This outcrop exposes rocks that range in age from the Middle Ordovician to Silur

Question

This outcrop exposes rocks that range in age from the Middle Ordovician to Silurian and includes the Reedsvills Formation, the Bald Eagle Formation, the Juneata Formation, the Tuscarora Formation and the Rose Hill shale.

Please answering the following: (Please answer all parts and asap!!!)

-What does the outcrop tell us about how sediment supply and accommodation creation were changing throughout the interval?

-What can we infer about climatic, tectonic, and eustatic changes throughout the interval?

Explanation / Answer

Answer-

First part-the stratigraphic framework gives an idea of the outcrops-

With ordovician started the onset of taconic sedimentation of the area.Martinsburg formation of northern virginia shows that it is a marine turbidite unit which has been deposited along strike at eastern edge of the basin and which changed facies basinward or westward into the Reedsville marine shale and limestone ,for the most part Martinsburg is a storm generated open marine platform deposit.Tuscarora sediments were deposited in shaallow water ,largely by fluvial processes and were dispersed westward from eastern part of the basin.Horowitz(1966) proposed wedge in the same general area ,grading upward from prodelta turbitites and delta forset deposits of the upper Reedsville to the marine topset and eventually to subaerial topset beds of Oswego of late ordovician .Bald eagle member is a basal member of Juniata formation with term oswego misapplied apparently in Pennsylvania.also the red green color boundary of the Juniata and Oswego doesnot correspond to the lithologic grain size boundaries .Study showed once that Bald eagle,Junaita and Tuscarora formations contained palaeozoic alluvial deposits and that they were non marine.However ,

reedsville formation was deposited in shallow marine conditions with the eastern part being affected by turbidity currents

Junaita fromation was deposited under supratidal to intertidal facies with cyclic sedimentation and deposited during low stand of sea level ,but with sealevel rise and land subsiding.

.Tuscarora formation was deposited wuth sea level rise ,

the accomodation will depend on the sediment flux that will tell whether transgression,regression or aggradation happened.

second part-

Tectonics-The strata investigated were all developed within the Central Appalachian basin where the formations from Reedsvills formation to Rose hill shales are the successions of the central part of West Virginia.the studied area is within the valley and ridge province ,where the late ordovician strata crop out ,and occur in the subsurface of synclironia and in the Appalachian plateau province ,where the untis are present in the subsurface.Hence the geologic setting and climate is basically due to appalachian tectonics.

Eustatic changes-sealevel was low during Reedsville deposition.Junaita and oswego were deposited during the low stand of sea level.As the strata were deposited ,they were compacted and the basin subsided isostatically .Sea level then may be rising slowly ,or it may have been fluctuating during the late ordovician glacial ages. the sea level lowering was aminly glacioeustatic but with the dawn of silurian period sea level gradually increased leading to deposition of tuscarora formation.

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