钢管土钉结合压密注浆在深厚杂填土基坑中的应用     

王涛  ;闫振环 《岩土工程技术》2014,(3):160-162

通过工程实例,介绍了一种在深厚杂填土基坑中运用钢管土钉结合压密注浆技术的围护方法,对钢管土钉及压密注浆的设计及施工作了详细说明。监测结果表明,该支护方法可以有效控制基坑变形,确保基坑及地下结构施工期的安全,为类似条件的基坑围护工程提供借鉴。  相似文献   

山东省沂源县金星头勘查区地质地球化学特征及找矿前景分析     

谢颂诗  宁振国  颜晓莉  马喻宏  王立功 《山东地质》2014,(5):23-27,36

山东省沂源县金星头地处沂源-沂南金及多金属成矿带北部,该成矿带位于中国东部矽卡岩金多金属矿带中北部,属于环太平洋带组成部分。通过对该区的地质、地球化学特征等分析,运用1∶1万土壤地球化学测量方法,发现了一批以Au为主的化探异常,对部分异常运用岩石地球化学测量和探槽进行查证,发现具有工业品位的金铜矿（化）体5处,提出下一步找矿的工作重点地段,即在中生代燕山晚期中偏碱性或中酸性侵入杂岩体与寒武纪朱砂洞组、馒头组白云岩、灰岩等接触部位及两侧寻找接触交代型（矽卡岩）金铜矿床。  相似文献   

Petrochemistry of ultrapotassic tephrites and associated cognate plutonic xenoliths with carbonatite affinities from the late Quaternary Qa’le Hasan Ali maars,central Iran     

《Journal of Asian Earth Sciences》2014

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The mafic–ultramafic complex of Aniyapuram,Cauvery Suture Zone,southern India: Petrological and geochemical constraints for Neoarchean suprasubduction zone tectonics     

《Journal of Asian Earth Sciences》2014

Several Precambrian mafic–ultramafic complexes occur along the Cauvery Suture Zone (CSZ) in Southern Granulite Terrain, India. Their origin, magmatic evolution and relationship with the associated high-grade rocks have not been resolved. The Aniyapuram Mafic–Ultramafic Complex (AMUC), the focus of the present study in southern part of the CSZ, is dominantly composed of peridotites, pyroxenites, gabbros, metagabbros/mafic granulites, hornblendites, amphibolites, plagiogranites, felsic granulites and ferruginous cherts. The rock types in the AMUC are structurally emplaced within hornblende gneiss (TTG) basement rocks and are highly deformed. The geochemical signature of the amphibolites indicates tholeiitic affinity for the protolith with magma generation in island arc-setting. N-MORB normalized pattern of the amphibolites show depletion in HFS-elements (P, Zr, Sm, Ti, and Y) and enrichment of LIL-elements (Rb, Ba, Th, Sr) with negative Nb anomalies suggesting involvement of subduction component in the depleted mantle source and formation in a supra-subduction zone tectonic setting. Our new results when correlated with the available age data suggest that the lithological association of AMUC represent the remnants of the Neoarchean oceanic lithosphere.  相似文献   

Early Paleozoic tectonic evolution of the Xing-Meng Orogenic Belt: Constraints from detrital zircon geochronology of western Erguna–Xing’an Block,North China     

《Journal of Asian Earth Sciences》2014

To better constrain the Early Paleozoic tectonic evolution of the western part of the Erguna–Xing’an Block, detrital zircon U–Pb dating was applied on the Ordovician to Devonian sedimentary strata along the southeast part of the China–Mongolia border. Most of the zircons from five sedimentary samples display fine-scale oscillatory growth zoning and Th/U ratios higher than 0.1, indicating a magmatic origin. All five Ordovician–Devonian samples display the similar age distribution patterns with age groups at ∼440 Ma, ∼510 Ma, ∼800 Ma, ∼950 Ma, and few Meso- to Paleo-Proterozoic and Neoarchean grains. This age distribution pattern is similar to those from adjacent blocks in the southeastern Central Asian Orogenic Belt. Considering previous tectonic studies, we propose bidirectional provenances from the Erguna–Xing’an Block and Baolidao Arc.Consequently, a new model was proposed to highlight the Early Paleozoic tectonic evolution of the western Erguna–Xing’an Block, which constrains two main Early Paleozoic tectonic events of the Xing-Meng Orogenic Belt: (a) pre-Late Cambrian collision between Erguna–Kerulen Block and Arigin Sum-Xilinhot-Xing’an Block; (b) the Early Paleozoic subduction of Paleo-Asian Ocean and pre-Late Devonian collision between Erguna–Xing’an Block and Songliao-Hunshandake Block.  相似文献   

Mid–Late Triassic metamorphic event for Changhai meta-sedimentary rocks from the SE Jiao–Liao–Ji Belt,North China Craton: Evidence from monazite U–Th–Pb and muscovite Ar–Ar dating     

