燕山地区寿王坟杂岩体锆石U-Pb年代学、Hf同位素和地球化学特征及其地质意义     

董朋生  董国臣  孙转荣  李华伟  王树树  王伟清  耿建珍 《地学前缘》2018,25(6):264-276

燕山地区寿王坟杂岩体由石英闪长岩、石英二长岩组成。LA-ICP-MS锆石U-Pb年代学研究表明,石英闪长岩和石英二长岩形成于(128±1) Ma,是早白垩世岩浆活动的产物。对比区域岩浆作用特点显示,研究区岩浆作用与华北克拉通东部大规模岩浆活动时代相近。寿王坟杂岩体富碱(Na2O+K2O含量为8.48%~9.06%(质量分数),属钾玄质系列(K2O 3.87%~4.96%)、准铝质岩石(A/CNK=0.69~0.89,A/NK=1.19~1.35),富集Rb、Ba、Sr等元素,亏损Nb、Ta、Th、P等元素,具高Sr((684~1 018)×10-6)和Ba((1 163~1 506)×10-6)、高Sr/Y(43~102)和La/Yb(31~91)比值、低Y((7.19~16.55)×10-6)和Yb((0.47~1.28)×10-6)、富集LREE、基本无Eu异常等特征。εHf(t)值较低,石英闪长岩εHf(t)=-18.1~-11.1,石英二长岩εHf(t)=-18.6~-13.2。研究认为寿王坟杂岩体主要形成于早白垩世古太平洋板块向欧亚大陆俯冲背景下的伸展环境,来源于古元古代地壳物质的部分熔融,并有不同程度富集地幔的贡献。Sr/Y值与SiO2含量呈正相关表明其不具源区特征,主要是岩浆在侵位过程中富水岩浆分异演化发生角闪石等矿物的结晶分异作用造成的。  相似文献   

河床高差对Y型汇流口螺旋流结构的影响   总被引：2，自引：0，他引：2       下载免费PDF全文

王晓刚  严忠民  张幸农 《水科学进展》2008,19(6):828-834

通过三维数值模拟分析了河床高差(定义为干支流河床高程差与尾水位之比)对Y型汇流口螺旋流结构的影响。通常情况下,Y型汇流口水流为表面汇聚的双螺旋流。河床高差的存在将减小干流侧水流的螺旋流强度,增强支流侧水流螺旋度,而当支流侧螺旋流很强烈时,干流侧螺旋流将受到破坏。  相似文献   

Cycling of calcite and hydrous metal oxides and chemical changes of major element and REE chemistry in monomictic hardwater lake: Impact on sedimentation     

《Chemie der Erde / Geochemistry》2016,76(1):133-148

The variation of major and rare earth elements and yttrium (REY) in the monomictic hardwater Lake Tiberias during the wet and dry seasons of the hydrological year was studied in two profiles. The average volume and Cl concentration of the known and unknown saline inflows of 1.6 × 10⁷ m³ and 1.2 × 10⁹ mol are derived by closing both balances. This brine corresponds to a mixture of 83% of groundwater from Cretaceous aquifers and 17% of very saline deep brine. Taking cycling of calcite in the hypolimnion into account, the settling rate of authigenic calcite is estimated to be 3.3 mol m⁻² a⁻¹.In the stratified lake of the dry season dissolved inorganic carbon increases by 490 μM at the thermo-/chemocline due to microbial reduction of SO₄²⁻, NO₃⁻, chemical reduction of Fe(III) and MnO₂ colloids, and cycling of calcite in the hypolimnion. REY distribution in the stratified water column is dominantly controlled by coprecipitation with calcite, hydrous ferric oxides and MnO₂ in the epilimnion and cycling of these compounds in the hypolimnion. The positive Ce anomaly in the hypolimnetic water is produced by cycling of MnO₂. The simulation of the increase of REY in the hypolimnion reveals that hydrous ferric and manganese oxides only play a negligible role except Ce. Only about 10% of REY from cycled matter enhance REY in solution. Most of the released REY are adsorbed by particular matter and thus settling on the floor of the lake.Different from Na, U, SO₄²⁻ and SiO₂, the other elements, in particular REY, increase in the mixed water column from the top to the lower third and mostly decrease thereafter toward the bottom in the mixed lake during the wet season. The behavior of REY is caused by some cycling of calcite and pH-dependent re-equilibration of REY bound to hydrous ferric and manganese oxides adsorbed by particular matter.  相似文献   

Middle Permian high Sr/Y monzogranites in central Inner Mongolia: reworking of the juvenile lower crust of Bainaimiao arc belt during slab break-off of the Palaeo-Asian oceanic lithosphere     

