Age and Lithogeochemistry of Volcanic-hosted Massive Sulfide Deposits of the Ambler District, Southern Brooks Range, Alaska

阿拉斯加南布鲁克斯山脉安布勒区火山块状硫化物矿床的年龄和岩石地球化学

• 批准号: 0208162
• 负责人: William McClelland
• 金额: $ 13.13万
• 依托单位: Regents of the University of Idaho
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-07-01 至 2005-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0208162&HistoricalAwards=false
• 关键词: Age; Lithogeochemistry; Volcanic; hosted; Massive

McClellandEAR-0208162Modern examples of volcanic-hosted massive sulfide (VMS) deposits suggest that hydrothermal activity associated with formation of these deposits is a steady-state process. In contrast, ancient examples typically define distinct age groups and recent genetic models relate VMS mineralization to specific tectonic events such as incipient intra-arc rifting. Distinction between steady state and punctual models for VMS mineralization requires high precision geochronologic data to establish the duration of magmatism at the scale of individual deposits and to establish correlation, distinction, or migration of magmatism observed at the regional scale. The widespread occurrence of Devonian to Mississippian VMS deposits in the northern North American Cordillera provides an ideal setting to examine this issue. U-Pb geochronology and Nd-Sr isotope geochemistry combined with major, trace, and REE geochemistry of felsic and mafic rocks associated with mineralization and hydrothermal alteration will establish the age and tectonic setting of VMS mineralization in the Ambler district, southern Brooks Range, Alaska. The resulting database will serve as a basis for comparison with and evaluation of broadly age equivalent VMS deposits in the Yukon-Tanana terrane as well as sediment-hosted deposits within adjacent terranes and the Cordilleran miogeocline. The results of this project will provide valuable insight into the temporal and tectonic setting of VMS mineralization throughout the northern Cordillera. This insight will potentially lead to the generation of new genetic models for the evolution and preservation of VMS deposits in additional settings. The project will also address the long-standing question of the tectonic setting of mid-Paleozoic magmatism in the Cordillera.

火山型块状硫化物（VMS）矿床的现代实例表明，与这些矿床形成相关的热液活动是一个稳态过程。相比之下，古代的例子通常定义了不同的年龄组，而最近的成因模型将VMS矿化与特定的构造事件（如早期弧内裂陷）联系起来。区分VMS矿化的稳态模型和点状模型需要高精度的地质年代学数据，以确定单个矿床尺度上岩浆活动的持续时间，并建立区域尺度上观测到的岩浆活动的对比、区分或迁移。北美科迪勒拉北部广泛分布的泥盆系至密西西比系VMS矿床为研究这一问题提供了理想的环境。U-Pb年代学和Nd-Sr同位素地球化学结合与成矿作用和热液蚀变有关的长英质和基性岩的主要、痕量和稀土地球化学，确定了阿拉斯加Ambler地区VMS成矿的年龄和构造背景。由此产生的数据库将作为比较和评价育空-塔纳纳地块大致年龄相当的VMS矿床以及邻近地块和科迪勒拉岩心地槽内沉积矿床的基础。该项目的结果将为整个北科迪勒拉地区VMS矿化的时间和构造背景提供有价值的见解。这一发现可能会导致新的遗传模型的产生，用于在其他环境下VMS沉积物的演化和保存。该项目还将解决科迪勒拉地区中古生代岩浆活动的构造环境这一长期存在的问题。