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热带海洋学报

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孟加拉湾下扇沉积炭屑证据发现HS1早期气候干旱

罗传秀1，林刚2，Thilakanayaka Adikari Mudiyanselage Vidusanka1，魏海成3，向荣1，杨艺萍1，万随1，   梁诗晴1，苏翔1，杜恕环1，张兰兰1，刘建国1，黄云1，Soe Moe Lwin4   

  1. 1. 热带海洋环境与岛礁生态全国重点实验室，中国科学院南海海洋研究所, 广东 广州 510301；

    2. 自然资源部南海生态中心，海南南沙珊瑚礁生态系统野外科学观测研究站，自然资源部海洋环境探测技术与应用重点实验室，广东 广州 510301；

    3.青海省盐湖地质与环境重点实验室（中国科学院青海盐湖研究所）, 青海 西宁 810008

    4. 缅甸仰光大公大学地质系，11422

  • 收稿日期:2025-06-27 修回日期:2025-08-15 接受日期:2025-09-30
  • 通讯作者: 魏海成
  • 基金资助:
    青海省盐湖地质与环境重点实验室奖励经费2024；国家自然科学基金项目(42376074)

Evidence of micro-charcoal deposited in the lower fan of the Bay of Bengal reveals that the climate was arid in the early HS1

LUO Chuanxiu1, LIN Gang2, THILAKANAYAKA Adikari Mudiyanselage Vidusanka1, WEI Haicheng3, XIANG Rong1, YANG Yiping1*, WAN Sui1, LIANG Shiqing1, SU Xiang1, DU Shuhuan1, ZHANG Lanlan1, LIU Jianguo1, HUANG Yun1, SOE Moe Lwin 4#br# #br#   

  1. 1. State Key Laboratory of Tropical Marine Environment and Island and Reef Ecology (South China Sea Institute of Oceanography, Chinese Academy of Sciences), Guangzhou, Guangdong 510301, China;
    2. South China Sea Ecological Center, Ministry of Natural Resources, Nansha Coral Reef Ecosystem Field Scientific Observation and Research Station, Key Laboratory of Marine Environment Detection Technology and Application, Ministry of Natural Resources, Guangzhou, Guangzhou, 510301, China;
    3. Key Laboratory of Salt Lake Geology and Environment of Qinghai Province (Qinghai Institute of Salt Lakes, Chinese Academy of Sciences), Xining, Qinghai 810008, China;

    4.Department of Geology, Dagon University, Yangon 11422, Myanmar

  • Received:2025-06-27 Revised:2025-08-15 Accepted:2025-09-30
  • Supported by:

    The Science and Technology Plan Project of Qinghai Province Incentive Fund 2024；the National Natural Science Foundation of China (42376074)

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摘要： 既往研究认为，受海因里希Ⅰ(Heinrich Stadial I，HS1 )早期（约18.3-16.3 ka B.P.）北半球降温的影响，热带辐合带（ITCZ）雨带的平均位置会向南移动。 但是，另一种观点认为， HS1早期（18.3-16.3 ka）热带降水在印太澳（IAA）季风区可能发生了经向收缩。可见，HS1早期ITCZ对北大西洋降温事件的响应方向及位移幅度仍存争议。孟加拉湾的海洋炭屑记录保存了北部陆地大量气候成因古火事件的信息。研究发现HS1早期（18.3-16.3ka），位于9.9°N的YDY09孔炭屑总浓度、木本炭屑百分比均降至最低，而草本炭屑百分比升高；结合有孔虫和石笋δ18O记录等指标记录的降水减少，指示火事件发生频率急剧减少，可能与当时气候干旱和温度降低引起的陆源区植被减少有关；与位于9.9°N的YDY10及孟加拉湾上扇的E87-32B常绿阔叶林低值反映的干旱情况一致，反映炭屑源区当时处于ITCZ雨带范围之外。说明炭屑与孢粉、有孔虫等其他指标重建的印度夏季风降水结果一致。同时，YDY09全新世中期火灾活动（尤其是草本炭屑）的急剧下降，与该孔的粪生真菌孢子百分比在4.5 ka以来急剧增加相对应，后者被认为是青藏高原南部、恒河平原和印度东部史前人类驯化动物的结果，暗示人为的放牧增加可能促使草本生物量减少，间接抑制了该区域的火灾强度。

关键词: 海因里希, 微炭屑, 粪生真菌孢子, 孟加拉湾

Abstract: Previous studies have suggested that the mean position of the tropical convergence zone (ITCZ) rain-belt shifted southward due to the cooling of the Northern Hemisphere during the Heinrich Stadial I (HS1) period (approximately 16.3 - 18.3 ka B.P.). However, an alternative perspective proposes that tropical precipitation in the Indo-Asian-Australian (IAA) monsoon region may have undergone a meridional contraction during the early HS1. It can be seen that the response and displacement amplitude of the ITCZ to the cooling event in the North Atlantic during HS1 remain controversial. Marine charcoal records from the Bay of Bengal may preserve critical information about climate-driven ancient fire events from the northern land. In this study, we find that the total concentration of charcoal and the percentage of woody charcoal in YDY09 core (located at 9.9°N) declined to the lowest levels in the Early HS1, while the percentage of herbaceous charcoal increased. This suggests a sharp reduction in the frequency of fire events, consistent with decreased rainfall inferred from the δ18O records of foraminifera and stalagmites, and other proxies. The decline in fire events may be related to reduced vegetation cover under drier climate and cooler climatic conditions，reflecting that the source area was outside the range of the ITCZ at that time. The change aligns with evidence of aridity from low pollen values of evergreen broad-leaved forest in YDY10 core (located at 9.9°N) and E87-32B core from the upper submarine fan of the Bay of Bengal. These findings support the coherence of Indian summer monsoon precipitation reconstructions using charcoal and other proxies. At the same time, the abrupt decline in fire activity in core YDY09 during the Holocene mid-period, especially the increase in herbaceous charcoal, corresponds to a sharp increase in the percentage of coprophilous fungal spore after 4.5 ka. The latter has been attributed to prehistoric human animal domestication on the southern Qinghai-Tibet Plateau, the Gangetic Plain, and eastern India. It implies that intensified grazing may have reduced herbaceous biomass, indirectly suppressing the fire intensity in this region.

Key words: Heinrich, Micro-Charcoal, Coprophilous fungal spore, the Bay of Bengal