TRANSPORT OF OXYGEN,NUTRIENTS AND CARBONATES BY THE KUROSHIO CURRENT

Measured concentrations of dissolved oxygen,phosphate,silicate,total alkalinity and calculated totalCO_2 in a section between 121°E and 125°E across the Kuroshio near 22°N off Taiwan and thegeostrophic velocity were used to estimate the gross transport of oxygen,nutrients and carbonates. The flux of dissolved oxygen is 6.7×10~6 mol/s northward and 0.9×10~6 mol/s southward.The netflux equals 5.8×10~6 mol/s down-stream.The northward flux of phosphate is 22.6×10~3 mol/s;the south-ward flux is 1.4×10~3 mol/s.The net phosphate flux is 21.2×10~3 mol/s northward.The flux of silicateis 967×10~3 northward and 59×10~3 mol/s southward;the net transport is 908×10~3 mol/s down-stream.The flux of alkalinity is 75.5×10~6 mol/s northward,and 10.8×10~6 mol/s southward,the net flux is64.7×10~6 mol/s northward.For total CO_2 the transport is 73.4×10~6 mol/s northward and 10.8×10~6 mol/ssouthward,or a net transport of 62.6×10~6 mol/s northward.     

SEAWATER FLUX OF THE SOUTH CHINA SEA

The South China Sea water can be divided according to depth into three boxes by the pycnoclineand a sill.Using a box model with matter balance,the net seawater fluxes were calculated to be317.9×10~4 m~3/s in box Ⅰ for the upper homogeneous layer outflowing to the adjoining oceans;67×10~4 m~3/s in box Ⅲ for the water entering the basin;240×10~4 m~3/s in box Ⅱ for water entering theSouth China Sea.The upward speed of basin water was calculated to be 8.4×10~(-5) cm/s and that ofseawater flowing up along the pycnocline was calculated to be 8.9×10~(-5) cm/s.     

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Spatiotemporal variations of the surface Kuroshio east of Taiwan Island derived from satellite altimetry data

Spatiotemporal variation of the surface Kuroshio east of Taiwan Island is investigated by quantitatively analyzing 23-year(1993–2015)sea surface Absolute Dynamic Topography data.The annual mean state of the Kuroshio is shown,with a flow width ~136 km and surface transport ~7.75×10~4 m~2/s.The corresponding standard deviations of these are 28 km and 2.14×10~4 m~2/s.Results of power spectrum analysis indicate that the primary periods of Kuroshio surface transport east of Taiwan Island are 1 and 2.8 years,respectively.Spatially,the Kuroshio surface transport southeast of Taiwan Island has greater variability than that to its northeast.That transport showed strong seasonality,with a maximum 8.8×104 m~2/s in summer and minimum 7.5×10~4 m~2/s in winter,which was mainly caused by local monsoon winds.A linear long-term upward trend of Kuroshio surface transport during 1993–2015 was found,during which the mean,southeast,and northeast of the Kuroshio east of Taiwan Island increased by 0.30×10~4,0.22×10~4 and 0.36×104 m~2/s,respectively.Correlation and composite analysis show that the Philippines-Taiwan Oscillation(PTO)is important in the interannual variability of the Kuroshio.PTO-induced relative intensity of anticyclonic and cyclonic eddies is the dominant influence on the interannual variability of the Kuroshio east of Taiwan Island.     

联合GRACE卫星轨道及距离变率数据反演地球重力场方法研究

基于动力学法,研究联合GRACE卫星精密轨道及距离变率数据反演地球重力场的方法,该方法可对重力位系数及卫星初始状态误差同时进行有效校正。通过对各观测值模拟不同的随机误差,研究了不同精度观测值联合反演所能达到的精度,以及用相同精度的观测值进行联合反演时不同采样率对反演结果的影响,模拟计算结果表明：联合反演模式下,当距离变率精度为1 μm/s,卫星位置精度为2~3 cm,速度精度为0.1~0.5 mm/s时,加速度计精度为(1.0×10 ^-10~1.0×10^-9 m/s ²比较适合;将距离变率精度由1 um/s提高到0.1 um/s时,反演精度可获得相应提高;在观测值精度一定的情况下,联合反演算法宜采用5 s采样率。     

