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Mechanism of magnetic property changes of serpentinites from odp Holes 897D and 1070A

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Science China Earth Sciences 2015年第4期58卷 815-829页

作者： SU Kai LIU QingSong JIANG ZhaoXia DUAN ZongQi Division of Tethys Research Center Institute of Geology and Geophysics Chinese Academy of Sciences College of Earth Sciences University of the Chinese Academy of Sciences

Serpentinites have great implications for the oceanic crust, subduction zones, island arc magmatism activity, and the formation of nickel ore deposits. To further determine the mechanism of magnetic property changes of serpentinites, samples from odp Holes 897 D and 1070 A were investigated by integrating both magnetic and non-magnetic methods. Detailed rock magnetic results demonstrate that magnetite prevails in the entire serpentinite section, while maghemite is present in the upper and altered parts. The concentration of Fe in the fresh peridotite is inhomogeneous; nonetheless, the magnetic properties are generally determined by the serpentinization process. The formation and state of the magnetite depend on the fracture conditioning and fluid activities which are controlled by the serpentinization process. By comparing these two holes, we found that the production of magnetite is consistent with the serpentinization process; serpentinization is a multi-stage process which involves early high-temperature serpentinization and later low-temperature oxidation. As the serpentinization continues, the fine magnetic particles become coarser, combined with the formation of new SP particles, and the later low-temperature oxidation leads to the maghemitization of the magnetites. The duration of oxidation also contributes to the differences of remanent magnetization between these two holes. These results greatly improve our understanding of the magnetic enhancement during the serpentinization process, and provide constraints on the interpretation of the paleomagnetic and aeromagnetic anomalies in this area.

关键词：蛇纹岩磁性能 odp 机理蛇纹石化低温氧化 TIC粒子磁铁矿

Unsupervised learning on scientific ocean drilling datasets from the South China Sea

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Frontiers of Earth Science 2019年第1期13卷 180-190页

作者： Kevin C.TSE Hon-Chim CHIU Man-Yin TSANG Yiliang LI Edmund Y.LAM Department of Earth Sciences The University of Hong KongPokfulamHong KongChina Department of Geography and Centre for Geo-computation Studies Hong Kong Baptist UniversityKowloon TongHong KongChina Department of Earth Sciences University of TorontoTorontoON M5S 2M8Canada Department of Electrical and Electronic Engineering The University of Hong KongPokfulamHong KongChina

Unsupervised learning methods were applied to explore data patterns in multivariate geophysical datasets collected from ocean floor sediment core samples coming from scientific ocean drilling in the South China Sea.Compared to studies on similar datasets,but using supervised learning methods which are designed to make predictions based on sample training data,unsupervised learning methods require no a priori information and focus only on the input data.In this study,popular unsupervised learning methods including K-means,self-organizing maps,hierarchical clustering and random forest were coupled with different distance metrics to form exploratory data clusters.The resulting data clusters were externally validated with lithologic units and geologic time scales assigned to the datasets by conventional methods. Compact and connected data clusters displayed varying degrees of correspondence with existing classification by lithologic units and geologic time scales.K-means and self-organizing maps were observed to perform better with lithologic units while random forest corresponded best with geologic time scales.This study sets a pioneering example of how unsupervised machine learning methods can be used as an automatic processing tool for the increasingly high volume of scientific ocean drilling data.

关键词： machine learning unsupervised learning odp Iodp clustering

Paleoceanographic evolution recorded in the northern South China Sea since 4 Ma

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Science China Earth Sciences 2005年第12期48卷 2166-2173页

作者： HUANG Baoqi1,2, JIAN Zhimin2 & WANG Pinxian2 1. School of Earth and Space Sciences, Peking University, Beijing 100871, China 2. Laboratory of Marine Geology, Tongji University, Shanghai 200092, China School of Earth and Space Sciences Peking University Beijing China Laboratory of Marine Geology Tongji University Shanghai China

Upper water structure over the last 4 million years in the northern South China Sea (SCS) was reconstructed by sea surface temperature (SST) and primary productivity estimated by changes in the abundance of planktonic foraminifer, planktonic foraminifer transfer function, and the accumulation rate of benthic foraminifera. Results of SST and primary productivity show that SST gradually decreased since 4 Ma, but differential seasonal temperature and primary productivity increased in steps mainly at about 3.1, 2.7, 2.1, 1.6, 0.9 and 0.5 Ma. Comparison with tectonics and orbital variations indicates that phased rising of the Tibet since 3.6 Ma, closing of Panama and Indonesian seaways, and orbital changes were responsible for the changes of upper water structure in the SCS, respectively.

