新疆东昆仑白干湖钨地球化学块体的确立及意义

新疆东昆仑是我国西部地质工作程度较低地区之一,白干湖钨地球化学块体的确定及白干湖钨锡矿床的发现成为该区矿产勘查中突破性的进展.文章概述了白干湖钨地球化学块体的地质、矿产及地球化学特征.对该块体与成矿的关系进行了探讨,认为钨地球化学块体为白干湖钨锡矿床的形成提供了丰富的成矿物质,钨的成矿与岩浆的演化有着密切的成因关系.指出白干湖钨锡矿床有望成为超大型矿床,新疆东昆仑地区有望成为我国一个新的钨矿远景区和新的钨矿产区.     

东昆仑祁漫塔格地区白干湖钨锡矿床成矿作用探讨

近年来,东昆仑祁漫塔格地区与花岗岩有关的钨锡找矿取得重大突破,相继发现了具有大型远景的白干湖钨锡矿床、戛勒赛钨锡矿床等,受到地质学者的广泛关注。以往对白干湖矿床的成矿地质背景(李洪茂等,2006)、矿床地质特征(邢延安等,2004;时友东等,2004;李洪茂等,     

新疆东昆仑成矿带找矿潜力分析

新疆东昆仑成矿带是我国地质工作程度较低的地区之一,在近年矿产勘查中发现了白干湖钨锡矿床等矿床(点)47处,圈定1:5(10)万水系沉积物异常114处,并确立了该区属钨的地球化学块体.在成矿地质背景分析的基础上,对白干湖钨锡矿床、喀拉曲哈铜矿床和克孜勒金矿床等典型矿床特征进行了讨论,对区域找矿潜力和白干湖钨锡矿床的找矿潜力进行了分析.结果表明,该成矿带钨锡金铜等矿产找矿潜力巨大,并将成矿带划分为4处成矿远景区和18处成矿预测区.白干湖钨锡矿床有望成为超大型矿床.     

新疆东昆仑白干湖钨锡矿床地球化学特征

本文简单地介绍了新疆白干湖钨锡矿床的地质特征,重点介绍了白干湖钨锡矿床1/10万地球化学特征和1/1万岩屑异常特征,其中包括异常面积、峰值、衬度、异常形态、NAP值、浓度分带等。     

新疆白干湖地区柯可卡尔德钨、锡矿床找矿模型

新疆白干湖钨锡矿田由吉林省地质调查院于2000年发现,该矿田包括三个矿床,其中的柯可.卡尔德钨、锡矿床于2006年首先转入勘探,笔者参考该矿床的地质勘探中间报告及1/5万矿产远景调查资料,分析了该区钨锡矿产的控矿条件、找矿标志等信息,建立了柯可.卡尔德钨、锡矿床的找矿模型。     

新疆东昆仑白干湖钨锡矿床矿段地质特征

白干湖钨锡矿床是东昆仑西段黑山—祁漫塔格钨锡成矿带中的一个特大型矿床,其中 矿段是新发现的矿段,仅 矿段就可构成大型的钨锡矿床。本文重点介绍了 矿段的地质特征,并对矿床成因进行了探讨,同时介绍了该区钨锡矿床的找矿标志。     

新疆东昆仑白干湖钨锡矿床Ⅲ矿段地质特征

白干湖钨锡矿床是东昆仑西段黑山—祁漫塔格钨锡成矿带中的一个特大型矿床,其中Ⅱ矿段是新发现的矿段．仅Ⅱ矿段就可构成大型的钨锡矿床。本文重点介绍了Ⅱ矿段的地质特征,并对矿床成因进行了探讨．同时介绍了该区钨锡矿床的找矿标志。     

新疆白干湖钨锡矿床简介

介绍了白干湖钨锡矿床地质特征、含矿围岩特征、矿体类型及各类型特点,确定了围岩蚀变类型及分带现象,指出了硅化、电气石化、金属硫化物矿化是寻找钨、锡矿的找矿标志。最后探讨了矿床成因,展望了发现该矿床的意义。     

新疆东昆仑白干湖钨锡矿床地质特征

白干湖钨锡矿床赋存在古元古界金水口群变质岩系中,矿体受北东向白干湖断裂带控制,加里东期酸性侵入岩与矿床关系密切.区内是钨元素地球化学高背景区,在各类地质体钨元素富集系数为9.57~25.30.目前共发现17条矿体,矿石类型为夕卡岩型白钨矿和石英脉型黑钨矿.矿床类型为沉积变质岩浆再造型钨锡矿床.     

