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

边缘盆地保存了大陆边缘造山系统时空演化的详细记录。研究的重点是造山系统的挖掘历史如何保存在古地层记录中，以及从衍生沉积序列中提取这一历史的保真度如何。它整合了互补的同位素碎屑物源技术，以限制源区的非均质性、挖掘模式和速率、沉积物扩散特征和盆地沉降机制。具体来说，该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、碎屑钾长石和白云母40Ar/39Ar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）相结合的实用性，以评估造山作用、盆地沉降以及大陆边缘弧系统中沉积扩散和堆积之间的动态联系。本研究的一个关键方面是开发和应用与碎屑矿物40Ar/39Ar闭合年龄分布相关的新分析和建模方法。对加利福尼亚半岛山脉北部沉积物中的钾长石进行40Ar/39Ar全融合分析的初步结果表明，该方法可以提供灵敏、高分辨率的深基底挖掘记录。要将该方法有意义地应用于岩浆岩源区，需要对侵入史进行表征，需要通过碎屑U-Pb锆石年代学来提供基底结晶年龄。通过对细粒碎屑岩的全岩钕同位素分析，对源区非均质性和沉积物扩散堆积模式的时空变化进行了约束。下加利福尼亚的Vizcaino盆地暴露在相对较浅（5-10公里）的半岛山脉基岩附近，在那里一个明显的加速弧剥蚀事件似乎是由大体积的基岩侵位引发的。不列颠哥伦比亚省南部的Nanaimo盆地暴露在深蚀（20-30 km）的海岸深部岩浆弧岩附近，这些岩浆弧岩是在深部作用和区域变形的复杂相互作用下被挖掘出来的。这两个盆地都具有年代确定的地层相干序列，这些序列跨越了各自源区的发掘事件。这为解释衍生沉积记录中记录的基底挖掘历史细节提供了必要的解释框架。本科生研究合作者在调查过程中深入参与了现场和实验室分析的各个方面。学生合作者（n~12）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。

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.