Mercury isotope constraints on the genesis of late Mesozoic Sb deposits in South China

The late Mesozoic antimony(Sb)mineralization belt in South China hosts a large portion of the world’s Sb reserves.However,the source and mineralization processes of these Sb deposits remain controversial.Here,we measured mercury(Hg)concentrations and isotopic compositions of stibnite in the Banpo Sb-only and Woxi Sbpolymetallic ore deposits,as well as associated rocks in the Yangtze Block in order to constrain the metal sources and ore formation processes in the South China Sb mineralization belt.Stibnite samples from both deposits exhibit significant enrichment in Hg(4.23–50.6 ppm)and have higher δ²⁰²Hg values(?0.47‰to 2.03‰)than the studied Precambrian basement rocks(?1.42‰to 0.59‰),Paleozoic sedimentary rocks(?2.40‰to?0.32‰),and other natural Hg reserves(e.g.,marine and continental systems).This indicates that significant mass-dependent fractionation of Hg isotopes occurred during hydrothermal processes.Negative to slightly positive Δ¹⁹⁹Hg values of?0.17‰to 0.02‰were obtained for stibnite from the studied deposits,similar to values for the Precambrian basement rocks,but different from those of the Paleozoic sedimentary rocks and data previously reported for mantle materials.This suggests that Precambrian basement rocks were the source of Hg and associated metals.Our data and the tectonic evolution of South China indicate that late Mesozoic asthenospheric upwelling,in response to the Paleo-Pacific oceanic slab foundering,generated heat that drove the circulation of fluids in the basement and crustal basinal rocks.These fluids leached Sb,Hg,and other metals from the Precambrian basement rocks and formed the world-class Sb mineralization belt in South China.     

安徽巢北地区下志留统坟头组沉积环境分析

巢北地区下志留统坟头组出露较好.巢北志留系仅发育下统高家边组、下统坟头组,缺失下统茅山组,志留系组成背斜核部.坟头组沉积物组分为石英细砂岩、泥质细砂岩夹粉砂质泥岩,向上变为互层状细碎屑沉积物.本文以巢湖7410厂剖面坟头组地层为研究对象,通过该区地层的野外形态和镜下特征的研究,以及成因分析、成岩后生变化的观察,同时,配合野外构造和薄片粒度分析等方法对沉积环境进行了判别分析.通过分析认为本地区坟头组属于沉积速度较快的滨浅海-陆棚相沉积环境.     

The East Asian monsoon during MIS 2 expressed in a speleothem δO record from Jintanwan Cave, Hunan, China

Stalagmite J1 from Jintanwan Cave, Hunan, China, provides a precisely dated, decadally resolved δ¹⁸O proxy record of paleoclimatic changes associated with the East Asian monsoon from ∼29.5 to 14.7 ka and from ∼12.9 to 11.0 ka. At the time of the last glacial maximum (LGM), the East Asian summer monsoon weakened and then strengthened in response to changes in Northern Hemisphere insolation. As the ice sheets retreated the East Asian summer monsoon weakened, especially during Heinrich event H1, when atmospheric and oceanic teleconnections transferred the climatic changes around the North Atlantic to the monsoonal regions of Eastern Asia. A depositional hiatus between ∼14.7 and 12.9 ka leaves the deglacial record incomplete, but an abrupt shift in δ¹⁸O values at ∼11.5 ka marks the end of the Younger Dryas and the transition into the Holocene. Comparisons of the J1 record to other Chinese speleothem records indicate synchronous climatic changes throughout monsoonal China. Further comparisons to a speleothem record from western Asia (Socotra Island) and to Greenland ice cores support hemispherical-scale paleoclimatic change. Spectral and wavelet analyses reveal centennial- and decadal-scale periodicities that correspond to solar frequencies and to oscillations in atmospheric and oceanic circulation.     

强干扰背景下水中微弱信号的垂直阵波束形成研究

针对垂直阵在强干扰背景下采用常规波束形成方法难以估计目标俯仰角的问题,研究了超波束与逆波束形成等方法在垂直阵中的应用。讨论了超波束与逆波束形成原理,仿真分析了其波束图,表明分辨率比常规波束形成有明显提高。实测数据分析表明：超波束方法可以分辨目标与干扰的俯仰角轨迹,对角加载逆波束 MVDR 方法可以获得目标的俯仰角轨迹。研究结果解决了强干扰背景下微弱目标信号俯仰角难以估计的问题,为微弱目标定位提供了新的途径。     

浙江长兴大银山金矿成因探讨

受燕山中晚期地质构造运动和岩浆活动的影响 ,在中酸性侵入岩体与钙镁碳酸盐岩外接触带 ,大银山金矿体呈扁平透镜状产于侵入体的舌状端部。是中低温热液型含金矽卡岩矿床。研究其成矿地质条件和控因素 ,对找矿和成矿预测均有重要意义     

