Radiocarbon dating and physical properties of sediment core GeoB17623-2

PARASOUND (3.5 kHz) subbottom echosounder profiles acquired on the southern Spitsbergenbanken, NW Barents Sea, show iceberg-keel scouring features which are buried by sediment that accumulated during the post Last Glacial Maximum (LGM) sea-level rise. Four acoustic units (Units 1 to 4 in stratigraphic order) were differentiated, based on the characterization of their acoustic facies and reflection surfaces. Unit 1 shows a chaotic internal structure and is interpreted as a glacial till, whereas the laminated Units 2 to 4 accumulated by sediment settling from suspension clouds and bottom currents during the last deglaciation phase. The top of Unit 2 was frequently incised by iceberg keels, resulting in up to 12 m deep ploughmarks which were later filled and buried by Unit 3 and 4 sediments. Three main paleo-evironmental changes controlled the evolution of the facies succession: (1) The major shift from till formation (Unit 1) below grounded ice to the accumulation of laminated sediments (Unit 2) which are inferred to reflect ice lifting and meltwater release; (2) Iceberg-keel scouring after sedimentation of Unit 2; (3) the probable abrupt termination of iceberg-keel scouring related to the glacio-eustatic sea-level rise. A linkage between these episodes of changes and short-lasting phases of rapid post LGM sea-level rise, such as meltwater pulses, is inferred, although further studies are needed to better understand the temporal and genetic relationships between the sedimentary events recognized in the Barents Sea and climate changes.

本数据集包含采集于巴伦支海西北部斯匹次卑尔根南浅滩的PARASOUND（3.5 kHz）浅地层回声测深剖面数据，其中揭示了被末次冰盛期（Last Glacial Maximum, LGM）后海平面上升期间堆积的沉积物所埋藏的冰筏龙骨刻蚀特征。研究基于声学相（acoustic facies）与反射界面（reflection surfaces）的特征识别，按地层顺序划分出4个声学单元（acoustic units，单元1至单元4）。单元1内部结构杂乱，被解释为冰碛物（glacial till）；而纹层状的单元2至单元4则形成于末次冰消期（last deglaciation phase），由悬浮云团与底流携带的沉积物沉降堆积而成。单元2的顶面常被冰筏龙骨刻蚀，形成最大深度可达12米的犁沟痕（ploughmarks），后续被单元3和单元4的沉积物填充并埋藏。控制该相序演化的三大主要古环境变化（paleo-environmental changes）事件包括：（1）从接地冰盖（grounded ice）下方的冰碛物（单元1）形成，转变为纹层状沉积物（单元2）的堆积，该转变被推断反映了冰盖抬升与融水释放过程；（2）单元2沉积后发生的冰筏龙骨刻蚀（iceberg-keel scouring）作用；（3）与冰川型全球海平面上升（glacio-eustatic sea-level rise）相关的冰筏龙骨刻蚀作用可能的突然终止。尽管需要进一步研究以明确巴伦支海识别出的沉积事件与气候变化之间的时间与成因联系，但本研究推断这些变化事件与末次冰盛期后快速海平面上升的短期阶段（如融水脉冲（meltwater pulses））存在关联。