Geochemical characterization of Archaean amphibolites from the eastern part of Anshan–Benxi iron producing area,northeastern China: implication for tectonic setting of BIFs     

En‐De Wang  Chang‐Ik Han  Jian‐Ming Xia  Jian‐Fei Fu  Guang‐Su Li  San‐Shi Jia  Ye‐Kai Men 《Geological Journal》2016,51(3):480-498

The Anshan–Benxi iron producing area, which is located at the northeastern margin of the North China Craton, is the main distribution area of Archaean BIFs in China. In their eastern part, including the Gongchangling and Waitoushan deposits, BIFs mainly are hosted in the Archaean middle Anshan Group. Amphibolites are widely distributed in the iron‐bearing rock series, reflecting the tectonic setting of BIFs. Amphibolites not only have MORB‐like compositional characteristics, but also have island arc‐like ones, and they are consistent with back‐arc basin basalts (BABB). In the study area, the protolith of amphibolites belongs to Okinawa‐type BABB; it indicates that tectonic setting of BIFs is the intra‐continental back‐arc basin. In the study area, the formation of sedimentary basins for BIFs had been associated with oceanic plate subduction. Amphibolites from Gongchangling deposit are characterized by relative enrichments in LILE and LREE, and depletions in HFSE. This indicates that they had a relatively large influence of subduction in their formation. Amphibolites from Waitoushan deposit are characterized by relative enrichments in LILE without conspicuous depletions in HFSE, indicating relatively low subduction rates. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

AVO异常分析在大杨树盆地油气勘探中的应用     

闫磊  刘招君  方石  陈永成  贾建亮 《物探化探计算技术》2011,33(4):435-439,348,349

大杨树盆地岩性复杂,储层含有大量孔隙及裂缝,但是在该区油气并没有取得重大突破,因此勘探方向成为研究区的重要问题。这里利用杨参1井测井数据计算了含气层位的阻抗,分析判断该含气层位AVO异常为第一类AVO异常。运用AVO分析软件处理杨参1井所在74号线的叠前道集资料,发现该含气层位AVO异常振幅为第一类AVO异常。运用AVO技术分析认为,杨参1井两侧存在范围较大的含气异常,而且存在含气性更好的第二类AVO异常特征。最后综合各类资料,认为74号线位于大杨树盆地南部坳陷最有利的勘探远景区,AVO异常特征段为下一步重点工作的地区,作为探井位置CDP3010附近应引起重视。  相似文献   

甘肃省临夏盆地更新世早期湖泊沉积孢粉记录的古气候演化          下载免费PDF全文

董铭  方小敏  史正涛  明庆忠  苏怀 《第四纪研究》2011,31(1):104-111

根据孢粉组合特征,将临夏盆地早更新统东山组(2.50-1.76Ma)的孢粉划分为3个孢粉带(含6个亚带),即3个植被、气候阶段,第一阶段(2.50-1.91Ma,带Ⅰ),植被类型是以柏科、榆属和禾本科为优势种的温带森林,气候表现为温凉稍干,并有逐渐干旱化的趋势.第二阶段(1.91-1.80Ma,带Ⅱ)是以云杉属、榆属和...  相似文献   

黄河源区陆面过程观测和模拟研究进展   总被引：2，自引：1，他引：1  

文军  蓝永超  苏中波  田辉  史小康  张宇  王欣  刘蓉  张堂堂  康悦  吕少宁  张静辉 《地球科学进展》2011,26(6):575-586

陆面过程对黄河源区水资源变化有重要的影响,探索黄河源区陆面过程和水分循环特征的关联机理有十分重要的意义.首先简述了黄河源区气候变化背景和陆面过程的基本特征,并详细介绍了近年来在黄河源区开展的一系列陆面过程野外观测试验及相关研究主题和研究进展;进一步给出了在野外试验观测资料分析、卫星遥感、数据同化应用和数值模拟等方面取得...  相似文献   

浙江萧山跨湖桥遗址动物骨骼表面微痕与人类行为特征     

施梦以  武仙竹 《第四纪研究》2011,31(4):723-729

浙江跨湖桥遗址位于中国东南沿海,是距今约8000年左右的新石器时代遗址.遗址中出土有大量哺乳动物骨骼,通过显微观测和统计,发现遗址动物骨骼表面有丰富的人工改造痕迹,并有家畜狗的啃咬痕迹等.其中人工改造痕迹的比重,达到所观察标本总数的17.57%.人工改造痕迹的显微特征、排列规律、分布位置等,反映遗址古居民已熟练掌握了剥...  相似文献   

基于耦合关系的干旱绿洲区农村居民点整理分区研究——以张掖市甘州区为例   总被引：1，自引：0，他引：1  

高小琛  石培基  潘竟虎  吕立刚 《地球科学进展》2011,26(10):1071-1078

以张掖市甘州区为例,利用系统科学理论与方法,研究农村居民点整理与农村社会经济之间的动态耦合规律,并以甘州区18个乡镇为研究单元,构建了农村居民点用地整理分区评价指标体系,利用熵值法确定权重,计算农村居民点整理的综合评价值,运用层次筛选法将研究区划分为5个整理区。研究结果：①甘州区农村居民点与农村社会经济的耦合度演化分为3个阶段：1995—1997年,二者不甚协调;1998—2003年,二者都处于持续、稳定、最佳协调发展状态;2004—2007年,二者处于相对稳定协调状态;目前二者处于不甚协调发展阶段。②农村居民点整理分区包括优先整理区、强化整理区、适度整理区、一般整理区和完善整理区。  相似文献   

