中国镍矿预测类型及主要战略接续区          下载免费PDF全文

娄德波王登红  肖克炎孙 涛王全明  阴江宁 《中国地质》2014,41(3):715-727

为了充分展示和利用全国镍矿预测的思路及其主要成果,本文根据矿产预测类型的划分标准,将镍矿划分为岩浆型镍-铜硫化物矿、风化壳型镍矿和海相沉积型镍-钼-钒矿3种类型,并系统总结了各矿产预测类型的基本特征、成矿规律、利用现状、预测要素和预测方法。在此基础上,对中国镍矿从成矿地质背景、地球化学特征、矿床分布密集程度、成矿强度以及资源潜力方面进行了分析与综合,结合矿床类型特点,提出了喀拉通克、觉罗塔格、北山、辽吉、龙首山、祁曼塔格、墨江—金平和宝坛等8个战略接续区,用以指导镍矿找矿工作部署。  相似文献   

降雨径流汇入背景下受纳水体可溶态Ni和As的动态变化     

刘浩峰  刘玉燕  张一玮  丁方方  张牛牛  王林 《热带地理》2022,42(12):2088-2097

选取降雨丰沛、降雨径流突出的热带海岛城市海口美舍河市区河段,使用室内分析与野外采样结合的方法开展降雨径流汇入后受纳水体可溶态Ni和As的动态变化研究。结果表明：降雨径流的汇入直接对受纳水体中Ni和As的固液分配产生干扰,且其对受纳水体Ni和As的输入贡献主要依赖悬浮态,可溶态Ni和As输入相对较弱。具体表现为：降雨径流汇入前受纳水体可溶态Ni和As占总质量浓度的比例分别达到55.67%和94.77%。降雨径流汇入后,受纳水体Ni和As发生一系列动态变化,排水口处可溶态Ni和As占比分别达总质量浓度的20.97%和76.92%,可溶态占比明显下降,变化较为剧烈;排水口下游可溶态Ni和As占比也均下降,分别为47.23%和88.38%。对不同降雨情境下的数据分析发现：当降雨量≤10 mm时,雨前干燥期长短是受纳水体可溶态Ni和As动态变化的主要影响因素;当降雨量在10~30 mm时,雨前干燥期长短、雨强峰值出现时间及其大小是受纳水体可溶态Ni和As对降雨径流响应时间及响应程度的主要影响因素;当降雨量≥30 mm时,雨强峰值出现时间是受纳水体可溶态Ni和As动态变化的主要影响因素。降雨径流对受纳水体可溶态Ni和As的影响存在差异,当干燥期短、且存在最大雨强值过高现象时,受纳水体可溶态As受降雨径流影响小,而可溶态Ni受降雨径流影响明显。  相似文献   

The Impact of an Abnormal Zonal Vertical Circulation in Autumn of Super El Ni?o Years on Non-tropical-cyclone Heavy Rainfall over Hainan Island     

Fei WANG  Lifang SHENG  Xiadong AN  Haixia ZHOU  Yingying ZHANG  Xiaodong LI  Yigeng DING  Jing YANG 《大气科学进展》2022,39(11):1914-1924

This study reveals a significant positive connection between autumn non-tropical-cyclone heavy rainfall on Hainan Island and the intensity of Eastern Pacific (EP) El Ni?o events. That is, the amount of rainfall in super EP El Ni?o years is more than that in normal EP El Ni?o years. Comparing EP El Ni?o years of different intensities, the cooler sea surface temperature in the northwestern Pacific during super EP El Ni?o years stimulates a negative surface latent heat flux (LHF) anomaly and abnormal anticyclonic circulation at 850 hPa. Under these conditions, an abnormal zonal vertical circulation develops in the northern South China Sea once a positive LHF anomaly and abnormal cyclonic circulation (ACC) at 850 hPa occur in the Beibu Gulf. The abnormal zonal vertical circulation further strengthens the ascending motion over Hainan Island, as the critical factor that leads to excessive rainfall. Further analysis shows that the positive LHF anomaly, which can be attributed to the increased latent heat transfer which resulted from the increased surface wind speed, is an important trigger for the ACC. However, the ACC is also the supplier of favorable moisture conditions because it intensifies vapor convergence over Hainan Island and meridionally transports moisture from the South China Sea to northeastern Hainan Island, thereby generating heavy rainfall. This paper emphasizes that the impact of El Ni?o events, especially super El Ni?o events, on rainfall over Hainan Island cannot be ignored, even if the traditional view is that frequent rainfall occurs mainly in La Ni?a years.  相似文献   

