...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Geosphere >Birth and evolution of the Virgin River fluvial system: ～1 km of post–5 Ma uplift of the western Colorado Plateau
【24h】

Birth and evolution of the Virgin River fluvial system: ～1 km of post–5 Ma uplift of the western Colorado Plateau

机译：维珍河河流系统的出生和演变：西科罗拉多州西部的5马隆起〜1公里

获取原文
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

The uplift history of the Colorado Plateau has been debated for over a century with still no unified hypotheses for the cause, timing, and rate of uplift. 40 Ar/ 39 Ar and K/Ar dating of recurrent basaltic volcanism over the past ～6 Ma within the Virgin River drainage system, southwest Utah, northwest Arizona, and southern Nevada, provides a way to reconstruct paleoprofiles and quantify differential river incision across the boundary faults of the Colorado Plateau–Basin and Range boundary. We compare differential incision data with patterns of channel steepness, bedrock erodibility, basaltic migration, and mantle velocity structure to understand the birth and evolution of the Virgin River system. New detrital sanidine ages constrain the arrival of the Virgin River across the Virgin Mountains to less than 5.9 Ma. Virgin River incision rates and amounts show an eastward stair-step increase in bedrock incision across multiple N-S–trending normal faults. Using block incision values away from fault-related flexures, average bedrock incision rates are near zero since 4.6 Ma in the Lower Colorado River corridor, 23 m/Ma from 6.8 to 3.6 Ma in the Lake Mead block, 85 m/Ma from 3 to 0.4 Ma in the combined St. George and Hurricane blocks, and 338 m/Ma from 1 to 0.1 Ma in the Zion block. Steady incision within each block is documented by incision constraints that span these age ranges. We test two end-member hypotheses to explain the observed differential incision magnitudes and rates along the Virgin River system over the past ～5 Ma: (1) as a measure of mantle-driven differential uplift of the Colorado Plateau relative to sea level; or (2) due to river integration across previously uplifted topography and differential rock types with down-dropping of Transition Zone blocks but no post–5 Ma uplift. We favor headwater uplift of the Colorado Plateau because basalt-preserved paleoprofiles indicate that eastern fault blocks have been the “active” blocks that moved upwards relative to western blocks with little base-level change of the lower Colorado River corridor in the past 4.6 Ma. Block-to-block differential incision adds cumulatively such that the Zion block (Colorado Plateau edge) has been deeply incised 880–1200 m (～338 m/Ma) over the 2.6–3.6 Ma period of Hurricane fault neotectonic movement, which has a slip magnitude of 1100 m. Mantle-driven uplift is implicated by a strong correlation throughout the Virgin River drainage between high normalized channel steepness (k sn ) and low underlying mantle velocity, whereas there is a weaker correlation between high k sn and resistant lithologies. Basaltic volcanism has migrated northeastward at a rate of ～18 km/Ma parallel to the Virgin River between ca. 13 and 0.5 Ma, also suggesting a mantle-driven mechanism for the combined epeirogenic uplift of the western Colorado Plateau, recurrent slip on its bounding faults, and headward propagation and differential incision of the Virgin River. Thus, we interpret the Virgin River to be a 5 Ma disequilibrium river system responding to ongoing upper-mantle modification and related basalt extraction that has driven ～1 km of young (and ongoing) surface uplift of the western Colorado Plateau.
机译：科罗拉多高原的升高历史已经争论了一个多个世纪，仍然没有统一的假设，因为隆起的原因，时间和级别。 40 AR / 39 AR和K / AR在过去〜6 MA的经常性玄武岩火山中的约会，西南犹他州，西北亚利桑那州西南部和内华达州南部，提供了一种重建古血管和量化的方法科罗拉多高原盆地与范围边界的边界断裂。我们将差分切口数据与频道陡，基岩易用，玄武岩迁移和地幔速度结构的模式进行比较，以了解维珍河系的出生和演变。新的诽谤萨内宁年龄限制维尔京河横跨处女山的到来少于5.9 mA。维珍河切口速率和金额显示出跨越多个N-S趋势正常故障的基岩切口的东楼梯。使用块切口值远离与故障相关的柔性，平均基岩切口率自4.6 mA在米德河街区的6.6至3.6 mA中以来，平均基岩切口速率接近零零，从3.8至3.6 mA，35米/马在佐治亚州的圣乔治和飓风块中0.4 mA，ZION块中的1至0.1 mA，338米/ mA。每个块内的稳定切口由跨越这些年龄范围的切口约束记录。我们测试两个最终构造假设，以在过去的约〜5 mA中解释沿着维尔京河系统的观察到的差分切口大小和速率：（1）作为Colorado高原相对于海平面的地幔驱动差动隆起的衡量标准;或（2）由于河流整合，以前提升的地形和差动岩石类型，具有过渡区块的下降，但没有5 mA隆起。我们有利于科罗拉多州高原的下线隆起，因为玄武岩保存的古血管缺陷表明东部故障块一直是“活跃的”块，它相对于西部块移动，在过去的4.6 mA中，较低的科罗拉多河走廊的基础级变化很少。块状差分切口累计增加，使得锡安块（Colorado Plateau Edge）在2.6-3.6 mA的飓风故障新的运动中被深入880-1200米（〜338米/ mA），其中有一个滑动幅度为1100米。通过在高归一化通道陡度（K Sn）和低底层的地幔速度之间的固体河流排水中具有强烈相关性的搭配隆起致力于涉及，而高K Sn和抗性岩性之间存在较弱的相关性。玄武岩山脉已经以〜18公里/马的速度迁移到CA之间的维尔京河。 13和0.5 mA，也表明了西色黄色高原的组合膨胀隆起的搭式驱动机制，反复间隔对其边界断层，以及维珍河的前向传播和差动切口。因此，我们将维珍河解释为＆ 5 ma不平衡河流系统，响应持续的上部地幔改性和相关玄武岩萃取，这些玄武岩萃取〜1公里的青年（和持续）表面隆起的西部科罗拉多州高原。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号