Detrital Zircon Dating of Meso- and Neoproterozoic Rocks in North China and Its Implications   总被引：4，自引：0，他引：4  

Gao Linzhi  Liu Pengju  Yin Chongyu  Zhang Chuanheng  Ding Xiaozhong  LIU Yanxue  Song Biao 《《地质学报》英文版》2011,85(2):271-282

New dates from Meso- and Neoproterozoic strata contribute to the recently defined Precambrian stratigraphical timescale of China agreed by the Subcommission on the Precambrian System, and the National Commission on Stratigraphy of China on Nov. 24, 2009. First, the age range of the Changcheng System, including the Changzhougou, Chuanlinggou, Tuanshanzi and Dahongyu formations has been constrained to 1.8–1.6 Ga. Second, the Jixian System including the Gaoyuzhuang, Yangzhuang, Wumishan, Hongshuizhuang and Tieling formations has been constrained to 1.6–1.4 Ga. Third, an as-yet unnamed (undefined) system (1.4–1.0 Ga) is only developed in the Xiamaling Formation at the Jixian section, Tianjing. Fourth, the Qingbaikou System, including the Luotuoling and Jing’eryu formations has been constrained to 1.0–0.78 Ga. Fifth, the Nanhuan System ranges between 780–635 Ma, and the Sinian System is within 635–542 Ma. However, according to a series of SHRIMP U-Pb dates from the late Precambrian in the Jiangnan Orogen Belt in South China Platform, the constrained strata will be redefined as in the upper part of the Qingbaikou System. To aid global geodynamics, it is useful to denote a late Precambrian section with unified, precise and high-precision chronological dating; this is here defined in North China Block and Jiaoliao-Korean Block. However, the Neoproterozoic Qingbaikou study in North China will be influence in whole Meso- and Neoproterozoic in the Jiangnan Orogenic Belt in between the Yangtze Block and the Cathaysia Block in South China.  相似文献   

西太平洋——我国深海科学研究的优先战略选区   总被引：2，自引：0，他引：2  

秦蕴珊  尹宏 《地球科学进展》2011,26(3):245-248

西太平洋是我国实施由浅海向深海发展战略的必经之地.从国家需求的角度来看,西太平洋海底资源丰富、海洋环境复杂,是维护国家权益的焦点、保障国防安全的屏障;从科学前沿的角度来看,西太平洋发育有独特的沟弧盆构造体系和弧后盆地热液系统,存有海底板块运动的遗迹和众多海山生态系统,更是"大洋传送带"冷暖水系的转换区.科学有序地进入西...  相似文献   

Postrift Rapid Subsidence Characters in Qiongdongnan Basin,South China Sea     

尹新义  任建业  雷超  王珊  张俊霞 《中国地质大学学报(英文版)》2011,(2)

In this article,the backstripping technique was used in studying the subsidence charac-ters of the Qiongdongnan(琼东南) basin(QDNB) in order to understand its dynamic mechanism of formation and evolution.Meanwhile,the geothermal characteristics of this area were summarized,and the stretching factors(β) of the upper crust,the whole crust,and the whole lithosphere were calculated.The QDNB is characterized by high subsidence rate,high geothermal gradient,high geothermal heat flow,and the lithosphere stretching an...  相似文献   

浅谈三因素方差分析在评价化探数据质量中的应用——以盐源县马思罗金矿土壤化探分析数据为例     

洪银  龚彬 《四川地质学报》2011,31(1):99-101

三因素方差分析是对分析数据质量合格与否的一种有效检验方法.它可以对元素的自然变化,采样、重复分析的系统误差,偶然误差等进行定量的评价.应用以三因素方差分析基本原理为基础,运用盐源县马思罗金矿土壤化探分析数据为实例,查证了分析数据的可靠性,为正确的指导化探找矿、加速矿权评价奠定了基础.  相似文献   

最可靠的非开挖地下岩体结构勘察方法——高精度超声波钻孔成像     

李印  沈茂丁  徐华文 《岩土工程技术》2011,25(2):55-58,67

主要通过超声成像测井在长江某穿越工程区勘察工程中的应用研究,类比常规勘察技术和其他钻孔成像技术,并结合超声测井在国内其他方面的案例,剖析新一代超声测井仪的优势所在：如在基岩风化带的描述、岩石质量指标RQD分析,特别是地下岩体裂隙、节理等地质结构信息的精确揭露上,具备其他勘察手段无法比拟的优势,可以提供大量有效可视的钻孔岩体定量数据,为工程设计的定量化分析提供了详细的数据资料。可以说在揭露地下岩体结构方面,高精度超声测井是目前为止最为有效可靠的手段。  相似文献   

基于灰色理论的真空堆载预压分层沉降预测     

赵鹏洲  印长俊 《岩土工程技术》2011,25(1):13-16

对真空堆载预压加固处理的软土地基,用灰色理论模型预测地基的分层沉降,结果表明：对于土层分布均匀的地基,verhulst模型能较准确地预测分层沉降,误差在10％以内。对于土层分布不均匀的地基,verhulst模型预测误差较大,进行残差修正,修正的verhulst模型能较准确地预测分层沉降。用不同点数预测地基的分层沉降,同实测沉降数据对比发现、对于土层均匀或不均匀的软土地基,在已知真空影响范围外土层的沉降时,灰色模型就能较准确地预测分层沉降。  相似文献   

Mineralogy,major and trace element geochemistry of riverbed sediments in the headwaters of the Yangtze,Tongtian River and Jinsha River   总被引：1，自引：0，他引：1  

Weihua Wu  Shijun Xu  Huayu Lu  Jiedong Yang  Hongwei Yin  Wen Liu 《Journal of Asian Earth Sciences》2011,40(2):611-621