《Journal of Asian Earth Sciences》2014

The precise constraints on the timing of metamorphism of the Changhai metamorphic complex is of great importance considering the prolonged controversial issue of the north margin and the extension of the Sulu–Dabie HP–UHP Belt. While the monazite U–Th–Pb and muscovite ⁴⁰Ar/³⁹Ar techniques are widely accepted as two of the most powerful dating tools for revealing the thermal histories of medium–low grade metamorphic rocks and precisely constraining the timing of metamorphism. The Changhai metamorphic complex at the SE Jiao–Liao–Ji Belt, North China Craton consists of a variety of pelitic schist and Grt–Ky-bearing paragneiss, and minor quartzite and marble. Analyses of mineral inclusions and back-scattered electric (BSE) images of monazites, combined with LA–ICP–MS U–Th–Pb ages for monazites and ⁴⁰Ar/³⁹Ar ages for muscovites, provide evidence of the origin and metamorphic age of the Changhai metamorphic complex. Monazites separates from various Grt–Mus schists and Grt–Ky–St–Mus paragneisses exhibit homogeneous BSE images from cores to rims, and contain inclusion assemblages of Grt + Mus + Qtz ± Ctd ± Ky in schist, and Grt + Ky + St + Mus + Pl + Kfs + Qtz inclusions in paragneiss. These inclusion assemblages are very similar to matrix minerals of host rocks, indicating they are metamorphic rather than inherited or detrital in origin. LA–ICP–MS U–Th–Pb dating reveals that monazites of schist and paragneiss have consistent ²⁰⁶Pb/²³⁸U ages ranging from 228.1 ± 3.8 to 218.2 ± 3.7 Ma. In contrast, muscovites from various schists show slightly older ⁴⁰Ar/³⁹Ar plateau ages of 236.1 ± 1.5 to 230.2 ± 1.2 Ma. These geochronological and petrological data conclude that the pelitic sediments have experienced a metamorphic event at the Mid–Late Triassic (236.1–218.2 Ma) rather than the Paleoproterozoic (1950–1850 Ma), commonly regarded as the Precambrian basement for the Jiao–Liao–Ji Belt. Hence, the Changhai metamorphic complex should be considered as a discrete lithotectonic group.This newly recognized Mid–Late Triassic metamorphic event (236.1–218.2 Ma) for the Changhai metamorphic complex is coeval with the HP–UHP metamorphic event (235–220 Ma) for Sulu–Dabie rocks. This leads us to speculate that the metamorphism of the Changhai complex belt along the SE margin of the North China Craton was genetically related to the Mid–Late Triassic collision of the North China and South China cratons. By the same token, the Sulu–Dabie HP–UHP Belt may have extended through Yantai, and the southern Yellow Sea, and to the southern side of the Changhai metamorphic complex.  相似文献   

Geochronology,geochemistry and Hf isotope of Late Triassic magmatic rocks of Qingchengzi district in Liaodong peninsula,Northeast China     

《Journal of Asian Earth Sciences》2014

The initiation timing and mechanism of lithospheric thinning of the North China Craton (NCC) was still controversial. Late Triassic igneous rocks especially mantle derived mafic rocks would provide constrains on Early Mesozoic lithospheric mantle geodynamics and initiation of lithospheric thinning. This paper reports Late Triassic magmatic rocks, including lamprophyre, diorite dykes and biotite monzogranite cropped out in Qingchengzi district of Liaodong peninsula, northeastern NCC. LA–ICPMS zircon U–Pb dating yield ages of 210–227 Ma and 224 Ma for lamprophyres and biotite monzogranite respectively. Lamprophyre is ultrapotassic, strongly enriched in REE and LILEs, depleted in HFSEs, and negative Hf isotopes, which are discriminating signatures of crustal source, but distinguishingly high compatible element contents indicate the primary magma originated from mantle source—a fertile one. Lamprophyre derived from partial melting of an enriched lithospheric mantle, which was modified by slab-derived hydrous fluids/melts associated with deep subduction between the Yangtze Craton and the NCC. The diorite displays distinct features with relatively enriched Nb, Ta, HREE and depleted Th, U, which suggest it derived from a relatively depleted source. The depletion was caused by break-off of the Yangtze slab during deep subduction introducing asthenospheric mantle into the source. The biotite monzogranite shows adakitic affinity, and originated from partial melting of the thickened lower crust with addition of small proportion of mantle material. The recognition of Late Triassic magmatism implies extensional tectonic settings in Liaodong peninsula and suggests initiation of lithospheric thinning of North China Craton in eastern segment might begin early in Late Triassic.  相似文献   

Geochronology,geochemistry, and mineralization of the granodiorite porphyry hosting the Matou Cu–Mo (±W) deposit,Lower Yangtze River metallogenic belt,eastern China     

