Sequence architecture of a Jurassic ramp succession from Gebel Maghara(North Sinai,Egypt):Implications for eustasy  

作　　者：Ahmed Awad Abdelhady Franz Theodor Fürsich 

机构地区：[1]Geology Department,Faculty of Science,Minia University [2]FG Pal?oumwelt,Geozentrum Nordbayern der Universit?t Erlangen

出　　处：《Journal of Palaeogeography》2015年第3期305-330,共26页古地理学报（英文版）

基　　金：the German Academic Exchange Service(DAAD);the Egyptian Ministry of Higher Education and Scientific Research(the "GERLS" Programme) for their financial support

摘　　要：The Jurassic succession at Gebet Maghara, North Sinai, Egypt, represents a mixed carbonate-siticictastic sequence. Combining information from both fossits and rocks attowed a ptausibte reconstruction of the depositionat environments and of the basin evotution. The Ju- rassic succession of Gebel Maghara was deposited on a ramp, and the architecture of the ramp facies was strongty controtted not onty by sea-revel changes but atso by extensionat tectonics in connection with rifting of the Tethys, North Gondwana. Seven tectonicalty modified thirdorder sequences （DS 1-DS 7） have been recognized. The first three sequences （DS 1-DS 3）, ranging from the Toarcian to the Bajocian, record sea invasion （intertidat to shattow subtida[lconditions） across an intracratonic area as a resutt of eustatic sea-fever changes during a quiescent rift stage. The remaining sequences （DS 4-DS 7） reflect open marine mid to outer ramp settings. Non-marine conditions around the Bajocian-Bathonian boundary, documented by catiche, represent the maximum regression of the sea. During an active extensionat stage, horsts, which formerty acted as barriers separating the Maghara sub-basin from the main ocean, subsided. Subsequent rejuvenation and reactivation of fautts shifted the homoctinat physiography of the ramp to a distatty steepened ramp during the earty Bathonian, creating a 200-m-thick dettaic wedge. SimiLar processes during the earty Kimmeridgian created a catcirudite-catcarenite succession of stope origin. The diversity and the epifaunat/infaunat percentage of the macrofauna disptay a cyctic pattern which coincides more or tess with the sequence stratigraphic architecture.The Jurassic succession at Gebet Maghara, North Sinai, Egypt, represents a mixed carbonate-siticictastic sequence. Combining information from both fossits and rocks attowed a ptausibte reconstruction of the depositionat environments and of the basin evotution. The Ju- rassic succession of Gebel Maghara was deposited on a ramp, and the architecture of the ramp facies was strongty controtted not onty by sea-revel changes but atso by extensionat tectonics in connection with rifting of the Tethys, North Gondwana. Seven tectonicalty modified thirdorder sequences （DS 1-DS 7） have been recognized. The first three sequences （DS 1-DS 3）, ranging from the Toarcian to the Bajocian, record sea invasion （intertidat to shattow subtida[lconditions） across an intracratonic area as a resutt of eustatic sea-fever changes during a quiescent rift stage. The remaining sequences （DS 4-DS 7） reflect open marine mid to outer ramp settings. Non-marine conditions around the Bajocian-Bathonian boundary, documented by catiche, represent the maximum regression of the sea. During an active extensionat stage, horsts, which formerty acted as barriers separating the Maghara sub-basin from the main ocean, subsided. Subsequent rejuvenation and reactivation of fautts shifted the homoctinat physiography of the ramp to a distatty steepened ramp during the earty Bathonian, creating a 200-m-thick dettaic wedge. SimiLar processes during the earty Kimmeridgian created a catcirudite-catcarenite succession of stope origin. The diversity and the epifaunat/infaunat percentage of the macrofauna disptay a cyctic pattern which coincides more or tess with the sequence stratigraphic architecture.

关 键 词：facies sequence stratigraphy RAMP extensional basin JURASSIC Gebel Maghara EGYPT 

分 类 号：P534.52[天文地球—古生物学与地层学] O632.12[天文地球—地质学]