Increase in rainfall during the early Holocene has been reported from different regions of Indian subcontinent, although the magnitude shows spatial variability with lower change in higher rainfall regions and vice versa. While the early-Holocene rainfall records are available from lowland areas of the Indian sub-continent, the record is poorly documented from the high-altitude Central Himalayan region where orography plays an important role in the spatial variability in the rainfall pattern. For the first time, δDC29, δ13CC29 values of alkane and δ13C values of organic matter from a relict lake of Benital area in the Central Himalaya have been used to reconstruct monsoonal rainfall and contemporary vegetation for last 10.5 ka with an emphasis on the early Holocene. The δDC29 values suggest that the early Holocene was characterized by a wet phase at ca. 9 ka with 25% higher rainfall compared to present while the middle-late-Holocene was relatively arid. The estimated increase in monsoonal rainfall for the early Holocene is the highest compared to the previous report from elsewhere. The magnitude of early-Holocene rainfall estimated in this study suggests that in addition to erosion of the bed-rocks at the head-water region, increased stream power reworked the older floodplain and resulted in 2.3 times higher sediment discharged into the Ganges-Brahmaputra (GB) delta compared to the present discharge. The δ13CC29 values of the lake sediments suggest a transition from woody to non-woody plant assemblages occurred at 7 ka. The poor correlation between δDC29 and δ13CC29 values suggests at higher rainfall, the δ13CC29 values of catchment vegetation were less responsive.

中文翻译：

---

早全新世印度夏季风及其对喜马拉雅中部植被的影响：从叶蜡脂的 δD 和 δ13C 值洞察

印度次大陆不同地区报告了全新世早期降雨量的增加，尽管幅度显示空间变异性，降雨量较高的地区变化较小，反之亦然。虽然可以从印度次大陆的低地地区获得早全新世降雨记录，但在高海拔喜马拉雅中部地区的记录却很少，那里的地形在降雨模式的空间变异性中起着重要作用。首次利用喜马拉雅中部贝尼塔尔地区孑遗湖的烷烃δDC29、δ13CC29值和有机质δ13C值重建过去10.5 ka的季风降雨和当代植被，重点是早期全新世。δDC29 值表明早期全新世的特征是在约 9 ka 与现在相比降雨量增加了 25%，而中晚期全新世相对干旱。与其他地方的先前报告相比，全新世早期季风降雨量的估计增幅最高。本研究估计的全新世早期降雨量表明，除了源头地区基岩的侵蚀外，增加的河流动力重新改造了较旧的漫滩，导致排入恒河-雅鲁藏布江的沉积物增加了 2.3 倍。 GB) delta 与当前放电相比。湖泊沉积物的 δ13CC29 值表明在 7 ka 时发生了从木本植物组合到非木本植物组合的转变。δDC29 和 δ13CC29 值之间的相关性较差表明降雨量较高时，