《International Geology Review》2012,54(17):2083-2099

ABSTRACT

The high Sr/Y geochemical feature of granitoids can be attributed to various mechanisms, and elucidating genesis of high Sr/Y granitoids provides insights into the material recycling and magmatic processes at depth. In southeastern Central Asian Orogenic Belt (CAOB), many Middle Permian granitoids exhibit high Sr/Y ratios, but their origins remain unclear, inhibiting a comprehensive understanding of the magmatic response to the final closure of the Palaeo-Asian ocean. Here we present new zircon U-Pb ages, Lu-Hf isotopes and whole-rock geochemical data for the Middle Permian high Sr/Y monzogranites from central Inner Mongolia, southeastern CAOB. LA-ICP-MS zircon U-Pb data shows that these high Sr/Y rocks were emplaced during 273–261 Ma. They are calc-alkaline, sodium-rich and metaluminous to weakly peraluminous, with enriched large-ion lithophile elements (Rb, Th, K and Pb) and depleted high field strength elements (Nb, Ta, P and Ti), suggesting a mafic lower crustal source rather than evolved potassic crustal materials. Their relatively low (Gd/Yb)_N (1.1–2.0), (Dy/Yb)_N (1.0–1.3), Nb/Ta (7.9–10.9) ratios and flat heavy rare earth element patterns are characteristics of derivation from a relatively shallow depth with amphibolite as dominant residue. They also have highly variable ε_Hf(t) values (?8.2 to +10.0) and T_DMC (1814 to 649 Ma), similar to those of the Early Palaeozoic high Sr/Y intrusions along the Bainaimiao arc belt. Combined with data from literatures, we suggest that the high Sr/Y monzogranites in this study were probably generated by reworking of the newly underplated juvenile high Sr/Y lower crust of the Bainaimiao arc belt. Moreover, taking into account the regional investigations, the sublinear distributed Middle Permian magmatic rocks in the southeastern CAOB were likely associated with the incipient slab break-off of the Palaeo-Asian oceanic lithosphere following initial collision between the North China craton and the South Mongolia terranes.  相似文献   

江南造山带东部旌德高Sr/Y花岗闪长岩的形成机制及其构造意义   总被引：1，自引：0，他引：1  

周洁 《地质学报》2014,88(1):53-62

旌德岩体是江南造山带东部一个典型的高Sr/Y岩体。锆石的原位U-Pb定年表明,该岩体侵位于141±1Ma。岩体由花岗闪长岩和二长花岗岩组成。岩体中黑云母为镁质黑云母。斜长石为奥长石、中长石。全岩地球化学表明,高的SiO2（66.01% ~ 70.87%）,Al2O3（14.91% ~16.24%）,全碱（K2O+Na2O = 6.64% ~ 8.01%）,K2O/Na2O变化范围在0.78～1.04,Sr（189×10-6 ~ 452×10-6）,和LREE;低的HREE和HFSE含量,Eu有轻微的负异常到弱的正异常（δEu＝0.81~1.18）。岩体具有高的Sr/Y（23 ~ 66）值和(La/Yb)N（13 ~ 58）值,且MgO、Cr、Ni含量较低。相对较高的εNd(t)＝‒12.92~‒6.28,二阶段模式年龄 tDM2 = 1.4~1.9Ga,岩体中发育有岩浆混合成因的暗色包体,指示有幔源岩浆参与。交代的岩石圈地幔发生部分熔融,岩浆底侵到壳幔过渡带附近,导致下地壳发生部分熔融形成了旌德岩体,且发生了岩浆混合作用。  相似文献   

浅析沿空留巷技术     

孙学军 《吉林地质》2014,(2):139-142

鄂尔多斯闫家渠煤矿1404采煤工作面上风巷采用沿空留巷技术,实现了工作面"Y"型通风,既解决了上隅角一氧化碳积聚问题,又解决了采掘接续紧张问题,同时提高了采区回采率。  相似文献   

Selection of Yarrowia lipolytica Strains with High Protein Content from Yeasts Isolated from Different Marine Environments     

CHI Zhenming WANG Fang WANG Lin LI Jing WANG Xianghong 《中国海洋大学学报(英文版)》2007,6(4):360-364

A total of 78 Yarrowia lipolytica yeast strains from seawater, sediments, mud of salterns, the guts of marine fish, and marine algae were obtained. After the crude protein of the yeasts was estimated by the method of Kjehldahl, we found that seven strains of the marine yeasts grown in soy bean cake hydrolysate with 20 g L-1 of glucose for 48 h at 28℃ contained more than 41.0 g protein per 100 g of cell dry weight and the cell dry weight was more than 4.4 g per L of the culture. Among them, strain SWJ-1b contained the highest crude protein. The results of Biolog identification and molecular methods further confirmed that they indeed belonged to Y. lipolytica.  相似文献   

