塔里木盆地奥陶系牙形石带及沉积层序

通过对塔里木盆地西部柯坪、巴楚及东部却尔却克奥陶系露头剖面及盆地覆盖区钻井岩心的大量牙形石样品分析,分别建立了塔里木盆地中西部及东部地区奥陶系牙形石带序列。盆地中西部地区牙形石带共计22个,由老到新分别为Variabiloconusaff.bassleri带、Rossodusmanitouensis-Cordylodusrotundatus-Chosonodinaherfurthi组合带、Scolopodusquadraplicatus带、Glyptoconusfloweri带、Tripodusproteus/Paltodusdeltifer带、Glyptoconusunicostatus带、Serratognathusdiversus/Paroistodusproteus带、Serratognathoideschuxianensis-Scolopoduseuspinus-Erraticodontarimensis组合带、Aurilobodusleptosomatus-Loxodusdissectus组合带、Amorphognathusvariabilis带、Eoplacognathussuecicus带、Pygodusserrus带、Pygodusanserinus带、Eoplacognathusjianyeensis/Baltoniodusva-riabilis带、Eoplacognathuselongatus带、Baltoniodusalobatus带、Belodinacompressa/Periodongrandis带、Phrag-modusundatus带、Belodinaconfluens带、Yaoxianognathusneimengguensis带、Yaoxianognathusyaoxianensis带和Aphelognathuspyramidalis带;盆地东部地区下奥陶统属于深水盆地相,其特有的牙形石带主要有5个,由老到新分别为Cordyloduslindstromi带、Cordylodusangulatus带、Prioniodusgilberti带、Paroistodusproteus带和Prionio-duselegans带。同时初步建立了塔里木盆地奥陶系三级层序地层格架,并探讨了上述牙形石带与盆地奥陶系主要构造单元岩石地层单位以及全盆地可对比的6个三级层序之间的关系。

ORDOVICIAN CONODONT ZONES AND SEDIMENTARY SEQUENCES OF THE TARIM BASIN, XINJIANG, NW CHINA

On the basis of a large number of conodont samples from outcrop sections of the Keping, Bachu, and Charchaq areas, as well as drilling cores in the Tarim Basin, Xinjiang, the Ordovician conodont zones in the central-western region and eastern region of the Tarim Basin have been established. A total of 22 conodont zones have been recognized in the central-western region of the basin. These are, in ascending order, Variabiloconus aff. bassleri Zone, Rossodus manitouensis-Cordylodus rotundatus-Chosonodina herfurthi Zone, Scolopodus quadraplicatus Zone, Glyptoconus floweri Zone, Tripodus proteus/Paltodus deltifer Zone, Glyptoconus unicostatus Zone, Serratognathus diversus/Paroistodus proteus Zone, Serratognathoides chuxianensis-Scolopodus euspinus-Erraticodon tarimensis Zone, Aurilobodus leptosomatus-Loxodus dissectus Zone, Amorphognathus variabilis Zone, Eoplacognathus suecicus Zone, Pygodus serrus Zone, Pygodus anserinus Zone, Eoplacognathus jianyeensis/Baltoniodus variabilis Zone, Eoplacognathus elongates Zone, Baltoniodus alobatus Zone, Belodina compressa/Periodon grandis Zone, Phragmodus undatus Zone, Belodina confluens Zone, Yaoxianognathus neimengguensis Zone, Yaoxianognathus yaoxianensis Zone, and Aphelognathus pyramidalis Zone. The Lower Ordovician in the eastern region of the basin was deposited in abyssal basin facies, and 5 conodont zones have been recognized. These are, in ascending order, the Cordylodus lindstromi Zone, Cordylodus angulatus Zone, Prioniodus gilberti Zone, Paroistodus proteus Zone, and Prioniodus elegans Zone. In addition, six third-order sequences have been recognized in the Ordovician successions of the Tarim Basin. The relationship between the conodont zones, lithostratigraphic divisions of major structural units, and the six third-order sedimentary sequences, is discussed.