Antidunes and antidune stratification in the Permo-Carboniferous Talchir Formation, Talchir Gondwana basin, Orissa, India
Antidunes and antidune stratification in the Permo-Carboniferous Talchir Formation, Talchir Gondwana basin, Orissa, India
复制标题
印度奥里萨邦塔尔奇冈瓦纳盆地二叠纪-石炭纪塔尔奇尔组的反沙丘和反沙丘分层
DOI：
--
复制
发表时间：
2009
期刊：
影响因子：
--
通讯作者：
B. Mishra
中科院分区：
文献类型：
--
作者：
W. Maejima;Rabindra Nath Hota;B. Mishra
印度奥里萨邦Talchir盆地二叠纪-石炭纪Talchir组的冲积扇序列中保存完好的指示反沙丘成因的层状和层理。它们要么是二维的，要么是三维的；后者很常见。在这些结构中，床板上广泛凸起的、协调的和连续的椎板是重要的。有些可见明显的背侧椎板。Talchir反沙丘的古水力重建表明，反沙丘形成的水流条件很宽，水流深度15-140 cm，流速125-370 cm/s。值得注意的是，许多反沙丘由于其波长很大，通常是几米到十几米的数量级，所以给出了非常大的流速和水流深度值，这在岩石记录中很少报道。塔尔契尔反沙丘最有可能是由高含沙量的席状洪水形成的。序列中常见的大规模反沙丘表明，Talchir冲积扇经常产生异常规模的席状洪水，并蔓延到扇面。在Talchir时代的沉积和盆地演化受到冈瓦那冰川消融高度控制的背景下，这种超级洪水的产生可归因于冰川的崩塌和具有巨大池塘的山地内冰川湖泊的爆发。关键词：席卷洪水、超临界水流、反沙丘、塔尔奇尔组、印度冈德瓦纳斯。
Bedforms and stratification indicative of an antidune origin are well preserved in the alluvial fan succession in the Permo-Carboniferous Talchir Formation, Talchir basin, Orissa, India. They are either two-dimensional or three-dimensional; the latter are common. Broadly convex-up, concordant and continuous laminae over the bedforms are significant in these structures. Some show distinct backset laminae. The paleohydraulic reconstruction for the Talchir antidunes indicates that the antidunes were formed in a wide range of flow conditions with variable flow depths of 15-140 cm and flow velocities of 125-370 cm/sec. It is notable that many of antidunes give enormously great values of flow velocity and flow depth as the consequence of their large wavelengths, commonly of the order of several meters to more than ten meters, seldom reported from rock records. Talchir antidunes were most likely formed by highly sediment-laden sheetflood flows. Common occurrence of large-scale antidunes in the succession indicates that sheetfloods of unusual magnitude were frequently generated on the Talchir alluvial fan and spread over the fan surface. In the context that sedimentation and basin evolution during Talchir time were highly controlled by deglaciation of Gondwana glaciers, generation of such super floods are attributable to the collapse of a glacier and outburst of intra-montane glacial lakes having a great pondage. Key-words: sheet flood, supercritical flow, antidune, Talchir Formation, Indian Gondwanas.