山东及辽宁晚寒武世长山期新三叶虫

报道了产于中国华北地台东部上寒武统长山阶三叶虫的４个新属和５个新种。新属Ｇｕｓｈａｎａｓｐｉｓ和Ｔａｎｇｗａｎｇｚｈａｉａ产于山东中部Ｅｏｃｈｕａｎｇｉａ带;新属Ｙａｎｚｈｕａｎｇｉａ和Ｆｕｚｈｏｕｗａｎｉａ均产于山东中部和辽宁大连Ｋａｏｌｉｓｈａｎｉａ带上亚带Ｋ．ｐｕｓｔｕｌｏｓａ亚带;新种Ｃｈｕａｎｇｉａｍｅｎｉｓｃａ产于大连Ｃｈｕａｎｇｉａ带。     

山东招掖金矿带花岗岩类单颗粒锆石U-Pb年代学研究及其意义

在占我国最著名的金矿域—胶北金矿域的金矿储量86.3%的招掖金矿带内,广泛分布的燕山期花岗岩类与金矿化作用密切相关。然而,这些花岗岩类的形成时代却是长期困扰地学界的棘手问题,并一直阻碍着有关金矿化问题的探讨。精确的单颗粒锆石U-Pb年代学研究表明,招掖金矿带内花岗岩类玲珑型花岗岩和郭家岭花岗闪长岩均形成于145Ma(分别为145.9±0.5Ma和144.1±0.8Ma)左右的燕山早期(晚侏罗世)。其中存在年龄为2.7Ga左右的继承性锆石,这显示了这些花岗岩类为壳源重熔的产物,而胶东岩群可能为其重要源岩之一。综合已有资料分析,该区与花岗岩类有关的金矿化作用可能发生于100～120Ma区间内。     

二步马氏折扣模型最优策略的结构

讨论二步马氏折扣模型的最优策略,分析该策略的结构。     

四产地卤虫休眠胚胎的发育期及细胞数的初步观察

用石蜡切片法观察了青海尕海(GH)、新疆阿其克库勒湖(AQK)、西藏(XZ,具体产地不明)、新疆鲸鱼湖(JYH)4个卤虫种群休眠胚胎所处的发育期,发现4个种群卤虫休胚胎均处于原肠期;通过压片染色法对4个卤虫种群休眠胚胎的细胞核计数显示,其胚胎细胞数分别为3441±164(GH),3412±171(AQK),3736±212(XZ),3861±155(JYH)个。     

不同发育期锯缘青蟹(Scylla serrata)幼体摄食的变化

每天从锯缘青蟹育苗池采集幼体,在实验室内依平衡法测定从孵化至大眼幼体各天青蟹幼体的摄食率,并同时测定青蟹幼体每天的干重和比能值,比较研究了饵料密度对青蟹不同发育阶段幼体摄食的影响,以及幼体蜕皮周期内摄食的变化。结果表明,轮虫是青蟹蚤状幼体(Z)Ⅰ期(Z1)和Ⅱ期(Z2)适宜的饵料,卤虫无节幼虫是青蟹幼体生长发育主要的能量来源,占整个幼体发育期摄入能量的96·48%。以干重和能量表示的青蟹幼体摄食率(CDW和CJ)随幼体蜕皮发育呈指数增长[CDW=13·463e0·8283(d 1)(r2=0·927),p<0·01;CJ=0·4018e0·7516(d 1)(r2=0·956),p<0·01];青蟹大眼幼体摄食强度显著上升,摄入能量高达整个幼体发育期摄入能量的77·25%。Z1、Z2期为被动摄食,青蟹幼体主动摄食的能力随幼体发育而逐渐提高,大眼幼体为主动摄食。锯缘青蟹各期幼体蜕皮周期内摄食率的变化是:Z1→Z4期蜕皮后上升,蜕皮前稍微下降;Z5期蜕皮后和蜕皮前较高,蜕皮间较低。Z5期日粮水平最低;青蟹大眼幼体期有2个摄食峰值,变化不规则。     

Diagenetic mineralization in Pennsylvanian coals from Indiana, USA: C/C and O/O implications for cleat origin and coalbed methane generation

