Complete Lab 6 answer sheetreal

Lab 6- Depositional Sedimentary Structures Answer Sheet 1. The table below contains descriptions of actual sedimentary rocks and suites of associated rocks. Use the three sedimentary environment tables (Tables 6.1, 6.2, and 6.3) to identify all possible sedimentary environments for each sample. For some of these, you will have to list several possible environments. Certain sedimentary structures (or other features) may be present in the environment but might not be in a particular sample (perhaps because of small sample size). By examining other features, such as sedimentary structures or fossils, you may be able to increase the certainty of your interpretation. Use Laboratory 10: Invertebrate Macrofossils and Classification of Organisms or a fossil identification book if you are unfamiliar with any fossils listed here (such as brachiopods, bryozoans, or molluscs). Sampl e Rock Type Sedimentary Structures Chemical Characterist ics Biological Characterist ics List All Possible Sedimentary Environments 1 Quartz sandstone None visible in this sample Quartz grains and cement, white to tan color Brachiopo d fossil molds Barrier Beach 2 Fossiliferou s limestone: very coarse, no mud None visible in this sample All calcium carbonate, white to gray color Rock is dominated by very coarse coral pieces reef 3 Fossiliferous limestone (fossils in a lime mud matrix) Vague layerin g All calcium carbonat e, gray color Rock is filled with whole and broken brachiopo d shells and branching bryozoan colonies Continental shelf

Sampl e Rock Type Sedimentary Structures Chemical Characterist ics Biological Characterist ics List All Possible Sedimentary Environments 4 Gypsum with very thin laminations of calcium carbonate Laminations Evaporit e minerals White color (due to gypsum), with gray calcium carbonate laminations No fossils Dunes, Tidal Flat, Lakes 5 Breccia Poorly sorted, some clasts up to 6 inches (15 cm) in diameter Silty matrix None visible in this sample Red color due to iron oxide cement Grains are fragment s of various types of metamorph ic rocks No fossils Fluvial- Alluvial Fan 6 Limestone and dolostone, interlayered Irregular layers and burrows Carbonat e minerals Burrows Tidal Flat. 7 Black shale Chert Chalk Very fine grained Lamination s in shale Organic- rich black shale Gray to black chert White to gray chalk (calcium carbonate) Microfossils probably present in the chalk although they were too small to identify in lab Abyssal Plain. 8 Limestone Fossiliferous shale Graywacke Lamination s, graded bedding Gray limestone and shale, greenish gray graywacke Fossils in shale and limestone, primarily molds of brachiopod s Continental Rise-Slope. 9 Quartz sandstone (some are pebbly and poorly sorted) Micaceous Pebbly sandstone is poorly layered Quartz sandstone is Reddish brown color due to iron oxides Quartz, muscovite, No fossils Dunes, Rivers