Zircon U–Pb and Molybdenite Re–Os Ages of the Lakange Porphyry Cu–Mo Deposit,Gangdese Porphyry Copper Belt,Southern Tibet,China          下载免费PDF全文

Qiu‐Feng Leng  Ju‐Xing Tang  Wen‐bao Zheng  Bin Lin  Pan Tang  Hao Wang  Hai‐Feng Li 《Resource Geology》2016,66(2):163-182

The Lakange porphyry Cu–Mo deposit within the Gangdese metallogenic belt of Tibet is located in the southern–central part of the eastern Lhasa block, in the Tibetan Tethyan tectonic domain. This deposit is one of the largest identified by a joint Qinghai–Tibetan Plateau geological survey project undertaken in recent years. Here, we present the results of the systematic logging of drillholes and provide new petrological, zircon U–Pb age, and molybdenite Re–Os age data for the deposit. The ore‐bearing porphyritic granodiorite contains elevated concentrations of silica and alkali elements but low concentrations of MgO and CaO. It is metaluminous to weakly peraluminous and has A/CNK values of 0.90–1.01. The samples contain low total REE concentrations and show light REE/heavy REE (LREE/HREE) ratios of 17.51–19.77 and (La/Yb)_N values of 29.65–41.05. The intrusion is enriched in the large‐ion lithophile elements (LILE) and depleted in the HREE and high field‐strength elements (HFSE). The ore‐bearing porphyritic granodiorite yielded a Miocene zircon U–Pb crystallization age of 13.58 ± 0.42 Ma, whereas the mineralization within the Lakange deposit yielded Miocene molybdenite Re–Os ages of 13.20 ± 0.20 and 13.64 ± 0.21, with a weighted mean of 13.38 ± 0.15 Ma and an isochron age of 13.12 ± 0.44 Ma. This indicates that the crystallization and mineralization of the Lakange porphyry were contemporaneous. The ore‐bearing porphyritic granodiorite yielded zircon εHf(t) values between ?3.99 and 4.49 (mean, ?0.14) and two‐stage model ages between 1349 and 808 Myr (mean, 1103 Myr). The molybdenite within the deposit contains 343.6–835.7 ppm Re (mean, 557.8 ppm). These data indicate that the mineralized porphyritic granodiorite within the Lakange deposit is adakitic and formed from parental magmas derived mainly from juvenile crustal material that partly mixed with older continental crust during the evolution of the magmas. The Lakange porphyry Cu–Mo deposit and numerous associated porphyry–skarn deposits in the eastern Gangdese porphyry copper belt (17–13 Ma) formed in an extensional tectonic setting during the India–Asia continental collision.  相似文献   

长江中游沿岸地下水中铵氮与磷的共存规律及其控制因素     

冷智超  杜尧  陶艳秋  黄艳雯  邓娅敏 《地质科技情报》2022,41(1):300-308

长江中游平原区面临着一系列严重的地质环境问题,其中地下水铵氮和磷的问题十分突出,但目前对于二者共存规律的认识还十分薄弱.以长江中游沿岸故道区为典型研究区,对采集的地下水样品进行了水文地球化学分析,并综合运用因子分析和随机森林模型探讨了铵氮和磷的赋存规律.结果 表明:地下水整体处于还原环境中,NH4N的质量浓度为0.03...  相似文献   

随机波作用下伞式吸力锚基础局部冲刷演变分析     

赵真  胡瑞庚  刘红军  冷浩 《中国海洋大学学报(自然科学版)》2022,52(3):139-147

为了验证新型伞式吸力锚基础的防冲刷效果,本文利用Flow-3D软件建立三维海床-吸力锚-波浪相互作用模型,基于JONSWAP随机波浪谱,结合某海域风区资料模拟随机波,对随机波浪作用下伞式吸力锚基础(USAF)局部冲刷演变进行分析,试验土体为非黏性土.首先探讨了随机波浪作用下基础周围流场变化规律和冲刷演变模式,其次分析了...  相似文献   

