Sequence stratigraphy of Qum Formation in Shurab Section with special reference to indicators used for stratal surfaces and system trackts identification

Category Sedimentology
Group GSI.IR
Location The 24 Symposium of Geosciences
Author Imandoust A. , Amini A.
Holding Date 18 August 2007

Abstract:

The Oligo-Miocene Qum Formation in Shurab Section (southeast of Qum), is composed of limestone, marl with thin layer of sandstone (Volcaniclastic) and evaporites. Its contact with the underlying Lower Red Formation is disconformable, whereas the upper contact with the overlying Upper Red Formation seems conformable (correlative conformity). Results from filed observations and petrographic studies indicate a carbonate shelf with scattered patch reef for its depositional environment. Considering the depositional environments of the studied facies and their ordering in vertical profile (sedimentological log), 7 major sequence boundaries were determined, witch bound the third order sequences of the formation. Three minor sequences (4th to 5th order) were also recognized. The whole formation is considered as a part of Tejas megacycle, that is bounded above and below by type I sequences boundaries. Some sequence boundaries in the formation (SB1, SB5, SB6, SB7) correlative with those on world- wide Eustatic curve. They are considered as the result of word wide sea level fall (Eustasy). Some others (SB2, SB3, SB4) show no significant correlation with eustatic curve. They are resulted from local sea level changes, due to tectonic movements and sediment supply variation

tags: QAZVIN