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.

现代火山岩块状硫化物（VMS）矿床的实例表明，与这些矿床形成有关的热液活动是一个稳态过程。与此相反，古代的例子通常定义不同的年龄组和最近的成因模型与VMS矿化特定的构造事件，如初期弧内裂谷。VMS成矿作用的稳态模型和点模型之间的区别需要高精度的地质年代学数据来确定单个矿床规模的岩浆活动持续时间，并建立在区域尺度上观察到的岩浆活动的相关性、区别或迁移。在北方北美科迪勒拉山脉泥盆纪到密西西比纪VMS沉积的广泛存在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矿化和热液蚀变有关的长英质和镁铁质岩石的主、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Ambler地区VMS矿化的时代和构造环境。由此产生的数据库将作为一个基础，比较和评价大致年龄相当的VMS矿床在育空-塔纳纳山脉，以及沉积物托管矿床在相邻的山脉和科迪勒拉山脉miogeocline。该项目的结果将为整个北方科迪勒拉山脉VMS矿化的时间和构造背景提供有价值的见解。这一见解将可能导致新的遗传模型的产生，在额外的设置VMS存款的演变和保存。该项目还将解决长期存在的问题，即科迪勒拉山脉中古生代岩浆活动的构造背景。