2-D crustal Poisson's ratio from seismic travel time inversion in Changbaishan Tianchi volcanic region

Based on the inversion method of 2D velocity structure and interface, the crustal velocity structures of P-wave and S-wave along the profile L1 are determined simultaneously with deep seismic sounding data in Changbaishan Tianchi volcanic region, and then its Poisson's ratio is obtained. Calculated results show that this technique overcomes some defects of traditional forward calculation method, and it is also very effective to determine Poisson's ratio distribution of deep seismic sounding profile, especially useful for study on volcanic magma and crustal fault zone. Study result indicates that there is an abnormally high Poisson's ratio body that is about 30 km wide and 12 km high in the low velocity region under Tianchi crater. Its value of Poisson's ratio is 8% higher than that of surrounding medium and it should be the magma chamber formed from melted rock with high temperature. There is a high Poisson's ratio zone ranging from magma chamber to the top of crust, which may be the uprise passage of hot substance. The lower part with high Poisson's ratio, which stretches downward to Moho, is possibly the extrusion way of hot substance from the uppermost mantle. The conclusions above are consistent with the study results of both tomographic determination of 3D crustal structure and magnetotelluric survey in this region.     

湖南芙蓉锡矿床中萤石的Sr－Nd同位素研究

芙蓉锡矿床是一个新探明的超大型锡矿床，产于湘南的骑田岭花岗岩体中。本次研究测试了该矿床中与锡石硫化物共生的萤石的Sr和Nd同位素组成。各矿脉中萤石的87Sr/86Sr比值并不相同，变化从0.70770～0.71484，反映了成矿流体的初始87Sr/86Sr比值并不均一。萤石的Sm－Nd同位素组成并没有构成很好的等时线，计算的ENd（t）值变化在－6.6～－9.8之间。萤石的Sr－Nd同位素组成并不同于花岗岩，成矿流体中的Sr和Nd有很大一部分来自围岩的碳酸盐岩地层。     

粤北下庄矿田太平庵地区闪长玢岩的发现及其年代学特征

粤北下庄矿田是我国南方重要的花岗岩型铀矿产地,矿田内部基性岩脉与铀矿成矿具有密切关系,侵位于产铀岩体-下庄岩体。野外地质接触关系表明,下庄岩体侵位较早,晚期NNE向岩脉在下庄岩体内部侵位,两者呈侵入接触关系。通过对太平庵地区岩脉的野外地质特征和岩石薄片镜下特征,认为岩脉多具杏仁构造,为斑状结构,斑晶主要为角闪石和斜长石,定名为闪长玢岩。本次研究团队通过锆石U-Pb年代学测试表明下庄岩体侵位时间为245Ma,矿田内部近EW向分布的五组辉绿岩脉侵位时间为193±4Ma(王连训等,2011),本人结合NNE向岩脉的锆石CL图像、U-Pb年龄分析了岩脉的年代学特征,认为样品的206Pb/238U年龄介于231～253 Ma之间(MSWD=0.77),加权平均结果为242±2Ma (MSWD=8.9),代表了太平庵地区NNE向中性岩脉闪长玢岩的侵位结晶年龄。     

运用社交网络分析淹水空间信息之关联性

随着社交网络的普遍发展,大量的讯息透过智能手机发布在个人的微博或其他社交网站。台湾地区的社交网站以脸书(Facebook)的使用量最大,平均每天有近千万笔的讯息量,大多数的讯息多以食衣住行或个人讯息为主,但从本研究所撷取自2010年至2015年的数据中显示,公众在社交网站所分享的信息中具有降雨、淹水或相关灾情的讯息,而这些讯息具有极高比例的正确性。由于社交网站无法提供私人讯息,故本研究将从社交信息中,以地点为单位撷取大量的数据信息再辅以语意关键词萃取出有关可作为淹水预判的讯息数据。为检核资料的可性度,本研究透过历史台风数据FLO-2D仿真重建淹水之空间信息进行检核。从研究比对分析中发现,经萃取后的公众信息其与灾害的关联性及正确性相当显着,故透过社交网站中大量的非结构讯息,透过语意及空间的转换,可萃取转化为防灾信息,对广域的都市治理而言,此一讯息将可作为预判区域淹水或防救灾情报之有效参考。     

基于 ArcG IS 和 Python 集成开发可达性分析工具的研究

为降低可达性度量的实现难度,弥补现有GIS软件没有集成可达性分析模型或方法的不足,在详尽分析有关模型或方法与GIS集成研究现状的基础上,提出以改进潜能模型作度量模型,按GIS内部集成方式,使用面向ArcGIS 10的Python脚本编程技术集成开发可达性分析工具的设想,对可达性潜能模型分析原理、工具开发环境配置、使用数据的预处理要求、工具的具体设计流程和实现方法等作了详细叙述。最后以评价某市小学教育资源空间布局合理性为例,阐述工具在实际应用中应采取的使用方法和流程,实例评价结果验证工具开发的有效性。     

