珠江口盆地珠一坳陷古近系构造样式分析

研究分析了近年来构造样式的研究现状和新的进展,结合珠江口盆地珠一坳陷张性构造环境下构造发育的特点,建立了利用三维空间构造信息的构造样式划分方案。据此对珠一坳陷的各类构造样式进行了研究。根据盆地(坳陷)结构、断层组合及动力学机制,将珠一拗陷构造样式划分为断块与板式正断层组合构造,断块与铲式正断层组合构造,转换带构造,潜山披覆构造,底辟构造和重力背形构造等6大类13小类。研究还指出了基于构造样式的油气有利聚集部位及勘探方向。     

山东沂南金-铜-铁矿床成矿条件分析——兼论不整合面的控矿作用

山东沂南金-铜-铁矿床中与成矿有关的岩体为燕山期多期次浅成侵入的钙碱性杂岩体,岩性主要为闪长玢岩类和花岗斑岩类,属相对富含硅质、碱质和磁铁矿并通常与氧化型含金矽卡岩有关的侵入岩系列。新元古界一寒武系碳酸盐岩与碎屑岩的频繁互层,为含矿气水热液的运移和顺层交代提供了良好的围岩条件,在靠近岩体接触带部位形成了多层矽卡岩矿体。区域性断裂控制了含矿岩体的侵位,而接触带、捕虏体、层间破碎带以及不整合面等构造控制了矿体的空间定位。成矿在中低压力的中浅成至浅成条件下进行,主成矿阶段的含矿流体具有中高温、高盐度的特点,流体的沸腾可能是金-铜-铁等成矿物质大量沉淀的主要原因。接触带的矽卡岩型Au—Cu—Fe矿化与内接触带的斑岩型Cu—Mo矿化、外接触带的热液充填一交代型Au—Cu矿化,以及岩体边部的隐爆角砾岩型Au—Cu矿化一起,构成了一个中酸性岩浆-热液成矿系统。作为一种容易失稳的构造薄弱带和地球化学屏障,不整合面极易产生破碎和滑脱,从而有利于岩浆及其所分泌的含矿气水热液的贯入和成矿,这是沂南矿床中新发现的一种具有重要找矿前景的控矿构造类型。     

河南省嵩县萑香洼金矿矿床地质特征

萑香洼大型构造蚀变岩型金矿床位于华北陆块南缘华山-熊耳山贵金属-多金属成矿带的东部,区内多期次构造岩浆活动频繁,成矿地质条件优越。矿体受F985主含金构造蚀变带严格控制。矿化作用分为五个阶段,其中钾长石-（金）黄铁矿阶段（Ⅱ）为主要成矿阶段。研究表明该矿床为浅成中低温岩浆期后热液金矿床,最佳成矿温度在180℃～265℃之间,成矿深度范围为0．68km～0．83km。成矿溶液总体以富钠、钙为特点,成矿流体为含卤素和碱质的水溶液,主要属于NaClH2O、CO2～H2O体系,主成矿阶段成矿溶液呈弱酸性,成矿后阶段为弱碱性。由早到晚δ^34S值从较小负值向较大负值变化,具深源硫特征。     

http://www.sciencedirect.com/science/article/pii/S167498711200148X

The Earth was born from a giant impact at 4.56 Ga. It is generally thought that the Earth subsequently cooled, and hence shrunk, over geologic time. However, if the Earth's convection was double-layered, there must have been a peak of expansion during uni-directional cooling. We computed the expansion-contraction effect using first principles mineral physics data. The result shows a radius about 120 km larger than that of the present Earth immediately after the consolidation of the magma-ocean on the surface, and subsequent shrinkage of about 110 km in radius within about 10 m.y., followed by gradual expansion of 11 km in radius due to radiogenic heating in the lower mantle in spite of cooling in the upper mantle in the Archean. This was due to double-layered convection in the Archean with final collapse of overturn with contraction of about 8 km in radius, presumably by the end of the Archean. Since then, the Earth has gradually cooled down to reduce its radius by around 12 km. Geologic evidence supports the late Archean mantle overturn ca. 2.6 Ga, such as the global distribution of super-liquidus flood basalts on nearly all cratonic fragments (>35 examples). If our inference is correct, the surface environment of the Earth must have undergone extensive volcanism and emergence of local landmasses, because of the thin ocean cover (3–5 km thickness). Global unconformity appeared in cratonic fragments with stromatolite back to 2.9 Ga with a peak at 2.6 Ga. The global magmatism brought extensive crustal melting to yield explosive felsic volcanism to transport volcanic ash into the stratosphere during the catastrophic mantle overturn. This event seems to be recorded by sulfur mass-independent fractionation (SMIF) at 2.6 Ga. During the mantle overturn, a number of mantle plumes penetrated into the upper mantle and caused local upward doming of by ca. 2–3 km which raised local landmasses above sea-level. The consequent increase of atmospheric oxygen enabled life evolution from prokaryotes to eukaryotes by 2.1 Ga, or even earlier in the Earth history.     