Provenance of late Ashgill (Hirnantian) fine-grained sediments and pebbles in the Welsh Basin: A ND and SR isotope study     

M. J. Leng  J. A. Evans 《Geological Journal》1994,29(1):1-9

The isotope characteristics of interbedded fine-grained sedimentary rocks and pebbles from an Ashgill sequence in the Welsh Basin show that they have different provenance. Gondwana-derived continental crustal material dominates the Nd-Sr isotope signatures of the fine-grained rocks whereas the pebbles sample the Avalonian basement. Detritus from Gondwana and Avalonia accounts for the isotopic composition of most of the lower Palaeozoic sedimentary rocks of Southern Britain and this suggests that any contribution from the reworking of Lower Palaeozoic volcanic rock is minimal.  相似文献   

2023年汛期气候预测效果评述及先兆信号分析     

支蓉  高辉  孙冷 《气象》2024,50(3):377-386

2023年夏季,我国整体表现为高温少雨的特征,旱涝分布不均。夏季台风虽然生成和登陆个数均较常年偏少,但破坏力极强。华北、西北等地阶段性高温事件异常突出,但长江流域的高温干旱强度明显弱于2022年同期。从预测效果来看,2023年汛期预测较好把握了我国北方主雨带特征,对松花江流域、嫩江流域、海河流域可能出现的较重汛情做出了准确的预测预警。对夏季热带气旋的生成个数、主要路径、影响区域等的预测与实况较为相符。对夏季全国大部地区气温偏高的特征预测与实况一致,并明确指出,长江流域发生类似2022年夏季大范围持续性高温干旱事件的可能性低。汛期预测的不足之处主要在于对华南等地的降水预测与实况出现较大偏差,对华北、黄淮等地的高温过程极端性估计不足。针对2023年汛期降水的先兆信号及其预报性能进行了回顾和评估,无论是年代际尺度还是年际尺度外强迫信号,均对我国北方主雨带有较好的指示意义。同时,几乎所有先兆信号都对华南降水给出了一致的错误信息,是导致华南降水预报失败的主要原因。  相似文献   

The influence of groundwater representation on hydrological simulation and its assessment using satellite‐based water storage variation     

Zhongwei Huang  Qiuhong Tang  Min‐Hui Lo  Xingcai Liu  Hui Lu  Xuejun Zhang  Guoyong Leng 《水文研究》2019,33(8):1218-1230

The interaction between surface water and groundwater is an important aspect of hydrological processes. Despite its importance, groundwater is not well represented in many land surface models. In this study, a groundwater module with consideration of surface water and groundwater dynamic interactions is incorporated into the distributed biosphere hydrological (DBH) model in the upstream of the Yellow River basin, China. Two numerical experiments are conducted using the DBH model: one with groundwater module active, namely, DBH_GW and the other without, namely, DBH_NGW. Simulations by two experiments are compared with observed river discharge and terrestrial water storage (TWS) variation from the Gravity Recovery and Climate Experiment (GRACE). The results show that river discharge during the low flow season that is underestimated in the DBH_NGW has been improved by incorporating the groundwater scheme. As for the TWS, simulation in DBH_GW shows better agreement with GRACE data in terms of interannual and intraseasonal variations and annual changing trend. Furthermore, compared with DBH_GW, TWS simulated in DBH_NGW shows smaller decreases during autumn and smaller increases in spring. These results suggest that consideration of groundwater dynamics enables a more reasonable representation of TWS change by increasing TWS amplitudes and signals and as a consequence, improves river discharge simulation in the low flow seasons when groundwater is a major component in runoff. Additionally, incorporation of groundwater module also leads to wetter soil moisture and higher evapotranspiration, especially in the wet seasons.  相似文献   

