南大洋普里兹湾沉积物中锗的含量与分布

本文利用中国第21-27次南极考察期间获得的沉积物样品,对南大洋普里兹湾沉积物中锗（Ge）的含量以及分布特征进行了初步研究。结果表明：普里兹湾表层沉积物中总Ge（Getotal）的含量在1.14×10-6~2.35×10-6之间变化,平均含量为1.71×10-6,最高值出现在湾外深海区P3-9站,最低值出现在湾内冰架边缘附近的P4-13站。在研究海域表层沉积物中生源Ge（Gebio）占Getotal的百分含量在16-68%之间变化。在表层沉积物中Gebio与Getotal分布变化趋势总体上相近,以67°S为界均呈现湾外高于湾内的趋势,在柱状沉积物中Ge的垂向分布呈现表层高于底层趋势。在普里兹湾湾内非冰间湖区域的表层沉积物中Gebio与生物硅（BSiO2）呈现一定的正相关,在P3-16站位柱状沉积物中Gebio与BSiO2垂向分布相似。     

热带三大洋海表温度和云水关系的初探

热带太平洋、大西洋和热带印度洋是全球海洋-大气相互作用最显著的海域。为了探讨热带三大洋局地海洋-大气相互作用中的某些特征,利用新的卫星遥感资料对热带三大洋的云水和海表温度(SST)异常变化进行了统计相关分析。研究发现:在赤道太平洋和赤道大西洋云水和SST二者在超前或滞后5周内都呈现明显的正相关关系,表明3个赤道海域云水和SST之间具有明显的相互作用正反馈机制;在热带西印度洋SST异常超前CLW异常一周时,正相关系数最大,SST的变化导致云水的变化;而在以较冷海水为下垫面的赤道外东北太平洋,东南太平洋以及赤道外的南大西洋海域,二者呈明显的负相关关系,云水的变化会引起SST的变化。位于菲律宾以东的热带西北太平洋区,云水量的变化引起SST的变化;而赤道东印度洋暖池区即存在云水量的增加(减少)引起SST降低(升高)的现象,也存在SST降低(升高)引起云水量的减少(增加)的现象。以上结果将为进一步理解海洋-大气相互作用,在数值模式中正确设计海洋-大气边界层参数化方案提供参考。     

New evidence on the sequence of deglacial warming in the tropical Indian Ocean

The transition from the Last Glacial Maximum to the Holocene was an internal of climate variability that was characterised by large spatial and temporal variations. Here we show that deglaciation warming in the northern Indian Ocean was initiated ca. 19 ka, which is contemporary with deglaciation warming in the Antarctica and Southern Ocean. A gradual warming occurred during the glacial/Holocene transition in the northern Indian Ocean, unlike the two‐step warming seen in Greenland and the North Atlantic. Synchronous deglacial warming ca. 19 ka in Antarctica and the northern Indian Ocean suggests a strong connection in the propagation of climate signals between Antarctica and the Indian Ocean, probably through the Indonesian Throughflow and/or Subantarctic Mode Water. Copyright © 2010 John Wiley & Sons, Ltd.     

岩浆与构造作用对洋壳厚度的影响——以西北印度洋为例

洋中脊及邻区洋盆的洋壳厚度能很好地反映区域岩浆补给特征,对于研究洋中脊内部及周缘岩浆活动和构造演化过程具有很好的指示意义.西北印度洋中脊作为典型的慢速扩张洋中脊,其扩张过程与周缘构造活动具有很强的时空关系.本文利用剩余地幔布格重力异常反演了西北印度洋洋壳厚度,由此分析区域内洋壳厚度分布和岩浆补给特征.研究发现,西北印度...     

Compilation of radiogenic isotope data in Mexico and their petrogenetic implications

Seven hundred and twenty-five Sr, two hundred and forty-three Nd and one hundred and fifty-one Pb isotopic ratios from seven different Mexican magmatic provinces were compiled in an extensive geochemical database. Data were arranged according to the Mexican geological provinces, indicating for each province total number of analyses, range and mean of values and two times standard deviation (2σ). Data from seven provinces were included in the database: Mexican Volcanic Belt (MVB), Sierra Madre Occidental (SMO), Baja California (BC), Pacific Ocean (PacOc), Altiplano (AP), Sierra Madre del Sur (SMS), and Sierra Madre Oriental (SMOr). Isotopic values from upper mantle and lower crustal xenoliths, basement outcrops and sediments from the Cocos Plate were also compiled. In the MVB the isotopic ratios range as follows:⁸⁷Sr/⁸⁶Sr 0.703003-0.70841;¹⁴³Nd/¹⁴⁴Nd 0.512496-0.513098;²⁰⁶Pb/²⁰⁴Pb 18.567-19.580;²⁰⁷Pb/²⁰⁴Pb 15.466-15.647;²⁰⁸Pb/²⁰⁴Pb 38.065-38.632. The SMO shows a large variation in⁸⁷Sr/⁸⁶Sr ranging from ∼0.7033 to 0.71387.¹⁴³Nd/¹⁴⁴Nd ratios are relatively less variable with values from 0.51191 to 0.51286. Pb isotope ratios in the SMO are as follows:²⁰⁶Pb/²⁰⁴Pb 18.060-18.860;²⁰⁷Pb/²⁰⁴Pb 15.558-15.636;²⁰⁸Pb/²⁰⁴Pb 37.945-38.625. PacOc rocks show the most depleted Sr and Nd isotopic ratios (0.70232-0.70567 for Sr and 0.512631-0.513261 for Nd). Pb isotopes for PacOc show the following range:²⁰⁶Pb/²⁰⁴Pb 18.049-19.910;²⁰⁷Pb/²⁰⁴⁷Pb 15.425-15.734;²⁰⁸Pb/²⁰⁴Pb 37.449-39.404. The isotopic ratios of the AP rocks seem to be within the range of those from the PacOc. Most samples with reported Sr and Nd isotopic data are spread within and around the “mantle array”. The SMO seems to have been formed by a mixing process between mantle derived magmas and continental crust. The MVB appears to have a larger mantle component, with AFC as the dominant petrogenetic process for the evolved rocks. There is still a need for Pb isotopic data in all Mexican magmatic provinces and of Nd isotopes in BC, AP, SMS, and SMOr.     

