天山赛里木湖—博罗霍洛地区大地构造演化、分区及成矿

赛里木湖—博罗霍洛地区大地构造演化经历了早元古代前地槽阶段、中元古代至古生代地槽阶段、三叠纪至侏罗纪地台阶段和白垩纪至新生代地洼阶段。本区经历二次造山作用 ,晚石炭世末的因尼卡拉运动使全区隆起褶皱成山 ,形成本区第一代山脉 ;第四纪强烈的断块运动造成本区今日所见的第二世代山脉——地洼断褶带山脉及断陷湖泊——赛里木湖。由北至南可分为 10个 级构造单元。中元古代的热水沉积、泥盆纪的岩浆侵入和火山喷溢、石炭纪的火山作用为本区主要的成矿热事件     

Te-Rich argyrodite occurrence in Roşia Montană ore deposit,Apuseni Mountains,Romania

A new argyrodite occurrence has been discovered in the Ro?ia Montan? ore deposit located in the South Apuseni Mountains, Romania. Argyrodite is associated with common base metal sulfides and sulfosalts (galena, sphalerite, chalcopyrite, tetrahedrite ± alabandite, pyrite, and marcasite), tellurides (hessite, altaite, sylvanite) and rare electrum grains in the Ag-rich Cârnicel vein hosted by an extracraterial phreatomagmatic breccia within the Cârnic massif. SEM and EPMA analyses revealed that this argyrodite is Te-rich and a mean Ag_8.04Ge_0.9Te_2.07S_3.77 formula was calculated. This phase could be the germaniferous equivalent of the previously-described Te-rich canfieldite. To cite this article: L. Bailly et al., C. R. Geoscience 337 (2005).     

Analysis of the mobilization of solid loads and heavy metals in runoff waters from granite quarries

The cutting operations of dimension stone at quarries produce a large amount of fines that, in turn, cause a negative environmental impact over local surface waters. This article presents a detailed analysis of the mobilized contamination associated with runoff waters in a large granite quarry (～200 ha) which is located in Porriño (Galicia, NW Spain), the most important production centre of dimension stone in Spain. There, an intensive monitoring survey was developed in order to characterize the hydrology of the system as well as the release and transport of pollutants. This was accomplished by means of different control sections for the flow and by the collection of 52 random water samples. Automatic samplers were also used to collect 192 water samples associated with runoff generated by significant rain events. For each of the samples collected, a wide battery of analytic determinations was performed, including solid loads, turbidity, organic pollution, nutrient and selected metals. Upon careful examination it has been possible to obtain different parameters related to the contamination control, like the “event mean concentration” (EMC), maximum concentrations and specific sediment loads. Moreover, a comprehensive statistical study including parameter correlation and cumulative probability analyses helped to understand the pollutant mobilization behaviour within the quarry system. It can be concluded that mobilized contamination shows the anomalous presence of some metals, whose concentrations are in excess when compared to the natural rock. This excess metal amount must be attributed to an anthropogenic source associated to mining and cutting operations.     

Molar volume and thermal expansion of glaucophane

The molar volume of glaucophane [Na₂Mg₃Al₂Si₈O₂₂(OH)₂] has been determined in this study by correcting synthetic glaucophane-rich amphiboles made in the system Na₂O–MgO–Al₂O₃–SiO₂–H₂O for very small deviations from ideal glaucophane composition using recent volume data on key amphibole components. The derived unit-cell volume for end-member glaucophane is 862.7±1.6 Å³, which gives a molar volume of 259.8±0.5 cm³/mol and a calculated density of 3.016±0.006 g/cm³. This value has been corroborated through an essentially independent method by correcting the volumes of natural sodic amphiboles reported in the literature for non-glaucophane components, particularly including calcium-rich components, to yield a value of 861.2±1.9 Å³. The unit-cell volume derived from the synthetic amphiboles, which is considered here to be more reliable, is somewhat smaller than that reported previously in the literature. A thermal expansion (α_V) at 298 K of 1.88±0.06×10^?5/K was derived from unit-cell volumes measured in the range of 25–500°C for a synthetic glaucophane sample, which is noticeably smaller than previously reported.     

The Taraklı Flysch in the Boyali area (Sakarya Terrane,northern Turkey): Implications for the tectonic history of the IntraPontide suture zone

In the Boyal? area, northern Turkey, the tectonic units of the ?stanbul–Zonguldak Terrane and the IntraPontide suture zone are thrust over the deposits at the top of the Sakarya Terrane, known as Tarakl? Flysch. It consists of Early Maastrichtian–Middle Paleocene turbidite and mass-gravity deposits, whose source mainly corresponds to the ?stanbul–Zonguldak Terrane, and, with a lesser extent, to the IntraPontide suture zone. These deposits were sedimented in a foredeep basin developed during the convergence between Sakarya and Eurasian continental microplates. In the Late Paleocene–Early Eocene time span, the Tarakl? Flysch was deformed (D1 phase) during the closure of the foredeep basin. In the Miocene time, the strike-slip tectonics (D2 phase) related to the North-Anatolian fault produced further deformations of the Tarakl? Flysch.     

