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EES 450: Sedimentary Geology

EES 450: Sedimentary Geology. INTRODUCTION ● Sedimentary petrology: - Study of sedimentary rocks (field, megascopic, microscopic) ● Sedimentary petrography: - Description and classification of sedimentary rocks, especially through microscopic examination

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EES 450: Sedimentary Geology

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  1. EES 450: Sedimentary Geology INTRODUCTION ● Sedimentary petrology: - Study of sedimentary rocks (field, megascopic, microscopic) ● Sedimentary petrography: - Description and classification of sedimentary rocks, especially through microscopic examination ● Sedimentary petrogenesis: - Origin and formation of sedimentary rocks

  2. EES 450: Sedimentary Geology INTRODUCTION ● How do we learn about sedimentary processes and rocks? - Classroom lectures and guest lectures - Laboratory work with hand samples and thin sections - Field examples - Combining all of the information together to allow us to think at higher levels

  3. EES 450: Sedimentary Geology INTRODUCTION ● What skills and knowledge do you need to bring to this class? - The ability to solve basic algebraic equations - How to work with logarithms - Basic knowledge of minerals and mineral groups - Common elements and compounds in geology, and their properties - How to balance chemical equations - Basic skills and knowledge from intro geology, field geology and mineralogy

  4. EES 450: Sedimentary Geology INTRODUCTION ● How can you be successful in this class? - ATTEND classes and laboratory sessions - Pay attention, observe carefully, ask questions - Review course materials regularly (DO NOT put off studying until just before an exam) - THINK and attempt to answer questions – the answer is not always important, but the thought process is - Work in groups when possible - Make use of your instructor and TA

  5. EES 450: Sedimentary Geology INTRODUCTION ● Geologic time: What is abstraction? How is this relevant to us?

  6. EES 450: Sedimentary Geology INTRODUCTION ● Some important geologic times to know: Holocene Epoch: 10,000 y Quaternary Period: 1.8 million Mesozoic-Cenozoic Eras (K-T) boundary: 66 million Paleozoic-Mesozoic Eras boundary (Permian-Triassic Periods): 252 million Precambrian-Paleozoic Eras boundary: 540 million Archean-Proterozoic Eons boundary: 2.5 billion Archean-Hadean Eons boundary: 4.0 billion Age of the Earth/solar system: ~4.6 billion

  7. EES 450: Sedimentary Geology INTRODUCTION ● Geologic time: *All highlighted text are hyperlinks to internet resources

  8. EES 450: Sedimentary Geology INTRODUCTION ● Geologic time: - Geochronology vs. Chronostratigraphy Geochronology (Time) – A defined division of absolute time; units in absolute time. Chronostratigraphy (Time-rock) – The body of rocks deposited during a specific time interval. Early/Middle/Late (geochronologic) vs. Lower/Middle/Upper (chronostratigraphic)

  9. EES 450: Sedimentary Geology INTRODUCTION ● Geologic time: - Geochronology vs. Chronostratigraphy Examples of usage: The Upper Ordovician Lexington Limestone. The Lexington Limestone was deposited during Late Ordovician time. Tyrannosaurus was a common Late Cretaceous dinosaur. Remains of dinosaurs are common in Upper Cretaceous rocks. Late Cretaceous dinosaurs are common on all continents. A large meteorite hit the planet in the Latest Cretaceous.

  10. EES 450: Sedimentary Geology INTRODUCTION ● Geology of Kentucky: Kentucky lithology by age

  11. EES 450: Sedimentary Geology INTRODUCTION ● Geology of Kentucky: Latest detailed geologic map of KY – KGS

  12. EES 450: Sedimentary Geology INTRODUCTION ● Local lithology: the Lexington Limestone - Middle to Upper-Ordovician in age. - Mostly fossiliferous with minor shale. - Ranges from 200-320’ in thickness.

  13. EES 450: Sedimentary Geology INTRODUCTION ●Lithostratigraphic units: - Body of sedimentary, extrusive igneous, metasedimentary or metavolcanic strata, distinguished and delimited based on lithic characteristics and stratigraphic position. Generally conforms to the Law of Superposition and is commonly stratified. (1) Boundaries placed at positions of lithic change. (2) Fundamental unit is formation(can be mapped on Earth surface). (3) Each lithostratigraphic unit has a binomial name, derived from the type locality (Lexington Limestone; Camp Nelson Fm.). (4) Basic units: Group, Formation, Member, Bed.

  14. EES 450: Sedimentary Geology INTRODUCTION ● Our studies will encompass a range of scales by necessity: Variability! Thin section – microscopic Hand sample – megascopic Outcrop – field scale

  15. EES 450: Sedimentary Geology INTRODUCTION ● Why should we study sedimentary processes and rocks? - We are surrounded by sediments and sedimentary rocks! These rocks cover ~66% of Earth’s surface, and on average are ~1,800 m thick. Why is this the case? - They (unconsolidated sediments AND sedimentary rocks) are MAJOR sources of information about Earth’s past, and the information they store can help us make predictions about Earth’s future.

  16. EES 450: Sedimentary Geology INTRODUCTION ● Why should we study sedimentary processes and rocks? - They supply the most significant of our natural resources (oil, natural gas, coal, iron, uranium, evaporites, etc.). - Unconsolidated sediment deposits and manykinds of sedimentary rocks comprise the most significant aquifers on the planet.

  17. EES 450: Sedimentary Geology INTRODUCTION ● What are sedimentary rocks? - They form from sediments, primarily sediments that accumulate in fluids (though aeolian environments are also important). What are aeolian environments? What are sediments? - These sediments are found, and the resulting rocks are formed at or near Earth’s surface. What kinds of surface settings/conditions do we need?

  18. EES 450: Sedimentary Geology INTRODUCTION ● What are sedimentary rocks? - Ultimately, the sedimentary rocks produced consist of accumulations of a. chemical and/or biological precipitates; b. fragments of or grains of rocks, minerals and fossils; and c. combinations of these. Mudcracks Travertine Lignite

  19. EES 450: Sedimentary Geology How many specific types of environments can you think of? Water INTRODUCTION ● Where can sediment accumulate and sedimentary rocks form? Viscous Fluids Ice Wind

  20. EES 450: Sedimentary Geology INTRODUCTION ● Characteristics of sedimentary rocks: None below are unequivocal. (1) Typically form from the consolidation of loose sediment. (2) Typically are composed of loose, isolated grains that are cemented together. (3) Typically are layered. (4) They often contain fossils. (5) They often exhibit sedimentary structures (e.g., cross beds, ripples, mudcracks, etc.). (6) Commonly obey the Law of Superposition and Law of Original Horizontality.

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