The hadal zone represents one of the last great frontiers in modern marine science,and deciphering the provenance of sediment that is supplied to these trench settings remains a largely unanswered question.Here,we exa...The hadal zone represents one of the last great frontiers in modern marine science,and deciphering the provenance of sediment that is supplied to these trench settings remains a largely unanswered question.Here,we examine the mineralogical and geochemical composition of a sediment core(core CD-1)that was recovered from the southwestern margin of the Challenger Deep within the Mariana Trench.Major element abundances and rare-earth element patterns from these sediments require inputs from both terrigenous dust and locally sourced volcanic debris.We exploit a two-endmember mixing model to demonstrate that locally sourced volcanic material dominates the sediment supply to the Challenger Deep(averaging^72%).The remainder,however,is supplied by aeolian dust(averaging^28%),which is consistent with adjacent studies that utilized Sr-Nd isotopic data.Building on a growing database,we strengthen our understanding of Asian aeolian dust input into the northwestern Pacific,which ultimately improves our appreciation of sedimentation in,and around,the hadal zone.展开更多
The concentrations of rare earth elements(REEs)in the bulk sediment of Core X2,which was collected from southeastern Hainan Island,were analyzed to investigate the relative contributions of various provenance regions ...The concentrations of rare earth elements(REEs)in the bulk sediment of Core X2,which was collected from southeastern Hainan Island,were analyzed to investigate the relative contributions of various provenance regions since mid-Holocene.The results show that sediments in Core X2 were primarily derived from Hainan Island with lesser amounts from Taiwan and limited input from the Pearl River.Based on the application of quantitative inversion to model the REE data,the average contributions of river materials from southeastern Hainan Island and southwestern Taiwan to the study area were 68%and 32%,respectively.Furthermore,starting at 4.0 kyr BP,the transport of fluvial sediments from Taiwan to the study region increased due to enhanced hydrodynamics in South China Sea(SCS).These results indicate that the contributions of mountain river materials from Hainan Island and Taiwan to the continental shelf of northern SCS are non-negligible.Furthermore,these results demonstrate that mountain rivers can play an important role in the material cycle of continental margins and may feature a greater impact than large river systems in specific continental shelf areas.展开更多
近年来,在线学习由于其巨大的实际应用价值,已经得到人们广泛的研究.然而,在许多开放环境应用场景下,当前时刻数据可能会增加新的特征,而下一时刻只有部分原有特征得以继承.例如,在环境监测中,新的传感器部署会产生数据新特征;下一时刻...近年来,在线学习由于其巨大的实际应用价值,已经得到人们广泛的研究.然而,在许多开放环境应用场景下,当前时刻数据可能会增加新的特征,而下一时刻只有部分原有特征得以继承.例如,在环境监测中,新的传感器部署会产生数据新特征;下一时刻部分旧的传感器失效,部分原有特征被保留.这样的数据被称为特征继承性增减的流式数据.传统的在线学习算法大多建立在数据特征空间稳定不变的基础之上,无法直接处理此种情形.针对上述问题,提出了一种面向特征继承性增减的在线分类算法(online classification algorithm with feature inheritably increasing and decreasing,OFID)及其2种变体.当新特征出现时,通过结合在线被动主动方法与结构风险最小化原则分别更新原始特征与新增特征上的分类器;当旧特征消失时,对数据流使用Frequent-Directions算法进行补全,使得旧分类器得以继续更新迭代.从理论上证明了OFID系列算法的损失上界,同时通过大量的实验验证了所提算法的有效性.展开更多
基金Supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDB06020204)the National Key Basic Research and Development Program of China(Nos.2017YFC0307704,2017YFC0307600)the Marine Geological Survey Program of China Geological Survey(No.DD20160218)
文摘The hadal zone represents one of the last great frontiers in modern marine science,and deciphering the provenance of sediment that is supplied to these trench settings remains a largely unanswered question.Here,we examine the mineralogical and geochemical composition of a sediment core(core CD-1)that was recovered from the southwestern margin of the Challenger Deep within the Mariana Trench.Major element abundances and rare-earth element patterns from these sediments require inputs from both terrigenous dust and locally sourced volcanic debris.We exploit a two-endmember mixing model to demonstrate that locally sourced volcanic material dominates the sediment supply to the Challenger Deep(averaging^72%).The remainder,however,is supplied by aeolian dust(averaging^28%),which is consistent with adjacent studies that utilized Sr-Nd isotopic data.Building on a growing database,we strengthen our understanding of Asian aeolian dust input into the northwestern Pacific,which ultimately improves our appreciation of sedimentation in,and around,the hadal zone.
基金funded by the National Natural Science Foundation of China (Nos. 41576058, 41106040)the China Postdoctoral Science Foundation (No. 2017M6 10403)+1 种基金the Taishan Scholar Project Funding (No. tspd2016 1007)Project of China Geological Survey (No. DD 20191010)
文摘The concentrations of rare earth elements(REEs)in the bulk sediment of Core X2,which was collected from southeastern Hainan Island,were analyzed to investigate the relative contributions of various provenance regions since mid-Holocene.The results show that sediments in Core X2 were primarily derived from Hainan Island with lesser amounts from Taiwan and limited input from the Pearl River.Based on the application of quantitative inversion to model the REE data,the average contributions of river materials from southeastern Hainan Island and southwestern Taiwan to the study area were 68%and 32%,respectively.Furthermore,starting at 4.0 kyr BP,the transport of fluvial sediments from Taiwan to the study region increased due to enhanced hydrodynamics in South China Sea(SCS).These results indicate that the contributions of mountain river materials from Hainan Island and Taiwan to the continental shelf of northern SCS are non-negligible.Furthermore,these results demonstrate that mountain rivers can play an important role in the material cycle of continental margins and may feature a greater impact than large river systems in specific continental shelf areas.
文摘近年来,在线学习由于其巨大的实际应用价值,已经得到人们广泛的研究.然而,在许多开放环境应用场景下,当前时刻数据可能会增加新的特征,而下一时刻只有部分原有特征得以继承.例如,在环境监测中,新的传感器部署会产生数据新特征;下一时刻部分旧的传感器失效,部分原有特征被保留.这样的数据被称为特征继承性增减的流式数据.传统的在线学习算法大多建立在数据特征空间稳定不变的基础之上,无法直接处理此种情形.针对上述问题,提出了一种面向特征继承性增减的在线分类算法(online classification algorithm with feature inheritably increasing and decreasing,OFID)及其2种变体.当新特征出现时,通过结合在线被动主动方法与结构风险最小化原则分别更新原始特征与新增特征上的分类器;当旧特征消失时,对数据流使用Frequent-Directions算法进行补全,使得旧分类器得以继续更新迭代.从理论上证明了OFID系列算法的损失上界,同时通过大量的实验验证了所提算法的有效性.