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新一代重力测量卫星核心指标分析

采用边界分析方法分析新一代重力测量卫星3个核心载荷--星间测距系统、非保守力测量仪和定位接收机的误差对恢复重力场的影响,提出新一代重力测量卫星的核心技术指标。分析表明,星间变率测量精度10~30 nm/s、非保守力测量精度（1~5）×10-11 m/s2、定轨精度2~3 cm时,可实现分辨率100 km、精度1~2 mGal的重力场测量。本文结论可为新一代重力测量卫星设计提供技术参考。     

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冬春季湖光岩玛珥湖水文特征的观测分析

【目的】分析湖光岩玛珥湖流场、温度、密度、浮性频率的三维空间结构、时间演变及其与风场的关系。【方法】于2017年1-4月,用三维超声风速仪、安德拉海流计、ADCP、CTD等进行每月一次的观测,对现场风速,流速、温盐等实测数据进行分析。【结果】表层平均流速为0.05 m/s,其中,表层的平均流速在1-2月为0.03 m/s,在3-4月较大,为0.08 m/s。流向以南向或东南向为主,与观测风向大致吻合。垂向上,次表层流速较小,为0.02 m/s,近底层流速有增大的趋势。1-2月观测表层温度为18.5~21.5℃,温度随深度的增加而下降。跃层主要出现在2~5 m,温度梯度为0.2℃/m。3-4月温度升高到19~26℃,温跃层加深,出现在6~10 m,温度梯度最大达到0.8℃/m。水深2 m处,近岸水浅站位表现为高温低密,12 m处部分深水站位呈现高温。     

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Crustal structure revealed by a deep seismic sounding profile of Baijing-Gaoming-Jinwan in the Pearl River Delta

The Pearl River Estuary area, located in the middle part of the southern China coastal seismic belt, has long been considered a potential source of strong earthquakes above magnitude 7.0. To scientifically assess the potential strong earthquake risk in this area, a three-dimensional artificial seismic sounding experiment, consisting of a receiving array and seabed seismograph, was performed to reveal the deep crustal structure in this region. We used artificial ship-borne air-gun excitation shots as sources, and fixed and mobile stations as receivers to record seismic data from May to August 2015. This paper presents results along a line from the western side of the Pearl River Estuary to the western side of the Baijing-Gaoming-Jinwan profile. A two-dimensional velocity structure was constructed using seismic travel-time tomography. The inversion results show that the Moho depth is 27 km in the coastal area and 30 km in the northwest of the Pearl River Estuary area, indicating that the crust thins from land to sea. Two structural discontinuities and multiple low-velocity anomalies appear in the crustal section. Inside both discontinuity zones, a low-velocity layer, with a minimum velocity of 6.05 km s~(-1), exists at a depth of about 15 km, and another, with a minimum velocity of 6.37 km s~(-1), exists at a depth of about 21.5 km between the middle and lower crust. These low velocities suggest that the discontinuities may consist of partly molten material. Earthquakes with magnitudes higher than 5.0 occurred in the low-velocity layer along the profile. The deep Kaiping-Enping fault, rooted in the crust, may be one of the most important channels for deep material upwelling and is related to tectonic movement since the Cretaceous in the Pearl River Delta tectonic rift basin.     

