This study addresses the nature and causes of post-Last Glacial Maxima (LGM) sedimentation in the Western Great Rann of Kachchh, Gujarat, India. Specifically, we report geochemical and isotopic data (Sr/Sr and Nd/Nd) for a 46.5 m sediment core from the Nara River bed. These data indicate that up to the beginning of the Holocene, sedimentation mostly comprised contributions from monsoon-dominated rivers of Western Himalaya. Later in the early Holocene, a shift towards Indus-derived sediments occurred, with a minor reversal at ∼7 ka, attributed to the rejuvenation of the Ghaggar-Hakra channel. A renewed contribution from the Indus River routed through the Nara River and through the Kori Creek (mouth of the Nara River) occurred during the mid- to late Holocene. Persistent availability of freshwater during the mid- to late Holocene helped sustain early Iron Age and medieval cultures in the region. However, significant decline in the hydrological system anchored in the shifting Indus River through the Nara channel after the medieval period, likely caused the gradual collapse of these cultures. Our study is important as it demonstrates that, if the sediment source is from regions of contrasting climatic domains (for example, monsoon-dominated western Himalaya rivers and the westerlies-dominated Indus River), temporal changes in precipitation intensities exert a first order control in modulating the sediment provenances.

中文翻译：

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使用印度卡奇西部大兰恩沉积物地球化学和同位素数据分析沉积物来源：对源区气候控制的影响

这项研究探讨了印度古吉拉特邦卡奇西部大沼泽地末次盛冰期（LGM）沉积的性质和原因。具体来说，我们报告了奈良河床 46.5 m 沉积岩芯的地球化学和同位素数据（Sr/Sr 和 Nd/Nd）。这些数据表明，直到全新世初期，沉积作用主要由喜马拉雅山西部季风主导的河流造成。后来在全新世早期，由于加加尔-哈克拉河道的复兴，发生了向印度河沉积物的转变，并在约 7 ka 发生了小幅反转。全新世中后期，印度河重新注入奈良河和科里溪（奈良河河口）。全新世中后期淡水的持续供应有助于维持该地区的早期铁器时代和中世纪文化。然而，中世纪之后，印度河流经奈良海峡的水文系统显着下降，可能导致这些文化逐渐崩溃。我们的研究很重要，因为它表明，如果沉积物来源来自不同气候域的地区（例如，季风主导的喜马拉雅山脉西部河流和西风主导的印度河），降水强度的时间变化对调节沉积物来源。