Collaborative Research: RUI: Intergrated Isotopic Provenance Analysis: Constraining the Dynamic Linkage between Orogenic Exhumation and Basin Evolution

合作研究：RUI：综合同位素来源分析：约束造山折返与盆地演化之间的动态联系

• 批准号: 0409869
• 负责人: J. Brian Mahoney
• 金额: $ 18.65万
• 依托单位: University of Wisconsin-Eau Claire
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-07-01 至 2008-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0409869&HistoricalAwards=false
• 关键词: Collaborative; Research; RUI; Intergrated; Isotopic

Marginal basins preserve a detailed record of the spatial and temporal evolution of orogenic systems along continental margins. This investigation focuses on the fundamental question of how the exhumation history of orogenic systems is preserved in the ancient stratigraphic record, and with what fidelity this history can be extracted from derivative sedimentary successions. It integrates complementary isotopic detrital provenance techniques to constrain source area heterogeneity, exhumation patterns and rates, sediment dispersal characteristics, and basin subsidence mechanisms. Specifically, the study is testing the utility of integrating multiple isotopic techniques (detrital zircon U-Pb geochronology, whole rock Nd analyses, and detrital K-feldspar & muscovite 40Ar/39Ar thermochronology) with traditional sedimentologic analyses (biostratigraphic, lithostratigraphic and petrologic studies) to assess the dynamic linkage between orogenesis, basin subsidence and resultant sediment dispersal and accumulation in continental margin arc systems. A key aspect of this investigation is development and application of new analytical and modeling approaches associated with 40Ar/39Ar closure age distributions of detrital minerals. Preliminary results utilizing total fusion 40Ar/39Ar analysis of K-feldspar from sediments derived from the northern Peninsular Ranges of California indicate that indicate this method can provide a sensitive, high-resolution record of deep basement exhumation. Meaningful application of the method to batholithic source regions requires characterization of intrusion history, necessitating detrital U-Pb zircon geochronology to provide basement crystallization ages. Source area heterogeneity and temporal and spatial variations in sediment dispersal and accumulation patterns are constrained using whole rock neodymium isotopic analyses of fine-grained clastic rocks. Two basins that share broad first-order similarities in age, provenance and depositional setting, but have strongly constrasting syn-sedimentary crustal exhumation records in their respective batholithic source regions are being examined The Vizcaino basin of Baja California is exposed adjacent to the relatively shallowly exhumed (5-10 km) Peninsular Ranges batholith where a distinct episode of accelerated arc denudation appears to have been triggered by large-volume batholith emplacement. The Nanaimo basin of southern British Columbia is exposed adjacent to deeply eroded (20-30 km) magmatic arc rocks of the Coast Plutonic Complex that were exhumed in response to a more complex interplay of plutonism and regional deformation. Both basins have well-dated stratigraphically coherent successions that span the exhumation events in their respective source regions areas. This provides the necessary interpretive framework to interpret details of basement exhumation histories recorded in the derivative sedimentary record.Undergraduate student research collaborators are heavily involved in all aspects of field and laboratory analyses conducted during this investigation. Student collaborators (n~12) are participating in stratigraphic analysis, sedimentary petrology, geochemistry, and isotopic analysis at both the University of Wisconsin-Eau Claire and San Diego State University.

边缘盆地保存了沿着大陆边缘造山系统时空演化的详细记录。 这项研究的重点是造山系统的折返历史如何保存在古代地层记录中的基本问题，以及如何从衍生的沉积序列中提取这一历史的保真度。 它集成了互补的同位素碎屑物源技术，以限制源区的异质性，折返模式和速率，沉积物分散特征，盆地沉降机制。 具体而言，这项研究正在测试将多种同位素技术（碎屑锆石U-Pb地质年代学、全岩Nd分析和碎屑钾长石白云母40 Ar/39 Ar热年代学）与传统沉积学分析（生物地层学、岩石地层学和岩石学研究）相结合的效用，以评估造山作用、盆地沉降和由此产生的大陆边缘弧系沉积物扩散和积累之间的动态联系。 这项研究的一个关键方面是开发和应用新的分析和模拟方法与碎屑矿物的40 Ar/39 Ar封闭年龄分布。 对加州北方半岛山脉沉积物中钾长石进行全熔融~（40）Ar/~（39）Ar分析的初步结果表明，该方法可以提供一个灵敏、高分辨率的深部基底折返记录。有意义的应用该方法的岩基源区需要表征的侵入历史，需要碎屑U-Pb锆石年代学提供基底结晶年龄。 利用细粒碎屑岩的全岩钕同位素分析，可以确定源区的不均匀性和沉积物分散和聚集模式的时空变化。 两个盆地在时代、物源和沉积背景方面具有广泛的一级相似性，但在其各自的岩基源区具有强烈的同沉积地壳折返记录，正在对这些记录进行检查。下加利福尼亚的比斯开诺盆地与相对较浅的折返（5-10 km）相邻出露。半岛山脉岩基，其中一个明显的插曲加速弧剥蚀似乎已被触发的大容量岩基侵位。 不列颠哥伦比亚省南部的纳奈莫盆地暴露于海岸深成岩杂岩的深度侵蚀（20-30 km）岩浆弧岩附近，这些岩浆弧岩是在深成岩作用和区域变形的更复杂相互作用下被挖掘出来的。 这两个盆地都有很好的年代地层连贯的继承，跨越折返事件在各自的源区地区。这提供了必要的解释框架，以解释在衍生沉积record.Undergraduate学生研究合作者记录的基底折返历史的细节大量参与在此调查过程中进行的现场和实验室分析的各个方面。 学生合作者（n~12）正在威斯康星大学欧克莱尔分校和圣地亚哥州立大学参与地层分析、沉积岩石学、地球化学和同位素分析。