关键词： northern South China Sea, upper water structure, Late Pliocene, planktonic foraminifer, odp 1146.

Concurrent optic disc pit and retinal cavernous hemangioma

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International Journal of Ophthalmology(English edition) 2017年第1期10卷 168-170页

作者： Alec L Amram Renata Picciani Jaafar El-Annan Department of Ophthalmology and Visual Sciences University of Texas Medical BranchGalvestonTexas 77555USA

We present, to the authors＇ knowledge, the first reported case of an optic disc pit （odp） and retinal cavernous hemangioma （RCH） in the same eye in addition to a review of both clinical entities. An odp is a rare... 详细信息

关键词： odp Concurrent optic disc pit and retinal cavernous hemangioma Figure

A greedy selection approach for query suggestion diversification in search systems

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Science China(Information Sciences) 2016年第11期59卷 227-229页

作者： Fei CAI Honghui CHEN Zhen SHU Science and Technology on Information Systems Engineering Laboratory National University of Defense Technology University of Amsterdam

Dear editor,Query suggestion is a widely known and well embedded mechanism in modern search systems to facilitate the task of formulating queries.The goal is to accurately predict user’s intended query with only few keystrokes(i.e.,typed prefix),thereby helping the user formulate a satisfactory query with less effort and avoid misspelling it as well.Suggested candidates are typically generated based on previous queries that have been

关键词： A greedy selection approach for query suggestion diversification in search systems MRR MMR DCG odp

Thirty million year deep-sea records in the South China Sea

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Chinese Science Bulletin 2003年第23期48卷 2524-2535页

作者： WANGPinxian ZHAOQuanhong JIANZhimin CHENGXinrong HUANGWei TIANJun WANGJiliang LIQianyu LIBaohua SUXin KeyLaboratoryofMarineGeology MinistryofEducationTongjiUniversityShanghai200092China NanjingInstituteofGeologyandPaleontology ChineseAcademyofSciencesNanjing210008China GeoscienceUniversityofChina Beijing100083China

In the spring of 1999 the Ocean Drilling Pro-gram (odp) Leg 184 Shipboard Party cored 17 holes at 6 deep water sites in the northern and southern parts of the South China Sea (SCS). Chinese scientists actively partici-pated in the entire process of this first deep-sea drilling leg off China, from proposal to post-cruise studies. More than 30 categories of analyses have been conducted post-cruise in various Chinese laboratories on a large number of core sam-ples, and the total number of analyses exceeded 60 thousand. The major scientific achievements of the Leg 184 studies are briefly reported in three successive papers, with the first one presented here dealing with deep-sea stratigraphy and evolu-tion of climate cycles. This odp leg has established the best deep-sea stratigraphic sequences in the Western Pacific: the 23-Ma isotope sequence from the Dong-Sha area is unique worldwide because of its continuity; the last 5-Ma sequence from the Nansha area represents one of the best 4 odp sites worldwide with the highest time-resolution for that time in-terval, and the sequences of physical properties enable a de-cadal-scale time resolution. All these together have provided for the first time high-quality marine records for paleoenvi-ronmental studies in the Asian-Pacific region. This new set of stratigraphic records has revealed changes in climate cyclic-ity over the last 20 Ma with the fluctuating power of the 100 ka, 400 ka, 2000 ka eccentricity cycles, indicating the evolv-ing response of the climate system to orbital forcing along with the growth of the Antarctic and Northern Hemisphere ice sheets.

关键词：南中国海海洋钻探工程深海沉积 odp SCS 轨道循环

THERMOTROPIC LIQUID CRYSTALLINE POLYMERS. AROMATIC COPOLYESTERS CONTAINING SUBSTITUTED BENZENE RINGS AND KINKING COMPONENTS

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Chinese Journal of Polymer Science 1985年第3期3卷 250-257页

作者：谢萍陆道惠宝净生 Institute of Chemistry Academia Sinica Beijing

A series of copolyesters were prepared from chloro-hydroquinone or methyl-hydroquinone,terephthalic acid, and two kinds of comonomers, such as oxy-4,4’-diphenol and isophthalic acid.which could provide kinking and bending in chain. The four-components copolyesters in certain range of compositions have low melting point,ssteady mesophase in a broad temperature range and fiber-forming tendency. This report focuses on the relations of their molecular composition-transitions-liquid crystallinityand fiber-forming tendency and the morphologic characterizations of mesophase.

