The Geology of Glaciated Sedimentary Basins

冰川沉积盆地地质

• 批准号: RGPIN-2015-05872
• 负责人: Eyles, Nicholas
• 金额: $ 2.4万
• 依托单位: University of Toronto
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2016
• 资助国家: 加拿大
• 起止时间: 2016-01-01 至 2017-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=613798
• 关键词: Geology; Glaciated; Sedimentary; Basins

The time interval from c. 750 to 600 million years ago (the Neoproterozoic) was dominated by the disintegration of the large supercontinent Rodinia. One unusual characteristic of the many extensional sedimentary basins that formed during continental rifting and breakup are exceptionally thick (~1 km) successions of diamictites that are poorly-sorted mixtures of particles ranging from mud to boulders. Despite decades of research their origin remains enigmatic. They are interpreted by some geologists as ancient glacial tills (‘tillites’) left by extensive ice sheets during world-wide ice ages (c. 770-735 Ma Kaigas, c. 715-680 Ma Sturtian, c. 660–635 Ma Marinoan, and c. 585-582 Ma Gaskiers events) with extremely low global temperatures (-50 °C) and frozen oceans. Other geologists argue that diamictites are glacially-influenced submarine debris flows deposited in open oceans akin to Pleistocene and modern glacially-influenced environments, or are entirely non-glacial and therefore lack climatic significance. The lack of agreement over the origin of diamictites is a fundamental data gap in understanding the history of Earth’s climate and the evolution of the biosphere. It is also of direct economic importance. Exploration for stratiform copper hosted within thick (1.25 km) Neoproterozoic diamictites of the Katanga Basin in the Democratic Republic of Congo (DRC) by a Canadian mining company (Ivanplats) and for unconventional oil in such rocks in Brazil by Petra Energia SA has generated exceptional (and hitherto unavailable) basin-wide databases of drill core through Neoproterozoic diamictites and related facies, together with downhole geophysical and regional seismic and aeromagnetic data. This project identifies a plan to exploit these new databases by analyzing drill core and geophysical data in conjunction with the description and sampling of targeted surface outcrop exposures across DRC and Brazil. This will allow a clear methodology for the description and interpretation of diamictite facies and resolution of their origin and their tectonic significance within evolving Neoproterozoic basins. The project will provide key insights into the nature of Neoproterozoic hydrological cycles and the cryosphere and climate system at a time of rapid biological diversification linked by some to global ice ages. Substantial progress can be made in five years and results will be communicated in first class journals during the course of the project. This timely and ambitious research project will enhance Canadian expertise in mineral exploration and glacial sedimentology, accelerate resource exploration and investment in developing economies and promote opportunities for advanced student training and employment of Canadian geologists.

从C开始的时间间隔。7.5亿至6亿年前（新元古代），大型超大陆Rodinia的解体占主导地位。在大陆裂谷和分裂过程中形成的许多伸展沉积盆地的一个不寻常的特征是异常厚（约1公里）的杂岩系列，这些杂岩是从泥到巨砾的颗粒混合物。尽管经过几十年的研究，它们的起源仍然是个谜。它们被一些地质学家解释为古代冰川冰碛物（“冰碛物”），是在世界范围的冰河时代（公元前200年）由大面积的冰盖留下的。770-735 Ma Kaigas，c. 715-680 Ma Sturtian，c. 660-635 Ma Marinoan，and c. 585-582 Ma Gaskiers事件），全球气温极低（-50 °C），海洋冻结。其他地质学家认为，杂岩是冰川影响的海底碎屑流，沉积在类似于更新世和现代冰川影响环境的开阔海洋中，或者完全是非冰川的，因此缺乏气候意义。对杂混岩的起源缺乏一致意见是理解地球气候历史和生物圈演变的一个基本数据缺口。它也具有直接的经济重要性。厚层层状铜矿的勘探（1.25公里）加拿大矿业公司拍摄的刚果（DRC）加丹加盆地新元古代杂岩（Ivanplats）和Petra Energia SA在巴西此类岩石中的非常规石油，通过新元古代杂岩和相关相的全盆地范围的岩心数据库，以及井下地球物理和区域地震和航磁数据。该项目确定了一项利用这些新数据库的计划，方法是分析岩心和地球物理数据，并结合刚果民主共和国和巴西目标地表露头暴露的描述和采样。这将允许一个明确的方法来描述和解释杂岩相和分辨率的起源和它们的构造意义在不断发展的新元古代盆地。该项目将提供有关新元古代水文循环的性质以及冰冻圈和气候系统的关键见解，因为当时生物迅速多样化，有些人认为这与全球冰河时代有关。五年内可以取得实质性进展，并在项目过程中在一流期刊上传播成果。这一及时而雄心勃勃的研究项目将加强加拿大在矿物勘探和冰川沉积学方面的专门知识，加速资源勘探和对发展中经济体的投资，并促进加拿大地质学家的高级学生培训和就业机会。