三叠纪牙形石的古环境与古地理意义

牙形石广泛分布于寒武纪至三叠纪的海洋里。三叠纪牙形石的种类、形态、大小和产出频率受海水盐度、深度、温度和水动力条件等因素控制，不同的牙形石生态特征即牙形石相反映不同的沉积环境，所以，根据三叠纪牙形石相和牙形石特征属种的丰度，不但可区分三叠纪不同的沉积相区（台地相区、台地边缘相区、盆地相区），恢复三叠纪古地理面貌，而且可划分出牙形石生物地理区。中国早三叠世牙形石归属特提斯生物大区亚洲生物省，并可进一步划分出两个生物亚省和若干生态区。     

南海海洋地磁固定观测站建设初步研究

为填补我国海洋地磁固定观测的空白,支撑科学研究、防灾减灾、海洋资源开发,维护国家的海洋权益和履行我国在南海海域负有的国际责任,急需在南海建设岛礁和海底地磁固定观测站。通过初步分析国外海洋地磁观测站案例、南海岛礁基础设施现状以及海底观测网计划实施情况,认为南海海洋地磁固定观测站建设的条件已经成熟。文中给出了合理空间布局、分步实施、因地制宜及智能化观测的建议。     

Decompression P–T path of coesite eclogite to granulite from Weihai, eastern China

Granulitized coesite-bearing eclogite from Weihai, northeastern part of the Shandong peninsula, eastern China was studied in detail to reveal the modification of mineral chemistry during decompression metamorphism. Considerable modification of chemical composition is recorded in clinopyroxene that occurs both as inclusions in garnet and as a matrix mineral. Careful examination of chemical variation with the change in microstructure made it possible to estimate the equilibrium composition of minerals at the coesite eclogite and garnet granulite stages. We were able to define three reference points on the P–T path, namely, coesite eclogite (3 GPa, 660±40°C), granulite (1 GPa, 700±30°C) and amphibolite (0.9 GPa, 600±20°C). The path thus obtained is similar to those obtained by previous workers and supports nearly isothermal decompression of coesite eclogite.     

中国西天山南缘盆山构造转换解析

在西天山南缘,天山造山带向塔里木盆地北缘的盆山过渡,是以前陆褶皱冲断构造形式向库车一拜城前陆盆地渐变,表现为一系列褶皱冲断组合的构造样式。根据独库公路南段构造变形分析,可组合成６个部分：库尔干一铁力买提达坂根带褶皱系、南天山南缘逆冲断裂带、前陆逆冲推覆构造带、前陆双冲褶皱构造带、前陆隐伏逆冲前缘构造带、沙雅一轮台前缘叠加变形构造带。前陆盆地的发展可以划分为晚二叠一早三叠世、中三叠世一侏罗纪、白垩一     

冷涡背景下不同类型强对流天气的成因对比分析

结合地理分布将中国北方高空冷涡划分为东北冷涡（120°-145°E,35°-60°N）,华北冷涡（100°-130°E,30°-45°N）以及东蒙冷涡（100°-130°E,40°-55°N）三类,根据2000-2018年NCEP/NCAR 1°×1°再分析资料和日降水资料对19 a冷涡个例进行筛选对比,统计分析三类冷涡的活动规律,利用动态合成分析方法分析三类冷涡的结构和降水特征。结果表明：在490例高空冷涡个例中,遗漏的冷涡个例有2个,重复的个例有13个,剩下475例个例都能较好的被选出和归类,给出的三类冷涡定义较为合理。东北冷涡和东蒙冷涡在全年皆可生成,而华北冷涡在12月和2月没有发现。东北冷涡在4、5月生成最多,在3月和8月生成较少。华北冷涡在5月生成最多,冬季生成较少。东蒙冷涡在5、6、9三个月生成较多,在2、3和11月生成较少。对三类冷涡的动态合成分析表明：在结构方面,考察位势高度、温度、涡度、和等熵位涡分布,得到东北冷涡平均强度最强,东蒙冷涡次之,华北冷涡最弱;在降水方面,冷涡强度最强的时段,冷涡降水主要出现在高空急流出口区以北,对应有强的高层辐散。由于低层湿度分布以及水汽输送强度的不同,三类冷涡的降水大值中心位置有所差别,并且华北冷涡平均降水强度最大,东北冷涡次之,东蒙冷涡相对较小。

     

