Oil & Gas Geology ›› 1993, Vol. 14 ›› Issue (1): 1-9.doi: 10.11743/ogg19930101

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GRAVITY FLOW DEPOSITS AND ASSOCIATED SEDIMENTS FROM MIDDLE ORDOVICIAN,FINCASTLE,VIRGINIA

Gao Zhengzhong1, K.A.Eriksson2, Zhou Jiarao3   

  1. 1. Department of Geology, Jianghan College of Petroleum;
    2. Department of Geological Sciences, Virginia Polytechnic Institute and State University;
    3. Petroleum Industry Press
  • Received:1992-06-15 Revised:1992-08-15 Online:1993-03-25 Published:2012-01-16

Abstract:

Fincastle Conglomerate which was considered as deposits in shallow water in the pastis mainly gravity flow deposits and associated sediments ia deep water submarine chan-nels.Five gravity flow facies have been recognized:1.pebbly mudstone facies;2.matrix-rich conglomerate facies;3.matrix-poor conglomerate facies;4.massive sandstone facies;5.graded sandstone facies.Among them 1 and 2 are debris flow deposits;3 and 4 belongto grain flow deposits;and 5 is turbidite including high density and low density currentdeposits.The associated facies comprise:6.dark shale and mudrock facies:suspension de-posit;7.contorted bed facies:slumping deposit;8.bidirectional cross-laminated sandstonefacies:internal-tide deposit;9.unidirectional cross-bedded and cross-laminated sandstonefacies:deposit of internal tide with superposing internal wave.The nine facies mentionedabove constitute five facies assemblages that show regular patterns.To sum up,the Fin-castle Conglomerate shows a clear upward-fining sequence,reflecting a process of that thesea level continued to rise and the source area was farther and farther to the sedimentarysite.