istorical Geology GLY2100C Unit #8: Cenozoic Climate & Earth History DUE Tuesday
ID: 232638 • Letter: I
Question
istorical Geology GLY2100C Unit #8: Cenozoic Climate & Earth History DUE Tuesday April 19, 2016 Individual Assignment Unit #8: Cenozoic Tectonics and Sedimentation DUE Tuesday April 19, 2016. No late work will be accepted after 5pm on Wednesday April 20, 2015. Th is means a zero if you are late with the assignment and do not have a reasonable excuse. The two diagrams provided are a theoretical start to a landscape following two different types of Cenozoic deformation -Laramide, and Basin and Range. In reality, erosion would have been occurring throughout the period of deformation. Please complete the following three tasks for each area marked A, B, C (and D). Task 1 and 2 can be combined in one set of bullet points Remember to consider the local climate. Death Valley in the Basin and Range Province has a hot and arid climate with periodic flash floods. The Rockies has a temperate climate with a lot of rainfall (least in my fantasy geology world it is) year round. There are no marine transgressions. Task 1: Describe the type of sedimentary processes occurring including mechanisms for weathering. erosion, transport and deposition as appropriate ie. there may be an area where little erosion is occurring or no deposition. Briefly explain your choices e.g. if you indicate that there is a large component of wind erosion and transport, explain why this is the case. Short bullet points/phrases will do. Task 2: Describe the rock type you would find in the geological record and include the kinds of observations you would make in order to identify the rock type and the conditions of it's formation e.g. color, rounding, sorting, composition, structures. Again, briefly explain your choices. Example for combined task 1 and 2: if it were a beach you might have high terrestrial detrital fluvial siliclastic input re-working and deposition by waves and long shore currents moderate-high energy environment periodic coarse sediment input from storm deposits (pebbles) well sorted, well rounded quartz sand and shell fragments symmetrical cross-bedding and ripple marks . · . Task 3: Let us assume that no further deformation occurs (includes subsidence from sediment loading), the climate is stable and the sedimentary processes you described above have continued for 10Ma (enough time for substantial erosion and deposition to have occurred. Using a colored pe Annotate your sketch with your reasoning e.g. for shapes of any sedimentary layers topography, maybe a change in composition? These may be similar to the processes you described in task 1 in which case you can just refer to their previous descriptions, but you may have additional comments or complexities. ncil, sketch in what you think the topography and sedimentary strata would look like. , changes in Diagram 1: Basin and Range e.g. Death Valley-Extensional Diagram 2: Laramide Deformation - Rocky Mountains-Compressional Area D on this diagram is a freshwater lake.Explanation / Answer
The exposed geology of the Death Valley area presents a diverse and complex set of sedimentary units, two major gaps in the geologic record called unconformities, and at least one distinct set of related formations geologists call a group.
The oldest rocks in Death Valley are extensively metamorphosed by intense heat and pressure.
Marine deposition occurred 1200 to 800 Ma, creating thick sequences of conglomerate, mudstone, and carbonate rock topped bystromatolites, and possibly glacial deposits.
The metamorphosed Precambrian basement rocks were uplifted and a nearly 500-million-year-long gap in the geologic record, a major unconformity, affected the region, the eroded sediment that overlain the complex & regional uplift was responsible; the area was originally below the surface of a shallow sea.
Fault systems move with a right-lateral offset along strike-slip faults; these type of faults rub past each other. Both fault systems run parallel to and at the base of the ranges. Very often the same faults move laterally and vertically, simultaneously making them strike-slip and normal (i.e. oblique-slip).
Pediments are erosion surfaces cut into bedrock beyond the present mountain front in arid regions. Pediments most commonly occur in desert areas with exterior drainage that can remove a portion of the erosion products. At many locations, pediment surfaces are covered with a thin veneer of alluvium, and their gently sloping surface may be interrupted by resistant knobs of bedrock, called inselbergs, that stick up above the pediment surface.
Erosion is defined as the removal of soil, sediment, regolith, and rock fragments from the landscape. Most landscapes show obvious evidence of erosion. Erosion is responsible for the creation of hills and valleys. It removes sediments from areas that were once glaciated, shapes the shorelines of lakes and coastlines, and transports material downslope from elevated sites. e.g are deflation, abration and attrition.
In order for erosion to occur three processes must take place: detachment, entrainment and transport. Erosion also requires a medium to move material. Wind, water, and ice are the mediums primarily responsible for erosion. Finally, the process of erosion stops when the transported particles fall out of the transporting medium and settle on a surface. This process is called deposition. e.g are precipitation and flocculation.
Alluvial fans are often found in desert areas subject to periodic flash floods from nearby thunderstorms in local hills. The typicalwatercourse in an arid climate has a large, funnel-shaped basin at the top, leading to a narrow defile, which opens out into an alluvial fan at the bottom. Multiple braided streams are usually present and active during water flows.
from diagram 1 a & b are alluvial fans and c is the playa and sand dune.
In rocky mountain area, we can observe symmetrical cross bedding & ripple marks in rocks at foot of the mountain and a well sorted, well rounded quartz sand and shell fragments are found at foot of the mountain.
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.