One day geology of oman (2) EarthCache
One day geology of oman (2)
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Al Khoud unconformity
Geological background:
At these location we have two different kind of rocklayers. The lower layer is a light yellowish cloured marlstone. The upper layer is a greyish gravel layer. The gravel layer is a conglomerate with many different rocktypes. Many rocks of the ophilolite sequenze are included. Ophiolitic rocks are part of an old marine crust which is on continental crust today. The boundary between these two layers is very sharp but occasionally there are inclusions of marlstone in the gravel.
Genisis:
The marlstone layer consits of many foraminifers. Foraminifers are single-celled organisms. This means that every organism you can find at this location is just one single cell. They are mainly marine organisms. These foraminifers are called nummulites. They are single celled. They have a size between 2 to 5 cm in diametre. These nummulites were abundant during the Paleogen and Neogene. This layer is Tertiary age. They formed a horizontal layer in the shallow marine water. After that the layer got uplift and tilted. Erosion started on the tertiary layer and the gravel layer were deposited on top of the erosional surface. This erosion is the reason for the sharp boundary between the layers. The pebbles in the gravel layer are from the ophiolites from the interior area and marlstone from the erosional surface. For further informations and for some questions is a sign on next to the road.
Questions:
1. Discribe the shape of the nummulites.
2. What do you think in which time the gravel layer were deposited?? Have a look at the sign or make a assumption.
3. What is an unconformity ??
Would be great if you could take a photo of yourself infront of the outcrop.
Please send an E-Mail with the answeres my profile.
References/Referencias
University of Greifswald, GUtech Muscat: Geological filed trip to Oman 2011
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