Discussion of: Development of carbonate platforms on an extensional (rifted) margin: the Valanginian–Albian record of the Prebetic of Alicante (SE Spain), by J.M. Castro et al., Cretaceous Research 29 (2008), 848–860

The original reconstruction (Granier, 1987, and subsequent revisions) of the Early Cretaceous tectono-sedimentary evolution of the northeastern border of the Citrabetic basin in the Alicante province (Spain) was made possible by the integration of sedimentological and palaeontological data. Its findings are based on direct evidence (synsedimentary fractures, reworking, etc.) that differentiates it significantly from the model proposed by Castro et al. (2008). Errors in their analysis of both the sequence and timing of events are corrected. In addition, their negligence with regard to citations of previous work in the region is discussed. In the Citrabetic basin a thick dominantly-siliciclastic wedge developed at the start of the Valanginian, as a consequence of the major transgression that flooded the "Upper Jurassic" carbonate platform. A rift phase occurred later in Valanginian times; the related block-faulting and fracturing persisted up to early Aptian times. At the edges of the blocks and in the starved basins they delimit, the synrift series is characterized by condensed sedimentation (ferruginous oolites, glauconite). This block-faulting initiated the migration of Triassic salts which possibly reached an apogee in Albian times.     

宁夏盐池县萌城矿区含煤地层赋存特征探析

萌城矿区位于宁东煤田的最南端,区内由一系列走向NNW或近SN向的褶皱群及与之相伴的断层组成。通过分析各个勘查区的地质特征,总结了矿区构造特征和含煤地层赋存规律：成煤后期的构造控制了本区含煤地层的赋存;延安组呈南北狭长带状分布存向斜及背斜与断层之间相对凹陷的区域内;含煤地层自北而南不仅赋存面积变小,而且含煤性变筹。位于矿区中部的叶庄子小－沙湾子向斜是萌城矿区含煤面积最大的赋煤构造,含煤面积约56km^2。     

Deformational history of the Precambrian Kolar Schist Belt,South India: Constraints for the tectonic evolution

In the Kolar Schist Belt well-preserved small-scale diastrophic structures suggest four phases of folding (F₁ — F₄). The near coaxial F₁ andF ₂folds are both isoclinal with long-drawn out limbs and sharp hinges. The axial planes of bothF ₁andF ₂folds are subvertical with N-S strikes; these control the linear outcrop pattern of the Schist belt. The later folds (F ₃and F₄) are important in small-to-intermediate scales only and are accommodation structures formed during the relaxation period of the early folding episodes. Mesoscopic shear zones, post-F₂ but pre-F₃ in age, are present in all the rock types in this area. The F₁ and F₂ folds and the mesoscopic shear zones were formed during a continuous E-W subhorizontal compression. Available geochemical and isotopic data show that the Kolar Schist Belt with ensimatic setting is bounded by two granitic terrains of contrasting evolutionary histories. This, together with E-W subhorizontal compression over a protracted period of time, strengthens the recent suggestions that the Kolar Schist Belt represents a suture. This belt then marks the site of a continent-continent collision event of late Archaean-early Proterozoic age.     

低地应力区碎裂结构围岩基本特征研究

以某市引水工程地下洞室围岩为例 ,采取试验样品若干件 ,分别做了围岩的平均化学成分与百分含量衍射以及电镜扫描分析 ,并得到了相应的结果。在此基础上 ,从成分和微观结构两方面入手 ,总结出低地应力区碎裂结构围岩组成与显微结构方面的特征和变化规律 ,初步探讨了低地应力区碎裂结构围岩微观变形特征 ,这为进一步研究低地应力区围岩宏观变形破坏及其稳定性等方面 ,将会起到重要的理论指导作用     

塔里木盆地阿瓦提—满加尔低梁构造特征和形成演化

阿瓦提－满加尔低梁是介于阿瓦提凹陷与满加尔凹陷之间一个特殊的隆起构造，其在东西向上表现为宽缓的隆起形态，而在南北方向上则为凹陷面貌。该区沉积盖层可分为下、中、上3个构造层。下构造层由震旦系－泥盆系构成，所谓阿－满低梁主要即发育于该构造层。上构造层由白垩系－第四系构成，构造形态为－北西倾斜坡。由石炭系－三叠系构成的中构造层则是上、下构造层构造形态的过渡，总体上仍呈西北倾。阿－满低满自前震旦纪末塔里木运动以来经历了4大演化发展阶段：震旦纪－泥盆纪阿－满低梁形成发育阶段、石炭纪－三叠纪阿－满低梁改造阶段、侏罗纪－早第三纪北东倾斜坡发育阶段与晚第三纪－第四纪现今构造形成阶段。     

辽西阜新金-多金属成矿区主要断裂带构造特征及其控矿作用

通过地质构造、显微构造和构造地球化学特征分析,论述了辽西阜新金-多金属成矿区主要断裂带的构造特征及其控矿作用,并着重指出NEE向、NNE向韧-脆性剪切带是本区主要的控矿和导矿构造,而NEE向构造的NW向次级断裂带和NNE向构造的EW向次级断裂带则为本区主要的容矿构造.现已探明的金-多金属矿体也多沿这两个方向展布.