新疆白干湖柯可·卡尔德钨锡矿控矿构造及成矿流体特征

位于新疆若羌县境内、东昆仑祁漫塔格山西段向北凸出的弧形转弯处的白干湖钨锡矿田是近年在我国西部地区勘查发现的一处具超大型远景规模的矿田,包括柯可.卡尔德、白干湖、巴什.尔希和阿瓦尔4个矿床。其中,柯可.卡尔德钨锡矿床勘查程度最高、规模最大,钨金属量达20余万吨,WO3平均品位0.29%,本文重点以其为对象开展控矿构造和流体包裹体特征     

Effectiveness of various dispersed alkaline substrates for the pre-treatment of ferriferous acid mine drainage

Dispersed alkaline substrates (DAS) have been successfully used in passive treatment of highly contaminated acid mine drainage (AMD) to limit coating and clogging issues. However, further optimization of DAS systems is still needed, especially for their long-term efficiency during the treatment of ferriferous AMD. In the present study, three types of DAS comprised of natural alkaline materials (wood ash, calcite, dolomite), in different proportions (20%v/v, 50%v/v, 80%v/v), and a substrate with high surface area (wood chips) were tested in 9 batch reactors. The testing was carried out, in duplicate, for a period of 91 days, to evaluate the comparative performance of the mixtures for iron pre-treatment in ferriferous AMD (2500 mg/L Fe, at pH 4). Results showed increasing of pH (between 4.15 and 7.12), regardless of the proportion of alkaline materials in the DAS mixtures. Among the tested mixtures, wood ash type DAS were more effective for Fe removal (99.9%) than calcite or dolomite type DAS (up to 66%). All tested DAS had limited efficiency for sulfate removal and an additional treatment unit, such as a sulfate-reducing biochemical reactor, is needed. Moreover, due to the similar performances of the calcite and dolomite DAS, they could be potentially substituted and rather be used in a polishing treatment unit. Based on these findings, the most promising mixture was the 50% wood ash type DAS (WA50-DAS).     

The structural preservation of a titanosaurid (Dinosauria: Sauropoda) vertebral ligament

Within the past decade exceptional preservation of original organic components have been reported from several dinosaurian families, including members of Sauropodomorpha. Here we document the partial preservation of a vertebral ligament in the dorsal and sacral series of a titanosaur. Unlike other cases of tissue preservation, this structure does not represent biomineralization of the original organic components. Histology, morphology, and comparative anatomy from extant taxa as well as the preferential placement on the vertebral column suggests that it represents the partial preservation of the nuchal ligament. While preservation of other sauropod connective tissues are known, this case represents the first reported non-biomineralized tissue from a sauropod. In consideration of the location and external and internal morphologies compared to modern vertebral ligaments, we believe this structure to be the micritic replacement of the original tissue via microbially-mediated processes. Along with the suggestive external morphology, internally we interpret some of the unusual structures to represent the remnants of the collagen and elastin fascicles that are strongly overprinted by a clotted, thrombolytic-like fabric recording microbial activity and deposition of micrite prior to lithification. In consideration of the interpreted depositional history, we theorize that post-deposition, bacteria deposited the micrite as a byproduct of metabolization. Subsequently, the recognition of this structure as a vertebral ligament, the largest of such thus documented, substantiates previous findings on the morphological attributes of sauropod vertebral ligaments.     

Emplacement of the La Peña alkaline igneous complex,Mendoza, Argentina (33° S): Implications for the early Miocene tectonic regime in the retroarc of the Andes

