流动注射-光度法测定地质样品中痕量碘

利用I~-对4,4′-四甲基二氨基二苯甲烷(4,4′-TMB-DPM)与氯胺T反应的催化作用,建立了流动注射-分光光度测定地质样品中痕量碘的方法。采用不等流速合并带法,分析速度快、节省试剂、灵敏度高。与高温水解法释放I~-相结合,使样品处理简单、干扰离子少。对于含I~-10μg/L的水样,其RSD(n=19)为1.1％,检出限为0.3ng/ml。用于水系沉积物、土壤分析时,含碘1.6×10~(-6)的样品RSD(n=10)为6.1％,检出限为0.08×10~(-6)。测量速度50N/h。     

东北地区的印支运动

东北地区的印支运动,一直受到地学界的关注(赵宗溥,1959;潘广,1963;黄振辉,1966),但由于缺乏三叠纪地层资料而未能作深入论述。近年来,本区三叠纪的调查研究有了重大进展,相继在东北南部发现或对比确定了早、中、晚三叠世的陆相地层(张武、董国义,1983);在东北北部,除早已报道的海相三叠系外,又发现早、晚三叠世的陆相堆积层和火山岩建造(长春地质学院等,1977;吴水波等,1980;陈巫基等,1981)¹⁾。     

随机森林模型预测岩溶区酸性煤矿井水锰污染

酸性煤矿井水严重威胁地下水的水质。如何更有效对受影响区域的地下水源进行动态监测是当前的一个关键问题。采用随机森林中的回归模型,利用自变量(采空区水位、岩溶水位、pH值、泉水流量、电导率)和因变量(污染离子浓度)的相关性,建立回归模型;使用测试数据进行误差分析,结果证明模型准度较高,所得预测值具有参考价值;得出各自变量对因变量影响的重要程度,分析结果与实际情况相符合。试验表明,随机森林回归模型在酸性煤矿井水污染预测方面具有适用性,可作为辅助手段监测水质污染情况,对今后工作有一定的指导意义和经济价值。     

无人机遥感技术在甘肃北山地区地质填图中的应用

甘肃北山地区岩浆岩及变质岩出露广泛,植被稀少,地势平缓,是无人机遥感开展地质填图试验的理想目标区。为解决传统地质填图方法受地形、环境限制和投入高及工作周期长等问题,选取北山长流水地区20 km²化探重点工作区为目标区,利用大疆精灵4专业版无人机采集图像,并采用Photoscan软件合成高分辨率正射影像以及三维模型,建立解译标志,对目标区域进行地质解译,获得比前人1：1万地质图更加精细的地质图。该方法较传统填图方法能够解译出地质体形态、岩脉产状、微小断裂等更详细的地质内容,并能提供划分岩脉期次的证据。     

Geochronological and geochemical evidence for a Late Ordovician to Silurian arc-back-arc system in the northern Great Xing'an Range,NE China

The early Paleozoic tectonic evolution of the Xing'an-Mongolian Orogenic Belt is dominated by two oceanic basins on the northwestern and southeastern sides of the Xing'an Block,i.e.,the Xinlin-Xiguitu Ocean and the Nenjiang Ocean.However,the early development of the Nenjiang Ocean remains unclear.Here,we present zircon U-Pb geochronology and whole-rock elemental and Sr-Nd isotopic data on the gabbros in the Xinglong area together with andesitic tuffs and basalts in the Duobaoshan area.LA-ICP-MS zircon U-Pb dating of gabbros and andesitic tuffs yielded crystallization ages of 443-436 Ma and 452-451 Ma,respectively.The Early Silurian Xinglong gabbros show calc-alkaline and E-MORB affinities but they are enriched in LILEs,and depleted in HFSEs,with relatively low U/Th ratios of 0.18-0.36 andεNd(t)values of-1.6 to+0.5.These geochemical features suggest that the gabbros might originate from a mantle wedge modified by pelagic sediment-derived melts,consistent with a back-arc basin setting.By contrast,the andesitic tuffs are characterized by high MgO(>5 wt.%),Cr(138-200 ppm),and Ni(65-110 ppm)contents,and can be termed as high-Mg andesites.Their low Sr/Y ratios of 15.98-17.15 and U/Th values of 0.24-0.25 and moderate(La/Sm)_n values of 3.07-3.26 are similar to those from the Setouchi Volcanic Belt(SW Japan),and are thought to be derived from partial melting of subducted sediments,and subsequent melt-mantle interaction.The Duobaoshan basalts have high Nb(8.44-10.30 ppm)and TiO2 contents(1.17-1.60 wt.%),typical of Nb-enriched basalts.They are slightly younger than regional adakitic rocks and have positiveεNd(t)values of+5.2 to+5.7 and are interpreted to be generated by partial melting of a depleted mantle source metasomatized by earlier adakitic melts.Synthesized with coeval arc-related igneous rocks from the southeastern Xing'an Block,we propose that the Duobaoshan high-Mg andesitic tuffs and Nbenriched basalts are parts of the Late Ordovician and Silurian Sonid Zuoqi-Duobaoshan arc belt,and they were formed by the northwestern subduction of the Nenjiang Ocean.Such a subduction beneath the integrated Xing'an-Erguna Block also gave rise to the East Ujimqin-Xinglong igneous belt in a continental back-arc basin setting.Our new data support an early Paleozoic arc-back-arc model in the northern Great Xing'an Range.     