Continental- Margin Structure of Northeast China and Its Adjacent Areas

The continental margin of Northeast China and its adjacent areas is composed of two tectonic belts. The inner belt is a collage made up of fragments resulting from breakup of an old land with the north part related to the evolution of the Palaeo-Asian Ocean and the south part to the evolution of the Palaeo - Pacific Ocean. The outer belt is a Mesozoic terrane, which is a melange made up of fragments of the Late Palaeozoic to Early Mesozoic oceanic crust and the Late M esozoic trench accumulations.There existed another ocean-the Palaeo - Pacific Ocean during the period from the closing of the Palaeo-Asian Ocean to the opening of the modern Pacific Ocean or from the Devonian to Jurassic, and the ocean-floor spreading of the Palaeo - Pacific Ocean led to the formation of the above-mentioned tectonic belts. The development of the strike-slip fault system after the Late Jurassic and the formation of an epicontinental volcano -plutonic rock belt in the Late Cretaceous to Early Tertiary are attributed to the i     

南极海冰问题评述:观测

海冰通过其对地面反照率的作用以及对大气和海洋之间热交换的局地障碍和对世界海洋环流的作用在全球热平衡和气候变化中起着重要的作用。南极海冰又因其极为显著的时空变化引起越来越多的关注。海冰的观测是海冰研究的重要内容 ,本文综述了南极海冰观测的发展过程 ,着重介绍了卫星在探测南极海冰方面的重要进展 .     

Geochronology,geochemistry and Sr-Nd-Pb-Hf isotopes of the Early Paleogene gabbro and granite from Central Lhasa,southern Tibet: petrogenesis and tectonic implications

ABSTRACT

The Tibetan Plateau is a composite orogenic belt that has experienced prolonged subduction, obduction, and collisional processes, during the opening and closure of successive Tethyan oceans. We present new zircon U-Pb ages and Hf isotopes, and whole-rock geochemical and Sr-Nd-Pb isotopic data from the Early Paleogene Longge’er gabbro and Qingduxiang granite of Central Lhasa, southern Tibet. Together these allow us to refine existing models for widespread magmatic activity associated with the subduction of the Neo-Tethyan Ocean. The Longge’er gabbro (53.5 ± 1.6 Ma) belongs to the low-K tholeiitic to medium-K and metaluminous series, while the Qingduxiang granite (54.5 ± 0.9 Ma) is characterized as high-K, calc-alkaline, metaluminous, and of I-type affinity. Both intrusions are enriched in the LREE and depleted in the HREE with negative Eu, Ba, Nb, Ta, Sr, and Ti anomalies. Trace elements characteristics and enriched whole-rock Sr-Nd-Pb and zircon Hf isotopic compositions demonstrate that the gabbro was derived from partial melting of enriched lithosphere mantle metasomatized by Central-Lhasa ancient crustal materials, while the I-type granite was generated by partial melting of Central-Lhasa ancient lower crust combined with magmas derived from Southern-Lhasa juvenile crust. Geochemical compositions of the gabbro and granite reveal the Early Paleogene magmatism was emplaced in a shallow extensional setting related to slab break off following the closure of the Neo-Tethyan Ocean. Combined with previous studies, we can infer slab rollback occurred from Late Cretaceous (~69 Ma) to Early Eocene (55 Ma), while slab break off was shortly lived at ca. 55–49 Ma. Consequently, the India-Asia collision must not have started later than ca. 55 Ma.     

青藏高原和热带印度洋5月热力异常与新疆夏季降水的关系

基于1979-2017年美国国家海洋和大气管理局(NOAA)提供的海表温度资料和美国国家环境预测中心(NCEP)/美国国家大气研究中心(NCAR)提供的大气环流再分析资料以及青藏高原地区149个站点观测资料计算的地表感热通量和新疆气象信息中心提供的全疆81站逐月降水资料等,研究了5月青藏高原和热带印度洋加热对新疆夏季降...     

基于GRACE资料研究南极冰盖消减对海平面的影响

利用5年的GRACE重力数据,计算了南极1°×1°等效水量时间序列,得到每个格网的趋势项,结果表明在西南极Amundsen区域有明显的负增长,超过-80 mm/a,南极半岛存在着负增长,东南极Enderby Land地区质量增长;计算得到2002年7月到2007年9月南极、东南极和西南极冰盖的等效体积变化分别为-78±37 km3/a,-3±46 km3/a和-75±50 km3/a,对应海平面变化的贡献为0.21±0.1 mm/a,0.008±0.127 mm/a和0.2±0.14 mm/a.该结果与国际最新研究结果一致.同时发现冰后回弹是影响利用GRACE研究南极冰盖质量变化的关键因素.