Lower Cretaceous in Colorado Plateau
Lower Cretaceous in Colorado Plateau
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科罗拉多高原下白垩纪
DOI：
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发表时间：
1952
期刊：
影响因子：
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通讯作者：
W. L. Stokes
中科院分区：
文献类型：
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作者：
W. L. Stokes
科罗拉多高原的雪松山和Burro峡谷地层最近采集了由非海洋微化石、植物和软体动物组成的化石。含矿沉积物以前被认为是侏罗纪或晚白垩世，但化石证据表明早白垩世。因此，先前所理解的莫里森组的厚度应该减少，而所谓的“达科他”被认为至少在局部由早白垩世沉积物组成。在许多地区，下白垩纪地层的分离是困难的，如果不是不可行的话，但在其他地区，基底的标志是一个薄的砾岩，它可能连接侏罗纪-白垩纪时间平面。
Fossil collections consisting of non-marine microfossils, plants, and mollusks have recently been made from the Cedar Mountain and Burro Canyon formations of the Colorado Plateau. The containing sediments have previously been considered to be either Jurassic or Late Cretaceous but the fossil evidence indicates early Cretaceous age. The Morrison formation as previously understood should therefore be reduced in thickness and the so-called "Dakota" regarded as consisting, locally at least, of early Cretaceous sediments. Separation of the Lower Cretaceous beds is difficult if not impracticable in many areas but in others the base is marked by a thin conglomerate which may bridge the Jurassic-Cretaceous time plane.