Toward Understanding the Extreme Floods over Yangtze River Valley in June?July 2020: Role of Tropical Oceans※     

Shaolei TANG  Jing-Jia LUO  Jiaying HE  Jiye WU  Yu ZHOU  Wushan YING 《大气科学进展》2021,38(12):2023-2039,中插8-中插11

The extreme floods in the Middle/Lower Yangtze River Valley (MLYRV) during June?July 2020 caused more than 170 billion Chinese Yuan direct economic losses. Here, we examine the key features related to this extreme event and explore relative contributions of SST anomalies in different tropical oceans. Our results reveal that the extreme floods over the MLYRV were tightly related to a strong anomalous anticyclone persisting over the western North Pacific, which brought tropical warm moisture northward that converged over the MLYRV. In addition, despite the absence of a strong El Ni?o in 2019/2020 winter, the mean SST anomaly in the tropical Indian Ocean during June?July 2020 reached its highest value over the last 40 years, and 43％ (57％) of it is attributed to the multi-decadal warming trend (interannual variability). Based on the NUIST CFS1.0 model that successfully predicted the wet conditions over the MLYRV in summer 2020 initiated from 1 March 2020 (albeit the magnitude of the predicted precipitation was only about one-seventh of the observed), sensitivity experiment results suggest that the warm SST condition in the Indian Ocean played a dominant role in generating the extreme floods, compared to the contributions of SST anomalies in the Maritime Continent, central and eastern equatorial Pacific, and North Atlantic. Furthermore, both the multi-decadal warming trend and the interannual variability of the Indian Ocean SSTs had positive impacts on the extreme floods. Our results imply that the strong multi-decadal warming trend in the Indian Ocean needs to be taken into consideration for the prediction/projection of summer extreme floods over the MLYRV in the future.  相似文献   

A CASE STUDY ON THE RELATIONSHIP BETWEEN A PRECEDING LA NINA EVENT AND EAST ASIAN SUMMER ATMOSPHERIC CIRCULATION^*          下载免费PDF全文

WANG Yafei  FUJIYOSHI Yasushi 《Acta Meteorologica Sinica》2004,18(4):387-396

This study examined the relationship between mature phase of the cold event in 1999 and the East Asian summer atmosphere circulation in 2000.The cold event reaches its mature phase in the autumn and winter of 1999,which is the strongest La Nina episode in recent 11 years.There is a clear anomalous pattern of the atmosphere circulation around East Asia in the summer of 2000, i.e.the negative anomaly centers around the Cherski Mountains and 20°N,170°E at 500 hPa,the main body of the subtropical high keeps in further northern position than usual and the negative anomaly of precipitation located in southern central China.This pattern is thought as the response to the preceding strong cold event in autumn of 1999.It is also identified that the response of the East Asian atmosphere circulation in summer of 2000 to the strong La Nina event in 1999 belongs to the top rank in recent 43 years.On the other hand,the inactive blocking anticyclone around East Asia in summer of 2000 is associated with the positive SST anomaly and the 850 hPa temperature anomaly around the Bering Sea simultaneously.Nevertheless,although the impact on the summer atmosphere circulation around East Asia from La Nina events could not rank with that from E1 Nino,the impact could not be neglected especially in a strong La Nina case.  相似文献   

