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Synorogenic evolution of large-scale drainage patterns: Isotope paleohydrology of sequential Laramide basins.

机译：大型排水模式的协同成因演化：拉美酰胺序贯盆地的同位素古水文学。

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摘要

Despite profound interactions of climate, tectonics and topography, tracing landscape evolution during orogeny remains difficult and controversial. This work uses the isotopic and elemental composition of authigenic minerals preserved in intermontane basins to reconstruct regional and basin-scale changes in hydrology and topography of the developing central North American Cordillera during Late Cretaceous and Paleogene (Laramide) time. In particular, the work focuses on the sedimentary records of large (>5,000 km2) lakes present at that time in sequential intraforeland basins of Utah, Wyoming and Colorado.;First, isotopic profiles of Paleogene Lakes Uinta, Flagstaff, and Claron in Utah reveal relatively large (>5‰) shifts to lower delta 18Ocalcite values that are diachronous among the basins. The results also indicate intense evaporation of lake water during intervals of hydrologic closure. The large shifts are interpreted as a combination of increased mean elevation of basin catchments and related freshening associated with basin infilling. Increasing catchment hypsometry is thought to result from the expansion of distal catchments into areas of active magmatism in the hinterland, thus adding to growing evidence that topographic development and dissection of the Cordilleran landscape occurred at large spatial scales and proceeded from north to south during the Early Cenozoic.;Second, to test the hypothesis of evolving drainage patterns, Sr isotope data was collected in order to identify sudden changes in the provenance of catchments feeding the largest lake, Uinta. The expanded isotopic record from the Uinta Basin demonstrated significant variations in 87Sr/ 86Sr ratios that record inflows from the Greater Green River Basin in Wyoming via the Piceance Creek Basin in northwest Colorado. The results thereby document integration of axial drainage over >1000 km, and serve as a warning to paleoaltimetry studies premised on too few isotopic systems, samples or localities.;Lastly, in order to further illuminate the hydrological linkages among the sequential Green River Lake basins, isotopic and elemental profiles of the Piceance Creek Basin were assembled. Interpreting the cumulative results of this dissertation in the context of an extensive dataset of O, C and Sr isotope stratigraphies from sedimentary basins throughout the Paleogene North American Cordillera, I argue that the hydrological linkages of the Green River lakes are emblematic of evolving drainage patterns throughout the Cordillera. Specifically, the data reflect (1) a period of throughgoing foreland rivers heading in the Sevier fold-and-thrust belt and flowing east, (2) ponding of freshwater lakes in the foredeep as Laramide uplifts blocked drainage, (3) hydrologic closure that led to both intensive evaporation in the terminal sink of the Piceance Creek Basin and integration of catchments over length-scales >1000 km, and (4) infilling of basin accommodation by southward migrating magmatism in distal catchments, leading to the freshening and demise of intraforeland lakes that also stepped south over time.;Samples from the Piceance Creek, Uinta, Flagstaff and Claron Basins were analyzed for their oxygen, carbon, hydrogen and strontium isotope composition, and concentrations of calcium, magnesium and strontium were also measured. Research was conducted and is presented in three stages, each building upon the previous:
机译：尽管气候，构造和地形发生了深远的相互作用，但在造山运动过程中追踪景观演变仍然是困难且有争议的。这项工作利用保存在山间盆地中的自生矿物的同位素和元素组成，重建了晚白垩纪和古近纪（拉拉米德）时期北美中部发展中的堇青菜的水文和地形的区域和盆地规模变化。特别是，这项工作着重于当时在犹他州，怀俄明州和科罗拉多州的陆上陆上陆相盆地中存在的大型（> 5,000 km2）湖泊的沉积记录;首先，古近纪湖泊Uinta，Flagstaff和Claron的同位素剖面揭示了犹他州相对较大的（> 5‰）转变为盆地之间不同的较低三角洲18O方解石值。结果还表明，在水文关闭期间，湖水大量蒸发。较大的变化被解释为盆地集水区平均海拔升高和与盆地充填有关的相关清新的综合作用。据认为，集水区测绘法的增加是由于远端集水区扩展到腹地的活跃岩浆作用区域，因此增加了越来越多的证据表明，科迪勒兰景观的地形发展和解剖发生在大空间尺度上，并在早期由北向南发展。第二，为检验不断演变的排水模式的假说，收集了Sr同位素数据，以识别进食最大湖泊Uinta的流域出处的突然变化。来自Uinta盆地的扩大的同位素记录显示87Sr / 86Sr比率存在显着变化，记录了从怀俄明州大绿河盆地经科罗拉多州西北部的Piceance Creek盆地流入的情况。因此，结果记录了超过1000 km的轴向排水系统的整合情况，并警告了以同位素系统，样本或位置太少为前提的古海洋学研究;最后，为了进一步阐明连续绿河湖流域之间的水文联系组装了Piceance Creek盆地的同位素和元素剖面。在整个古近纪北美山脉山脉沉积盆地的O，C和Sr同位素地层的广泛数据集的背景下，解释了本文的累积结果，我认为，格林河湖泊的水文联系象征着整个演化过程中排水方式的演变山脉。具体而言，数据反映了（1）在Sevier褶皱-冲断带中通行的前陆河流并向东流动的时期；（2）由于Laramide隆起阻塞了排水，因此在前缘深处的淡水湖泛滥；（3）水文关闭导致Piceance Creek盆地终端汇的密集蒸发和长度范围大于1000 km的集水区的整合，以及（4）远端集水区向南迁移的岩浆作用充填盆地，导致林地的新生和消亡随着时间的流逝，湖泊也逐渐向南。分析了来自Piceance Creek，Uinta，Flagstaff和Claron盆地的样品的氧，碳，氢和锶同位素组成，并测量了钙，镁和锶的浓度。进行了研究，并分三个阶段进行介绍，每个阶段都建立在之前的基础上：

著录项

  • 作者

    Davis, Steven Joseph.;

  • 作者单位

    Stanford University.;

  • 授予单位 Stanford University.;
  • 学科 Geology.;Geochemistry.
  • 学位 Ph.D.
  • 年度 2008
  • 页码 204 p.
  • 总页数 204
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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