川南地区渐变型盆—山边界条件下龙马溪组页岩气(藏)富集主控因素:构造—沉积分异与差异性演化

川南地区龙马溪组全面进入3500 m以浅的页岩气开发、上产关键阶段。油气地质学界长期以来针对页岩岩相、岩石学与孔隙特征等储层静态参数的重视以及对龙一11小层的单一层系开发的局限,对川南地区龙马溪组页岩气整体产能的提高产生了一定制约。回归基础地质本质,采用地质—地球化学综合研究思路,以构造控制下的沉积分异格局为框架,补充完善川南地区笔石生物地层划分体系;依靠多期节理构造与古应力反演等构造解析方法,建立川南渐变型盆—山边界条件下龙马溪组多期构造演化与流体温压模型,明确川南地区复杂构造背景下页岩气差异富集机理。奥陶纪—志留纪之交的“三隆一坳”古构造—沉积分异,控制了川南地区五峰组—龙马溪组优质页岩渐进式发育与分布。在川南—大娄山渐变型盆山结构边界条件下,晚白垩世以来所经历的4期不同应力场构造变形事件,使威远、泸州—大足与长宁—宁西地区五峰组—龙马溪组具有差异性构造变形—抬升剥蚀与演化特征。差异性的埋深—隆升过程,对受埋深与构造热事件控制的页岩有机地球化学特征及流体充注体系产生重要影响。构造—沉积分异、盆山建造与热演化过程,最终控制川南地区五峰组—龙马溪组早期有限聚集—中期相对富集—晚期调整改造的页岩气成藏演化过程。     

The Strandja Massif and the İstanbul Zone were once parts of the same palaeotectonic unit: new data from Triassic detrital zircons

Spatially continuous rock assemblages that share similar environmental evolution or structural features can be classified as a single tectonic unit. This approach enables to link dispersed units or massifs with each other and sometimes can be subjective, depending on the classification criteria. The relationship and the nature of the contact between the Strandja Massif and the ?stanbul Zone have been controversial due to the Cainozoic cover. Amalgamation of these units was claimed as early as the Aptian-Albian.

Lower Triassic sedimentary rocks, which are overlain by the Carboniferous flysch with a N-verging thrust fault are exposed NW of the ?stanbul Zone. This study reveals the spatial relationship between the Strandja Massif and the ?stanbul Zone deduced from the U-Pb dating and Lu-Hf isotopes of the detrital zircons from these Lower Triassic clastics. Our results show that the early Triassic basin was fed from a provenance that included arc-related Upper Carboniferous-Lower Permian magmatic rocks which is much more likely to be the Strandja Massif than the ?stanbul Zone. The second outcome of this study is that a unit that previously assigned to Palaeozoic turned out to be Triassic, which brings the Strandja Massif farther to the east, into the northern ?stanbul Zone.     

Late Cretaceous arc igneous activity: the Eğrikar Monzogranite example

The geochemical and Sr–Nd–Pb isotope properties, as well as the Laser Ablation Inductively Coupled Plasma and Mass Spectrometry (LA-ICP-MS) U–Pb zircon age, of E?rikar Monzogranite in the eastern Pontides, are primarily investigated in this study with the aim of determining its magma source and geodynamic evolution. The U–Pb zircon age obtained from E?rikar Monzogranite is 78 ± 1.5 Ma, thereby re?ecting the age of monzogranite. The I-type E?rikar Monzogranite comprises quartz, plagioclase (An_35–45), orthoclase, muscovite, and biotite. The geochemical analyses of the E?rikar Monzogranite indicate being medium K calc-alkaline, peraluminous, and resembling magmatic arc granite. The E?rikar Monzogranite is enriched in large ion lithophile elements and light rare earth elements relative to high field strength elements. Chondrite-normalized rare earth element patterns have concave upward shapes (La_N/Yb_N 2.47–8.58) with pronounced negative Eu anomalies (Eu_N/Eu* = 0.29–0.65). Initial εNd_(i) values vary between 1.85 and 2.18 and initial ⁸⁷Sr/⁸⁶Sr values between 0.7048 and 0.7067. Fractionation of plagioclase, hornblende, and apatite played an important role in the evolution of E?rikar Monzogranite. The crystallization temperatures of the melts ranged from 770°C to 919°C based on zircon and apatite saturation temperatures. The geochemical and isotopic data suggest being generated by the partial melting of ma?c lower crustal sources.     

Application of Uranium Isotope Chronology for Partical Comminution in the Eolian Dust System

The wind dust system is an important part of the terrestrial surface system and plays an important role in many key belts. The mechanism of wind dust and the handling process are important to understand the environmental function of wind dust and to interpret the paleoclimate record. In the past, traditional geochemical methods can only reflect the rock composition or age in the final denudation zone, and it is not possible to distinguish the different silt mechanism and the intermediate process under the same eventual source background, which is one of the biggest challenges of the present research. The ²³⁴U/²³⁸U ratio of fine matter caused by alpha decay recoil reflects the time experienced by the particle since it was broken and may be able to effectively trace the mechanism of wind dust generation and the transport of the intermediate process, but the age of uranium isotope fragmentation is rarely used in the wind dust system. The complicated factors restricting the wide application of uranium isotope were summarized, and according to the latest research progress, the verification and development of the uranium isotope comminution age in the wind dust system, and the problem solution of the mechanism of wind dust production and the way of transporting were discussed.