全球海平面变化指标及海相构造层序研究方法——以塔里木盆地奥陶系为例  

Indicators of global sea-level change and research methods of marine tectonic sequences:take Ordovician of Tarim Basin as an example

作　　者：赵宗举 

机构地区：[1]中国石油学会 [2]北京陆海丰科技咨询服务中心,北京100724

出　　处：《石油学报》2015年第3期262-273,共12页Acta Petrolei Sinica

基　　金：国家重大科技专项(2008ZX05004-001);中国石油天然气集团公司重大专项(2008E-0702)资助

摘　　要：基于碳、氧同位素长期分馏原理,提出海相碳酸盐岩全岩或古生物化石壳的碳、氧同位素可作为反映全球海平面相对变化的指标。一般地,碳同位素变重或氧同位素变轻反映了全球海平面相对上升,反之则相对下降,对于古近纪之前的古老碳酸盐岩,碳同位素较氧同位素更为稳定且更适于作为全球海平面相对变化指标。由于三级层序时限（1~10 Ma）内碳酸盐台地一般不会发生大的纬度带变迁及其碳酸盐产率的显著变化,据此提出了海相构造层序研究方法——碳、氧同位素-沉积旋回对比分析法。该方法将海相三级层序划分为主要受全球海平面变化控制的全球海平面层序及主要受地区性构造沉降-抬升作用控制的构造层序2类,全球海平面层序的沉积旋回及沉积古水深变化趋势与碳、氧同位素反映的全球海平面相对变化趋势总体一致,构造层序的沉积旋回及沉积古水深变化趋势则与碳、氧同位素反映的全球海平面相对变化趋势不同。对塔里木盆地奥陶系三级层序研究表明,下奥陶统所发育的2个三级层序属于全球海平面层序,而中—上奥陶统所发育的6个三级层序主要受阿尔金岛弧及库地岛弧与塔里木板块的碰撞挤压运动控制、属于构造层序,尤其是上奥陶统层序OSQ6（良里塔格组）属于典型的构造层序。Based on the long-term fractionation principle of carbon and oxygen isotopes,the author proposed that,the carbon and oxygen isotopes in marine carbonate rocks or paleontology fossil shells,as the indicators,could reflect the global relative sea-level change.In general,the carbon isotope heavier or oxygen isotope lighter reflects the relative rise in global sea-level,whereas the relative decline.For ancient carbonate rocks before Paleogene,carbon isotope,as an indicator,is more stable than oxygen isotope,and thus more suitable to represent the global sea-level relative change.Since within the time limit of a 3rd-order sequence（1-10 Ma）,carbonate platforms have little changes in latitude belt and carbonate productivity,the research methods of marine tectonic sequences as contrastive analysis method of the carbon and oxygen isotopes and sedimentary cycles is put forward.In this way,marine 3rd-order sequences are divided into two types：global sea-level sequences which controlled by global sea-level change and tectonic sequences which controlled by regional tectonic subsidence-lifting effect.The sedimentary cycle and sedimentary water depth change tendency of global sea-level sequence generally concurred with the global relative sea-level change trend reflected by carbon and oxygen isotopes,otherwise,the ones of tectonic sequence is different from the tendency of carbon and oxygen isotopes.The studies on3rd-order sequences in the Ordovician of Tarim Basin showed that,there are two 3rd-order global sea-level sequences in Lower-Ordovician,while in Middle and Upper Ordovician,there are six 3rd-order tectonic sequences which controlled by the collision and compression movements between Arkin island arc,Kuda island arc and Tarim plate.In particular,the sequence OSQ6 in the Upper Ordovician（Lianglitage Formation）is a typical tectonic sequence.

关 键 词：碳、氧同位素 全球海平面 沉积旋回 碳酸盐岩 海相 层序地层 奥陶系 塔里木盆地 

分 类 号：TE112.3[石油与天然气工程—油气勘探]