Positive carbon isotope excursions:global correlation and genesis in the Middle-Upper Ordovician in the northern Tarim Basin,Northwest China  

作　　者：Cun-Ge Liu Li-Xin Qi Yong-Li Liu Ming-Xia Luo Xiao-Ming Shao Peng Luo Zhi-Li Zhang 

机构地区：[1]State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation,Chengdu University of Technology [2]Northwest Oilfield Company,China Petroleum & Chemical Corporation [3]Institute of Petroleum Exploration and Development [4]Petroleum & Chemical Corporation

出　　处：《Petroleum Science》2016年第2期192-203,共12页石油科学（英文版）

基　　金：supported by the National Key Scientific Project of China(No.2011ZX05005-004;2016ZX05005-002);the National Basic Research Program of China(973 Program)(No.2012CB214806)

摘　　要：Stable carbon isotope ratio （δ13Ccarb） analysis has been widely applied to the study of the inter-conti- nental or global marine carbonate correlation. Large-scale Cambrian-Ordovician carbonate platforms were developed in the Tarim Basin. But research on fluctuation character- istics and global correlation of δ13Ccarb is still weak. Based on conodont biostratigraphy and whole-rock δ13Ccarb data in the Tahe oil-gas field of the northern Tarim Basin, the global correlation and genesis of positive carbon isotope excursions in the Darriwilian--Early Katian was exam- ined. Three positive excursions were identified in the Tahe oil-gas field including the middle Darriwilian carbon iso- tope excursion （MDICE）, the Guttenberg carbon isotope excursion （GICE）, and a positive excursion within the Pygodus anserinus conodont zone which is named the Early Sandbian carbon isotope excursion （ESICE） in this paper. Furthermore, these positive excursions had no direct relation with sea level fluctuations. MDICE and GICE could be globally correlated. The Middle-Upper Ordovi- cian Saergan Formation source rocks of the Kalpin outcrops were in accordance with the geological time of MDICE and ESICE. GICE had close relationship with the source rock of the Lianglitag Formation in the basin.Massive organic carbon burial was an important factor controlling the genesis of these positive excursions.Stable carbon isotope ratio （δ13Ccarb） analysis has been widely applied to the study of the inter-conti- nental or global marine carbonate correlation. Large-scale Cambrian-Ordovician carbonate platforms were developed in the Tarim Basin. But research on fluctuation character- istics and global correlation of δ13Ccarb is still weak. Based on conodont biostratigraphy and whole-rock δ13Ccarb data in the Tahe oil-gas field of the northern Tarim Basin, the global correlation and genesis of positive carbon isotope excursions in the Darriwilian--Early Katian was exam- ined. Three positive excursions were identified in the Tahe oil-gas field including the middle Darriwilian carbon iso- tope excursion （MDICE）, the Guttenberg carbon isotope excursion （GICE）, and a positive excursion within the Pygodus anserinus conodont zone which is named the Early Sandbian carbon isotope excursion （ESICE） in this paper. Furthermore, these positive excursions had no direct relation with sea level fluctuations. MDICE and GICE could be globally correlated. The Middle-Upper Ordovi- cian Saergan Formation source rocks of the Kalpin outcrops were in accordance with the geological time of MDICE and ESICE. GICE had close relationship with the source rock of the Lianglitag Formation in the basin.Massive organic carbon burial was an important factor controlling the genesis of these positive excursions.

关 键 词：Tarim Basin Tahe oil-gas field - Middle-Upper Ordovician Carbon isotope DARRIWILIAN Sandbian Katian source rock 

分 类 号：P618.13[天文地球—矿床学] P597[天文地球—地质学]