Palynological records of Holocene monsoon change from the Gulf of Tonkin (Beibuwan), northwestern South China Sea

Palynological records in cores C4 and B106 from the Gulf of Tonkin reveal signals of paleo-monsoon and paleoenvironmental change during the late Pleistocene and Holocene. Before ∼ 13.4 cal kyr BP, the Gulf of Tonkin was exposed to the atmosphere and covered by grassland. Starting at ∼ 11.7 cal kyr BP, the Gulf of Tonkin was inundated by brackish water, indicated by the appearance of the brackish algae Cleistosphaeridium, Sentusidinium and Spiniferites, a decrease of herb content, and an increase of Pinus. After Hainan Island was completely separated from the Leizhou Peninsula by Qiongzhou Strait at ∼ 8.5 cal kyr BP, a continuous marine sedimentary environment was found. The current patterns were similar to those of the present, with a general trend of current homogenization reflected by gradually decreasing quantities of Quercus pollen and a narrowing gap between the palynological concentrations of the southern and northern parts of the region. The data suggest that three short periods of strengthened winter monsoons and currents were centered at ∼ 6.0 cal kyr BP, ∼ 2.7 cal kyr BP and ∼ 0.2 cal kyr BP and that two short periods of strengthened summer monsoons and currents were centered at ∼ 7.5 cal kyr BP and ∼ 3.4 cal kyr BP.     

Rare earth elements and yttrium in ferromanganese deposits from the South China Sea: distribution, composition and resource considerations

Ferromanganese nodules and crusts contain relatively high concentration of rare earth elements(REE) and yttrium(REY),with a growing interest in exploitation as an alternative to land-based REY resources.On the basis of comprehensive geochemical approach,the abundance and distribution of REY in the ferromanganese nodules from the South China Sea are analyzed.The results indicate that the REY contents in ferromanganese deposits show a clear geographic regularity.Total REY contents range from 69.1×10~(–6) to 2 919.4×10~(–6),with an average value of 1 459.5×10~(–6).Especially,the enrichment rate of Ce content is high,accounting for almost 60% of the total REY.This REE enrichment is controlled mainly by the sorption of ferromanganese oxides and clay minerals in the nodules and crusts.Moreover,the total REY are higher in ferromanganese deposits of hydrogenous origin than of diagenetic origin.Finally,Light REE(LREE) and heavy REE(HREE) oxides of the ferromanganese deposits in the study area can be classified into four grades: non-enriched type,weakly enriched type,enriched type,and extremely enriched type.According to the classification criteria of rare earth resources,the Xisha and Zhongsha platform-central deep basin areas show a great potential for these rare earth metals.     

华北地区定点台站形变资料分析

对华北地区定点台站形变观测资料,采用傅立叶去年周期和线性拟合的方法进行处理.结果表明,华北地区现阶段的变化未形成主体异常时段,反映出断层未进入强烈活动阶段;首都圈地区跨断层资料异常数量不多,没有形成同步异常,异常变化幅值也不是很大,中短临地震异常不明显.     

海岛礁光学和雷达影像基于改进非子采样小波变换的自动配准

Homologous feature point extraction is a key problem in the optical and synthetic aperture radar （SAR） image registration for islands. A new feature point extraction method using a threshold shrink operator and non-subsampled wavelet transform （TSO-NSWT） for optical and SAR image registration was proposed. Moreover, the matching for this proposed feature was different from the traditional feature matching strategies and was performed using a similarity measure computed from neighborhood circles in low-frequency bands. Then, a number of reliably matched couples with even distributions were obtained, which assured the accuracy of the registration. Application of the proposed algorithm to SPOT-5 （multi-spectral） and YG-1 （SAR） images showed that a large number of accurately matched couples could be identified. Additionally, both of the root mean square error （RMSE） patterns of the registration parameters computed based on the TSO-NSWT algorithm and traditional NSWT algorithm were analyzed and compared, which further demonstrated the effectiveness of the proposed algorithm. The algorithm can supply the crucial step for island image registration and island recognition.     

用不完整的地震资料估计地震矩年变化率

在充分考虑现有地震资料的不完备性和震级服从两端截去泊松分布的条件下,建立了用历史地震资料和现代地震资料及考古地震资料计算地震矩年变化率的方法。计算了西南地区几个地震带的地震矩年变化率,并与地质资料得到的结果进行了比较,结果表明该方法是切实可行的