Testing the Neoproterozoic Snowball Earth in Svalbard

测试斯瓦尔巴群岛的新元古代雪球地球

• 批准号: 9817244
• 负责人: Paul Hoffman
• 金额: $ 29.61万
• 依托单位: Harvard University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-03-15 至 2003-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9817244&HistoricalAwards=false
• 关键词: Testing; Neoproterozoic; Snowball; Earth; Svalbard

The Hecla Hoeck succession in Svalbard is one of the most complete and well-exposed late Neoproterozoic sections of carbonate rocks in the world. It contains the deposits of two glacial episodes and carbon-13 isotopic (d13C) evidence for two other glacial episodes. This preservation is important because evidence suggests that events preceding the metazoan explosion were among the most extraordinary in Earth's history. Prior research indicate that a series of runaway ice albedo catastrophes occurred with each one leading to a virtual collapse of biological productivity in the surface ocean for millions of years. Stratigraphic evidence includes a unique association of glacial diamicrites, cap carbonates, and extreme d13C swings. The Principal Investigator will test the Neoproterozoic "snowball" Earth hypothesis in the Hecla Hoek succession in Svalbard. He will use integrated sequence and chemostratigraphic tools successfully used in Neoproterozoic carbonates worldwide. There is a strong possibility of unforeseen structural complications on such old rocks. Therefore, he will address the classical problem of the "bottomless" Hecla Hoeck geosyncline by testing the hypothesis that a Caledonian extensional detachment separates the Neoproterozoic sedimentary succession of eastern Ny Friesland from the Caledonian metamorphic complex to the west. This bears on the relationship between geon-18 basement to the west and geon-18 basement to the east. This relationship is key to the reconstructions of the North Atlantic in the supercontinent Rodinia. Existing paleogeographic reconstructions of this part of Rodinia are controversial, but they are believed to serve as boundary conditions for models of Neoproterozoic paleoclimate. Argon-argon (4040-3940) stable isotope analyses will be used to establish the geochronolgy.

斯瓦尔巴特群岛的Hecla Hoeck序列是世界上新元古代晚期最完整、出露最多的碳酸盐岩剖面之一。它包含两个冰期的沉积物和另外两个冰期的碳-13同位素(D13C)证据。这种保存很重要，因为有证据表明，后生动物爆炸之前的事件是地球历史上最不寻常的事件之一。先前的研究表明，发生了一系列失控的冰反照率灾难，每一次都导致数百万年来表层海洋的生物生产力实际上崩溃。地层学证据包括一种独特的冰川硅质岩、冰帽碳酸盐和极端d13C波动的组合。首席调查员将在斯瓦尔巴特群岛的Hecla Hoek序列中检验新元古代“滚雪球”地球假说。他将使用在世界各地新元古代碳酸盐岩中成功使用的综合层序和化学地层学工具。在这些古老的岩石上，极有可能出现不可预见的构造复杂情况。因此，他将通过检验加里东伸展滑脱将纽约弗里斯兰东部的新元古代沉积序列与加里东变质杂岩向西分开的假设，来解决赫克拉霍克地槽这一经典问题。这关系到Jon-18西侧地下室和Jon-18东侧地下室之间的关系。这种关系是在罗迪尼亚超大陆重建北大西洋的关键。现有的罗迪尼亚这一部分的古地理重建是有争议的，但它们被认为是新元古代古气候模型的边界条件。将使用Ar-Ar(4040-3940)稳定同位素分析来建立地质年代学。