Precambrian geotectonic units of the Río de La Plata craton     

《International Geology Review》2012,54(1):32-50

The main Precambrian tectonic units of Uruguay include the Piedra Alta tectonostratigraphic terrane (PATT) and Nico Pérez tectonostratigraphic terrane (NPTT), separated by the Sarandí del Yí high-strain zone. Both terranes are well exposed in the Río de La Plata craton (RPC). Although these tectonic units are geographically small, they record a wide span of geologic time. Therefore improved geological knowledge of this area provides a fuller understanding of the evolution of the core of South America. The PATT is constituted by low- to medium-grade metamorphic belts (ca. 2.1 Ga); its petrotectonic associations such as metavolcanic units, conglomerates, banded iron formations, and turbiditic deposits suggest a back-arc or a trench-basin setting. Also in the PATT, a late to post-orogenic, arc-related layered mafic complex (2.3–1.9 Ga), followed by A-type granites (2.08 Ga), and finally a taphrogenic mafic dike swarm (1.78 Ga) occur. The less thoroughly studied NPTT consists of Palaeoproterozoic high-grade metamorphic sequences (ca. 2.2 Ga), mylonites and postorogenic and rapakivi granites (1.75 Ga). The Brasiliano-Pan African orogeny affected this terrane. Neoproterozoic cover occurs in both tectonostratigraphic terranes, but is more developed in the NPTT. Over the past 15 years, new isotopic studies have improved our recognition of different tectonic events and associated processes, such as reactivation of shear zones and fluids circulation. Transamazonian and Statherian tectonic events were recognized in the RPC. Based on magmatism, deformation, basin development and metamorphism, we propose a scheme for the Precambrian tectonic evolution of Uruguay, which is summarized in the first Palaeoproterozoic tectonic map of the Río de La Plata craton.  相似文献   

Geochronology and geochemistry of the Nantianwan mafic–ultramafic complex,Emeishan large igneous province: metallogenesis of magmatic Ni–Cu sulphide deposits and geodynamic setting     

《International Geology Review》2012,54(15):1746-1764

The Nantianwan mafic–ultramafic complex is situated in the northwest part of the Panxi district, southwest China. It consists predominantly of gabbros, gabbronorites, and lherzolites. LA–ICP–MS U–Pb zircon dating of the gabbronorites yields an age of 259.7 ± 0.6 million years, consistent with the ages of other mafic–ultramafic intrusions in the Emeishan large igneous province (ELIP). Gabbronorites and lherzolites host Cu–Ni sulphide ores. Cumulus texture is pronounced in these rocks, containing magnesium-rich olivine (up to 81.4% forsterite). SiO₂ contents of the lherzolites range from 42.93 to 44.18 wt.%, whereas those of the gabbronorites vary between 44.89 and 52.76 wt.%. Analysed samples have low rare earth element (REE) contents (23.22–30.16 ppm for lherzolites and 25.21–61.05 ppm for gabbronorites). Both lherzolites and gabbronorites have similar chondrite-normalized REE patterns, suggesting that they are comagmatic. All samples are slightly enriched in large ion lithophile elements (LILEs, e.g. Rb, Ba, and Sr) relative to high field strength elements (HFSEs, e.g. Nb, Ta, and Ti), very similar to those of ocean island basalts (OIBs). The presence of cumulus textures and geochemical signatures indicates that fractional crystallization played an important role in the petrogenesis of these rocks. Initial (⁸⁷Sr/⁸⁶Sr) _t (t?=?260 Ma) ratios and ?_Nd(t) values of the mafic–ultramafic suite vary from 0.70542 to 0.70763, and??0.4 to 1.7, respectively. Compared to the Cu–Ni-bearing Baimazhai and Limahe intrusions in the ELIP, which were considerably contaminated by variable crustal materials, the Nantianwan complex exhibits much lower (⁸⁷Sr/⁸⁶Sr) _t . Their ?_Nd(t) versus (Th/Nb)_PM ratios also indicate that the ore-bearing magmas did not undergo significant crustal contamination. In combination with (Tb/Yb)_PM versus (Yb/Sm)_PM modelling, we infer that the magmas originated from an incompatible elements-enriched spinel-facies lherzolite that itself formed by interaction between the Emeishan plume and the lithospheric mantle. Most plots of NiO versus Fo contents of olivine suggest that sulphides are separated from the parental magma by liquid immiscibility, which is also supported by bulk-rock Cu/Zr ratios of the lherzolites (7.04–102.67) and gabbronorites (0.88–5.56). We suggest that the gabbronorites and lherzolites experienced undersaturation to oversaturation of sulphur; the latter may be due to fractional crystallization in a high-level magma chamber, accounting for the sulphide segregation.  相似文献   