滨海地区地下水泄流研究进展     

李丹  王刚  丁丽娜  石磊 《化工矿产地质》2011,33(1):50-53

20世纪90年代以来出现的对滨海地下水的研究方式取得了有意义的结果.其中W.S.Moore通过对226Ra富集揭示了地下水对海岸水体大量补给的研究以及Jacob、Sun等关于潮夕动力地下水流法的研究对解决环境地质问题具有一定的意义.  相似文献   

基于水污染物通量的小流域生态补水研究     

石成春 《地质灾害与环境保护》2011,22(2):99-102

为改善水质环境,对福建省龙江中下流进行补水效果实验.根据控制断面测得的水质浓度和流量数据,计算水污染物通量.使用该通量评估污染负荷,计算生态补水量.所得污染物通量良好地反映出流域污染状况,实验效果显著,河流水质达到了国家规定标准.  相似文献   

Continual erosion of bare rocks after the Wenchuan earthquake and control strategies   总被引：1，自引：0，他引：1  

Zhaoyin Wang  Wenjing Shi  Dandan Liu 《Journal of Asian Earth Sciences》2011,40(4):915-925

The newly bared rocks created by the Wenchuan earthquake are undergoing continual intensive erosion in the form of detachment and movement of individual grains. Grain erosion is defined as the phenomenon of breaking down bare rocks under the action of insolation and temperature change, detachment of grains from the rockwalls by wind, flow down of grains on the slope under the action of gravity, and accumulation of grains at the toe of the mountain, forming a deposit fan. The Wenchuan earthquake, which occurred in Sichuan on May 12, 2008, caused thousands of avalanches and landslides and left scars on slopes and a huge area of bare rocks. Grain erosion causes flying stones, injured humans and resulted in numerous slope debris flows. The process of grain erosion and strategies to limit the erosion were studied by field investigations and field experiments. According to these field investigations and field studies, the most serious grain erosion occurs in spring and early summer when it is very dry. Rocks are broken down to grains under the action of insolation and temperature change. Then, wind blows the grains from the bare rock down slope. Experimental results showed that the amount of grains blown down by wind per area of rock surface per unit time is proportional to the fourth power of the wind speed. However, the size of the grains blown down by wind increases linearly with the wind speed. An experiment proved that grain erosion can be controlled with two moss species. Moss spores were mixed with clay suspension and splashed on bare rocks. The moss species germinated on the rock surface in one month and greened the bare rocks in two months. The moss layer protected the rocks from insolation and mitigated the effects of temperature change, thus effectively mitigated grain erosion.  相似文献   

Chemical and Strontium Isotopic Compositions of the Hanjiang Basin Rivers in China: Anthropogenic Impacts and Chemical Weathering   总被引：1，自引：0，他引：1  

Zhifang Xu  Chao Shi  Yang Tang  Hongyin Han 《Aquatic Geochemistry》2011,17(3):243-264

The Hanjiang River, the largest tributaries of the Changjiang (Yangtze) River, is the water source area of the Middle Route of China’s South-to-North Water Transfer Project. The chemical and strontium isotopic compositions of the river waters are determined with the main purpose of understanding the contribution of chemical weathering processes and anthropogenic inputs on river solutes, as well as the associated CO₂ consumption in the carbonate-dominated basin. The major ion compositions of the Hanjiang River waters are characterized by the dominance of Ca²⁺ and HCO₃ ⁻, followed by Mg²⁺ and SO₄ ²⁻. The increase in TDS and major anions (Cl⁻, NO₃ ⁻, and SO₄ ²⁻) concentrations from upstream to downstream is ascribed to both extensive influences from agriculture and domestic activities over the Hanjiang basin. The chemical and Sr isotopic analyses indicate that three major weathering sources (dolomite, limestone, and silicates) contribute to the total dissolved loads. The contributions of the different end-members to the dissolved load are calculated with the mass balance approach. The calculated results show that the dissolved load is dominated by carbonates weathering, the contribution of which accounts for about 79.4% for the Hanjiang River. The silicate weathering and anthropogenic contributions are approximately 12.3 and 6.87%, respectively. The total TDS fluxes from chemical weathering calculated for the water source area (the upper Hanjiang basin) and the whole Hanjiang basin are approximately 3.8 × 10⁶ and 6.1 × 10⁶ ton/year, respectively. The total chemical weathering (carbonate and silicate) rate for the Hanjiang basin is approximately 38.5 ton/km²/year or 18.6 mm/k year, which is higher than global mean values. The fluxes of CO₂ consumption by carbonate and silicate weathering are estimated to be 56.4 × 10⁹ and 12.9 × 10⁹ mol/year, respectively.  相似文献