Mobility of Rare Earth Elements in Basalt‐Derived Laterite at the Bolaven Plateau,Southern Laos     

Kenzo SANEMATSU  Laochou SOTOUKY  Yasushi WATANABE 《Resource Geology》2011,61(2):140-158

Geochemical and geochronological studies were conducted on basalts and laterites from the Bolaven Plateau in southern Laos in order to evaluate the mobility and mineralization of REE, Y and Sc during laterization. The basalts are classified into three categories: (i) small volumetric alkali basalt (eruption age: 15.7 Ma), large volumetric olivine tholeiite (1.2 Ma) and quartz tholeiite with olivine tholeiite (younger than 0.5 ± 0.2 Ma). Formation of REE minerals during laterization result in mobilization and fractionation of REE and Y in laterite profiles. Occurrence of florencite‐(Ce) in a laterite profile derived from alkali basalt immobilizes REE (particularly LREE) and this leads the laterites to be enriched in LREE relative to the parent basalt. Few positive Ce anomalies in this profile suggest that florencite‐(Ce) [(Ce)Al₃(PO₄)₂(OH)₂] formation was followed by CeO₂ precipitation due to the change of redox condition. In tholeiite‐derived laterite profiles, florencite is not recognized and REE and Y tend to be depleted relative to the parent basalts with positive Ce anomalies. This is interpreted as scavenging REE³⁺ except for Ce⁴⁺ from the laterite profile in oxidizing conditions. Sc behaves similarly to Fe during laterization and it is more abundant in the tholeiitic laterite than that in the alkali basaltic laterite. Results of sequential extraction indicate that REE of the alkali basaltic laterite are contained in residual phase, which is dominantly florencite‐(Ce), but they are rarely present in ion‐adsorption phase. It is concluded that basaltic laterites have a low potential of REE resource in terms of low REE contents and a difficulty in REE extraction.  相似文献   

The formation of a detached shell around the carbon star Y CVn     

Y. Libert  E. Gérard  T. Le Bertre 《Monthly notices of the Royal Astronomical Society》2007,380(3):1161-1171

  相似文献   

Two successive phases of ultrahigh temperature metamorphism in Rogaland,S. Norway: Evidence from Y‐in‐monazite thermometry          下载免费PDF全文

Antonin T. Laurent  Stephanie Duchene  Bernard Bingen  Valerie Bosse  Anne‐Magali Seydoux‐Guillaume 《Journal of Metamorphic Geology》2018,36(8):1009-1037

In Rogaland, South Norway, a polycyclic granulite facies metamorphic domain surrounds the late‐Sveconorwegian anorthosite–mangerite–charnockite (AMC) plutonic complex. Integrated petrology, phase equilibria modelling, monazite microchemistry, Y‐in‐monazite thermometry, and monazite U–Th–Pb geochronology in eight samples, distributed across the apparent metamorphic field gradient, imply a sequence of two successive phases of ultrahigh temperature (UHT) metamorphism in the time window between 1,050 and 910 Ma. A first long‐lived metamorphic cycle (M1) between 1,045 ± 8 and 992 ± 11 Ma is recorded by monazite in all samples. This cycle is interpreted to represent prograde clockwise P–T path involving melt production in fertile protoliths and culminating in UHT conditions of ~6 kbar and 920°C. Y‐in‐monazite thermometry, in a residual garnet‐absent sapphirine–orthopyroxene granulite, provides critical evidence for average temperature of 931 and 917°C between 1,029 ± 9 and 1,006 ± 8 Ma. Metamorphism peaked after c. 20 Ma of crustal melting and melt extraction, probably supported by a protracted asthenospheric heat source following lithospheric mantle delamination. Between 990 and 940 Ma, slow conductive cooling to 750–800°C is characterized by monazite reactivity as opposed to silicate metastability. A second incursion (M2) to UHT conditions of ~3.5–5 kbar and 900–950°C, is recorded by Y‐rich monazite at 930 ± 6 Ma in an orthopyroxene–cordierite–hercynite gneiss and by an osumilite gneiss. This M2 metamorphism, typified by osumilite paragenesis, is related to the intrusion of the AMC plutonic complex at 931 ± 2 Ma. Thermal preconditioning of the crust during the first UHT metamorphism may explain the width of the aureole of contact metamorphism c. 75 Ma later, and also the rarity of osumilite‐bearing assemblages in general.  相似文献