An Experimental Melting—crystallization Study on Basalt at High Pressures

A series of melting-crystallization experiments on alkali basalt samples from Minqing, Fujian Province was carried out in dry and waterbearing systems at high pressures. A high-pressure melting curve was obtained. The results indicate that clinopyroxene crystallized from basalt melt at 13.5–23.7 kbar. spinel at 23.7–28.6 kbar and garnet at > 28.6 kbar. With increasing pressure, the CaSiO₃ contents of clinopyroxenes increase; and the FeSiO₃ decreases, but the chemical composition of garnet does not show any significant difference. The minerals are larger and euhedral in the water-bearing system. Therefore, we consider that natural megacrysts of the basalt can crystallize from the water-bearing basalt magma at high pressure. So the megacrysts may be derived from the upper mantle as a result of magmatic crystallization-fractionation under high pressure. This project was financially supported by the National Natural Science Foundation of China.     

湘西汞矿床的地质特征与成因

湘西汞矿床是湘黔汞矿带的重要组成部分.湘西汞矿受层位和构造双重控制,与岩浆活动没有直接联系,具有层带式整合矿体,矿物成分简单,汞锌矿化分带及后生成矿等地质特征.矿石硫来源于古海水硫酸盐的沉积硫;而汞的来源.则以上地幔去气作用产生的汞为主,寒武系等富汞建造的汞次之.燕山期地台活化时,以硫络合物或硫氢络合物的形式,在碱性溶液中沿深大断裂向上运转,当其与富含膏盐的客矿层相遇时,便与还原硫结合沉淀成矿.形成湘西层控后生汞矿床.     

河南祁雨沟爆破角砾岩型金矿床包裹体研究

本文通过包裹体研究了祁雨沟爆破角砾岩型金矿床成矿流体来源、性质和成矿物理化学条件,为该类型金矿找矿与评价提供依据。     

冀东麻粒岩流体包裹体研究

用各种方法对冀东麻粒岩中的包裹体进行分析后发现,第一类高温包裹体在石榴石和石英中呈负晶形出现,主要为高密度CO_2,对应的温度和压力表明该类包裹体是在麻粒岩相变质作用期间捕获的。第二和第三类包裹体的H_2O含量增加,形成温度依次降低,表明它们是在麻粒岩地体抬升的不同阶段捕获的。     

Determination ofQ S,spreading factor and S-wave acceleration by inversion of seismic intensity data

In this paper, on the basis of intensity data from 85 earthquakes occurred in China, the method of resolving overdetermined equations by using the damped least squares method is applied to inversing for the mean value of 1 s. S wave quality factor, the spreading factor and the S-wave acceleration at the foci of earthquakes in 7 regions of China. The relation between S-wave acceleration at the foci of earthquakes and magnitude is discussed. As an example, 2-DQ _S distribution in Taiwan Province is obtained by inversion. It is found that there exists some corresponding relation between this distribution and Bouguer gravitational anomaly and seismicity. Preliminary analysis and discussion on results of the inversion, and estimation of error inQ _S are made.     

东亚冬季冷暖变化与El Ni?o事件

近十年来,东亚冬季气温明显升高。本文分析证明,东亚温度变化与赤道东太平洋和北太平洋重要洋流区的海表面温度(SST)有密切的遥相关。如果赤道东太平洋SST异常偏高(或异常偏低),即出现埃尔尼诺(或反埃尔尼诺)事件,则在其后7～24个月中,我国华北和东北将出现暖冬(或冷冬),渤海冰情将出现轻冰年(或重冰年)。据此建立的回归预报方程,对1988/1989年和1989/1990年冬季渤海海冰的预报结果完全正确。     

Discussion on Rb-Sr Isochron Ages of Granitoids in the Hengduan Mountains1

Abstract Based on the Rb-Sr isotopic study of the granitoids in the Hengduan Mountains, the classification and geologic significance of whole- rock Rb- Sr isochrons as well as the factors influencing homogenization of the isotopic systems are discussed. Usually, there is no good linear correlation of isochrons for diorites and alkali-rich intrusive rocks (including alkaline rock and alkalic granite). But by means of the external isochron of monominerals from the rocks, isochrons with good linear correlation as well as ages and Sr initial ratios with a high confidence can be obtained. In order to obtain a satisfactory isochron, the discriminant parameters should be calculated from the Rb / Sr ratios and estimated ages of samples. Only those that meet the requirements can be used as the Rb-Sr isochrons. The quality of an isochron should be judged from three factors, i.e. correlation coefficient, MSWD and homogenization degree.     

TCM－90现场科学试验台风FLO“β陀螺”“通风流”非对称动力结构特征

采用ＴＣＭ－９０台风现场科学试验期间加密观测资料,揭示出目标台风Ｆｌｏ非对称动力、热力结构及其转向运动的特征,尤其通过分离处理的偏差场,突出了ＴＣＭ－９０现场试验有关飞机下投（ｄｒｏｐｓｏｎｄｅ）加密探测资料对台风Ｆｌｏ内部非对称结构物理图象的描述,提出了实际台风动力结构存在类似Ｇｒａｙ认为的非对称偶极子型,即中低层“β陀螺”偶极子型（β－ｔｏｐｄｉｐｏｌｅ）,及其“通风流”（Ｖｅｎｔｉｌａｔｉｏｎｆｌｏｗ）特征,高层辐合－辐散结构的变形偶极子系统概念模型,并认为这类三维非对称结构对台风运动（转向现象）有一定“引导”作用。文中还强调了“β陀螺”偶极子非对称结构的垂直差异,并揭示了目标台风暖心结构及其热力非对称结构特征。