华北陆台北缘前寒武纪基底构造与陆台演化

华北陆台北缘“基底”是由不同时代,不同特征的独立的构造单元组成的。它们原岩主体是以花岗质为主的深成侵入杂岩,层状岩石呈不同尺度的包体包裹在其中,这些构造单元是由构造原因,依一定的时空序列拼贴在一起的。     

扬子板块西南部古元古代岩浆及变质事件——兼论扬子板块对Nuna超大陆事件的响应

寻找扬子板块西南地区古老结晶基底一直是众多地质学者追寻的目标,其涉及扬子板块在Nuna超大陆重建中的位置和演化过程,也是前寒武纪研究的重要课题。继在扬子板块西南部中国云南石屏撮科村首次报道2.35Ga花岗片麻岩结晶基底后,又在撮科村—高家坡一带3个花岗岩样品中分别获得了2347.3±4.9Ma、2324.3±8.6Ma和2329.4±5.9Ma的SHRIMP锆石U-Pb年龄,进一步确认扬子板块西南部中国境内存在2.32～2.35Ga的岩浆事件,其应为Nuna超大陆汇聚期Arrowsmith造山事件在扬子板块的响应。另在1件糜棱岩化花岗闪长岩样品中获得了1909.8±5.7Ma和1843.1±7.6Ma两组年龄,在扬子板块西南部中国境内首次发现1.90Ga和1.84Ga的构造或变质事件。结合前人研究成果,确定扬子板块西南部存在2.91～2.84Ga,2.36～2.32Ga,2.28～2.19Ga的岩浆事件,以及1.97～1.95Ga,1.90Ga,1.84～1.83Ga的变质事件,为确定扬子板块在Nuna超大陆重建中的位置提供了更多证据。     

吉林延边地区斑岩型－浅成热液型金铜矿床

吉林延边地区为我国滨太平洋带的一个重要的金属成矿区。与中生代火山－次火山侵入活动有关的斑岩型。浅成热液型矿床在时空上、成因上构成一个成矿系列。本文选择四个代表性矿床（小西南岔、闹枝、五凤和刺猬沟），较详细地介绍它们的成矿地质背景、矿床地质特征、流体包裹体、稳定同位素及成矿机制等。通过这些矿床的描述，勾画出一幅从中生代火山盆地边缘的隆起带的斑岩型矿床（小西南岔）→中生代火山盆地内部的断隆块的斑岩－浅成热液过渡型矿床（闹枝）→中生代火山盆地内部断裂带的浅成热液型矿床（五凤和刺猬沟）的全景。     

准南前陆冲断带构造分段及其与油气关系

通过大量地面地质、地震和非地震资料的综合解释,分析了准南前陆冲断带的构造分段特征.认为乌鲁木齐-米泉断裂和红车断裂等盆内大型基底断裂是控制构造分段的主要因素,其形成演化决定了构造分段特征的出现或消失;盆缘调节构造是造成次级构造分段的主要原因.准南前陆冲断带构造分段对该区主要烃源岩与生储盖组合的形成及分布、对油气成藏期等方面具有重要的控制作用.     

塔里木盆地前寒武地层岩石磁化率

在塔里木盆地前寒武结晶基底研究过程中,为了准确建立地层地磁模型,对库鲁克塔格地区岩浆岩、柯坪地区沉积岩、塔什库尔干地区变质岩地层进行系统取样及岩石薄片鉴定和准确命名,并测量岩石密度、磁化率.研究发现:①库鲁克塔格地区:基性、超基性岩蛇纹石化析出磁铁矿,磁化率剧烈变化,而中、酸性侵入岩磁化率随黑云母含量增加而增大;②柯坪...     

辽宁结晶基底斜长角闪岩地球化学特征

辽宁结晶基底斜长角闪岩为贫碱低铝型斜长角闪岩,从鞍山期至辽河期斜长角闪岩基性度循序增高,主元素地球化学模型显示基底层和幔岩层之间的过渡特点。鞍山群斜长九闪岩微量元素主要分3大群;辽河群斜长角闪岩微量元素分2大群。其原岩主要为基性岩浆岩,少数为钙泥质沉积岩。该类岩石为 Ag、Co、Cu、Zn、Au 等成矿元素的主要荷载岩石。     

Garnet Sm–Nd data from the Saualpe and the Koralpe (Eastern Alps, Austria): chronological and P–T constraints on the thermal and tectonic history

Garnets from recrystallized, staurolite- and kyanite-bearing mica schists from the central Saualpe basement, representing the host rocks of the type-locality eclogites, give concordant Sm–Nd garnet–whole-rock isochron ages between 88.5±1.7 and 90.9±0.7 Ma. The millimetre-sized, mostly inclusion-free grains show fairly homogeneous element profiles with pyrope contents of 25–27%. Narrow rims with an increase in Fe and Mn and a decrease in Mg document minor local re-equilibration during cooling. According to phengite geothermobarometry, peak metamorphic conditions at 90 Ma were close to 20  kbar and 680  °C and similar to those recorded by the eclogites. The garnet rims record about 575  °C/7  kbar for the final stages of metamorphism. A phengitic garnet–mica schist, sampled at the immediate contact with the Gertrusk eclogite, gave a garnet–whole-rock Sm–Nd age of 94.0±2.7 Ma.
Garnet porphyroclasts separated from a pegmatite–mylonite of the Koralpe plattengneiss near Stainz are unzoned and show spessartine contents of 15%. Composition and Sm–Nd ages of close to 260 Ma point to a magmatic origin for these garnets.
The garnet data from the Saualpe document an intense Alpine metamorphism for this part of the Austroalpine basement. The mica schists recrystallized during decompression and rapid exhumation, at the final stages of and immediately following a high- P event. The Koralpe data show that high Alpine temperatures did not reopen the Sm–Nd isotope system, implying a closure temperature in excess of c . 600  °C for this isotopic system in garnet.     

南秦岭隆滑构造

在南秦岭,发生于加里东─—海西期的隆滑构造,由基底杂岩、滑覆层状岩系和其之间的滑脱构造带组成。它是主选山期前,在盆地演化过程中,由地慢上隆,导致基底减压深熔,并局部隆起,并引起上覆层状岩系分层滑脱所形成的一套地质要素组合。它与形成于主造山以后的“变反核条岩”在造山带演化过程的动力学意义有着本质的区别。     

The effectiveness of “clay” liners as basal isolation of landfills: a case study

A sodium bentonite is being used in the basal-isolation of landfills installed on strongly fractured granitic rocks of N Portugal (NW Iberia). To evaluate the performance of this clay as the ultimate impermeable basal barrier, a detailed study was carried out of the granite fracture network; the Na-bentonite was tested to characterize its mechanical and geotechnical behavior; geophysical surveys were made to search for landfill leakage and the waters found around the landfill were geochemically characterized. Fractures in the granite are usually open and devoid of mineral infillings or clay materials and, thus, permeability of the granite is very high. Dispersal of contaminants can be further enhanced by the position of the landfill on a high steep-sided ridge. Geophysical and geochemical data show evidence for seepage and dispersion of pollutants, which means that the clay failed as an ultimate isolation barrier against seepage. This investigation shows that this can be due to fracturing of the clay under load and/or to its non-homogeneous saturation and extreme shrinking character upon drying, which are accompanied by the formation of extensive cracking. Observations and experimental results suggest that the use of synthetic clays in the safe building of landfill bottom liners needs further research, and extreme care should be taken in preventing that clay water content suffers large variations after saturation, as this process considerably degrades the mechanical behavior and sealing properties of the studied Na-bentonite.