青海省南部侏罗纪地层问题讨论

青海省南部侏罗纪海相双壳类异常丰富.根据近年来新测制的地层剖面和化石资料,本文分析了该区双壳类动物群的时代意义,从而确立了本区侏罗系应包括中,上侏罗统;海相侏罗纪沉积大致自巴柔阶到基末里阶.东特提斯区北缘的弧形地带,诸如青海南部、藏东、藏北、滇西,缅甸掸邦和泰国呵叻等地在中,晚侏罗世基本上属于同一个生态环境较特殊的双壳类生物地理分区,双壳类动物群表现出强烈的地方性色彩,特别是淡水双壳类动物群cuneopsis—Psilunio—Lamprotula组合,半咸水动物群Corbula—Neomindon组合以及淡水（微咸水）动物群Peregrinococha组合完全是该区特有的土著分子,从时代对比意义上来说,它们之间可对比度更高.云南和平乡组双壳类动物群和本区相比较后表明,和平乡组沉积时代大致相当于巴柔期（含早巴通期）.缅甸南瑶系中的双壳类动物群时代不应晚于巴通期.藏东和青海南部产出的奇异蛤动物群时代则应不早于基末里期.     

298K时三元体系K^＋／CO3^2—,B4O7^2——H2O和Li^＋／CO3^2—,B4O7^2——H2O相关系

研究了二个三元体系Ｌｉ＋／ＣＯ２－３,Ｂ４Ｏ２－７Ｈ２Ｏ（１）和Ｋ＋／ＣＯ２－３,Ｂ４Ｏ２－７Ｈ２０（２）２９８Ｋ时的相平衡关系和平衡液相的物化性质（密度、折光密、粘度、电导率、ｐＨ值）。研究表明：这二个三元体系均属简单共饱型,无复盐或固溶体形成。体系（１）的两段溶解度曲线对应于无水Ｌｉ２ＣＯ３和Ｌｉ２Ｂ４Ｏ７·３Ｈ２Ｏ结晶区,体系（２）的两段溶解度曲线对应于Ｋ２ＣＯ３·３／２Ｈ２Ｏ和Ｋ２Ｂ４Ｏ７·４Ｈ２Ｏ结晶区。     

海滩上的新一代天气雷达系统防雷要点浅析

通过湛江新一代天气雷达系统的防雷设计与实际防护效果,总结地处海滩的雷达站防雷设计的要点．提出相关防雷设计思路。     

云南西双版纳地区闪电活动特征

应用2017—2018年云南省VLF/LF三维闪电定位数据和1987—2006年云南省人工雷暴日观测数据,运用数理统计、空间插值等方法分析"雷都"西双版纳闪电活动的时空分布特征,运用网格法将闪电定位数据转化为网格雷电活动日,研究人工观测雷暴日与闪电定位监测资料的相关性。结果表明:西双版纳地区雷电活动从3月就开始逐渐增多,峰值出现在7—8月。就闪电频次而言,云闪少于地闪、正闪少于负闪,正地闪明显多于云南省其他地区。11月闪电强度较大,但频次较少;7月闪电频次较多,但强度较小。云闪多发生在8 km以下,平均高度为4.914 km。地闪和云闪密度分布一致,北部高而南部和东西部低;云闪的强度明显高于地闪,但在空间分布上均是北部弱而南部和东西部强。人工观测雷暴日与网格雷电活动日的逐月分布特征较一致。研究还表明:西双版纳在云南省范围内是人工观测雷暴日最多区域,也是网格雷电活动日最多区域。     

Adaptation strategies for mitigating agricultural GHG emissions under dual-level uncertainties with the consideration of global warming impacts

Agriculture plays a central role in maintaining food security and achieving sustainable development for human society. It is a challenge for the agricultural sector to mitigate greenhouse gas (GHG) emissions and maintain agricultural production. However, dual-level uncertainties exist in the processes of agricultural GHG accounting and emission reduction management. In this research, an integrated approach for identifying adaptation strategies in agricultural GHG emission reduction management was developed through incorporating life cycle analysis (LCA) of agricultural production into a general mathematical programming model. This approach strengthened the applicability of LCA and the comprehensiveness of programming models in generating agricultural adaptive actions under different GHG emission restriction targets. Also, dual-level uncertainties of LCA and adaptation management can be effectively addressed. A case study was proposed to illustrate application of the approach in Dalian City, China. The results indicated that farming patterns in eight districts would change significantly. The total area of maize fields would account for the primary proportion (i.e., 40–45 %) in its agricultural sector. Rice, peanut and cabbage fields would be the minor contributors in terms of GHG emissions. In addition to effective rainfall (i.e., [156, 259] mm/ha), a certain amount of water would be supplied for agricultural irrigation to maximize the city’s agricultural yields. Compared with other agricultural crops, rice fields would need the largest amount of irrigation water (i.e., [153.72, 277.98] Mt) to meet the requirements of local government plans.