摘要
通过岩石岩屑组分分析、重矿物组分分析、倾角测井、地层厚度分析等方法 ,对准噶尔盆地西北缘车排子地区侏罗系进行了物源及古水流方向分析。岩屑组分分析指示着大致的物源前进方向 ,重矿物分析明确了物源泄入的主要通道 ,倾角测井在单井点处对古流向有相当高的测量精度 ,但这 3种方法均存在数据平面覆盖率较低和分布密度差异大的缺陷。而运用地震层位解释所得的地层等厚度图则可以在较大尺度上的二维平面内推测沉积时期的古地形 ,进而可以推测古流向。但它仅是一种间接预测方法 ,对局部古流向的预测精度较低。文中综合各种方法 ,将直接预测方法的高精度和间接方法的高覆盖能力结合起来 ,对古流向作出较高精度的预测。在古流向研究的基础上建立了车排子地区侏罗系冲积扇—辫状河—河泛平原沉积体系的沉积相模式。该模式表明 ,对于水流能量保持能力差的冲积扇 ,其古流向应该沿短轴陡坡降方向 ,即大致为SEE方向 ;而对于水流能量保持能力较强的辫状河来说 ,其古流向应该沿长轴缓坡降方向 ,即为SE甚至SSE方向。
With several methods,such as analysis of detritus component,heavy mineral component, dip log, and thickness of strata, the provenance and palaeocurrent direction of Jurassic at Chepaizi region in northwest edge of Junggar Basin are analyzed. Analysis restllt of detritus component indicates the overall progressing direction of provenance.Heavy mineral component analysis makes the main passage of source clear,and dip log data give an accurate palaeocurrent direction in the place of each well. These three methods have the disadvantages of low data covering rate and high variety of covering density in two demensional space. In contrast,an isoline map of strata from seismic data can be used to predict palaeotopography and palaeocurrent direction in much large two demensional scale, but it is virtually an indirect predicting method with disadvantage of low accuracy in local place. Integrating the high covering faculty of indirect methods and the high local accuracy of direct methods, a much accurate prediction about paleocurrent direction is put forward in this paper. Based on the palaeocurrent direction,a sedimentary facies model of alluvial fan-braided river-river plain sedimentary system is constructed. The model shows that current of alluvial fan progressed in the direction of SEE along the short axle with steep slope,and its current energy can keep only in short distance. By contraries,the braided river has an ability of keeping current energy in much long distance,and its current progresses in the direction along the long axle with mild slope,namely SE or even SSE. The model is much beneficial to raising the accuracy of turning seismic facies to sedimentary facies.
出处
《古地理学报》
CAS
CSCD
2001年第3期49-54,共6页
Journal of Palaeogeography：Chinese Edition
关键词
准噶尔盆地
侏罗系
物源
古水流
ZTR指数
沉积相
Junggar Basin,Chepaizi region,Jurassic,ZTR maturity index,sedimentary facies,provenance,paleocurrent
