Initial Rifting Age of the Nearly N–S Rifts in Southern Tibetan Plateau: New Evidence from the Age limit of the Early Sediments

<正>Objective The nearly parallel N–S-trending rifts in southern Tibet represent the E–W extension of the Tibet Plateau.Most data which constrained the age of the extensional deformation come from isotopic dating of the dikes probably related to the activity of the nearly N–S faulting and micas from hydrothermal activity and the lowtemperature thermochronology of plateau uplift.Previous     

基于LabVIEW队列状态机的岸基海洋水质集成在线监测系统控制方法研究

随着经济社会的发展,海洋环境监测受到越来越多的关注。针对当前海洋环境监测中,采用海洋水质集成在线监测系统,开展现场自动化监测的实际需求,以国家海洋技术中心自主研发的四参数水质仪、浊度传感器和营养盐自动分析仪为基础,开发岸基海洋水质集成在线监测系统。按照海洋水质集成在线监测系统的总体工作顺序,将工作流程划分为多个状态进行管理。应用LabVIEW编程语言,采用队列状态机,对各状态进行合理安排,最终实现了岸基海洋水质集成在线监测系统工作流程的有序调度以及可靠控制。     

多测量装置水质监测仪器集成控制系统开发

介绍了一种具有多个测量装置的水质监测仪器集成控制系统的开发设计方案。该设计方案针对5套功能相似但相互独立的水质测量装置,以嵌入式系统为控制核心,灵活运用Modbus RTU通信协议及RS485总线,并自主开发通信协议,实现控制核心与触摸屏、PC机以及5套测量装置的通信连接;进而采用多任务的处理架构,对上述外围设备操作任务进行分时处理,最终成功将5套测量装置集成为一台水质监测仪器,并支持PC机和触摸屏双终端进行显示和控制。实际应用效果表明,该设计方案稳定、可靠。     

Infiltration of refractory melts into the lowermost oceanic crust: evidence from dunite- and gabbro-hosted clinopyroxenes in the Bay of Islands Ophiolite

Up to 3 km of dunitic rocks occur below crustal gabbro in the Blow Me Down massif (Bay of Islands Ophiolite, Newfoundland). Analyses of dunite- and gabbro-hosted clinopyroxene grains (cpx) for rare earth elements (REE), Zr, and Ti reveal three types of chondrite-normalized patterns: N-group patterns are similar to cpx grains as they would form by fractionation from a range of mid ocean ridge basalts (MORB). They are typical for a few higher level dunitic samples as well as mafic cumulates. F-group patterns show light REE depletion, very strong middle REE fractionation and a positive Zr anomaly and occur in dunites only. R-group patterns are severely depleted in both light and heavy REEs relative to MORB-like cpx and two samples of the group display a positive Ti anomaly. They are also restricted to dunitic rocks. The patterns are explained in a two stage model in which an established dunite sequence, dominated by MORB-type cumulate signatures (N-group), was infiltrated by extremely refractory melts. During infiltration of the refractory melt chromatographic fractionation occurred, transforming N-group dunites into F-group and R-group dunites. The F-group patterns are composite patterns: heavy REE, Ti ± Zr reflect the original MORB-like cumulate dunite host, light REEs indicate equilibrium with the infiltrating, refractory melts. Steep slopes in the middle REEs reflect the position of the chromatographic front. For more intense percolation of refractory melts, R-group patterns with a positive Ti anomaly will form by the same process. The rest of the R-group patterns displaying no positive Ti anomaly may represent either the most intensely reacted host rocks or these dunites derive directly as cumulates from refractory melts. Only small volumes of refractory melt (a 5 m column) are required to imprint the observed trace element pattern on the thick original dunite sequence. One of several possible origins for the refractory melts is transformation of original MORB-type melts by way of chromatographic fractionation within the highly depleted, residual uppermost mantle. In the framework of an oceanic spreading centre, the migrating, refractory liquids are considered a late event following the main constructive stage dominated by aggregated melts. The study demonstrates that highly refractory melts can exist under oceanic spreading centres dominated by a MORB-like cumulate and volcanic sequence. Received: 2 September 1996 / Accepted: 20 November 1997     

A Climatological Perspective on Extratropical Synoptic-Scale Transient Eddy Activity Response to Western Pacific Tropical Cyclones

An observational study focusing on the contribution of tropical cyclones(TCs)that form over the western North Pacific(WNP)to the synoptic-scale transient eddy activity(STEA)over the North Pacific during the boreal autumn and early winter in the period 1979–2019 is presented in this paper.Statistical results show that WNP TCs entering the midlatitudinal North Pacific provide significant positive effects on the pentad mean strength of STEA,which is primarily concentrated over the Kuroshio/Oyashio Extensions(KOE)and regions from east of Japan to 160°W in the lower and midto-upper troposphere,respectively.TC intensity is highly indicative of the subsequent STEA with a correlation coefficient of 0.37/0.33/0.45 at 300 hPa/500 hPa/850 hPa exceeding the 99%confidence level for the period 1979–2019.The strength of STEA in the upper troposphere associated with TCs presents a more significant linear growth with TC intensity than that at the mid-to-lower levels after the cyclones enter the KOE region,suggesting that the impact of TCs on STEA gradually increases with height.Further analyses reveal that the contribution of TCs accounts for 4%–6%of the total STEA change over the KOE region during the late autumn and early winter.In addition,the influence of TCs on STEA experienced an interdecadal decrease from the early 2000 s through the early 2010 s.     

