Geologic History of Texas: The Making of Texas Over 1.5 Billion Years

Transcription

1 # 4 Geologic History of Texas: The Making of Texas Over 1.5 Billion Years Dr. Richard Kyle March 24, 2000 Produced by and for Hot Science - Cool Talks by the Environmental Science Institute. We request that the use of these materials include an acknowledgement of the presenter and Hot Science - Cool Talks by the Environmental Science Institute at UT Austin. We hope you find these materials educational and enjoyable.

2 Geologic History of Texas: The Making of Texas over 1.5 Billion Years Geologic History of Texas: The Making of Texas over 1.5 Billion Years J. Richard Kyle Department of Geological Sciences The University of Texas at Austin

3 Acknowledgments I am grateful to many individuals who have contributed to my understanding of the geologic history of Texas, particularly present and former colleagues at The University of Texas at Austin in the Department of Geological Sciences, the Bureau of Economic Geology, the Institute for Geophysics, and the Texas Memorial Museum. These individuals and institutions have contributed many of the illustrative materials contained in this CD-ROM. The presentation contained herein was made by J. Richard Kyle and is intended for educational purposes only. Any use of this work, partial or complete, must cite J. Richard Kyle and this Outreach Lecture Series Volume 4. No portion of this product may be reproduced or distributed in any form. March 2000

4 3. Texas Today

5 Plate Tectonics

6 Texas Geography Austin

7 Texas Geology Austin

8 7. Geologic time scale major Texas events

9 Geologic Time Principles 8. Geologic Time Principles Several geologic principles are fundamental to using the rock record to interpret processes. Original Horizontality: Most rocks that form at the Earth's surface are deposited in essentially horizontal layers. Therefore, when layered rocks are not horizontal, they probably have been affected by postdepositional processes such as a tectonic event. Superposition: When layered rocks are formed, they are deposited in an orderly sequence with the oldest being at the base of the sequence and the strata becoming progressively younger upward. Therefore when a sequence of rocks differs from the predicted sequence, or layers are missing, then an explanation for the cause of these differences is required. Cross-cutting Relationships: Features such as faults or igneous intrusions generally cross-cut or affect all rocks that were present locally at the time of the faulting or intrusive event. Uniformitarianism: Present Earth processes are useful in understanding the types and rates of processes that have affected the Earth during past periods of geologic history.

10 Central Texas roadcut

11 Llano stratigraphic column

12 Time Interpretation Based on Llano Stratigraphic Column Llano rocks D B C A Geologic Time D Erosion Mesozoic Erosion C Erosion Paleozoic B Erosion 0 Ma A Proterozoic

13 Central Texas geologic map

14 Deformed metamorphic rocks cut by granite dike Intrusive dike crosscutting folded metamorphic rocks.

15 Enchanted Rock

16 Granite slabs

17 Tectonic Model for the Precambrian History of the Llano Region

18 Tibet Plateau Himalayas Himalayas India

19 Late Proterozoic Position of Texas

20 Precambrian Paleozoic time chart

21 Complex topography on Enchanted Rock

22 Great Barrier Reef, eastern Australia Tree Covered Island Bird

23 PLATES Lower Paleozoic reconstruction

24 Lower Paleozoic life panorama

25 Marathon map Marathon Uplift

26 Marathon exposures Dip direction Flat-lying Cretaceous Limestones Haymond Formation

27 Caballos Novaculite aerial exposures

28 Marathon tectonic evolution

29 New Guinea

30 PLATES Late Paleozoic

31 Ouachita Orogeny and Formation of the Permian Basin

32 Delaware Basin

33 Delaware Basin Section

34 El Capitan Reef

35 Permian Basin filling by Evaporites OPEN OCEAN

36 Evaporation

37 Potash-bearing salt at Carlsbad

38 Mesozoic Cenozoic time chart

39 PLATES Early Mesozoic

40 Rifting and Formation of the Gulf of Mexico Basin

41 Death Valley, California Volcano Salt Lake

42 Gulf of Mexico Pacific Connection

43 Distribution of northern Gulf of Mexico Salt Diapirs

44 East Texas Basin Salt Structures

45 Salt in a Salt Dome Mine

46 Distribution of Cretaceous Limestones

47 Cretaceous Limestone Exposures along the Colorado River in Austin

48 Cretaceous Volcanoes in Central and South Texas Pilot Knob Uvalde area

49 Hawaii volcano

50 Cretaceous Interior Seaway

51 West Texas Cretaceous Stratigraphy

52 Clean up Formation of the Rocky Mountains

53 Mesozoic Life Dinosaurs

54 PLATES End Cretaceous Asteroid Impact

55 Subduction off the Western Coast of Southern North America

56 Mid-Tertiary Volcanic Field

57 Explosive Volcanic Eruption

58 Bofecillos Mountains ignimbrites

59 West Texas caldera field

60 Laccolith Formation Corazones Peaks (laccoliths)

61 Solitario

62 Gulf Coast sedimentary sequence

63 Louisiana Bayou

64 Tertiary Lignite Deposits in East Texas

65 Gulf of Mexico Shoreline since the Cretaceous

66 Ogallala Formation OGALLALA FORMATION

67 Pecos River Headward Erosion

68 Rifting in West Texas and New Mexico

69 Salt Basin Guadalupe Peak (8,749 feet) El Capitan

70 Cave Decoration at Carlsbad

71 Late Cenozoic Life

72 Ice Ages

73 Barrier island development

74 Texas Coastal Bend Brazos River Delta Corpus Christi Bay Mississippi River Delta Barrier Island Gulf of Mexico

75 Padre Island

76 Conclusion: Conclusion The geologic history of Texas is recorded in rocks that are exposed throughout the state and fill sedimentary basins. These rocks document more than a billion years of change. Those changes include the building and erosion of major mountain ranges, explosive volcanoes, strong earthquakes, vast deserts, evaporating salt basins, tropical forests, river and delta systems, tropical seas and barrier reefs, and beaches and barrier islands. Erosion of highlands filled subsiding sedimentary basins and adjacent continental margins. Colliding plates deformed, metamorphosed, and uplifted these materials to continue the rock cycle. Texas' abundant and varied mineral resources are products of these geologic events.

77 Professor Richard Kyle Richard Kyle is the Third C. E. Yager Professor of Geology at The University of Texas at Austin. He received a Ph. D. from the University of Western Ontario and worked as a minerals exploration geologist for several companies prior to joining the UT faculty in Kyle is the author of more than 75 publications, including writing or editing six books. His research contributions have been recognized by awards from regional and national professional societies. Professor Kyle is the Editor of Ore Geology Reviews, an international economic geology journal. His teaching responsibilities and research interests include Texas geology, ore deposits geology and geochemistry, minerals exploration, industrial minerals, and multimedia approaches to geoscience education. He has received departmental and college awards for teaching, program development, and student advising. Since1988, Kyle has taught a nonmajors course on the Geology and Mineral Resources of Texas.