The sediment core collected at a water depth of 260.2 m off Mahanadi, western Bay of Bengal was analyzed for grain size fractions, clay minerals, and major and trace elements to understand changing depositional environments, source and processes with time, from ~ 2300 cal yr before present (BP) to the year of the collection (2014). Age was estimated using accelerator mass spectrometer (AMS) ¹⁴C dates of two planktonic foraminifera samples. The core was divided into six distinct zones based on the significant changes in the sediment components and clay minerals. The presence of higher than average clay and smectite and lower silt and illite, in Zone II (2000 years BP–1070 cal yr BP) and Zone V (300–130 cal yr BP) revealed their deposition in low energy conditions, while, Zone III (1070 to 530 cal yr BP) and Zone VI (132 cal yr BP to present) exhibited higher silt and illite and lower clay and smectite than average suggesting their deposition in a high energy environment. Similar depositional environments observed between Zones II and V and also between Zones III and VI indicated the reoccurrence of similar hydrodynamic conditions with time. Zone II represents the Roman Warm Period and part of the early Medieval Warm Period, while, zone V corresponds to the retreating phase of the Little Ice Age. High Al in zone III and fluctuating trend in zone VI indicates higher Al release along with silt and illite from physical weathering in a cold and arid climate, while, smectite showed a positive correlation with Ti indicating the source of Ti and smectite as basic igneous rocks released during the enhanced southwest monsoon and warm climate. Mn and Zn distribution revealed fluctuations in the Oxygen Minimum Zone (OMZ) intensity to changing hydrodynamic conditions and depositional environments. The present study revealed changing depositional environments in the western Bay of Bengal with time with respect to changing material influx, reflecting fluctuating monsoons and climate.

分析了孟加拉西部海湾Mahanadi附近260.2 m水深处收集到的沉积物核的粒径分数，粘土矿物以及主要和微量元素，以了解约2300 cal年以来沉积环境，来源和过程随时间的变化从现在（BP）到集合年份（2014）。使用加速器质谱仪（AMS）估算年龄¹⁴两个浮游有孔虫样品的C日期。根据沉积物成分和粘土矿物的显着变化，岩心被分为六个不同的区域。II区（2000年BP-1070 cal yr BP）和V区（300-130 cal yr BP）中存在高于平均水平的粘土和蒙脱石以及较低的粉质和伊利石，表明它们在低能条件下沉积。 III（1070至530 cal BP BP）和VI区（目前为132 cal BP）的泥沙和伊利石含量较高，粘土和蒙皂石含量低于平均水平，表明它们在高能环境中沉积。在II区和V区之间以及III区和VI区之间观察到相似的沉积环境表明，随着时间的流逝，相似的流体动力学条件再次出现。第二区代表罗马温暖时期，是中世纪早期的一部分，而 V区对应于小冰河时代的后退阶段。在寒冷和干旱的气候中，III区较高的Al含量和VI区的波动趋势表明较高的Al释放量以及泥沙和伊利石的物理风化，而蒙脱石与Ti呈正相关，表明Ti和绿土的来源为基本火成岩在西南季风增强和气候温暖时释放。锰和锌的分布揭示了最小氧气最小区域（OMZ）强度的变化，以改变流体动力条件和沉积环境。本研究表明，随着物质流入的变化，孟加拉西部海湾的沉积环境随时间变化，反映了季风和气候的变化。在寒冷和干旱的气候中，III区较高的Al含量和VI区的波动趋势表明较高的Al释放量以及泥沙和伊利石的物理风化，而蒙脱石与Ti呈正相关，表明Ti和绿土的来源为基本火成岩在西南季风增强和气候温暖时释放。锰和锌的分布揭示了最小氧气最小区域（OMZ）强度的变化，以改变流体动力条件和沉积环境。本研究揭示了孟加拉湾西部沉积环境随时间的变化而变化，这反映了物质流入的变化，反映了季风和气候的变化。在寒冷和干旱的气候中，III区较高的Al含量和VI区的波动趋势表明较高的Al释放量以及泥沙和伊利石的物理风化，而蒙脱石与Ti呈正相关，表明Ti和绿土的来源为基本火成岩在西南季风增强和气候温暖时释放。锰和锌的分布揭示了最小氧气最小区域（OMZ）强度的变化，以改变流体动力条件和沉积环境。本研究表明，随着物质流入的变化，孟加拉西部海湾的沉积环境随时间变化，反映了季风和气候的变化。绿土与Ti呈正相关关系，表明西南季风增强和气候温暖时，钛和绿土的来源为基本火成岩。锰和锌的分布揭示了最小氧气最小区域（OMZ）强度的变化，以改变流体动力条件和沉积环境。本研究表明，随着物质流入的变化，孟加拉西部海湾的沉积环境随时间变化，反映了季风和气候的变化。绿土与Ti呈正相关关系，表明西南季风增强和气候温暖时，钛和绿土的来源为基本火成岩。锰和锌的分布揭示了最小氧气最小区域（OMZ）强度的变化，以改变流体动力条件和沉积环境。本研究表明，随着物质流入的变化，孟加拉西部海湾的沉积环境随时间变化，反映了季风和气候的变化。