冈底斯地区林子宗群火山岩岩石地球化学特征及地球动力学意义

错卧莫-惩香错火山-沉积盆地位于西藏冈底斯陆块中部南缘。盆地内火山-沉积地层称古新世-渐新世林子宗群，岩石地球化学数据分析表明：这套火山岩系属钙碱性系列，轻稀土富集，不同程度表现出负Eu、负Ce、负Nb异常。微量元素K、Rb、Th、Ce富集，Sr、Ba，尤其是Nb、P、Ti亏损。初步认为这套火山-沉积岩系形成于俯冲造弧的构造背景中，是来自于俯冲带的地幔源区基性分异岩浆与陆壳重熔的酸性岩浆在不同的时间段内，按不同的比例混合形成的。同时，俯冲板块上深海沉积物与基性岩浆混合作用也是不容忽视的因素。在综合分析基础上，笔者认为印度板块与欧亚板块的碰撞启动时间在45Ma以后。     

吉林红旗岭超基性岩体的锆石U-Pb年龄、Sr-Nd-Hf同位素特征及岩石成因

锆石LA-ICP-MS U-Pb年龄(220.6±2.0Ma)表明研究区超基性岩属于印支晚期岩浆活动的产物.主微量元素研究显示超基性岩具有相对较低的SiO2(43.22％～44.48％)、K2O(0.10％ ～0.17％)和Na2O(0.15％ ～2.13％)以及较高的MgO含量(29.23％ ～30.38％)和Mg#...     

黑龙江省铁力市鹿鸣钼矿床地质特征

鹿鸣钼矿床位于小兴安岭-张广才岭多金属成矿带内,矿体产在印支期二长花岗岩体中,矿床的围岩蚀变、元素地球化学特征、含矿岩体的岩石学特征等均具有斑岩型矿床的特点,且与国内同类型矿床具有可比性.     

新疆西准噶尔发现早泥盆世埃达克岩:大地构造及成矿意义

新疆西准噶尔博什库尔-成吉斯(Boshchekul-Chingiz)岩浆弧南缘,额敏县东南约100km的阿克乔克含铜花岗闪长岩和花岗闪长斑岩,其锆石U-Pb年龄为410.5±2.9Ma,形成于泥盆世早期.岩石具有埃达克岩的地球化学特征,表现为高钾钙碱性-钙碱性,SiO2含量在61％～66％之间,具高Al(Al2O3=15.67％ ～ 16.87％)、Sr(475×10-6 ～ 879×10-6)及高Sr/Y比值(36 ～77),低Y(9.87×10-6～14.46×10-6)、Yb(0.96×10-6～ 1.49×10-6),富钠贫钾(Na2O =4.25％ ～5.58％,K2O=2.26％ ～3.27％,Na2O/K2O=1.40～ 2.47),MgO=1.51％ ～2.58％,Mg#=41～48,并显示富集强不相容元素(Ba、Rb、Sr、Th、U)和LREE,(La/Yb)N=6.0～10.2,强烈亏损高场强元素(Nb-Ta、Ti),Y/Yb=10,无Eu异常(Eu/Eu*≈1.0)和HREE呈平坦型的配分特点,以及与环太平洋新生代埃达克岩相当的Rb/Sr(0.04 ～0.07)和La/Ce(0.42 ～0.51)比值,但偏低的Nb/U比值可能与俯冲沉积物加入有关.阿克乔克花岗闪长岩及花岗闪长斑岩是早泥盆世早期库吉拜-和布克赛尔(Kujibai-Hebukesaier)及洪古勒楞蛇绿岩带所代表的古大洋向南俯冲的玄武质洋壳部分熔融的产物,源区残留相主要为角闪石+辉石+石榴石,源岩应为石榴角闪岩;阿克乔克早泥盆世埃达克岩及谢米斯台-赛尔山晚志留世-早泥盆世A-型花岗岩(422～405 Ma,Chen et al.,2010)构造岩浆岩带可东延至扎河坝-阿尔曼太蛇绿岩带之北的岛弧带,构成一条贯穿东、西准噶尔北部的巨型构造带;阿克乔克埃达克岩伴有斑岩型Cu成矿作用,因此,在东、西准噶尔博什库尔-成吉斯-达拉特-巴依塔格巨型岩浆弧带有可能存在与埃达克岩有关的Cu-Au矿带.     

海相火山—沉积建造区铜,多金属成矿系列及铁—铜型矿床的勘查前景

拟建了海相火山岩地区的铁－铜－硫成矿系列,它包含两个亚系列,即含铜黄铁矿型亚系列和含铜铁矿型亚系列;并充分肯定了铁－铜型矿床的潜在地位与勘查前景,为新一轮矿产资源大调查拓宽了思路,为铜、多金属矿产的勘查扩展了就矿（铁矿、黄铁矿）找矿（铜、铅、锌、金）的有效途径。     

东昆仑清水泉蛇纹岩中铬铁矿环带成因

东昆仑造山带清水泉超基性岩已蚀变成蛇纹岩,部分浸染状铬铁矿颗粒具有环带结构,这将为研究铬铁矿形成后所经历的变质过程及其寄主岩体的构造演化提供可靠的信息.通过对铬铁矿进行显微结构观察和电子探针分析得出:所研究铬铁矿的环带结构从核部到边缘依次为铝铬铁矿、高铁铬铁矿和铬磁铁矿,被绿泥石所包裹.从铝铬铁矿到高铁铬铁矿,Cr2O3,Al2O3和MgO含量下降,Fe2O3和FeO含量升高;Cr#,TiO2含量,YFe值以及Fe2+#值明显具有升高的趋势,而Mg#值却急剧下降.以上变化规律表明本文所研究的铬铁矿经历了由高温到低温,同时氧逸度上升的过程,并伴随有蛇纹石化作用、热液流体以及区域变质作用等改造,最终形成环带结构.此过程与铬铁矿寄主岩体经历的由地幔抬升至浅部地壳以及相关的变质作用过程相对应.     