ICP-AES法测定金属硅中硼磷铝锰钙镁铁等28种微量和痕量元素

采用ICP-AES法对金属硅中的B、P、Al、Mn、Ca、Mg、Fe等28种微量和痕量元素进行分析。根据元素的化学性质制定预处理方法,优化ICP-AES光谱仪测试样品的最佳工作条件。在缺少金属硅标准物质的情况下,选择硅含量较高的国家一级岩石标准物质（GBW07106）进行试验,该标准物质的回收率在95.0%～104.4%之间,相对标准偏差RSD在0.21%～4.01%之间。实际分析工作表明,该方法准确、快速,符合DZ/T 0130—2006的要求。     

贵州寒武系底部黑色岩系成矿序列划分与对比

一系列的黑色岩系多金属矿床广泛分布于中国南方地区寒武系底部,前人对多金属矿特征、成因等方面进行许多研究,但对Mo-Ni、V、P和Ba矿的成矿顺序研究较少。本文对云南德泽、贵州纳雍-坝黄-天柱及湘西柑子坪等地区的寒武系底部黑色岩系多金属矿的成岩成矿环境、矿石矿物微观特征、成矿地球化学等方面研究,结合元素富集层出现先后可将寒武系底部成矿作用自下而上分为四个成矿序列:即磷矿成矿序列、重晶石矿成矿序列、钒矿成矿序列、镍钼矿序列。同时,根据岩石组合、矿物组合、含矿性等特征,将贵州境内Mo-Ni、V、P和Ba矿床划分为三个成矿区,即纳雍-遵义-福泉黔中镍钼成矿区、铜仁-镇远-岑巩黔东南钒(镍钼)成矿区、天柱-新晃重晶石成矿区。     

Energy transition,CO2 mitigation,and air pollutant emission reduction: scenario analysis from IPAC model

The salinization of freshwater-dependent coastal ecosystems precedes inundation by sea level rise. This type of saltwater intrusion places communities, ecosystems, and infrastructure at substantial risk. Risk perceptions of local residents are an indicator to gauge public support for climate change adaptation planning. Here, we document residential perspectives on the present and future threats posed by saltwater intrusion in a rural, low-lying region in coastal North Carolina, and we compare the spatial distribution of survey responses to physical landscape variables such as distance to coastline, artificial drainage density, elevation, saltwater intrusion vulnerability, and actual salinity measured during a synoptic field survey. We evaluate and discuss the degree of alignment or misalignment between risk perceptions and metrics of exposure to saltwater intrusion. Risk perceptions align well with the physical landscape characteristics, as residents with greater exposure to saltwater intrusion, including those living on low-lying land with high concentrations of artificial drainages, perceive greater risk than people living in low-exposure areas. Uncertainty about threats of saltwater intrusion is greatest among those living at higher elevations, whose properties and communities are less likely to be exposed to high salinity. As rising sea levels, drought, and coastal storms increase the likelihood of saltwater intrusion in coastal regions, integrated assessments of risk perceptions and physical exposure are critical for developing outreach activities and planning adaptation measures.

     

Numerical investigation of groundwater outbursts near faults in underground coal mines

Permeable geologic faults in the coal seam can cause intermittent production problems or unexpected amounts of groundwater outburst from the underlying aquifers. With the acknowledgment of the basic mechanism for groundwater outbursts, the groundwater outburst along the fault zones in coal mines are numerically investigated using RFPA, a numerical code based on FEM. The fracture initiation, propagation, and coalescence in the stressed strata and the seepage field evolution in the stress field are represented visually during the whole process of groundwater outburst. The numerically obtained damage evolution shows that the floor strata could be classified as three zones, i.e. mining induced fracture zone, intact zone and fault reactivation zone, in which the intact zone is the key part for resisting groundwater outburst and directly determines the effective thickness of water-resisting rock layer. With understanding of the evolution of stress field and seepage flow in floor strata, the groundwater outburst pathway is calibrated and the transformation of floor rock mass from water-resisting strata to outburst pathway is clearly illuminated. Moreover, it is shown that geometrical configuration, including inclination angle of faults and seam drop along faults, have an important influence on groundwater outburst. Finally, based on geological, hydrogeology survey and numerical results, the mechanism analysis of groundwater outburst in an engineering case is studied, which can provide significantly meaningful guides for the investigation on mechanism and prevention of groundwater outburst induced by faults in practice.     

Late Devonian OIB alkaline gabbro in the Yarlung Zangbo Suture Zone: Remnants of the Paleo-Tethys?

The Yarlung Zangbo Suture Zone (YZSZ) is believed to be composed of material largely derived from the destruction of the Neo-Tethys that occurred from early Mesozoic to early Cenozoic. We report here geochronological and petrological data obtained for newly discovered alkaline gabbro blocks embedded in a mélange zone of the western YZSZ. Single zircon U–Pb analyses from one representative gabbro sample by SIMS (Secondary Ion Mass Spectrometry) yielded a combined crystallization age of about 363.7 ± 1.7 Ma (1σ). In situ Hf isotopic analyses yielded ε_Hf(t) values of + 2.6 to + 5.5, suggesting an enriched mantle source. All of the gabbro samples show typical Ocean Island Basalt (OIB) affinity with little or no continental crust contamination. They also display strong geochemical similarities with the Hawaii basalts and the Xigaze seamount basalts suggestive of their intra-oceanic setting. These observations, in combination with the Early Carboniferous layered gabbros reported at Luobusa, indicate that these rocks could represent remnants of the Paleo-Tethys. We propose that a branch ocean separating the Western Qiangtang terrane and the Lhasa terrane from the Gondwana continent might have been present during the Late Devonian and the Early Carboniferous, providing new constrains on the configuration of Paleo-Tethys in Tibetan Plateau during early Late Paleozoic.