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在本区正常海盆的表层沉积物中首次发现了微晶——细晶的自生石膏。细晶石膏0.5~2mm,呈单晶或双晶散布在S_2站位的砂、砾质沉积物中。石膏晶体中常包裹有细小的石英砂粒或岩屑。有的呈放射状晶簇选择性地附生于砾石表面或凹坑中;微晶石膏十几至几十微 相似文献
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南极布兰斯菲尔德海峡及周边区域是南极大陆火山、地震等新构造活动最活跃的地区,与南设得兰海沟、南设得兰群岛一同构成南极大陆边缘现存唯一的"沟-弧-盆"构造体系。本文基于"雪龙"船第28、第30航次实测数据及两个航次的国际共享资料,利用均衡改正数据处理方法获得布兰斯菲尔德海峡的莫霍面深度及其分布规律,分析深部构造-断裂的区域分布及其重力异常特征等。布兰斯菲尔德海峡内的空间重力异常呈条带状分布,走向总体与地形相近,布格重力异常则由两侧向中间升高,大致在坡折处形成异常场值为100×10-5 m/s2的分界线,在中央次海盆和东部次海盆海山处形成两个异常高值圈闭,异常值最高为150×10-5 m/s2。莫霍面深度以弧后扩张中心为最低值,向南设得兰群岛和南极半岛两个方向递增,深度从12 km递增至陆坡位置的24 km。 相似文献
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南极布兰斯菲尔德海峡表层沉积物的酸解烃 总被引:1,自引:0,他引:1
本文研究了南极布兰斯菲尔德海峡表层沉积物的酸解烃分布特征,并佐以热释汞和蚀变碳酸盐的分析。从酸解烃中甲烷含量的低值和C1/(C2+C3)比值,以及乙烯的存在等判断,布兰斯菲尔德海峡沉积物的烃类气体来自于生物成因。 相似文献
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南极布兰斯菲尔德海峡及邻区地壳结构反演及构造解析 总被引:1,自引:0,他引:1
南极布兰斯菲尔德海峡及邻区是南极半岛海域火山、地震等新构造运动最活跃的地区,由于前人对资料处理解释的差异,导致盆地的构造格局仍部分存疑。本文以研究区的卫星重力数据为基础,以多道反射地震和部分岩性资料为约束,采用重震联合反演方法构建了三条横跨研究区的地壳结构剖面,并进一步研究布兰斯菲尔德海峡盆地的地壳结构。研究结果表明布兰斯菲尔德海峡盆地莫霍面深度为33—38km。菲尼克斯板块俯冲消减下沉至南设得兰岛弧之下,导致南设得兰海沟的俯冲带后撤,产生3—4km厚的岩浆混染地壳,密度为2.9g/cm3。分析认为受板块运动和弧后扩张影响,沿布兰斯菲尔德海峡盆地扩张脊分布的海底火山裂隙式喷发,并进一步导致盆地的持续性扩张。 相似文献
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南极布兰斯菲尔德海峡晚第四纪沉积物磁组构特征及其古环境学意义 总被引:4,自引:1,他引:4
吴能友 《海洋地质与第四纪地质》1998,18(1):77-88
通过南极布兰斯菲尔德海峡沉积物岩心PC10的磁化率各向异性测量及统计分析,揭示了磁组构参数随深度的变化特征。结合沉积物粒度、物质成份、碎屑矿物百分含量及同位素测年等资料进行综合分析,探讨布兰斯菲尔德海峡晚更新世以来的古水流方向及古气候变化史。结果表明:(1)112.5ka以来海峡古水流主要有两组,一组为源自环南极流、流速相对较大的NE向水流,另一组为由于气温升高而产生的南极半岛、南设得兰群岛冰盖消融水流,NNW—NS向;(2)112.5ka以来海峡的古气候大致可分为六期,相当于岩性段753.5~620cm(Ⅰ,早凉期)、620~488.5cm(Ⅱ,早暖期)、488.5~391cm(Ⅲ,早冷期)、391~140cm(Ⅳ,晚冷期)、140~25cm(Ⅴ,晚暖期)和25~0cm(Ⅵ,晚凉期),基本上反映了末次间冰期—末次冰期—冰后期的古气候变化史,与全球晚更新世以来的气候变化情况基本一致,其中Ⅰ、Ⅱ期相当于末次间冰期的早、晚期,Ⅲ、Ⅳ期分别对应于玉木冰期Ⅰ和Ⅱ期,而Ⅴ期为冰后期,Ⅵ期相当于2320年的寒冷气候事件。由此可见,磁组构方法不失为一种经济且便利地研究海洋沉积物古环境的工具。 相似文献
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南极布兰斯菲尔德海峡及象岛邻近水域小型浮游植物的分布特征研究 总被引:1,自引:0,他引:1
本文分析研究了布兰斯菲尔德海峡及象岛邻近水域小型浮游植物的种类组成、数量分布、群落结构及其与环境因子的关系,共鉴定了小型浮游植物54属201种,平均细胞丰度为4406×10~3个/m~3,大部分为硅藻类,数量最大的为扭链角刺藻、长形环毛藻、克革伦氏菱形藻和翼根管藻等种类。小型浮游植物最高丰度分布在南设得兰群岛近岸、陆架水域,这是由近岸冷水性的小型浮游植物群落组成。小型浮游植物的密度与硅酸盐浓度呈正相关(r=0.438,n=28,P<0.05)。 相似文献
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南极布兰斯菲尔德海域地球物理场与地质构造 总被引:1,自引:0,他引:1
本文通过对1991年“海洋四号”船在南极布兰斯菲尔德海域所采集的地球物理资料的分析解释,指出:区内重磁异常反映为北东向条带状展布,从北向南呈高-低-高带相间,第一带内皮状起伏,地震反射层展布及厚薄变化上应类似特征。由此揭示出区内地质构造2特征及隆坳展布格局。对布兰斯菲尔德盆地发展演变与断裂、岩浆活动、地壳拉伸、地壳深部物质变动及板块构造运动等因素的关系作了尝试性的探讨。 相似文献
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《Deep Sea Research Part I: Oceanographic Research Papers》2006,53(7):1244-1252
The Bransfield Strait west of the Antarctic Peninsula has been considered as a highly productive region for all trophic levels from primary production, to zooplankton aggregations, especially krill, to birds and mammals. The western boundary current, referred to as the Bransfield Current, plays an important role in determining the transport and retention of biota in the Bransfield Strait. Following the study of surface current characteristics in the strait