Discovery and significance of Lizifang metamorphic core complex in Zhuanghe area of southern Liaoning

On the basis of the previous regional geological survey, based on the macroscopic and microscopic structural survey, combined with the comprehensive analysis of the regional magmatic activity and dating data, the authors in this paper revealed that there is another metamorphic core complex structure in Lizifang area of Southern Liaoning, namely Lizifang metamorphic core complex. A typical three-layer structure and five parts exist in the core complex, which are the footwall composed of Neo-archean metamorphic plutonic rocks and mesozoic granite intrusive rocks, the detachment fault zone composed of different levels of tectonic rocks, and the upper plate composed of Precambrian sedimentary cap and Cretaceous extensional basin. Lizifang metamorphic core complex formed in the Early Cretaceous Epoch, and the upper plate moved from NWW to SEE relaive to the footwall, which was similar with Jinzhou metamorphic core complex and Wanfu metamorphic core complex in geometry, kinematics polarity and formation time, indicating the same dynamic background. The determination of the metamorphic core complex may provide a basis for the late Mesozoic lithospheric thinning process and the mechanical and rheological properties of the lithosphere in the east of North China Craton. At the same time, the metamorphic core complex is closely related to the mineralization of gold deposits. So the detachment fault zone of Lizifang metamorphic core complex can serve as the key work area for further gold exploration, which may possess large mineralization potential.     

台风Chanchu(0601)变性过程中的强度变化及环境场分析

利用非静力中尺度WRF模式模拟的台风Chanchu(0601)的输出资料,探讨了Chanchu减弱变性过程的强度及结构变化。分析结果表明:在台风Chanchu北移过程中,高层的暖心被破坏,强度快速减弱,眼壁对流发展高度降低,眼壁对流由对称结构演变为非对称,内核对流减弱。此减弱变性过程与惯性稳定度减小、垂直风切变增强、低层锋生等环境要素有关。惯性稳定度与台风强度变化一致,随着惯性稳定度降低,最大切向风减弱并不断外扩,Rossby变形半径增大从而潜热释放不集中难以维持台风强度,台风减弱;同时,内核区的高层暖心更易径向频散,从而高层暖心难以维持;环境的垂直风切变增强使台风的斜压性增强,台风垂直结构的倾斜度增大,对流发展高度降低;低层冷空气侵入台风中心趋于填塞,也利于台风强度减弱;台风登陆以后冷暖空气对比导致的锋生使得不稳定能量释放从而重新加强了Chanchu环流内的中低层对流活动,但较台风最强时刻而言对流强度减弱。总体减少的对流和降低的对流高度,导致潜热能释放减小,其向心输送也减少,不足以维持强暖心结构,最终使得台风减弱并变性。      

Microplastic pollution in surface water and sediments of Qinghai-Tibet Plateau: Current status and causes

To study the current status and causes of the microplastic pollution in surface water of the Qinghai-Tibet Plateau, this paper compared the average microplastic abundance in sediments and surface water of the Qinghai-Tibet Plateau and the results are as follows. First, the average microplastic abundance in surface water of the independent rivers and the whole area is 247–2686 items/m³ and 856 items/m³, respectively. The average microplastic abundance in sediments of independent rivers or lakes and the whole area is 0–933 items/m² and 362 items/m², respectively. Meanwhile, the degree of microplastic pollution in river sediments is higher than that in lake sediments, and the rivers suffering from microplastic pollution mainly include the Brahmaputra River, Tongtian River, and Nujiang River. Second, compared with the microplastic pollution in other areas of the world, the levelof microplastic pollution in the lakes and rivers of the Qinghai-Tibet plateau is not lower than that of well-developed areas with more intensive human activities. Finally, this study suggests that relevant government departments of the Qinghai-Tibet Plateau should strengthen waste management strategies while developing tourism and that much attention should be paid to the impacts of microplastics in the water environment.©2021 China Geology Editorial Office.     

核心筒部分悬挂结构抗震分析的简化力学模型

提出了核心筒部分悬挂结构体系,在已有该体系振动台试验基础上,建立了该体系的抗震分析简化力学模型及其理论公式。按小震、中震和大震3种不同的地震作用情况,分析了该结构体系力学模型和动力方程的差异。利用有限元分析程序SAP2000,对这种结构体系进行了小震和大震作用下的结构地震反应分析,计算结果与试验结果吻合较好。     

基于技术经济评价的取心钻进方法设计

提出了一种进行取心钻进设计的新方法,其特点是将技术经济学的思想引入钻探工程设计中,从而实现取心钻进方法的优选。该方法具有通用性,可用于任何钻探项目取心钻进方法的选择。在研究中,建立了评价取心钻进施工的技术经济评价指标体系;推导了钻进时间和成本的计算公式,并以一个5000m取心钻进项目的设计为例,对CCSD科钻一井的取心钻进方法进行了评价,证明由中国大陆科学钻探工程中心发明和研制成功的螺杆马达-液动锤-提钻取心法是一种高效、优质、低成本和安全的取心钻进方法。     