Palaeoproterozoic Chibaisong mafic intrusion and mineralization (Northeast China), the oldest Cu–Ni sulphide deposit in China: evidence from Re–Os dating of pyrrhotite     

《International Geology Review》2012,54(14):1783-1791

The Chibaisong magmatic Cu–Ni sulphide deposit is located in Tonghua City, Jilin Province, in the eastern part of the northern margin of the North China Craton. The geological characteristics of the deposit have been investigated, and pyrrhotite Re–Os isotope dating has been utilized to constrain the age. Five pyrrhotite samples separated from the Chibaisong Cu–Ni sulphide deposit yielded a Re–Os isotopic isochron age of 2237 ± 62 Ma (mean squared weighted deviation = 1.13, n = 5), indicating that the only Palaeoproterozoic magmatic Cu–Ni sulphide deposit in China is the Chibaisong Cu–Ni sulphide deposit. The geodynamic setting during ore formation was related to the Liaoning–Jilin Palaeoproterozoic rift split. The Re–Os isotope analyses showed an initial ¹⁸⁷Os/¹⁸⁸Os ratio of 0.778 ± 0.033, and (¹⁸⁷Os/¹⁸⁸Os)_i and γOs(t) values ranged from 0.7531 to 0.8013 (average 0.7734) and from 574 to 617 (average 592), respectively, indicating that abundant crustal material (5–10%) was mixed with the Cu–Ni sulphide ore system during magma ascent and ore formation.  相似文献   

Frequent central Pacific La Ni?a events may accelerate Arctic warming since the 1980s     

Jing Li  Lin Mu  Linhao Zhong 《海洋学报(英文版)》2021,40(11):62-69

Including significant warming trend, Arctic climate changes also exhibit strong interannual variations in various fields, which is suggested to be related to El Ni?o and Southern Oscillation (ENSO) events. Previous studies have demonstrated the different impacts on the Arctic of central Pacific (CP) and eastern Pacific (EP) ENSO events, and suggested these impacts are largely of opposite sign for ENSO warm and cold phases. Our results illustrate asymmetrical changes for the cold and warm ENSO events, especially for the La Ni?a events. Compared to the past frequent basin-wide cooling La Ni?a events, since the 1980s the cooling center for the La Ni?a event has strengthened and moved westward along with the increasing frequency for the canonical and CP La Ni?a events. Contrary to the basin-wide cooling and canonical La Ni?a events, the frequent CP La Ni?a events induce significant warming from the Beaufort Sea to Greenland via the convection center moving northward over the western Pacific. Observation analysis and numerical experiments both suggest that the changes in La Ni?a type may also accelerate Arctic warming.  相似文献   

云南筇竹寺组黑色岩系矿化特征及找矿前景     

段生杰  佘中明  丁德生  刘汉和 《地球学报》2013,34(S1):146-150

本文在野外调查及相关资料分析的基础上, 对云南筇竹寺组的地质特征及产于其黑色岩系中的钼(镍)矿化特征做了初步分析, 对云南东部筇竹寺组黑色岩系钼(镍)矿找矿前景做出了初步预测。对钼(镍)的找矿方向、牛蹄塘组与筇竹寺组的对比分析、钼(镍)矿床后生变化、黑色岩系多金属成矿时代等问题进行了初步讨论、分析。本文认为, 筇竹寺组黑色岩系钼(镍)多金属矿的找矿方向, 应为云南马龙—曲靖麒麟区—沾益—会泽—巧家(南北向)—永善及镇雄—贵州西北部(北东、北东东向)一带。初步估计云南省中东部地区筇竹寺组黑色岩系钼、镍金属远景资源量在一百万吨以上。  相似文献