地震数据规则化应用效果分析     

冷广升 《中国煤炭地质》2010,(2):49-53

传统面元规则化处理主要采用静态和动态面规则化等技术,但因丢道或借道原因,仍存在覆盖次数不均匀或振幅信息误差。煤炭地震勘探一般具有覆盖次数低、面元小的特点,借鉴同济大学辛可锋利用DMO实现三维数据规则化的方法和Biondi提出的三维叠前地震数据方位角校正方法,从方位角校正的角度入手,利用DMO和DMO-1相结合的处理流程对煤炭地震数据进行规则化。某煤矿区的地震数据规则化处理效果证实,在施工条件复杂、测线方向变化频繁、观测系统规则性很差的勘探区,对采集数据进行规则化处理,可使CMP的空间位置趋于规则分布,缺失的偏移距得到一定的弥补,更符合数据处理对观测系统的要求。处理后的数据既保持了原来的振幅特征,同时也提高了时间剖面的信噪比,数据规则化处理效果明显。  相似文献   

A geological constraint on relative sea level in Marine Isotope Stage 3 in the Larsemann Hills, Lambert Glacier region, East Antarctica (31 366–33 228 cal yr BP)     

Dominic A. Hodgson  Elie Verleyen  Wim Vyverman  Koen Sabbe  Melanie J. Leng  Matthew D. Pickering  Brendan J. Keely 《Quaternary Science Reviews》2009,28(25-26):2689-2696

In this paper we present geological evidence from the Larsemann Hills (Lambert Glacier – Amery Ice Shelf region, East Antarctica) of marine sediments at an altitude of c. 8 m a.s.l., as revealed by diatom, pigment and geochemical proxies in a lake sediment core. The sediments yielded radiocarbon dates between c. 26 650 and 28 750 ¹⁴C yr BP (31 366–33 228 cal yr BP). This information can be used to constrain relative sea level adjacent to the Lambert Glacier at the end of Marine Isotope Stage 3. These data are compared with the age and altitude of Marine Isotope Stage 3 marine deposits elsewhere in East Antarctica and discussed with reference to late Quaternary ice sheet history and eustatic sea-level change.  相似文献   

武陵山经济协作区空间协调发展程度评价   总被引：2，自引：1，他引：1  

冷志明 《地理研究》2012,31(3):521-533

与以往区域协调发展程度评价研究不同,本文基于协调发展概念强调经济联系、区域差异、动态收敛和可持续发展的本质特点,构建空间（区域）评价体系,分别从基本公共服务均等化程度、区际一体化程度、区际人均GDP均等化程度、城乡人均消费水平差异程度四个方面评价武陵山经济协作区空间协调发展程度。评价结果显示,2001～2009年间,武...  相似文献   

A reassessment of late glacial – Holocene diatom oxygen isotope record from Lake Baikal using a geochemical mass‐balance approach     

Anson W. Mackay  George E. A. Swann  Melanie J. Leng  David W. Morley  Natalia Piotrowska  Patrick Rioual  Dustin White 《第四纪科学杂志》2011,26(6):627-634

We present a new palaeoenvironmental record of hydrological variability in Lake Baikal, based on re‐modelled δ¹⁸O_diatom values of diatom silica (δ¹⁸O_modelled), where the residual contaminants are identified and compensated for using electron optical imaging and whole‐sample geochemistry. δ¹⁸O_modelled interpretations are based on the balance between rivers with high δ¹⁸O values and rivers with low δ¹⁸O values. Isotopic variability is related to latitudinal differences in precipitation which feed these rivers. The δ¹⁸O_modelled record suggests that rather moist conditions prevailed in the Lake Baikal region during the latter stages of the Younger Dryas. Throughout the Holocene, episodes of low δ¹⁸O_modelled values are, in general, in good agreement with increases in percentage haematite‐stained grains in North Atlantic sediments (indicative of ice‐rafted debris events). Rivers with southerly catchments dominate fluvial input especially between c. 3.3 and 2 cal ka BP, concurrent with high precipitation in the Lake Baikal region. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献