新疆富蕴盆地下石炭统“底砾岩”特征及其大地构造意义

研究表明新疆富蕴盆地早石炭世黑山头组、南明水组主要为一套滨、浅海相沉积,地层之间发育多套砾岩层,呈透镜体状,横向上延伸不远,为河流入海时形成的一系列水下河道沉积,而并非前人所认为的萨吾尔造山运动形成的构造底砾岩。砾岩层横向特征的对比及交错层理、波痕等古流向数据,表明地层沉积时期水体古流向总体自北西向南东(介于93°~125°),物源区位于盆地北西方向。研究区内黑山头组与南明水组之间为连续沉积,整合接触,并非准噶尔地块与西伯利亚板块的碰撞形成的构造不整合面。

Characteristics of the Lower Carboniferous "Basal Conglomerate" from Fuyun Basin of Xinjiang and Its Tectonic Significance

This study shows that it was a littoral- and neritic- facies during sedimentation of the Lower Carboniferous Heishantou Formation and Nanmingshui Formation. Several sets of "basal conglomerates" developped between the two Formation and the first sub-formation of Nanmingshui. The conglomerates, usually as a shape of lens and not far-extending, are occurrences of subaqueous channel when rivers flow into the sea, but not basal conglomerates previously considered.Lateral comparison of conglomerate characteristics and the study of oblique beddings and asymmetrical ripple mark indicate that the provenance is in the direction of NE, and the paleocurrence direction concentrates in 93°-125°.The contact relationship between Heishantou Fm. and Nanmingshui Fm. is conformable and successive. It is not an unconformity of plate collision between Junggar block and Siberia plate.