Understanding palaeoenvironmental constraints on glaucony formation – insights from Late Cretaceous greensand giants

了解古环境对青绿砂形成的限制——来自晚白垩世绿砂巨星的见解

• 批准号: 423948533
• 负责人: Privatdozent Dr. Markus Wilmsen
• 金额: --
• 依托单位: Senckenberg Naturhistorische Sammlungen Dresden
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2019
• 资助国家: 德国
• 起止时间: 2018-12-31 至 2023-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/423948533?language=en
• 关键词: Understanding; palaeoenvironmental; constraints; glaucony; formation

Green authigenic marine clays developed in Earth history from the late Palaeoproterozoic to the Recent with an accumulation maximum centered on the Cretaceous Period. This project aims at understanding the environmental parameters which controlled the massive formation of green marine clay minerals during the (early) Late Cretaceous (Cenomanian to Coniacian) and their accumulation to thick, widespread sequences of greensands ("greensand giants") characterising nearshore settings in many basins worldwide. The integrated approach combines stratigraphical, sedimentological, mineralogical and geochemical analyses with the Cretaceous palaeoenvironmental/-geographical context. Regionally tied to and based on well-dated sections around the Mid-European Island, the project also challenges the geological principle of uniformitarianism positing that "the present is the key to the past": the massive, very widespread formation and accumulation of glaucony-dominated greensands in nearshore settings is not matched by data from recent depositional systems. These observations suggest that the presence is not always the key to the past and we suggest that the widespread shallow-marine green marine clay formation during Cretaceous times was basically controlled by the (physico-)chemical properties of the riverine flux from the low-lying, deeply weathered continents. The main goals of the project can thus be summarised as follows:1) to investigate stratigraphical, sedimentological and palaeogeographical conditions of greensand giants around the Mid-European Island;2) to obtain quantitative data on the rock-forming green grains (morphology, colour, abundance, mineralogy, geochemistry);3) to characterise and understand the geochemical environment of shallow-marine Late Cretaceous greensand formation;4) to test the hypothesis that widespread shallow-marine glaucony formation during the (early) Late Cretaceous is related to the deep weathering of the continents and the chemical properties of the fluvial run-off.Although the application is regionally based on sections from Germany, it deals with a global phenomenon of considerable importance that can be narrowed down and tackled well in the proposed study area: the integrated analysis and comparison of different settings around the Mid-European Island will provide clues for the formation conditions of Late Cretaceous greensand giants.

绿色自生海相粘土发育于古元古代晚期至近代，以白垩纪为最大聚集期。该项目旨在了解控制晚白垩世(早白垩世至科尼阿西期)绿色海洋粘土矿物大量形成的环境参数，以及它们在全世界许多盆地的近岸环境中聚集到厚重、广泛的绿砂(“绿砂巨人”)序列中的控制因素。综合方法将地层学、沉积学、矿物学和地球化学分析与白垩纪古环境/地理环境相结合。该项目在地区性上与中欧岛屿周围年代较长的部分联系在一起，并以此为基础，还挑战了统一论的地质学原理，即“现在是过去的关键”：在近岸环境中，以青绿石为主的绿地的大规模、非常广泛的形成和积累与来自最近沉积系统的数据不相匹配。这些观察表明，这种存在并不总是过去的关键，我们认为，白垩纪广泛存在的浅海绿色海洋粘土的形成基本上是由来自低洼、深度风化的大陆的河流通量的(物理化学性质)控制的。因此，该项目的主要目标可以概括为：1)调查中欧岛群周围绿巨人的地层、沉积学和古地理条件；2)获得形成岩石的绿色颗粒的定量数据(形态、颜色、丰度、矿物学、地球化学)；3)描述和了解晚白垩世浅海绿砂建造的地球化学环境；4)验证晚白垩世(早期)广泛的浅海青光体形成与大陆深部风化和河流径流的化学性质有关的假设。虽然该应用是基于德国的区域切片，但它涉及一个相当重要的全球现象，可以在拟议的研究区内缩小范围并很好地解决：对中欧岛周不同背景的综合分析和比较将为晚白垩世绿色和巨型岩石的形成条件提供线索。