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191.
对北京首都机场高速公路旁采集的土壤柱状T01剖面的磁学参数和金属元素分析,探讨了研究区内现代交通导致的土壤磁学性质的变化及其对环境污染的响应.结果表明,磁参数(χ,ARM和SIRM)与重金属含量呈同步垂向变化趋势.来源于交通运输排放的污染物是土壤剖面上部(0~8 cm)磁性和金属含量增强的主要原因,8cm以下,土壤基本未受到污染,磁性矿物和重金属含量较低,磁性颗粒变化稳定,基本代表了该地区土壤的自然背景.尽管土壤岩石磁学分析表明剖面上下部受污染和未受污染样品的磁载体均是粒度较粗的多畴磁铁矿,但是结合磁参数比值曲线,说明底部样品的磁颗粒的粒度较顶部偏细.磁性矿物的含量变化没有影响磁颗粒的粒度特征.指标聚类等相关分析表明,土壤磁参数(χ,ARM和SIRM)与重金属元素(Pb,Zn和Cu)含量显著相关;结合模糊聚类分析,磁参数可用于追踪、识别交通污染物质在土壤剖面中的富集、迁移状态,揭示不同深度土壤的污染程度. 相似文献
192.
Recent activity–composition models for clinopyroxene and amphibole are revised to provide better consistency with observed phase relations in natural rocks. For clinopyroxene, the calibration in NCFMAS is retained, but the incorporation of acmite is revised to improve the partitioning of ferric iron between coexisting clinopyroxenes. For amphibole, the NCFMASH calibration is retained, but the addition of ferric iron is changed to provide consistency with the clinopyroxenes. The thermodynamics of orthoamphibole (gedrite) is also adjusted to resolve an unrelated inconsistency. The effects of these improvements are illustrated through comparison of calculated pseudosections produced with the existing and new models with natural data from lawsonite eclogites. 相似文献
193.
J. L. Mair V. J. Ojala B. P. Salier D. I. Groves S. M. Brown 《Australian Journal of Earth Sciences》2013,60(5):895-912
Stress mapping is a numerical modelling technique used to determine the distribution and relative magnitude of stress during deformation in a mineralised terrane. It is based on the general principle that fluid flow in the Earth's crust is primarily related to pressure gradients. It is best applied to epigenetic hydrothermal mineral deposits, where fluid flow and fluid flux are enhanced in dilational sections of structures and in sites of enhanced rock permeability due to high fracture density. These are defined by sites of low minimum principal stress (σ3). Most stress mapping is carried out in two dimensions in plan view using geological maps. This is suitable for terranes with steeply dipping lithostratigraphy and structures in which the distribution of mineral deposits is largely controlled by fault structures portrayed on the maps. However, for terranes with gently dipping sequences and structures, and for situations where deposits are sited in and near the hinges of complex fold structures, stress mapping in cross‐section is preferable. The effectiveness of stress mapping is maximised if mineralisation was late in the evolutionary history of the host terrane, and hence the structural geometry of the terrane and contained deposits were essentially that expressed today. The orientation of syn‐mineralisation far‐field stresses must also be inferred. Two examples of orogenic gold deposits, which meet the above criteria, are used to illustrate the potential of stress mapping in cross‐section. Sunrise Dam, located in the Archaean Yilgarn Craton, is a lode‐gold deposit sited in a thrust‐fold belt. Stress mapping illustrates the heterogeneity of stress distribution in the complex structural geometry of the deposit, and predicts the preferential siting of ore zones around the intersections of more steeply dipping, linking thrusts and banded iron‐formation units, and below the controlling more gently dipping basal thrust, the Sunrise Shear. The Howley Anticline in the Pine Creek block hosts several Palaeoproterozoic gold deposits, sited in complex anticlinal structures in greywacke sequences. Stress mapping indicates that gold ores should develop in the hinge zones of symmetrical anticlines, in the hinge zones and more steeply dipping to overturned limbs of asymmetric anticlines, and in and around thrusts in both anticlines and parasitic synclines. The strong correlation between the predictions of the stress mapping, based on the distribution of low σ3, and the location of gold ores emphasises the potential of stress mapping in cross‐section, not only as an exploration tool for the discovery of additional resources or deposits, but also as a test of geological models. Knowledge of the potential siting of gold ores and their probable orientations also provides a guide to drilling strategies in both mine‐ and regional‐scale exploration. 相似文献
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197.
铈硼硅石是一种罕见的稀土矿物,由于它含有某些化学性质近似的元素,故分析难度较大。本文研究了应用纸色层法和离子选择性电极法对铈硼硅石中某些主要成分和微成分的分离和测定条件,设计了较合理的铈硼硅石微量全分析流程。该流程也适合类似矿物的分析,与常法比较,本法具有快速、准确、成本低和用样少等优点。 相似文献
198.
本文报道的纤碳铀矿产于湖南某花岗岩型铀矿床氧化带中。纤碳铀矿是一种铀酰碳酸盐矿物,在中国是首次发现。本文作了系统的矿物研究并与国外资料作了对比。 相似文献
199.
米仓山碱性岩中的主要矿物为富铝的(次硅)铝铁质透辉石、钙质角闪石、霞石等,且大量出现霞石,但无或极少有碱性暗色矿物。研究表明:氧逸度低是碱性岩浆不能结晶出碱性暗色矿物的原因。本区这种无碱性暗色矿物的碱性岩是在封闭体系及深成条件下结晶的,而其它地区含有碱性暗色矿物的岩石则是在开放体系中形成的。 相似文献
200.
Mineral composition variation in Alpine Schist, Southern Alps, New Zealand: Implications for recrystallization and exhumation 总被引:1,自引:0,他引:1
Abstract Compositional variation of silicates (plagioclase, K-feldspar, epidote, titanite, garnet, white mica, biotite, chlorite), ilmenite, carbonates (calcite, ankerite) and apatite, in quartzofeldspathic lithologies of the Alpine Schist, New Zealand, is discussed in terms of increasing metamorphic grade and possible isograd-producing reactions. The mineral data, in conjunction with geological considerations, are used to determine polychronous P-T arrays of an early high P/T event (c. 16°C/kb; 5°C/km) overprinted by a lower P/T event (c. 50°C/kb; 15°C/km) that provides an estimation of Mesozoic and Cenozoic exhumation of schist of 11 to 13 km and 19 to 22 km respectively. The effects of possible shear heating and recrystallization to form K-feldspar zone schist near the Alpine Fault is consistent with movement along a mid to lower crustal detachment surface during Cenozoic shortening, and near isothermal exhumation of the schists to form the Southern Alps. 相似文献