华北克拉通东部鲁西早白垩纪基性岩墙成因:来自锆石年龄、地球化学和Sr-Nd-Hf同位素的证据

中生代基性辉绿岩墙广泛分布于华北克拉通东部山东地区。本研究给出代表性岩墙的U-Pb锆石年龄、地球化学和Sr-Nd-Hf同位素证据,4个代表性锆石的LA-ICP-MS年龄范围处于121.9±0.6Ma和124.3±0.5Ma之间(早白垩纪)。岩石的主量元素组成变化较小,岩石富集轻稀土元素和大离子亲石元素(如,Rb、Ba、U、K和Pb),以及亏损高场强元素(如,Nb、Ta和Ti)。另外,基性岩墙具有相对一致的(⁸⁷Sr/⁸⁶Sr)_i比值(~0.7098),负的ε_Nd(t)值(-14.7~-14.5)、ε_Hf(t)值(-31.4~-26.7)和高的Hf模式年龄(t_DM1=1817~2024Ma)。研究显示基性岩墙来自富集岩石圈地幔的部分熔融作用,并在上升侵位过程中经历了一定程度的地壳混染作用影响。总体研究表明,基性岩墙的成因机制与扬子克拉通与华北克拉通的碰撞有关,岩浆源区为晚中生代前受俯冲扬子地壳沉积物交代后的富集岩石圈地幔。     

Genesis of the Cenozoic Sodic Alkaline Basalt in the Xiahe–Tongren Area of the Northeastern Tibetan Plateau and its Continental Dynamic Implications

正Objective The Cenozoic Indo-Asian collision caused significant crustal shortening and plateau uplift in the central Tibet.The extrusion tectonic model has been widely accepted to explain the strike-slip faults around the Tibetan Plateau.Previous studies indicate that the lower crust flow is the     

Status of Stratigraphy Research in China

Scientific research and productive practice for earth history are inseparable from the accurate stratigraphic framework and time framework. Establishing the globally unified, precise and reliable chronostratigraphic series and geological time series is the major goal of the International Commission on Stratigraphy(ICS). Under the leadership of the ICS, the countries around the world have carried out research on the Global Standard Stratotype-section and Points(GSSPs) for the boundaries of chronostratigraphic systems. In the current International Chronostratigraphic Chart(ICC), 65 GSSPs have been erected in the Phanerozoic Eonothem, and one has yet been erected in the Precambrian Eonothem. Based on the progress of research on stratigraphy especially that from its subcommissions, the ICS is constantly revising the ICC, and will publish a new International Stratigraphic Guide in 2020. After continual efforts and broad international cooperation of Chinese stratigraphers, 10 GSSPs within the Phanerozoic Eonothem have been approved and ratified to erect in China by the ICS and IUGS. To establish the standards for stratigraphic division and correlation of China, with the support from the Ministry of Science and Technology, the National Natural Science Foundation of China and the China Geological Survey, Chinese stratigraphers have carried out research on the establishment of Stages in China. A total of 102 stages have been defined in the "Regional Chronostratigraphic Chart of China(geologic time)", in which 59 stages were studied in depth. In 2014, the "Stratigraphic Chart of China" was compiled, with the essential contents as follows: the correlation between international chronostratigraphy and regional chronostratigraphy of China(geologic time), the distributive status of lithostratigraphy, the characteristics of geological ages, the biostratigraphic sequence, the magnetostratigraphy, the geological events and eustatic sea-level change during every geological stage. The "Stratigraphical Guide of China and its Explanation(2014)" was also published. Chinese stratigraphers have paid much attention to stratigraphic research in south China, northeast China, north China and northwest China and they have made great achievements in special research on stratigraphy, based on the 1:1000000, 1:250000, 1:200000 and 1:50000 regional geological survey projects. Manifold new stratigraphic units were discovered and established by the regional geological surveys, which are helpful to improve the regional chronostratigraphic series of China. On the strength of the investigation in coastal and offshore areas, the status of marine strata in China has been expounded. According to the developing situation of international stratigraphy and the characteristics of Chinese stratigraphic work, the contrast relation between regional stratigraphic units of China and GSSPs will be established in the future, which will improve the application value of GSSPs and the standard of regional stratigraphic division and correlation. In addition, the study of stratigraphy of the Precambrian, terrestrial basins and orogenic belts will be strengthened, the Stratigraphic Chart of China will be improved, the typical stratigraphic sections in China will be protected and the applied study of stratigraphy in the fields of oil and gas, solid minerals, etc. will be promoted. On the ground of these actions, stratigraphic research will continue to play a great role in the social and economic development of China.