using 39 tracks of mixed-layer drifters deployed between 1988 and 1990, a high-resolution transect of temperature, salinity and current measurements crossing the Bransfield Current was conducted between 13 and 14 March 2004, for understanding its horizontal and vertical structure and dynamics. The results from current, temperature and salinity measurements using a vessel mounted narrow band acoustic doppler current profiler and conductivity–temperature–depth (CTD) sensors revealed the magnitude of this current of approximately 50 cm/s within a horizontal distance of 15 km associated with a narrow and deep density front 4–6 km wide and 500 m deep. The comparison between the direct current measurements and the geostrophic current estimates from the density field implies that the Bransfield Current is geostrophically balanced. The mechanism forming this current is explored with Sverdrup dynamics. Results indicate that the negative wind stress curl and β-effect lead to a southwestward transport in the Bransfield Strait. When this transport is restricted by land and shelves, a narrow western boundary current is formed. 相似文献
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Mukhametyanov R. Z. Frei D. I. Morozov E. G. 《Izvestiya Atmospheric and Oceanic Physics》2022,58(5):500-506
Izvestiya, Atmospheric and Oceanic Physics - In January 2022, several sections were made across the Bransfield Strait during an Antarctic expedition on the R/V Akademik Mstislav Keldysh.... 相似文献
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The study of the sedimentary body of the Bransfield Strait has made it possible to identify several sedimentary complexes, to construct the first electronic charts for the acoustic basement, and to establish four stages of the evolution of its floor, which updates the previous knowledge about the formation of the strait. At the first stage, there was an increase in tension stresses that were accompanied by the local splits of the continental crust at the periphery of the Antarctic Peninsula. At the second stage, a graben-like structure filled with the Lower stratigraphic complex was formed northward of the Antarctic Peninsula. At the third stage, the continuing processes of extension led to intensive explosive activity of the growing volcanic structures and filling of the graben with sediments of the Middle seismostratigraphic complex. The fourth stage, which has continued until recently, is characterized by quasi-linear localization of the major centers of volcanic activity in the band closer to the South-Shetland Islands and the formation of the Upper seismostratigraphic sedimentary complex. The evolution of the floor of the Bransfield Strait reflects the process of penetration of the American-Antarctic ridge to the continental lithosphere of the Antarctic Peninsula for the last million years. 相似文献
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《Marine Chemistry》1987,20(3):255-264
