华北克拉通中部造山带中条山地区绛县群地层划分与构造背景

Stratigraphic division and tectonic settings of the Jiangxian Group in the Zhongtiao Mountains of the Trans-North China Orogen,North China Craton

中条山地区是华北克拉通中部造山带的重要组成部分,保存了中部造山带演化的重要记录。绛县群划分为横岭关亚群和铜矿峪亚群,横岭关亚群为一套由石英岩和绢云片岩组成的变质碎屑岩;铜矿峪亚群则以酸性、基性火山岩为主,夹有正常沉积碎屑岩的“双峰式”火山岩。笔者对绛县群岩石组合及地层特征开展详细调查研究,经过对绛县群火山岩、侵入岩和碎屑锆石同位素年龄的综合分析,认为绛县群的形成年龄大约在2200~2120 Ma,时代为古元古代。结合碎屑岩、火山岩的地球化学特征和华北克拉通中部造山带的演化过程,推测绛县群形成的构造环境很可能为古活动大陆边缘。其中,横岭关亚群沉积在活动大陆边缘盆地,而铜矿峪亚群则形成于活动大陆边缘火山弧环境。

The Zhongtiao Mountains,an important part of the Trans-North China Orogen,North China Craton,holds well preserved significant evolution records of the Trans-North China Orogen.The Jiangxian Group is divided into the Henglingguan Subgroup and the Tongkuangyu Subgroup,the Henglingguan Subgroup consists predominantly of metamorphic clastic rocks,specifically quartzite and phyllite.In contrast,the Tongkuangyu Subgroup primarily comprises acid and basic volcanic rocks,with“bimodal”volcanic rocks alternating with normal sedimentary clastic rocks.Based on field investigation on the rock composition and stratigraphic characteristics and comprehensive analysis of zircon isotopic ages of the volcanic rocks,intrusive rocks,and detrital zircon of the Jiangxian Group,the age for this Group is estimated to be around 2200~2120 Ma,corresponding to the Paleoproterozoic Era.By integrating the geochemical characteristics of clastic and volcanic rocks with the evolutionary history of the Trans-North China Orogen,it is inferred that the Jiangxian Group likely originated in a tectonic setting linked to a paleo-active continental margin.Specifically,the Henglingguan Subgroup was deposited in an active continental margin basin,whereas the Tongkuangyu Subgroup originated in a volcanic arc of an active continental margin.