椒江河口沉积物As、Hg黄铁矿矿化程度及其生物有效性

本文利用取自浙江椒江河口3个未扰动柱状沉积物样,进行了孔隙水化学测试、固相沉积物的活性分量与黄铁矿分量的分级提取和测试,结果表明：Hg主要以黄铁矿态形式存在于沉积物中。As在有机碳较高的河口区潮上带和沉积速率较慢的潮下带主要以黄铁矿形态存在[DTMP（degree of trace metal pyritization,痕量元素黄铁矿矿化程度）〉50%）],而在中潮带As的黄铁矿矿化程度略低（DTMP均值为40.99%）,研究区DOP（Fe的黄铁矿矿化程度）值普遍较低（〈35%）,Mn-DTMP低于3.32%。从而揭示了浙江椒江河口沉积物在数厘米以下,毒性痕量元素Hg和As被高度黄铁矿矿化的规律性,并指出在遇有海事活动或风暴潮事件对海底沉积物进行扰动时,河口沉积物与充氧的海水反应,高度黄铁矿矿化的痕量元素会转变成活性态,从而导致近海生态系统的毒性事件。     

闽西南地区块状硫化物矿床的喷流-沉积成矿作用

通过对闽西南地区石炭纪—早二叠世主要块状硫化物矿床的区域成矿背景、贮矿层位特征以及矿石矿物成分、结构构造,硫同位素地球化学特征、成矿温度等分析研究,指出该地区石炭纪—早二叠世块状硫化物矿床的形成多与海底火山活动有关,贮矿层中伴有典型的喷流沉积岩—硅质岩,并提出闽西南地区块状硫化物矿床存在海底喷流-沉积成矿作用的新认识。     

DRY-SEASON VARIABILITY IN SUSPENDED SEDIMENT CONCENTRATIONS IN THE SOUTH PASSAGE OF THE CHANGJIANG ESTUARY

This paper reports the results of continuous monitoring of turbidity, water depth, salinity (using an Optical Backscatter Sensor (OBS)), and current velocity (using a Current meter (SLC9-2)) in the South Passage of the Changjiang Estuary over a spring–neap period in February 2003 (dry season). The turbidity measured via OBS was closely correlated with the suspended sediment concentration (SSC), which was highly variable. Over the study period, the SSC in the middle layer ranged from 110 to 1400 mg/l. The minimum SSC occurred during a late ebb tide, and the maximum SSC occurred during a late flood tide. On average, the SSC was 1.5 times higher during flood tide than during ebb tide. Vertically within the water column, SSC increased downward, with the ratio of SSC measured near the bed to that measured at the surface ranging from 1.90 to 18.3. The temporal variability in SSC is jointly governed by tides and wind-induced waves, whereas the vertical variability in SSC is attributed to the effect of gravity and vertical water circulation.     

攀西水系沉积物铂、钯异常及对找寻铂、钯矿的启示

利用攀枝花幅（永仁幅）、会理幅、盐边幅、米易幅、盐源幅和西昌幅共6个1：20万图幅的区域铂、钯地球化学资料,运用了数据滤波处理方法圈定铂族元素异常.讨论了水系沉积物中铂、钯地球化学背景和异常与峨眉山玄武岩、基性-超基性岩等地质体的空间关系,并做了该地区铂族矿产的找矿远景预测.     

Spatial variation and driving mechanism of soil organic carbon components in the alluvial/sedimentary zone of the Yellow River

Alluviation and sedimentation of the Yellow River are important factors influencing the surface soil structure and organic carbon content in its lower reaches. Selecting Kaifeng and Zhoukou as typical cases of the Yellow River flooding area, the field survey, soil sample collection, laboratory experiment and Geographic Information System(GIS) spatial analysis methods were applied to study the spatial distribution characteristics and change mechanism of organic carbon components at different soil depths. The results revealed that the soil total organic carbon(TOC), active organic carbon(AOC) and nonactive organic carbon(NOC) contents ranged from 0.05–30.03 g/kg, 0.01–8.86 g/kg and 0.02–23.36 g/kg, respectively. The TOC, AOC and NOC contents in the surface soil layer were obviously higher than those in the lower soil layer, and the sequence of the content and change range within a single layer was TOCNOCAOC. Geostatistical analysis indicated that the TOC, AOC and NOC contents were commonly influenced by structural and random factors, and the influence magnitudes of these two factors were similar. The overall spatial trends of TOC, AOC and NOC remained relatively consistent from the 0–20 cm layer to the 20–100 cm layer, and the transition between high-and low-value areas was obvious, while the spatial variance was high. The AOC and NOC contents and spatial distribution better reflected TOC spatial variation and carbon accumulation areas. The distribution and depth of the sediment, agricultural land-use type, cropping system, fertilization method, tillage process and cultivation history were the main factors impacting the spatial variation in the soil organic carbon(SOC) components. Therefore, increasing the organic matter content, straw return, applying organic manure, adding exogenous particulate matter and conservation tillage are effective measures to improve the soil quality and attain sustainable agricultural development in the alluvial/sedimentary zone of the Yellow River.