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.

McClellandEAR-0208162火山块状硫化物 (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，而最近的遗传模型将 VMS 矿化与特定的构造事件（例如早期的弧内裂谷）联系起来。 VMS 成矿的稳态模型和准时模型之间的区别需要高精度的地质年代学数据，以确定单个矿床规模的岩浆活动持续时间，并建立在区域规模观察到的岩浆活动的相关性、区别或迁移。北美科迪勒拉山脉北部泥盆纪至密西西比纪 VMS 沉积物的广泛存在为研究这一问题提供了理想的环境。 U-Pb 地质年代学和 Nd-Sr 同位素地球化学，结合与矿化和热液蚀变相关的长英质和基性岩的主量、微量和稀土元素地球化学，将确定阿拉斯加布鲁克斯山脉南部安布勒地区 VMS 矿化的年龄和构造环境。由此产生的数据库将作为比较和评估育空-塔纳纳地体中大致年龄相当的 VMS 沉积物以及邻近地体和科迪勒拉斜地斜内沉积物托管沉积物的基础。该项目的结果将为了解整个科迪勒拉山脉北部 VMS 矿化的时间和构造环境提供宝贵的见解。这一见解可能会产生新的遗传模型，用于在其他环境中进化和保存 VMS 沉积物。该项目还将解决科迪勒拉山脉中古生代岩浆作用的构造环境这一长期存在的问题。