Devonian Rock Units of the Cayuga Lake Basin Description Name of Rock Uni Sherbu
ID: 115009 • Letter: D
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Devonian Rock Units of the Cayuga Lake Basin Description Name of Rock Uni Sherburne Geneseo shale with increasing sand black shale, about 10 m thick limestone; about 3 m thick shale with limestone at base; about 15 m thick shale: about 25 m thick shale with limestone on top; total thickness about 28 m primarily shale, black shale at base, then think limestone; nearly 4 m thick limestone at top, total thickness nearly 25 ully Moscow Ludlowville Skaneateles Marcellus Onondaga Oriskany Manilus Rondout limestone: >25 m thick sandstone; about 1.2 m thick limestone; about 7.6 m thick dolomite: about 7.6 m thick 3.Describe the plate tectonic setting (spreading center, passive margin, subduction) of the Cayuga Lake region. Be sure to include the following: How do the rocks substantiate what was occurring'? . What type of sea level changes do you see (transgression, regression)? . Related orogenic events.Explanation / Answer
As the Stratigraphy of the area is well marked by the presence of the alternate layers of Limestone and sandstone, shale types of rocks its depicts the region was subjected to the Passive margin setup containing the signature of the lithosphere condition of the ocean as well as the continent.
Its evident from the rock type the sea level was changing with time during the Manilus time sea have transgressed towards the land whereas during the Oriskany time it undergoes regression subsequently during the Onondaga time it has transmigrated. So, in short, we can say that sea was not static and it was changing its level during the geological time.
In the history of the basin, the sedimentation has changed with time and the result is evident from the variation in the grain size of the rock unit. There are basically three main stages of the passive margins:
1. Firstly the continental rift is established due to stretching and thinning of the crust and lithosphere by the plate movement.
2. In this stage, the oceanic basin is formed, this lead to the development of the normal faulting in the continental crust.
3. In the last stage, the streaching of the crust ceases and the crust and lithosphere subside result in the cooling and thickening finally followed the drainage to deposit sediment over the rifted zone.
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