The Proterozoic Qinggouzi microfossil assemblage and its biostratigraphic constraints on the Great Unconformity in northeastern North China Craton
The Proterozoic Qinggouzi microfossil assemblage and its biostratigraphic constraints on the Great Unconformity in northeastern North China Craton
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DOI：
10.1016/j.precamres.2023.107130
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发表时间：
2023-09
影响因子：
3.8
通讯作者：
W. Zheng;Q. Tang;S. Xiao;K. Pang;Junyao Kang;Guang-Jin Li;Chuanming Zhou;Xunlai Yuan;B. Wan
中科院分区：
文献类型：
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作者：
W. Zheng;Q. Tang;S. Xiao;K. Pang;Junyao Kang;Guang-Jin Li;Chuanming Zhou;Xunlai Yuan;B. Wan
前寒武纪-寒武纪边界的大不整合已在几个大陆上得到承认，并可能为寒武纪大爆炸的环境背景提供重要的见解。然而，在许多情况下，大不整合的地球动力学驱动因素、年代学持续时间和古地理范围仍然不受限制。最近，在中国北部多个地区的前寒武纪-寒武系界线附近发现了一个不同程度的重大沉积空白区，这导致了大不整合可能是横跨中国克拉通北部的广泛而历时的解释。然而，中国东北部的大不整合强度尚不清楚，这主要是因为该地区元古界-寒武纪厚层层序的年龄限制较差。本文利用生物地层学资料确定了中国北部大不整合面下元古界地层的沉积时代。本文报道了中国克拉通北缘吉林省南部青沟子组的一组不同的有机壁微体化石组合。青沟子组合中存在典型的中元古代晚期至新元古代早期微体化石，包括古陆壳、古古陆等，为青沟子组提供了坚实的生物地层约束。考虑到上覆的水东组含有典型的早寒武世小壳化石，我们的新数据表明，中国东北部的大不整合代表了一个约200Myr的主要沉积缺口。因此，新的数据与来自世界各地的其他生物地层学和地质年代学数据一起，对大不整合的古地理范围、年代地层持续时间和历时性质提供了强有力的约束。
The Great Unconformity at the Precambrian-Cambrian boundary has been recognized on several continents and may provide critical insights into the environmental context of the Cambrian explosion. However, the geodynamic drivers, geochronological duration, and paleogeographic extent of the Great Unconformity remain unconstrained in many cases. Recently, a major depositional gap of varying magnitudes has been reported around the Precambrian-Cambrian boundary in several regions of North China, leading to the interpretation that the Great Unconformity may have been widespread but diachronous across the North China Craton. However, the magnitude of the Great Unconformity remains unknown in northeastern North China, largely because of the poor age constraints on the thick Proterozoic–Cambrian successions in this region. Here we use biostratigraphic data to constrain the depositional age of Proterozoic strata below the Great Unconformity in northeastern North China. We report a diverse organic-walled microfossil assemblage from the Qinggouzi Formation in southern Jilin Province, northeastern margin of the North China Craton. Typical late Mesoproterozoic to early Neoproterozoic microfossils, includingTrachyhystrichosphaera aimikaandProterocladus antiquus, are present in Qinggouzi assemblage, providing a solid biostratigraphic constraint on the Qinggouzi Formation. Given that the overlying Shuidong Formation contains typical early Cambrian small shelly fossils, our new data indicate that the Great Unconformity in northeastern North China represents a major depositional gap of >200 Myr. Thus, the new data, along with other available biostratigraphic and geochronological data from over the world, provide robust constraints on the paleogeographic extent, chronostratigraphic duration, and diachronous nature of the Great Unconformity.