柴西红三旱一号-牛鼻子梁地区下油砂山组物源与沉积体系

目前普遍认为位于柴达木盆地西部阿尔金山前的红三旱一号-牛鼻子梁地区在新近系下油砂山组(N_2xy)沉积时,只发育向西南方向流动的牛鼻子梁物源所形成的冲积扇-辫状河三角洲-湖泊沉积体系,这种认识难以解释以下事实:第一,在红三旱一号地面构造南翼露头发育一套约650 m厚的N_2xy灰色砾岩;第二,二维地震测线QY0680和CDM1150以及露头剖面表明,在N_2xy沉积时,不整合地面构造及其附近约190 km~2的区域呈一个北西走向的剥蚀区,该剥蚀区有效地分隔了红三旱一号物源体系和牛鼻子梁物源体系;第三,在N_2xy沉积时,牛鼻子梁地区是阿尔金山向东南方向延伸的古鼻梁,该古鼻梁是牛鼻子梁以北地区物源向西南方向流动的屏障.在综合研究的基础上,提出在N2xy沉积时,研究区发育由红三旱一号物源、牛鼻子梁西口物源和牛参1井以北物源所控制的扇三角洲-滨浅湖滩坝沉积体系.

Provenance and Sedimentary System of Lower Youshashan Formation in Hongsanhanyihao Niubiziliang Area in Western Qaidam Basin

People commonly considered that in Hongsanhanyihao-Niubiziliang area in piedmont of Altun mountain in western Qaidam basin there is alone alluvial fan-braided river delta-lake depositional system formed by Niubiziliang sedimentary provenance flowing towards the southwest in period of the Lower Youshashan formation(N_2xy).It is hard to explain the following facts by this point of view:1)a set of gray conglomerate of N_2xy in thickness of about 650 m lies to the outcrop of south side of Hongsanhanyihao structure;2)it is confirmed from 2-D seismic lines of QY0680 and CDM1150 that a denudation zone about 190 km~2 in trend of NW in the unconformity and its surroundings,which separates Hongsanhanyihao system from Niubiziliang system;3)Niubiziliang system is an old nose-like structure extending to the southeast of Altun mountain and plays a barrier part in the source materials in north of Niubiziliang area flowing or moving towards the southwest.This paper presents the fan delta-offshore/shallow lake beach/bar system developed in this studied area,which is controlled by Hongsanhanyihao provenance,the west valley of Niubiziliang provenance and the source material in north of Well Niucan-1.