张渤地震构造带中西段及邻区深部构造探测

利用穿过张渤地震构造带中西段及邻区的多条地震测深资料．详细研究了张渤地震构造带中西段及邻区的地壳深部速度结构与构造。结果表明,该区地壳深部速度结构与构造在纵向和横向上具有明显的不均一性。在三河-平谷8级震区、延庆-怀来盆地及张家口附近地区莫霍面埋深分别为35、39和42km,其地壳厚度由东至西逐渐增加。该区基底断裂发育。在其深部,根据地震波动力学及运动学特征和二维速度结构中的地震界面与速度等值线起伏变化推测,在大兴、延庆、涿鹿等地均存在深部断裂带,在深部断裂带一侧或两侧的上地壳存在6．0km／s左右的低速层（体）。     

汶川地震对湖北地震活动趋势的影响

探讨汶川地震对湖北地震活动的影响，认为龙门山断裂带与襄樊-广济构造带同属于扬子板块西部和北部边缘，是扬子板块逆冲插入青藏板块和秦岭微板块之下形成的。历史强震统计结果表明，四川中西部及周边强震活动对湖北及周边地区中强地震活动影响明显，且对应率较高。汶川地震后3年内，湖北及周边地区具有发生中等强度地震的可能。同时也指出，近几年湖北及周边的地震活动是汶川地震前期东部地区应力场调整的结果。     

陕西关中盆地地热资源及壳幔温度结构的地球物理分析

陕西关中盆地地下热水资源丰富,是中国典型的隐伏型中、低温地热资源分布区。为研究关中盆地中、低温地热系统形成机理,认识深部热源条件,利用地球物理方法分析了该区壳幔温度结构。结果表明:计算得到的居里面平均深度为25.0 km,莫霍面平均深度为36.6 km,地壳平均地温梯度为22.60℃·km-1,咸礼断阶、西安凹陷、固市凹陷地壳地温梯度高于平均值,是地热地质条件较好的构造分区。咸阳、西安之下,上地幔存在向南下倾的高温带,咸阳北侧约175 km深度是一个温度大于1500℃的高温区;其上,莫霍面、居里面上隆,形成高温基底,加热沉积地层中的地下水。富平、渭南之间,上地幔存在“下沉”低温区,低温区北、南两侧约175 km深度分别对应温度大于1450℃的高温区;高温区之上,莫霍面、居里面上隆,形成聚热中心,为地表地热资源提供稳定热源条件。总体上,关中盆地新生代潜水受莫霍面、居里面上隆带入的地幔热量传导加热,热物质随莫霍面、居里面向上抬升,是盆地中、低温地热田的深部热源。上地幔流变边界层控制研究区重要的构造活动,此边界层受周缘构造带不同动力作用,在重力均衡调整过程中,导致深大断裂活动,进而引起地壳深、浅部水体沿断裂带热对流,形成带状分布热泉。     

南、北松潘-甘孜块体及扬子板块壳幔过渡带结构研究

采用接收函数方法，研究南、北松潘-甘孜块体及扬子板块的壳幔过渡带结构，得到3个不同构造块体的壳幔过渡带厚度和速度结构。结果显示，南松潘-甘孜块体壳幔过渡带厚度为1.79~3.4 km，速度结构为高低速相间结构，该块体壳幔过渡带不断变厚，改变了原有的壳幔过渡带温压条件，且东南东北向都有剧烈的构造活动，产生高、低速相间的速度结构；巴颜喀拉松潘-甘孜块体壳幔过渡带厚度为2.22~3.72 km，该块体受到持续挤压，壳幔过渡带逐渐变厚，逐渐改变壳幔过渡带温压条件，形成速度渐变结构；扬子块体壳幔过渡带厚度为0.86~1.58 km，扬子块体四川盆地有坚硬的岩石圈，壳幔过渡带没有遭受破坏，为完好的一级间断面，过渡带厚度较薄，结构为速度突变结构。     

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???????????1990??1997??1997??2003??1994??2006??????????????????????λ??????о???Ms8.0???????????Ms6.1?????????????????????????????????????????????????????????????????????????μ???????????????????????????????????????μ??Χ??????????????????10???????????????????????????????????????????????????????1997??2003?????????????????????????????????????????     

