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广西姑婆山里松花岗岩中闪长质包体的地球化学特征及其成因探讨 总被引：8，自引：0，他引：8
广西姑婆山里松花岗岩中广泛发育有大量的闪长质包体,包体的野外地质特征、显微结构、矿物组合及化学组成等特征显示其岩浆快速结晶成因。它们的主量元素在相关图上呈不同程度的直线变异关系。在微量元素方面,包体和寄主花岗岩都富含大离子亲石元素和高场强元素。用锆石饱和温度和角闪石成分估算了包体和寄主花岗岩结晶的温度和压力表明,它们的结晶温度和压力条件相近,分别在793—824℃和（3．5—5．1）×10^8Pa范围内。岩石学和同位素地球化学特征也表明,里松包体和寄主花岗岩基本同时结晶,但壳幔比例和来源有所不同。这些特征总体上说明了里松闪长质包体可能是两种岩浆混合时不完全消化的产物 相似文献
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Nutrient and suspended sediment concentrations were measured in the dry season and during the rising and falling stages of flood events in the Annan and Daintree rivers to estimate catchment exports. These flood events were also sampled along the salinity gradient in the estuary and nearshore shelf to quantify the modification of terrestrial sediment and nutrient loads as they pass through estuaries into the Great Barrier Reef lagoon. In the Daintree River TSS concentrations were found to increase between the catchment and the estuary plume. The source of TSS may have been scour of the estuarine channel or from land use in the catchment of the lower estuary. In the dry season nitrogen enters the Annan and Daintree estuaries predominantly in the form of PON and DON in roughly equal proportions. Nitrogen exports to the GBR are mostly in the form of DON. In the wet season the majority of nitrogen enters the estuaries as DON and leaves as PON. Nitrogen removal in the estuaries and plumes appears to be biologically mediated once suspended sediment concentrations decrease to a point where phytoplankton growth is not light limited. In the dry season phosphorus enters and leaves the estuaries primarily in organic form. PIP is the dominant form of phosphorus in river water, but leaves the estuary more evenly distributed between all forms. These estuarine processes result in less nitrogen and phosphorus being delivered to the GBR lagoon than is exported from the catchment. The differences between these estuaries highlights the need for further work to explore modifications in estuaries that drain into the Great Barrier Reef lagoon. 相似文献
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东坪金矿是产于正长杂岩内接触带的特大型金矿床。矿石以富碲、少硫化物为特点。主要载金矿物为自然金和金、银碲化物。后包裹于黄铁矿为主的硫化物内,属于氰化法的“难溶金”,在表生条件下的氧化产物种类丰富的含金碲酸盐相中含量与自然金相当。 相似文献
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华北克拉通北缘富碱侵入岩带是我国重要的金矿成矿带,金矿成矿与克拉通边缘深大断裂的活动、富碱侵入岩岩浆活动关系密切。河北张-宣地区与正长岩有关的金矿床产于水泉沟正长岩杂岩体的内外接触带,与水泉沟碱性杂岩体有成因联系。近年来对其及与之有关的金(碲)矿化进行了深入研究,现就岩体成因、岩体形成年龄及金矿化年龄代等问题作一简要探讨。 相似文献
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1.引言高层和低层等熵位涡(IPV)距平的相互作用,对斜压不稳定和温带气旋的形成提供了一种简明的描述(Hoskins等,1985).最近,这种提法作为背风坡气旋产生的一种似乎可信的理由,已经引起人们的注意(如,Mattocks和Bleck,1986).但是,这种机制能否成立还需由理论的和观测的依据所证实.这里,用戈达德大气实验室(GLA)的资 相似文献
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Trace metal uptake by the Chinese mitten crab Eriocheir sinensis: the role of osmoregulation 总被引：2，自引：0，他引：2
Changes in salinity affect the bioavailability and consequent uptake of trace metals by euryhaline invertebrates. In many cases, salinity-related effects on metal uptake can be explained by changes in chemical speciation but salinity may also influence uptake indirectly through its action on osmoregulatory mechanisms. Specifically, it can be hypothesised that trace metal uptake may be reduced at salinities approaching the isosmotic point of a species because, at this point, there is reduced activity of ionic exchange pumps. The present study tested this hypothesis using the Chinese mitten crab, Eriocheir sinensis, a hyper-hypoosmoregulator with an isosmotic point around 33 per thousand. Crabs were exposed to radio-labelled cadmium and zinc at 23, 33 and 43 per thousand for 4 days. To eradicate speciation effects, crabs were exposed to the same concentration of the radio-labelled free metal ion (estimated using MineQL computer software) at each salinity. Haemolymph samples were taken daily and radio-labelled metal concentrations were estimated from radioactivity counts and used to provide relative measures of metal uptake. Neither cadmium nor zinc uptake was lowest at the isosmotic point. The uptake of cadmium increased significantly with increase in salinity, while the uptake of zinc showed no significant change with increased salinity. Thus changes in trace metal uptake rates in E. sinensis do not appear to be controlled only by changes in free metal ion concentrations. The different effects of salinity change on the uptake of cadmium and zinc (in the absence of free metal ion change) also indicate that physiological responses to osmotic change alone do not control metal uptake rates for this species. 相似文献
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Seafloor photography from three cruises is combined with multibeam sonar imagery to characterize benthic substrates and associated fauna of Santa Monica Bay, California. The multibeam EM1000 imagery was collected in 1996. Two sampling cruises (in 1998 and 1999) provided photographs at 142 sites throughout the Bay; a final cruise (in 2000) collected still photographs and continuous video along nine transects on the mainland shelf from Pt. Dume to the Palos Verdes peninsula. Muddy substrates (typically low backscatter) were the predominant habitat throughout the Santa Monica Bay, from the 20 m isobath to the adjacent Santa Monica basin floor (780 m). Bioturbation was pervasive as evidenced by abundant open burrows, mounds, and faunal tracks and trails. Sandy substrates (typically intermediate to high backscatter) were restricted to the innermost mainland shelf and a narrow outer shelf band north of Santa Monica Canyon. Cobble and gravel substrates (high backscatter) were restricted to the innermost shelf south of El Segundo and limited parts of the shelf edge. Rocky substrates (high backscatter) with interspersed patches of sand and gravel occurred on the high-relief marginal plateau and along parts of the shelf break offshore of Malibu. 相似文献