《Journal of Asian Earth Sciences》2014

Porphyry and skarn Cu–Fe–Au–Mo deposits are widespread in the Middle and Lower Yangtze River metallogenic belt (MLYMB), eastern China. The Matou deposit has long been regarded as a typical Cu–Mo porphyry deposit within Lower Yangtze part of the belt. Recently, we identified scheelite and wolframite in quartz veins in the Matou deposit, which is uncommon in other porphyry and skarn deposits in the MLYMB. We carried out detailed zircon U–Pb dating and geochemical and Sr–Nd–Hf isotopic studies of the granodiorite porphyry at Matou to define any differences from other ore-related granitoids. The porphyry shows a SiO₂ content ranging from 61.85 wt.% to 65.74 wt.%, K₂O from 1.99 wt.% to 3.74 wt.%, and MgO from 1.74 wt.% to 2.19 wt.% (Mg^# value ranging from 45 to 55). It is enriched in light rare earth elements and large ion lithophile elements, but relatively depleted in Nb, Ta, Y, Yb and compatible trace elements (such as Cr, Ni, and V), with slight negative Eu anomalies (Eu/Eu^* = 0.88–0.98) and almost no negative Sr anomalies. Results of electron microprobe analysis of rock-forming silicate minerals indicate that the Matou porphyry has been altered by an oxidized fluid that is rich in Mg, Cl, and K. The samples show relatively low ε_Nd(t) values from −7.4 to −7.1, slightly high initial ⁸⁷Sr/⁸⁶Sr values from 0.708223 to 0.709088, and low ε_Hf(t) values of zircon from −9.0 to −6.5, when compared with the other Cu–Mo porphyry deposits in the MLYMB. Zircon U–Pb dating suggests the Matou granodiorite porphyry was emplaced at 139.5 ± 1.5 Ma (MSWD = 1.8, n = 15), which is within the age range of the other porphyries in the MLYMB. Although geochemical characteristics of the Matou and other porphyries in the MLYMB are similar and all adakitic, the detrital zircons in the samples from Matou suggest that Archean lower crust (2543 ± 29 Ma, MSWD = 0.25, n = 5) was involved with the generation of Matou magma, which is different from the other porphyries in the belt. Our study suggests that the Matou granodiorite porphyry originated from partial melting of thickened lower crust that was delaminated into the mantle, similar to the other porphyries in the MLYMB, but it has a higher proportion of lower crustal material, including Archean rocks, which contributed to the formation of the porphyry and related W-rich magmatic-hydrothermal system.  相似文献   

Cenozoic high-K alkaline magmatism and associated Cu–Mo–Au mineralization in the Jinping–Fan Si Pan region,southeastern Ailao Shan–Red River shear zone,southwestern China–northwestern Vietnam     

《Journal of Asian Earth Sciences》2014

The Jinping–Fan Si Pan (JFP) Cenozoic magmatic and Cu–Mo–Au metallogenic belt in the southeastern part of the Ailao Shan shear zone host the Tongchang, Chang′an, Habo, and Chinh Sang Cu–Mo–Au deposits. These deposits form an integrated epithermal-porphyry regional mineralization system associated with 40–32 Ma high-K alkaline magmatism. The magmatic rocks in the belt have relatively low TiO₂ (<0.73 wt%), P₂O₅ (<0.29 wt%), and FeO^* (<4.99 wt%), and high Na₂O (2.86–4.75 wt%) and K₂O (4.01–7.98 wt%). They also have high contents of incompatible trace elements, and are enriched in LILE (Rb, Ba, K, Sr) and LREE. They have marked Nb, Ta, Ti and P depletion in primitive mantle-normalized spidergrams, and plot close to the EMII mantle field in the Sr–Nd isotopic diagram. These characteristics are similar to those of the Eocene high-K alkaline rocks along the northern Ailao Shan belt, eastern Tibet plateau. The sulfur and lead isotope analyses of sulfide minerals from both the ores and related magmatic rocks confirm the involvement of a magmatic ore fluid. The Cenozoic alkaline intrusions and Cu–Mo–Au mineralization in the JFP were formed prior to the initiation of left-lateral shearing along the Ailao Shan shear zone. The magmas appear to have been derived from enriched mantle, possibly with mixing of materials from the buried Tethyan oceanic lithosphere, and/or crust.  相似文献   

Restudy of conodont biostratigraphy of the Permian–Triassic boundary section in Zhongzhai,southwestern Guizhou Province,South China     

《Journal of Asian Earth Sciences》2014

New conodont samples have been systematically collected at high stratigraphic resolution from the upper part of the Longtan Formation through to the lower part of the Yelang Formation at the Zhongzhai section, southwestern Guizhou Province, South China, in an effort to verify the first local occurrence of Hindeodus parvus in relation to the Permian–Triassic boundary at this section. The resampled conodont fauna from the Permian–Triassic boundary interval comprises five identified species and two undetermined species in Hindeodus and Clarkina. Most importantly, the first local occurrence of Hindeodus parvus is found for the first time from the bottom of Bed 28a, 18 cm lower than the previously reported first local occurrence of this species at this section. Considering the previously accepted PTB at the Zhongzhai section, well calibrated by conodont biostratigraphy, geochronology and carbon isotope chemostratigraphy, this lower (earlier) occurrence of H. parvus suggests that this critical species could occur below the Permian–Triassic boundary. As such, this paper provides evidence that (1) the first local occurrences of H. parvus are diachronous in different sections with respect to the PTB defined by the First Appearance Datum (FAD) of this species at its GSSP section in Meishan, China and that (2) the lower stratigraphic range of H. parvus should now be extended to latest Permian.  相似文献