Cleats and fractures in southwestern Indiana coal seams are often filled with authigenic kaolinite and/or calcite. Carbon- and oxygen-stable isotope ratios of kaolinite, calcite, and coalbed CO₂ were evaluated in combination with measured values and published estimates of δ¹⁸O of coalbed paleowaters that had been present at the time of mineralization. δ¹⁸O_mineral and δ¹⁸O_water values jointly constrain the paleotemperature of mineralization. The isotopic evidence and the thermal and tectonic history of this part of the Illinois Basin led to the conclusion that maximum burial and heat-sterilization of coal seams approximately 272 Ma ago was followed by advective heat redistribution and concurrent precipitation of kaolinite in cleats at a burial depth of < 1600 m at  78 ± 5 °C. Post-Paleozoic uplift, the development of a second generation of cleats, and subsequent precipitation of calcite occurred at shallower burial depth between  500 to  1300 m at a lower temperature of 43 ± 6 °C. The available paleowater in coalbeds was likely ocean water and/or tropical meteoric water with a δ¹⁸O_water  − 1.25‰ versus VSMOW. Inoculation of coalbeds with methanogenic CO₂-reducing microbes occurred at an even later time, because modern microbially influenced ¹³C-enriched coalbed CO₂ (i.e., the isotopically fractionated residue of microbial CO₂ reduction) is out of isotopic equilibrium with ¹³C-depleted calcite in cleats.     

基于SPI的1960~2012年西南地区水稻生长季干旱时空特征分析

基于1960~2012年逐月降水资料,选取标准化降水指数（SPI）为干旱衡量指标,将SPI1与水稻各生长阶段（Growth Period of Rice,GPR）相结合,研究西南地区近53 a来整体和水稻（Oryza sativa）4个生长阶段的干旱时空演变特征。结果表明：整体上,西南地区历年干旱站次比均高于50%,全域性干旱特征显著。水稻不同生长阶段干旱时空分布特征差异显著。① GPR1和GPR2阶段以全域性干旱为主,GPR3和GPR4阶段则呈现局域性干旱>区域性干旱>全域性干旱的特征;② 生长阶段内干旱连续性特征明显,尤其是GPR2 阶段,易发生周期为2~6 a的全域性干旱和区域性干旱。③ 轻旱高值区呈现由东北向西南转移的趋势;中旱高发区呈现出明显的从北部向南部移动的趋势;重旱高发区各阶段空间分布差异较大。④ 水稻在GPR1和GPR2阶段主要受轻旱和中旱影响;GPR3和GPR4阶段重旱发生频率上升,影响范围增大。     

Major Advances in the Study of the Precambrian Geology and Metallogenesis of the North China Craton: A Review

The North China Craton(NCC) is one of the most ancient cratons in the world and records a complex geological evolution since the early Precambrian. In addition to recording major geological events similar to those of other cratons, the NCC also exhibits some unique features such as multistage cratonization(late Archaean and Palaeoproterozoic) and long-term rifting during the Meso–Neoproterozoic. The NCC thus provides one of the best examples to address secular changes in geological history and metallogenic epochs in the evolving Earth. We summarize the major geological events and metallogenic systems of the NCC, so that the evolutionary patterns of the NCC can provide a better understanding of the Precambrian NCC and facilitate comparison of the NCC with other ancient continental blocks globally. The NCC experienced three major tectonic cycles during the Precambrian:(1) Neoarchaean crustal growth and stabilization;(2) Palaeoproterozoic rifting–subduction–accretion–collision with imprints of the Great Oxidation Event and(3) Meso–Neoproterozoic multi-stage rifting. A transition from primitive- to modern-style plate tectonics occurred during the early Precambrian to late Proterozoic and is evidenced by the major geological events. Accompanying these major geological events, three major metallogenic systems are identified:(1) the Archaean banded iron formation system;(2) Palaeoproterozoic Cu–Pb–Zn and Mg–B systems and(3) a Mesoproterozoic rare earth element–Fe–Pb–Zn system. The ore-deposit types in each of these metallogenic systems show distinct characteristics and tectonic affinities.