The La Peña alkaline complex (LPC) of Miocene age (18–19 Ma) lies on the eastern front of the Precordillera (32°41ʹ34ʺS, 68°59ʹ48″W, 1400–2900 m a.s.l.), 30 km northwest of Mendoza city, Argentina. It is a subcircular massif of 19 km² and 5 km in diameter, intruded in the metasedimentary sequence of the Villavicencio Formation of Silurian-Devonian age. It is the result of integration of multiple pulses derived from one or more deep magma chambers, which form a suite of silicate rocks grouped into: a clinopyroxenite body, a central syenite facies with a large breccia zone at the contact with the clinopyroxenite, bodies of malignite, trachyte and syenite porphyry necks, and a system of radial and annular dikes of different compositions. Its subcircular geometry and dike system distribution are frequent features of intraplate plutons or plutons emplaced in post-orogenic settings. These morphostructural features characterize numerous alkaline complexes worldwide and denote the importance of magmatic pressures that cause doming with radial and annular fracturing, in a brittle country rock. However, in the LPC, the attitude of the internal fabric of plutonic and subvolcanic units and the preferential layout of dikes match the NW–SE extensional fractures widely distributed in the host rock. This feature indicates a strong tectonic control linked to the structure that facilitate space for emplacement, corresponding to the brittle shear zone parallel to the N–S stratigraphy of the country rock. Shearing produced a system of discontinuities, with a K fractal fracture pattern, given by the combination of Riedel (R), anti-Riedel (R′), (P) and extensional (T) fracture systems, responsible for the control of melt migration by the opening of various fracture branches, but particularly through the NW–SE (T) fractures. Five different pulses would have ascent, (1) an initial one from which cumulate clinopyroxenite was formed, (2) a phase of mafic composition represented by dikes cross-cutting the clinopyroxenite, (3) a malignite facies that causes a small breccia in the clinopyroxenite, (4) a central syenite facies that develops breccias at the contact with the clinopyroxenite and, finally, (5) porphyry necks and a system of radial dikes intruding all units. At the moment of the emplacement different mechanisms would have acted, they summarized in: 1) opening of discontinuities synchronous to the magma circulation as the principal mechanism for formation of dikes and conduits; 2) stoping processes, that play an important role in the development of the breccia zone and enabling an efficient transference of material during the emplacement of the syenitic magma and 3) shear-related deformation (regional stress), affected the internal fabric of the facies, causing intracrystalline deformation and submagmatic flow, which is very evident in the central syenite intrusive. The kinematic analysis of shear planes allows proposing that emplacement of the LPC took place in a transtensive regime, which would have occurred in the back-arc of the Andes orogen, during a long period spanning from Miocene to the present, of the compressive deformation responsible, westward and at the same latitude, for the development of the Aconcagua fold and thrust belt.     

A new tribe,new genus,and new species of Mordellidae (Coleoptera: Tenebrionoidea) from the Early Cretaceous amber of Spain

The new tribe Mediumiugamiini (Coleoptera: Polyphaga: Tenebrionoidea: Mordellidae) is described based on Mediumiuga sinespinis gen. et sp. nov. It is a fossil beetle from Albian (Early Cretaceous) amber from the Peñacerrada I outcrop (Spain). It is the first Spanish beetle described in amber. The mesotibiae and mesotarsi bearing multiple dorsal–lateral ridges, running oblique, metatibiae without any dorsal or dorsal–lateral ridge, only showing a subapical ridge, and metatibiae without apical spurs, define the new tribe. A key for worldwide tribes of Mordellinae, including Mediumiugamiini, is provided. Evolution of some characters of Mordellidae along Cretaceous is discussed.     

The persistence and role of basin structures on the 3D architecture of the Marañón Fold-Thrust Belt,Peru

The 3D architecture of fold-thrust belts commonly involves thin-skinned and thick-skinned deformation. Both thick- and thin-skinned deformation styles have been suggested to occur in the Marañón Fold-Thrust Belt (MFTB) in Peru, but the relative timing and strain partitioning associated with them are not well understood. We demonstrate that inherited basement structures along the Peruvian convergent margin reactivated during the evolution of the MFTB. We present results from field mapping, interpretation of remote sensing imagery, and cross section construction and restoration. The results show that the Chonta Fault, a median pre-folding basin normal fault, was inverted and acted as a mechanical buttress during initial east-vergent contraction of the fold-thrust belt. This fault separates the belt into two domains of distinctly different structural styles. During the Eocene, units to the west of the Chonta Fault deformed by folding, using the fault as a buttress, and subsequently propagated eastward by thin-skinned thrusting. This was followed in the Miocene by west-vergent, basement-involved deformation, which overprinted the earlier east-vergent, thin-skinned structures. The proposed tectonic model of the MFTB highlights the role of basement-fault reactivation during orogenesis and the involvement of deep structures in partitioning deformation styles.     

