摘要
华北板块南缘中元古代沉积地层的时代归属以及区域古地理格局和构造演化等是近年来地质界探讨的热点问题。本文对豫西鲁山下汤地区的汝阳群云梦山组和黄连垛组进行了碎屑锆石U-Pb年代学和锆石微量元素研究,获得云梦山组年龄最小(年轻)的一批碎屑锆石年龄加权平均值为1658±63Ma,从而限定了汝阳群最早沉积年龄不早于1700Ma。结合洛峪群(上覆于汝阳群)上部洛峪口组近年的年代学标定(1611~1638Ma),将汝阳群-洛峪群的形成年代限定为1700~1600Ma,即中元古代长城纪的中晚期,对应于国际地质年表的固结纪。云梦山组与黄连垛组中碎屑锆石207Pb/206Pb年龄范围为1644~3179Ma,呈现1850Ma、2100Ma、2300Ma、2500Ma、2670Ma和2900Ma六个年龄峰值,对应于华北克拉通中太古代-古元古代重要的地质事件。云梦山组与黄连垛组分别以1850Ma峰值年龄段与2500Ma峰值年龄段的地质体为主要的物源区。根据云梦山组沉积组合性质及形成背景、熊耳群火山岩及其对应锆石的地球化学特征、熊耳群沉积岩夹层的沉积特征和盆地构造属性,综合分析认为熊耳群及其上覆的汝阳群形成于与"岛弧"共生的弧后盆地地区。并且根据云梦山组"同沉积锆石"具"岛弧"地球化学特征,暗示云梦山组沉积时期附近的岛弧火山仍在持续活动中。
The issue of age attribution of the Mesoproterozoic sedimentary strata, regional paleogeographic pattern, and tectonic evolution in the southern margin of the North China Plate has recently been the subject of vigorous debate. This study reports U-Pb geochronology and characteristics of trace elements in detrital zircons from the Yunmengshan Formation of the Ruyang Group, and the Huanglianduo Formation in the Lushan-Xiatang area of the western Henan Province. The weighted average age of the youngest batch of zircons from the Yunmengshan Formation is 1658±63 Ma which constraints the earliest sedimentary age of the Ruyang Group to no earlier than 1700 Ma. Combined with the chronological calibration of the Luoyukou Formation(1611~1638 Ma) of the upper part of the Luoyu Group, the formation age of the Ruyang and the Luoyu groups was limited to 1700~1600 Ma, which is the middle and late period of the Mesoproterozoic Changcheng period, corresponding to the international Statherian Period. The 207Pb/206Pb ages of the detrital zircons from the Yunmengshan and the Huanglianduo formations range from 1644 Ma to 3179 Ma, displaying six age peaks of 1850 Ma, 2100 Ma, 2300 Ma, 2500 Ma, 2670 Ma and 2900 Ma, corresponding to the Middle Archean-Palaeoproterozoic geological events of the North China Craton(NCC). The provenance of the Yunmengshan Formation is dominated by the 1850 Ma peak age geological body, and the Huanglianduo Formation by the 2500 Ma peak age geological body. According to the sedimentary properties and the formation background of the Yunmengshan Formation, the geochemical characteristics of the Xiong’er Group volcanic rocks and their corresponding zircons, the sedimentary characteristics of the Xiong’er Group sedimentary rocks and the basin’s tectonic attributes, would indicate that the Xiong’er Group and the overlying Ruyang Group were formed in the post-arc basin symbiotic with the "island arc". Based on the "synsedimentary zircon" of the Yunmengshan Formation with the geochemical characteristics of
作者
王淼
周洪瑞
张恒
WANG Miao;ZHOU Hongrui;ZHANG Heng(School of the Earlh Sciences and Resources,China University of Geosciences,Beijingi 100083;Institute of Geology,Chinese Academy af Geological Sciences,Beijing,100037)
出处
《地质学报》
EI
CAS
CSCD
北大核心
2020年第4期1027-1045,共19页
Acta Geologica Sinica
基金
中国地质调查局地质调查项目《全国陆域及海区地质图件更新与共享》(编号DD20190370)
科技部基金项目《中国标准地层建立-中国地层表的完善》(批准号2015FY310100)联合资助的成果。
关键词
华北南缘
云梦山组
黄连垛组
熊耳群
碎屑锆石
物源分析
大地构造演化
southern margin of the North China Craton
the Yunmengshan Formation
the Huanglianduo Formation
the Xiong’er Group
detrital zircon
provenance
tectonic evolution