关键词： TPA IPA AROMATIC COPOLYESTERS CONTAINING SUBSTITUTED BENZENE RINGS AND KINKING COMPONENTS THERMOTROPIC LIQUID CRYSTALLINE POLYMERS odp

Evolution of the South China Sea and monsoon history revealed in deep-sea records

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Chinese Science Bulletin 2003年第23期48卷 2549-2561页

作者： WANGPinxian JIANZhimin ZHAOQuanhong LIQianyu WANGRujian LIUZhifei WUGuoxuan SHAOLei WANGJiliang HUANGBaoqi FANGDianyong TIANJun LIJianru LIXianhua WEIGangjian SUNXiangjun LUOYunli SUXin MAOShaozhi CHENMuhong LaboratoryofMarineGeology MOETongjiUniversityShanghai200092China GuangzhouInstituteofGeochemistry ChineseAcademyofSciencesGuangzhou510640China InstituteofBotany ChineseAcademyofSciencesBeijing100093.China ChinaUniversityofGeosciences Beijing100083China SouthChinaSeaInstituteofOceanology ChineseAcademyofSciencesGuangzhou510301China

As the third summary report of odp Leg 184 to the South China Sea (SCS), this paper discusses the evolution of the East Asian monsoon and the SCS basin. A multi-proxy approach, involving geochemistry, micropaleontology, pollen and other analyses, was adopted for reconstructing the evolutionary history of the East Asian monsoon, which was characterized by a series of paleo-climate events especially at 8, 3.2, 2.2 and 0.4 Ma. The new record indicates similar stages in the development of the East and South Asian monsoons, with an enhanced winter monsoon over East Asia being the major difference. The rich spectrums of monsoon variability from the southern SCS also reveal other characteristic features of the low latitude ocean. Evidence for the evolution of the SCS includes the hemipelagic Oligocene sediments, implying the existence of deep water environments during the early seafloor spreading stage of the SCS basin. The four major unconformities and some remarkable diagenetic features in upper Oligocene deposits indicate the strongest tectonic events in the region. From a careful comparison of lithologies and sedimentation rates, we conclude that the prominent differences in sedimentary environments between the southern and northern SCS were established only by ～3 Ma.

关键词：南中国海深海沉积 odp 海洋钻探工程东亚季风

Deep-water Oligocene pollen record from South China Sea

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Chinese Science Bulletin 2003年第22期48卷 2511-2515页

作者： WUGuoxuan QINJungan MAOShaozhi LaboratoryofMarineGeology TongjiUniversityShanghai200092China ChinaUniversityofGeosciences Beijing100083China

Leg 184 of odp recovered a record of deep- water sediments spanning the past 32.8 Ma from the South China Sea (SCS). The sediments of the Oligocene (32.8 23.8 Ma) at Site 1148 contain relatively abundant fossil pollen. The pollen analysis at Site 1148 has established the first pollen assemblage sequence of deep-water Oligocene in the China Sea. The pollen assemblages of the Oligocene are dominated by montane conifer tree pollen. The abundances of broad-leaved tree pollen are lower in the assemblages. Both of the montane conifer and broad-leaved tree pollen groups include mainly tropical-subtropical components. The pollen of cold and drought-enduring plants is present in lower content. The distinct change in pollen assemblage sequence of deep-water Oligocene of the SCS occurred at 32.0 Ma, indicative of an important shift of the Oligocene climate in the SCS region. The characteristics of the pollen flora of the deep-water Oligocene indicate the tropical montane rainforest and lowland rainforest developed on the areas around the SCS before 32.0 Ma, reflecting the warm and wet climatic condition. In the pollen flora of the Oligocene after 32.0 Ma, the temperate montane conifer and cool and drought-en- during deciduous tree taxa remarkably increased, indicating that the climate in the SCS region became comparatively cool and dry.

关键词：渐新统花粉南中国海海上钻井工程 odp