塔里木盆地塔中-巴楚地区上奥陶统良里塔格组米兰科维奇旋回性沉积记录研究
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国家科技重大专项课题(编号:2008ZX05000-004-001)和中国石油重大研发项目(编号:070201)


The Study of Milankovitch Cycles in the Upper Ordovician Lianglitage Formation in Tazhong-Bachu Area, Tarim Basin
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    摘要:

    通过露头、钻井岩芯沉积相观察及高频旋回识别,结合全岩碳氧同位素旋回、自然伽玛能谱测井ln(Th/K)值频谱分析及地震反射特征,研究了塔里木盆地塔中-巴楚地区分布的上奥陶统良里塔格组开阔台地及外缓坡相碳酸盐岩中发育的四~六级高频层序(旋回)特征及其叠置关系。认为其六级米级旋回、五级准层序及四级准层序组可能分别与20~40 ka、100 ka及400 ka周期的Milankovitch日-地轨道气候旋回有关,并识别出该区良里塔格组由11~12个400 ka周期的准层序组构成。提出海相碳酸盐岩全岩或生物壳碳同位素值可作为反映全球海平面相对变化的指标及识别形成三级层序的主控因素(全球海平面变化、地区性构造沉降-抬升运动)的方法——碳同位素-沉积旋回对比分析法。晚奥陶世良里塔格组沉积时期,塔中台地北缘总体表现为向上变浅的加积型沉积叠置型式,主要与塔中I号断裂活动控制形成的高陡型镶边台地边缘有关;巴楚台地西北缘则表现为向上变浅的加积-进积复合型沉积叠置型式,主要与其断裂活动弱、受沉积作用控制为主的缓坡台地边缘有关。塔中-巴楚台地良里塔格组表现为一个完整三级层序的形成与演化,主要受控于该台地的构造(沉降-抬升)运动而不是全球海平面变化,属于典型的地区性构造层序及不具有全球对比意义。

    Abstract:

    According to sedimentary facies and high-frequency cycles observation to outcrop and drilling cores, analysis to rock carbon isotope cycles, Gamma ray log ln(Th/K) time-series and seismic reflection characteristics, it’s studied to 6th, 5th and 4th order sequences (high-frequency cycles) and their stacked pattern developed in platform and outer ramp carbonates of Upper Ordovician LiangLiTaGe Fm. distributed in TaZhong-BaChu area, Tarim basin. The 6th order sequence (meters cycle), 5th order sequence (parasequence) and 4th order sequence (parasequence set) maybe separatedly related to Milankovitch cycles as 20~40 ka, 100 ka and 400 ka, and 11 to 12 parasequence sets as 400ka cycle has been identified in LiangLiTaGe Fm. in this area. It’s first advanced the carbon isotope of marine carbonate rock or fossil shell can be as the good index of relative eustatic sea level change and the carbon isotope – sedimentary cycle contrasting analyzing method to identify the chief controlling factor for formation of 3rd order sequence (eustatic sea level change, regional tectonic subsidence & uplifting). At the Early Katian stage as sedimentation of LiangLiTaGe Fm. in Upper Ordovician, the northern brim of TaZhong Platform behaved as shallowing upward aggradation stacking pattern, which mainly related to high steep rimmed platform margin formed from the controlling of TaZhong-I thrust fault movement; and the northwestern brim of BaChu Platform behaved as shallowing upward aggradation-progradation stacking pattern, which mainly related to ramp platform controlled by sedimentation as feeble faulting movement. The LiangLiTaGe Fm. distributed in TaZhong-BaChu Platform was able to form a 3rd order sequence, its chief controlling factor was the tectonic (subsidence-uplifting) movement of this Platform otherwise the eustatic sea level change, so it’s a typical regional tectonic sequence and no global correlation significance.

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赵宗举,陈轩,潘懋,吴兴宁,郑兴平,潘文庆.2010.塔里木盆地塔中-巴楚地区上奥陶统良里塔格组米兰科维奇旋回性沉积记录研究[J].地质学报,84(4):518-536.
ZhaoZongju, CHEN Xuan, PAN Mao, WU Xingning, ZHENG Xingping, PAN Wenqing.2010. The Study of Milankovitch Cycles in the Upper Ordovician Lianglitage Formation in Tazhong-Bachu Area, Tarim Basin[J]. Acta Geologica Sinica,84(4):518-536.

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  • 收稿日期:2009-10-26
  • 最后修改日期:2009-12-22
  • 录用日期:2009-12-28
  • 在线发布日期: 2010-03-30