A densely feathered ornithomimid (Dinosauria: Theropoda) from the Upper Cretaceous Dinosaur Park Formation,Alberta, Canada

A recently discovered articulated partial skeleton of Ornithomimus from the Upper Cretaceous Dinosaur Park Formation of Alberta, Canada is remarkable in the extent and quality of preservation of integumentary structures including feathers. It is the first ornithomimid to preserve a tail bearing extensive plumaceous feathers that are slightly more elongate in comparison to those present on the remainder of the body. However, the underside of the tail and the hind limb distal to the middle of the femur appear devoid of plumage. Overall, the plumage pattern in Ornithomimus is similar to that of Struthio camelus (ostrich) and other large palaeognaths, indicating a probable function in thermoregulation. The specimen also preserves the body outline around the legs, including a skin contour anterior to the femur, analogous to skin webs in extant birds. Whereas the knee web of birds bridges the knee to the abdomen, in Ornithomimus it spans from the mid-femoral shaft to the abdomen, and is herein referred to as an anterior femoral web. This is the first report of such soft tissue structures in non-avian theropods. It may indicate that the resting position of the femur was positioned more anteroventrally in ornithomimids than in most theropods, and in that sense may have been transitional to the situation in modern birds.     

3S技术在土地利用中的应用

针对目前我国土地普遍存在的土地环境问题、原生土地问题、次生土地土地问题和社会土地问题,提出了应用“3s”技术进行辅助决策,以解决这些问题。     

Cretaceous amber inclusions of Spain and Myanmar demonstrate early diversification and wide dispersal of Cephenniitae (Coleoptera: Staphylinidae: Scydmaeninae)

The taxonomic status of previously misplaced species of an ant-like stone beetle from Spanish amber (Albian) is clarified. Specimens of Kachinus magnificus (originally placed as incertae sedis within Scydmaenitae) were re-examined and their characters were found different from those of the type species of Kachinus from Myanmar amber. Consequently, Archeutheia gen. nov. is proposed to accommodate the Spanish species, resulting in Archeutheia magnifica comb. nov. Moreover, in a comprehensive phylogenetic analysis Archeutheia was placed as a sister group to extant Eutheia, within the tribe Eutheiini of Cephenniitae. A specimen of an undetermined genus from Myanmar amber clearly belonging in Cephenniini is also recorded. Both taxa represent the first definite Cretaceous Cephenniitae, a supertribe whose recent members are distributed on all continents but are especially diverse in the Oriental and East Palaearctic regions. This finding demonstrates a diversification of two presently most species-rich tribes of Cephenniitae already in Early Cretaceous. Archeutheia is strikingly similar to the extant species of Eutheia and Veraphis, showing male dimorphic characters (modified protrochanters) and antennal cavities characteristic of Palaearctic Eutheiini. This fact suggests a long morphological stability in the supertribe. A previously proposed hypothesis of an early presence of the Cephenniitae in the Northern Hemisphere is for the first time supported by the fossil record, and the palaeolocalities (western Europe and Southeast Asia) demonstrate a wide distribution of Cephenniitae in the Cretaceous and an early split of its ancestral lineage.     

A ceratopsian dinosaur from the Late Cretaceous of eastern North America,and implications for dinosaur biogeography

Tyrannosaurs and hadrosaurs from the Late Cretaceous of eastern North America (Appalachia) are distinct from those found in western North America (Laramidia), suggesting that eastern North America was isolated during the Late Cretaceous. However, the Late Cretaceous fauna of Appalachia remains poorly known. Here, a partial maxilla from the Campanian Tar Heel Formation (Black Creek Group) of North Carolina is shown to represent the first ceratopsian from the Late Cretaceous of eastern North America. The specimen has short alveolar slots, a ventrally projected toothrow, a long dentigerous process overlapped by the ectopterygoid, and a toothrow that curves laterally, a combination of characters unique to the Leptoceratopsidae. The maxilla has a uniquely long, slender and downcurved posterior dentigerous process, suggesting a specialized feeding strategy. The presence of a highly specialized ceratopsian in eastern North America supports the hypothesis that Appalachia underwent an extended period of isolation during the Late Cretaceous, leading the evolution of a distinct dinosaur fauna dominated by basal tyrannosauroids, basal hadrosaurs, ornithimimosaurs, nodosaurs, and leptoceratopsids. Appalachian vertebrate communities are most similar to those of Laramidia. However some taxa-including leptoceratopsids-are also shared with western Europe, raising the possibility of a Late Cretaceous dispersal route connecting Appalachia and Europe.     

A simple procedure to simulate a smooth elastic-plastic transition in Cam-Clay models

A simple procedure is proposed to simulate a smooth transition from elastic to elastoplastic behaviour in Cam-Clay models. The procedure consists of the definition of an external constitutive surface where full yield is assumed, and an internal one that allows the definition of the position in which plastic strains start to appear before the external yield surface is reached. The comparison of the model results with different laboratory tests shows the validity of the procedure. The method considers one additional parameter with regard to a “standard” critical state model, and it can easily be implemented in existing integration modules.