SGER: Platinum Group Element Anomalies at Cryogenian Glacial Terminations

SGER：本项目旨在确定新元古代冰川终端是否具有地外铂族元素（PGE）异常。 原始数据（Bodiselitsch等人，科学，2005年）与地球外的铱富集在终端Sturtian和Marinoan沉积物。 相比之下，未公布的数据，在麦肯齐山脉，加拿大西北部的终端Marinoan沉积物，显示铂族元素异常的陆地血统。 这些陆地异常反映了从冰川杂岩到上覆冰后期帽碳酸盐岩的沉积速率的显着变化。根据现有的数据，从这两个位置，目前还不清楚是否在新元古代冰川终端的地球外异常的共同特点。 该项目的目的是测试PGE的谱系在连续的，良好的表征部分跨越部分的马里诺冰川终端，代表一个横断面从浅大陆架深坡沉积设置在纳米比亚西北部。 沉积环境的梯度使得它更有可能在至少一个位置完整的冰川-冰后期过渡？从而产生了假设的地外铱异常如果证实地外存在铂族元素富集现象，则需要开展后续研究，以更好地限制全球综合异常幅度。 这些异常的空间异质性也可能有助于改进低温期冰川的冰盖模型。

SGER: Platinum Group element Anomalies at Cryogenian Glacial TerminationsBernhard Peucker-EhrenbrinkWoods Hole Oceanographic InstituteEAR-0821878AbstractThis project aims at determining whether Neoproterozoic glacial terminations are characterized by extraterrestrial platinum group element (PGE) anomalies. The original data (Bodiselitsch et al., Science, 2005) are consistent with extraterrestrial iridium enrichments in terminal Sturtian and Marinoan sediments. In contrast, unpublished data for the terminal Marinoan sediments in the Mackenzie Mountains, NW Canada, show PGE anomalies that are of terrestrial pedigree. These terrestrial anomalies reflect significant changes in sedimentation rates from glacial diamictites into the overlying postglacial cap carbonates.Based on the existing data from both locations it is unclear whether extraterrestrial anomalies are common features at Neoproterozoic glacial terminations. This project is designed to test the pedigree of PGE in continuous, well-characterized sections across sections of Marinoan glacial terminations that represent a transect from shallow shelf to deep slope depositional settings in NW Namibia. The gradient in depositional environments makes it more likely that in at least one location the full glacial-postglacial transition ? and thus the hypothesized extraterrestrial iridium anomaly ? is preserved.If extraterrestrial enrichments of PGE are confirmed, follow-up studies are needed to better constrain the globally integrated magnitude of the anomaly. The spatial heterogeneity of these anomalies may also help to improve ice-sheet models for Cryogenian glaciations.