Carbohydrate fluxes were determined for five drifting sediment traps (max. 30 h) in the Bransfield Strait and one moored trap array (52 days) in the Drake Passage in December/January 1980. In a Phaeocystis-dominated zone in the Bransfield Strait the carbohydrate composition was comparable to that of water column suspended material with absolute fluxes of 9.0 and 56.7 mg carbohydrate carbon m−2d−1. In Bransfield Strait waters dominated by bacillariophyceae, fluxes were 75.4, 92.6 and 276.8 mg carbohydrate carbon m−2d−1 with a pronounced dominance of glucose. This is attributed to the presence of the reserve polysaccharide chrysolaminarin in diatom resting spores. Drake Passage fluxes were 1–2 orders of magnitude lower with a distinct degradation of glucose with depth. 相似文献
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《Deep Sea Research Part I: Oceanographic Research Papers》1999,46(10):1755-1778
Hydrographic station and current meter data are used to estimate circulation and transport in the eastern basin of the Bransfield Strait. The short distance between adjacent hydrographic stations (20 km) allows evaluation of structures at scales seldom addressed in previous studies. The main feature of the derived circulation is the Bransfield Front and its associated baroclinic jet (the Bransfield Current). This frontal current crosses the northern half of the basin in a generally SW–NE direction, has maximum geostrophic speeds of 22 cm s−l (at the jet entrance), and has geostrophic transport relative to 500 dbar estimated to be 1 Sv. Dynamically significant mesoscale features associated with the Bransfield Current are seen to be relevant down to 500 dbar. Specific aspects inferred from our analysis are the apparent high degree of stationarity of the described circulation, the shallow intrusions of Circumpolar Deep Water through the northern boundary of the domain (from the Drake Passage), and the northward sinking of Weddell Sea water over most of the domain. 相似文献
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Four sediment cores were collected to determine the depositional environments of the King George Basin northeast of Bransfield Strait, Antarctica. The cored section revealed three distinct lithofacies: laminated siliceous ooze derived from an increased paleoproductivity near the receding sea-ice edges, massive muds that resulted from hemipelagic sedimentation in open water, and graded sediments that originated from nearby local seamounts by turbidity currents. Clay mineral data of the cores indicate a decreasing importance of volcanic activity through time. Active volcanism and hydrothermal activity appear to be responsible for the enrichment of smectite near the Penguin and Bridgeman Islands. 相似文献
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Polonik N. S. Ponomareva A. L. Eskova A. I. Shakirov R. B. Obzhirov A. I. Morozov E. G. 《Oceanology》2021,61(6):892-898
Oceanology - Methane concentrations were measured in the water layers on two transects crossing the central part of Bransfield Strait and along the Antarctic Sound. In the abyssal sea of the... 相似文献