深地震测深揭示的济阳坳陷地壳结构特征

对穿过济阳坳陷的3条深地震测深剖面进行解释、对比分析显示,济阳坳陷地壳结构分为上、中、下3层,莫霍面深度在31 km左右,区域起伏变化不大,深浅部构造呈镜像对称关系。济阳坳陷内中地壳存在低速体发育,为其顶面滑脱层的发育以及滑脱构造的形成提供了必要条件,也导致上下地壳厚度的横向变化存在差异。惠民凹陷下方Pm震相之前出现P4震相表明,其莫霍面以壳幔过渡带形式存在;东营凹陷下方Pm震相尖锐,其莫霍面则表现为一级间断面性质,体现了不同凹陷深部壳幔作用的差异。结论表明,济阳坳陷地壳结构具有典型的华北地区地壳结构特征,上下地壳厚度横向变化差异与滑脱构造密切相关,而莫霍面性质差异与深部软流圈上涌以及下地壳小规模拆沉有关。     

沂沭断裂带及邻区双差层析成像

利用双差层析成像方法,选取2008-10～2017-12山东及周边区域182个地震台站记录的1190个近震观测资料,对沂沭断裂带及邻区的震源位置和三维速度结构进行联合反演.结果表明,沂沭断裂带内部介质速度结构具有明显的不均匀性,并呈现分段特性;在郯城和莒县中上地壳内存在明显的低速结构;胶南地块总体速度低于鲁西地块;鲁西...     

青藏高原东南缘碰撞造山结构与物质组成:来自岩石地球化学和地球物理的联合约束

青藏高原东南缘位于印度板块与欧亚板块侧向汇聚部位,是检验碰撞造山动力学模型的理想场所。尽可能全面收集该区已有地球物理和新生代岩浆岩数据,探讨这些资料对碰撞造山带结构和物质组成的指示。结果表明:青藏高原东南缘不同部位的壳幔结构和组成存在较大差异。兰坪—思茅地块、保山地块和腾冲地块等的中地壳(15~30 km深度)普遍发育低速层,表明富水层或者部分熔融物质的存在,为青藏高原物质向东南流动提供了可能。部分熔融产物以大型剪切带内具有高Sr、低Nd同位素特征的淡色花岗岩脉为代表。但是,扬子板块同等深度下却发育高速层,其组成很可能是峨眉山玄武岩,它的存在阻隔了碰撞带物质向东流动。扬子板块和兰坪—思茅地块下地壳底部均出现呈条带状展布的高速体。根据新生代具有高Sr、低Y的岩石显示的下地壳源区特征,结合该区地质演化历史,将上述两套呈条带状展布的高速体分别解释为新元古代铁镁质弧岩浆岩和二叠纪—三叠纪铁镁质弧岩浆岩。青藏高原东南缘地幔各向异性存在明显南、北分区特征,在26°N以北表现为SN向,在26°N以南表现为近EW向。这一差异跟俯冲的印度板片撕裂有密切关系。该撕裂在综合地球物理剖面上显示为突变的印度板片俯冲角度,在地表表现为苦橄岩、煌斑岩、埃达克岩以及淡色花岗岩等的集中出露。这一新模型明显区别于前人的岩石圈拆沉和对流减薄等作用。     

利用GPS观测资料分析2015年尼泊尔MS8.1地震震前及震后形变

通过对尼泊尔MS8.1地震前后附近区域GPS台站记录到的观测数据进行处理,获得了震区以及中国青藏高原地区地震前后GPS站点速度场以及震后形变场。震前速度场显示,喜马拉雅构造带整体呈现出约16 mm/a的压缩特征。同时,震前喜马拉雅构造带根据形变特征可分为东、中、西3段,其地震发生在中段,主要以北向挤压为主,而东西两段分别具有逆时针旋转和顺时针旋转的特征。震后GPS站点形变场显示,此次地震对中国新疆、青海、西藏等地区的影响较大,其最大震后位移达20 mm左右。震后速度场显示,本次地震对尼泊尔地区以及中国藏南地区的构造形变影响较大,主要表现为喜马拉雅构造带的年推挤速度减小,藏南地区的南北向运动速率减小,而东西向速度有增大的现象。这一现象可能对藏南地区的走滑断层有较大影响。