We collected riverbed sediments of the headwaters of the Yangtze River (Chumaer River, Tuotuo River, Gaerqu River and Buqu River), Tongtian River and Jinsha River (HTJR) flowing on the eastern Tibetan Plateau and analyzed their mineralogical features, major and trace element contents. The results show: (i) very poor correlations of Na₂O, K₂O, CaO, Ba, and Sr to SiO₂, LREE to Th, HREE to Hf, and Ta/La to Ti, and characteristics of Eu anomaly (the ratios of (Eu/Eu^*)_N range from 0.60 to 0.83 with an average value of 0.71) all indicate that the Jinsha River sediments have not undergone much mineralogical sorting; (ii) illite and chlorite are predominant clay minerals, and quartz, calcite, dolomite, albite, and K-feldspar are prevailing non-clay minerals. The characteristics of mineral assemblage indicate relatively weak chemical weathering degree in these river basins; (iii) very high contents of Fe₂O₃, MgO, TiO₂, Sc, V, Cr, Co, and Ni at Panzhihua mainly result from the huge-sized V–Ti magnetite deposits occurred in layered gabbroic intrusion; and (iv) the chemical alteration index (CIA) in the HTJR ranges from 46.5 to 69.2 and with an average value of 60.5 which indicates relatively weak weathering degree.  相似文献   

Origin of native sulfur ball from the Kueishantao hydrothermal field offshore northeast Taiwan: Evidence from trace and rare earth element composition     

Zhigang Zeng  Chen-Tung A. Chen  Xuebo Yin  Xueying Zhang  Xiaoyuan Wang  Guoliang Zhang  Xiaomei Wang  Daigeng Chen 《Journal of Asian Earth Sciences》2011,40(2):661-671

We first report the trace and rare earth element compositions of native sulfur ball with sulfur contents varying from 97.08 wt.% to 99.85 wt.% from the Kueishantao hydrothermal field, off NE Taiwan. We then discuss the sources of trace and rare earth elements incorporated into the native sulfur ball during formation. Comparison of our results with native sulfur from crater lakes and other volcanic areas shows the sulfur content of native sulfur ball from the Kueishantao hydrothermal field is very high, and that the rare earth element (REE) and trace element constituents of the native sulfur balls are very low (∑REE < 35 ppb). In the native sulfur ball, V, Cr, Co, Ni, Nb, Rb, Cs, Ba, Pb, Th, U, Al, Ti and REE are mostly derived from andesite; Mg, K and Mn are mostly derived from seawater; and Fe, Cu, Zn and Ni are partly derived from magma. Based on the sulfur contents, trace and rare earth element compositions, and local environment, we suggest that the growth of the native sulfur ball is significantly slower than that of native sulfur chimneys, which results in the relatively higher contents of trace and rare earth element contents in the native sulfur ball than in the native sulfur chimneys from the Kueishantao hydrothermal field. Finally, we suggest a “glue pudding” growth model for understanding the origin of the native sulfur ball in the Kueishantao hydrothermal field, whereby the native sulfur ball forms from a mixture of oxygenated seawater and acidic, low-temperature hydrothermal fluid with H₂S and SO₂ gases, and is subsequently shaped by tidal and/or bottom currents.  相似文献   

Study on capillary rise from shallow groundwater and critical water table depth of a saline-sodic soil in western Songnen plain of China     

Fan Yang  Guangxin Zhang  Xiongrui Yin  Zhijun Liu  Zhigang Huang 《Environmental Earth Sciences》2011,64(8):2119-2126

The objective of this study was to develop an empirical equation for estimating the capillary rise in the saline-sodic soil area of Songnen Plain in China based on the Averianov formula. The capillary rise was observed under five controlled groundwater levels by lysimeters. Field experiment results indicated that capillary rise had close relationship with the groundwater table depth, soil moisture of 10–40 cm soil layer and leaf area index. These factors have been taken into account to develop the empirical equation for capillary rise simulation. The model parameters for Songnen Plain were derived by Levenberg–Marquardt and global optimization calculating method. The modeled capillary rise has a good agreement with the observed data (r ² = 0.875). With the simulation model, the critical water table depth was identified as 2.5 m, indicating that soil secondary salinization will not occur when the water table depth is deeper than 2.5 m. Therefore, in the irrigation areas, groundwater table depth should be controlled to be higher than 2.5 m to prevent the occurrence of soil secondary salinization. The results from this research will provide useful information for the water sources management and soil secondary salinization control in Songnen Plain of China, one of the most serious saline-affected areas in the world.  相似文献   

Hydrogeochemical and isotopic study of groundwater in the Habor Lake Basin of the Ordos Plateau,NW China   总被引：2，自引：2，他引：0  

Lihe Yin  Guangcai Hou  Yan Dou  Zhengping Tao  Ying Li 《Environmental Earth Sciences》2011,64(6):1575-1584

Hydrogeochemistry and isotopes were used to understand the origin and geochemical evolution in the Habor Lake Basin, northwestern China. Groundwater samples were taken, and the isotopic compositions δD, δ¹⁸O and major ions were analyzed. The groundwater can be divided into three types: the Quaternary groundwater, the shallow Cretaceous groundwater and the deep Cretaceous groundwater. The groundwater chemistry is mainly controlled by the feldspar weathering and dolomite weathering, the dissolution of Glauber’s salt, and cation exchange. Chemistry of lake water is mainly controlled by evaporation and precipitation. The stable isotopes of oxygen and hydrogen in groundwater cluster along the local meteoric water line, indicating that groundwater is of meteoric origin. Comparing with shallow groundwater, deep groundwater is depleted in heavy isotopes indicating that deep groundwater was recharged during late Pleistocene and Holocene, during which the climate was more wetter and colder than today.  相似文献