea - Early Triassic

6: Late Triassic � Rifting E Orogeny W

7: Pangaea � Early Jurassic

8: E Jurassic � Atlantic Rift Shallow

9: E Jurassic � Another Look

10: Pangaea � Jurassic

11: Late Jurassic � Early Cretaceous

13: Late K � Epeiric Sea until 70 mya

14: Mesozoic Global Climates Carbonates (for example the stable isotope index d13C) reveal large concentrations of carbon dioxide present in the Mesozoic atmosphere. This suggests a greenhouse climate. No glaciers, no coal, so CO2 abundant. Greenhouse gasses pass sunlight which hits the land and sea. Re-radiate heat (IR) Greenhouse gasses hold the heat, not lost to space as quickly. Warmer equilibrium.

15: Global Climates in the Mesozoic

16: Next: Mesozoic Tectonics NA Cretaceous : global rise in sea level until 75 -70 mya, vast MOR Jurassic: Atlantic opens E, began building the Cordillera W, Gulf of Mexico begins to form and experiences evaporite deposition Late Triassic: Begin rifting in East

18: Late Triassic: Rifting opens the Atlantic The Newark Supergroup documents the rifting of Pangaea to form the Atlantic Early Triassic saw coarse detrital sediments deposited from the erosion of Appalachian highlands fault-block basins developed as N. America separated from Africa and filled with nonmarine sediment plus dikes and sills eroded to a flat plain by the Cretaceous

19: Mesozoic rift basins

20: Structure of the Newark basin

21: Lake cycles, East Berlin formation

22: E. Jurassic Gulf Coast Evaporites

23: Gulf Coastal Region First, as continents separate, restricted basin, thick evaporites formed in the Gulf Normal marine deposition returned to the Gulf by Late Jurassic, with transgressions and regressions thousand of meters of sediments were deposited

24: Gulf Coast continental margin

27: Next: Western North AmericaTectonics Building the western margin of North America and the Cordillera

28: Western Region Cordilleran Orogeny Laramide - built the present day Rockies K-Tertiary Sevier � J-K thrust faulting to the east Nevadan - Jurassic batholith intrusion in the Sierra Nevada and elsewhere on the western edge

29: Displaced terranes � Western Cordillera

30: Western Margin during Orogens

31: Sierra Nevada Mountains

32: Mesozoic orogenic events

33: Buoyant Subduction Laramide Orogeny

34: Sevier thin-skinned deformation

35: Sevier thrust belt

37: Look in detail at western plate margin

38: Next: Mesozoic Sedimentation on the Craton Cretaceous extensive marine deposition, thin to the east Jurassic clean cross-bedded sandstones marine sediments in the Sundance Sea Triassic shallow-water marine clastics red beds

39: North America - Triassic

40: Late Triassic Chinle Fm.

41: Triassic caliche paleosol- Nova Sc.

42: North America - Jurassic period

43: Sedimentation

44: Jurassic Eolian sandstone

45: Jurassic Morrison Formation

46: Fossils of Jurassic dinosaurs

47: Late Cretaceous really big epeiric sea

50: Dakota Sandstone

51: Then, at 75-70 my, Regression

53: 75 mya Regression

54: K-T Boundary