豫西义马地区中—晚三叠世古地震引起的欠沉积物变形构造

摘要

Soft-sediment deformation structures, which contain cylindrical structure, pillow struc ture, load structure and curly bedding structure, were largely preserved in the Middle-Upper Triassic in Yima region, western Henan Province. Most of them occurred in the upper part of fluvial and deltaic de posits , which represents fine-grain and more water-contained sediments. Although it is beneficial to lique faction of sediments, the trigger of soft-sediment deformation structures is the palaeoearthquake activities from the Qinling Orogen. Comparison of soft-sediment deformation assemblages from the Youfangzhuang Formation with data from the Chunshuyao Formation reveals the initial orogeny of the Qinling Orogenic Belt happened in the later Middle Triassic and more intense activities in the Late Triassic.%豫西义马地区中-上三叠统发现大量软沉积物变形构造,包括柱状构造、枕状构造、负载构造和卷曲层理构造,它们大多保存在河流沉积的上部及湖泊三角洲沉积中.通过形态学、遗迹学及镜下薄片分析表明,这些软沉积物变形与沉积物液化有关,其中河-湖相快速沉积为沉积物液化创造了条件,古地震活动是它们形成的主要触发因素.对比该地区中三叠统油房庄组与上三叠统椿树腰组软沉积物变形组合特征,认为秦岭造山带初始造山时间应在中三叠世油房庄组沉积时期,更强烈的造山活动发生在晚三叠世.