Sedimentological and Paleoclimate Modeling Evidence for Preservation of Jurassic Annual Cycles in Sedimentation, Western Gondwana
Sedimentological and Paleoclimate Modeling Evidence for Preservation of Jurassic Annual Cycles in Sedimentation, Western Gondwana
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DOI：
10.1175/ei-d-15-0046.1
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发表时间：
2016-07
影响因子：
2
通讯作者：
M. Gugliotta;J. Fairman;D. Schultz;S. Flint
中科院分区：
文献类型：
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作者：
M. Gugliotta;J. Fairman;D. Schultz;S. Flint
阿根廷内乌肯盆地的拉哈斯组是一套以三角洲沉积为主的沉积层系。在中侏罗世（1.7亿年前），该盆地位于冈瓦纳西部，与现在的位置（32°-40 ° S）大致相同。分米级，互层，粗粒和细粒床在渠化和非渠化三角洲沉积已被解释为一个产品的变化，河流流量。粗粒砂岩层具有侵蚀基底，并含有泥岩碎屑;内部交错层理通常朝向古海洋。这些河床被解释为河流洪水条件下的沉积。相比之下，细粒层由层间砂岩和泥岩组成，在洪水期间沉积。双向波纹和毫米级的砂泥纹层表明潮汐的影响。这一沉积学证据提出了一个问题，即这些周期是否代表河流输入的年度变化。敬安...
AbstractThe Lajas Formation in the Neuquen Basin, Argentina, consists of a succession of mainly deltaic deposits. In the Middle Jurassic (170 million years ago), the basin was in western Gondwana roughly at the same paleolatitude as its present location (32°–40°S). Decimeter-scale, interbedded, coarser-grained and finer-grained beds in channelized and nonchannelized deltaic deposits have been interpreted as a product of variability in river discharge. The coarser-grained sandstone beds have erosional bases and contain mudstone clasts; internal cross bedding is commonly directed paleoseawards. These beds are interpreted as deposition during river-flood conditions. In contrast, the finer-grained beds are composed of interlaminated sandstone and mudstone, deposited during interflood periods. Bidirectional ripples and millimeter-scale sand–mud laminae suggest the influence of tides. This sedimentological evidence raises the question of whether these cycles represent annual variability in fluvial input. To ans...