江淮梅雨与梅雨期西北太平洋热带气旋的关系

基于梅雨综合指数,本文对1955—2010年江淮梅雨与梅雨期西北太平洋TC的变化关系及成因进行统计分析研究。结果表明:梅雨强弱与梅雨期TC频数存在显著的负相关,达到-0.41。同时,挑选出强梅雨年和弱梅雨年,发现强、弱梅雨异常年的TC特征差异显著,表现在:强梅雨年TC生成较少,以西、西北行为主,主要影响我国南部地区;弱梅雨年TC生成偏多,以转向路径为主,影响我国东南沿海众多省份。此外,两者通过大气环流场相互影响,梅雨期季风槽的位置与强度影响TC生成频数与源地,TC的活动又反作用于梅雨期的环流形式与水汽输送。     

沙坡头地区新月形沙丘粒度特征

由腾格里沙漠东南缘沙坡头附近新月形沙丘表面沉积物的系统采集分析结果,发现从北部沙漠主体向黄河南岸,沙丘沙平均粒径变细但分选变差。同时,粒径及分选性在沙丘断面出现两种变化模式,其一是沙漠主体新月形沙丘由两侧坡部向丘顶区域粒径变细分选变好;其二为黄河两岸阶地和湖盆滩地的新月形沙丘丘顶沙粒粗于其它部位但分选仍然最好。根据粒度参数间的相互关系和其它环境条件的分析,对沙丘沙粒度变化的原因及偏度等也作了初步探讨。     

The 30–60-day oscillation in the East Asian summer monsoon and its time-dependent association with the ENSO

Based on 30–60-day oscillation in the East Asian summer monsoon (EASM), the relationship between its northward propagation and ENSO (El Niño and Southern Oscillation) was investigated. To explicitly describe the 30–60-day monsoonal evolution, an empirical orthogonal function (EOF) analysis was carried out on the temporal-latitude section of the longitudinal average for 115°E–120°E. The principal 30–60-day EASM mode captures a northward propagation of well-organized intraseasonal oscillation (NISO). Using the associated time series of the first mode, we found a significant lagged correlation between interannual variability of the NISO and ENSO. Its lagged correlations with NINO indices have a quasi-biennial (QB) characteristic through the preceding summer and the concurrent summer. Their relationship was found by the regression analysis relating the low-level circulation to the ocean temperature. The western North Pacific anticyclone and the anticyclone-induced easterly vertical wind shear anomalies induce the dynamical linkage between the NISO and QB-type ENSO. It is shown that the NISO is more closely tied with QB-type ENSO in its phase than in its amplitude, and may be connected to the anomalous easterly wind and the eastward evolution of an oceanic Kelvin wave, which is associated with abrupt ENSO transition. The predictability on ENSO and NISO is examined through the canonical correlation analysis.     

ROLE OF EQUATORIAL PACIFIC OCEAN SUBSURFACE OCEANIC TEMPERATURE MODE IN ENSO CYCLE

Based on the simple ocean data assimilation (SODA) reanalysis dataset from the University of Maryland and the method of Empirical Orthogonal Functions (EOF), the characteristics of interannual and interdecadal variabilities of the equatorial Pacific subsurface oceanic temperature anomaly (SOTA) are captured. The first and second modes of the equatorial Pacific SOTA in the interannual and interdecadal variations are found respectively and the effect of the second mode on the ENSO cycle is discussed. Results show that the first mode of SOTA’s interannual and interdecadal variabilities exhibit a dipole pattern, indicating that the warm and cold temperature anomalies appear simultaneously in the equatorial subsurface Pacific. The second mode shows coherent large-scale temperature anomalies in the equatorial subsurface Pacific, which is a dominant mode in the evolution of ENSO cycle. The temporal series of the second mode has a significant lead correlation with the Ni?o-3.4 index, which can make a precursory prediction signal for ENSO. The function of this prediction factor in SOTA is verified by composite and case analyses.     

藏南及邻区典型晚新生代盆地磁性地层研究现状与时代对比分析

在系统梳理扎达盆地、尼泊尔Thakkhola半地堑盆地、吉隆—沃马盆地、乌郁盆地磁性地层研究成果的基础上, 对古地磁年代所代表的地质事件进行了对比和分析, 认为藏南及邻区各近南北向裂谷盆地自形成以来均发育2次明显的沉积变动事件, 第一次为距今10.6~8.1 Ma期间各盆地分别开始接受沉积, 第二次为距今3.5~2.0 Ma各湖盆的连续消亡; 总结高原的气候变化可以发现, 高原在距今约8 Ma及3 Ma左右也有明显的2次气候变化, 即沉积事件与气候变化事件在时间上具有近同时性。扎达盆地、吉隆—沃马盆地、达涕盆地三趾马化石的时代都处于距今7.0~6.5 Ma之间, 也具有近同时性。结合高原的整体演化, 认为其可能在距今10.6~8.1 Ma、3.5~2.0 Ma发生了2期比较强烈的隆升运动。同时, 分析指出了青藏高原南部及邻区晚新生代盆地磁性地层研究过程中存在的问题及解决方法, 并对今后青藏高原南部及邻区地区晚新生代磁性地层研究提出了建议。