Environmental and Biologic Controls on Carbonate Platform and Reef Development, Terminal Neoproterozoic Nama Group, Namibia

碳酸盐台地和珊瑚礁发育的环境和生物控制，新元古代末期纳马群，纳米比亚

• 批准号: 9628257
• 负责人: John Grotzinger
• 金额: --
• 依托单位: Massachusetts Institute of Technology
• 依托单位国家: 美国
• 项目类别: Continuing grant
• 财政年份: 1996
• 资助国家: 美国
• 起止时间: 1996-09-15 至 1999-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9628257&HistoricalAwards=false
• 关键词: Environmental; Biologic; Controls; Carbonate; Platform

Grotzinger 9628257 This project will attempt to improve our understanding of the first-order, long-term evolution of carbonate platforms by investigating the transition from Proterozoic platforms formed of microbial and abiotic carbonates to Phanerozoic platforms formed of calcified metazoan and metaphyte skeletons. The proposed research will attempt to document the detailed paleoenvironments of several carbonate platforms and reefs in the Nama and Witvlei groups (Namibia) that span terminal Neoproterozoic time, and the first influences of calcified invertebrates and metaphytes on sediment production, platform paleoecology, and facies development. We will specifically study: 1) the composition and distribution of various facies, 2) the relationships between microbialite morphology and microfabric, 3) the relationships between microbialities and calcified metazoans and metaphyytes, and 4) primary mineralogy of skeletal grains, microbial components, and cements. We have selected three representative units for investigation based on their diversity of facies, microbialite and skeletal fossil assemblages, and progressively younger stratigraphic positions and age. In ascending stratigraphic order these include: 1) the Bushmanskippe Formation (Witvlei Group), whose basal unit (Bildah Member) is considered to be a "cap carbonate" (peculiar carbonates possibly associated with deglaciation of Neoproterozoic ice sheets; 2) the Omkyk Member of the basal Nama Group which has 3-D stratigraphic exposures and contains spectacular microbialite-Cloudina pinnacle reefs; and, 3) the Huns Member of the middle Nama Group which contains calcified metaphyte-microbialite patch reefs and microbialite-shelly fossil pinnacle reefs. The proposed research will provide important information that will be useful in understanding interactions within the earliest calcified metazoan/metaphyte and microbial ecosystems, the sources of terminal Neoproterozoic carbonate sediment, and impact of skeletal sediment on the f acies and long-term evolution of carbonate depositional systems.

Grotzinger 9628257该项目将尝试通过研究从由微生物和非生物碳酸盐形成的proterokoic平台到形成的Phanerozoic平台形成的碳酸盐平台的过渡，从而提高我们对碳酸盐平台的一阶长期演变的理解，该平台由钙化的梅唑烷和平方传统骨骼组成。 拟议的研究将尝试记录跨越末期新元古代时间的纳马和维特维利群体（Namibia）中几个碳酸盐平台和珊瑚礁的详细古环境，以及钙化无脊椎动物和代孢子对沉积物生产，平台古生物学和面的开发的第一个影响。 我们将专门研究：1）各种相的组成和分布，2）微生物形态和微型代表之间的关系，3）微生物与钙化后生动物和形态细胞之间的关系，以及4）骨骼粒，微生物成分，微生物成分和水泥的原发性矿物质学。 我们已经根据其相的多样性，微生物和骨骼化石组合以及逐渐年轻的地层位置和年龄来选择三个代表单位进行调查。 按照地层的顺序，其中包括：1）Bushmanskippe组（Witvlei组），其基础单位（Bildah成员）被认为是“碳酸盐含量”（特殊的碳酸盐（特殊的碳酸盐）（可能与Neoperoterotorotorosoic Ice Sheets的脱毛相关的特殊碳酸盐群；微生物 - 卢比纳峰礁； 3）中间纳玛组的HUNS成员，其中包含钙化的西班皮 - 微生物斑块礁和微生物 - shelly shelly化石峰礁。 拟议的研究将提供重要的信息，这些信息将有助于理解最早的钙化后代/比喻和微生物生态系统的相互作用，终末氧化碳酸盐沉积物的来源，以及骨骼沉积物对FESIES的影响以及碳酸盐深度深度系统的长期进化。