Collaborative Research: Neoproterozoic Rifting of Utah: Geochronology, Tectonics, Sequence Stratigraphy

合作研究：犹他州新元古代裂谷：地质年代学、构造学、层序地层学

• 批准号: 0819810
• 负责人: W.A. Yonkee
• 金额: $ 3.22万
• 依托单位: Weber State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-08-01 至 2011-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0819810&HistoricalAwards=false
• 关键词: Collaborative; Research; Neoproterozoic; Rifting; Utah

Various plate reconstructions have been proposed for break up of Rodinia and for the associated rifting history of western Laurentia, but models remain controversial. To address this problem, a research team from Idaho State University, Utah State University, and Weber State University is investigating Neoproterozoic (between 1,100 and 542 million years ago) deposits in Utah and southern Idaho in order to test different models for rift initiation and development: 1) protracted rifting at approximately 750 million years ago associated with an initial breakout of a magmatic plume; 2) continental separation between 720 and 670 million years ago; or 3) rift initiation near the beginning of the Cambrian (about 540 million years ago). The team will employ an integrated field, stratigraphic, structural, zircon provenance, and geochronologic study of Neoproterozoic strata. Specific approaches include: detailed sequence stratigraphic, sedimentologic, and petrologic studies of critical sections; geochemical trace-element analysis of associated volcanic rocks to determine tectono-magmatic setting; U-Pb dating of primary volcanic and detrital zircons using a combination of laser ablation-multicollector-inductively coupled plasma mass spectrometry, sensitive high-resolution ion microprobe, and thermal ion mass spectrometry methods; Ar-Ar dating of hornblende from basalt flows; Hf isotopic analysis of zircons; and modeling of regional subsidence histories. U-Pb dating and Hf isotopic analysis of detrital zircon populations will shed light on source areas and paleogeography, with ages of youngest reworked volcanic zircons providing important brackets for maximum depositional ages.The Neoproterozoic marks some of the most profound geologic changes in Earth history, including break up of the supercontinent Rodinia, extreme climate changes, and rapid biologic diversification. Various plate reconstructions have been proposed for break up of Rodinia and for the associated rifting history of western Laurentia, but models remain controversial. Evidence important for the resolution of this controversy lies in the Neoproterozoic strata of Utah and southeastern Idaho. These strata form a critical, but incompletely understood part of the rifted western margin of Laurentia and subsequent Cordilleran orogenic belt. This research project will make important strides in understanding the history of these beds and lead to discrimination between opposing models for the early tectonic development of the western United States.

已经提出了各种板块重建，以分解罗迪尼亚和西部劳伦氏菌的相关裂纹史，但模型仍然有争议。为了解决这个问题，来自爱达荷州立大学，犹他州立大学和韦伯州立大学的一支研究团队正在调查犹他州和爱达荷州南部的Neoperorozoic（在1,100至5.42亿年前）的沉积物（在1,100至5.42亿年前），以测试不同的裂谷启动和发展模型，以测试大约75亿年前的裂开式启动和发展模型。 2）在720至6.7亿年前的大陆分离；或3）在寒武纪开始（大约5.4亿年前）附近的裂谷开始。该团队将采用综合领域，地层，结构性，锆石出处和新多元地层的测量学研究。特定方法包括：详细的序列地层，沉积学和核切片的岩石学研究；相关的火山岩的地球化学痕量分析，以确定构造岩浆环境；使用激光烧蚀 - 菌群诱导耦合等离子体质谱法，敏感的高分辨率离子离子微探针和热离子质谱法的组合，将原代火山和碎屑锆石的U-PB约会使用；玄武岩流的角闪烁；锆石的HF同位素分析；和区域沉降历史的建模。 U-Pb dating and Hf isotopic analysis of detrital zircon populations will shed light on source areas and paleogeography, with ages of youngest reworked volcanic zircons providing important brackets for maximum depositional ages.The Neoproterozoic marks some of the most profound geologic changes in Earth history, including break up of the supercontinent Rodinia, extreme climate changes, and rapid biologic diversification.已经提出了各种板块重建，以分解罗迪尼亚和西部劳伦氏菌的相关裂纹史，但模型仍然有争议。解决这一争议的重要证据在于犹他州和爱达荷州东南部的新元古代地层。这些地层构成了laurentia裂开的西部边缘和随后的脐带造山带。该研究项目将在理解这些床的历史方面取得重要成就，并导致对反对模型的歧视，以期为美国西部的早期构造发展。