The 2020/21 Extremely Cold Winter in China Influenced by the Synergistic Effect of La Niña and Warm Arctic

In the first half of winter 2020/21,China has experienced an extremely cold period across both northern and southern regions,with record-breaking low temperatures set in many stations of China.Meanwhile,a moderate La Ni?a event which exceeded both oceanic and atmospheric thresholds began in August 2020 and in a few months developed into its mature phase,just prior to the 2020/21 winter.In this report,the mid?high-latitude large-scale atmospheric circulation anomalies in the Northern Hemisphere,which were forced by the negative phase of Arctic Oscillation,a strengthened Siberian High,an intensified Ural High and a deepened East Asian Trough,are considered to be the direct reason for the frequent cold surges in winter 2020/21.At the same time,the synergistic effect of the warm Arctic and the cold tropical Pacific(La Ni?a)provided an indispensable background,at a hemispheric scale,to intensify the atmospheric circulation anomalies in middle-to-high latitudes.In the end,a most recent La Ni?a prediction is provided and the on-coming evolution of climate is discussed for the remaining part of the 2020/21 winter for the purpose of future decision-making and early warning.     

Experiments with the Improved Dynamical-Statistical-Analog Ensemble Forecast Model for Landfalling Typhoon Precipitation over South China

In recent work, three physical factors of the Dynamical-Statistical-Analog Ensemble Forecast Model for Landfalling Typhoon Precipitation (DSAEF_LTP model) have been introduced, namely, tropical cyclone (TC) track, TC landfall season, and TC intensity. In the present study, we set out to test the forecasting performance of the improved model with new similarity regions and ensemble forecast schemes added. Four experiments associated with the prediction of accumulated precipitation were conducted based on 47 landfalling TCs that occurred over South China during 2004-2018. The first experiment was designed as the DSAEF_LTP model with TC track, TC landfall season, and intensity (DSAEF_LTP-1). The other three experiments were based on the first experiment, but with new ensemble forecast schemes added (DSAEF_LTP-2), new similarity regions added (DSAEF_LTP-3), and both added (DSAEF_LTP- 4), respectively. Results showed that, after new similarity regions added into the model (DSAEF_LTP-3), the forecasting performance of the DSAEF_LTP model for heavy rainfall (accumulated precipitation ≥250 mm and ≥100 mm) improved, and the sum of the threat score (TS250 + TS100) increased by 4.44%. Although the forecasting performance of DSAEF_LTP-2 was the same as that of DSAEF_LTP-1, the forecasting performance was significantly improved and better than that of DSAEF_LTP-3 when the new ensemble schemes and similarity regions were added simultaneously (DSAEF_LTP-4), with the TS increasing by 25.36%. Moreover, the forecasting performance of the four experiments was compared with four operational numerical weather prediction models, and the comparison indicated that the DSAEF_LTP model showed advantages in predicting heavy rainfall. Finally, some issues associated with the experimental results and future improvements of the DSAEF_LTP model were discussed.     

Experiments of DSAEF_LTP Model with Two Improved Parameters for Accumulated Precipitation of Landfalling Tropical Cyclones over Southeast China

The Dynamical-Statistical-Analog Ensemble Forecast model for landfalling tropical cyclones (TCs) precipitation (DSAEF_LTP) utilises an operational numerical weather prediction (NWP) model for the forecast track, while the precipitation forecast is obtained by finding analog cyclones, and making a precipitation forecast from an ensemble of the analogs. This study addresses TCs that occurred from 2004 to 2019 in Southeast China with 47 TCs as training samples and 18 TCs for independent forecast experiments. Experiments use four model versions. The control experiment DSAEF_LTP_1 includes three factors including TC track, landfall season, and TC intensity to determine analogs. Versions DSAEF_LTP_2, DSAEF_LTP_3, and DSAEF_LTP_4 respectively integrate improved similarity region, improved ensemble method, and improvements in both parameters. Results show that the DSAEF_LTP model with new values of similarity region and ensemble method (DSAEF_LTP_4) performs best in the simulation experiment, while the DSAEF_LTP model with new values only of ensemble method (DSAEF_LTP_3) performs best in the forecast experiment. The reason for the difference between simulation (training sample) and forecast (independent sample) may be that the proportion of TC with typical tracks (southeast to northwest movement or landfall over Southeast China) has changed significantly between samples. Forecast performance is compared with that of three global dynamical models (ECMWF, GRAPES, and GFS) and a regional dynamical model (SMS-WARMS). The DSAEF_LTP model performs better than the dynamical models and tends to produce more false alarms in accumulated forecast precipitation above 250 mm and 100 mm. Compared with TCs without heavy precipitation or typical tracks, TCs with these characteristics are better forecasted by the DSAEF_LTP model.     

基于布格重力异常研究运城盆地的构造特征

利用运城及周边地区的布格重力资料,对布格重力数据进行小波分解得到不同阶次的重力异常信息。依据各个阶次的小波变换结果并结合该区域的地质构造环境,对小波变换细节图中存在的特征较为明显的布格重力异常带进行深入分析,对异常所揭示的构造现象在地壳不同深度的分布特性等进行分析研究。结果表明:小波变换细节与区内地壳内部的隆起、凹陷及断裂构造具有很好的对应关系,可以对运城盆地的构造特征及地壳结构做更加深入的研究。