藏南确当地区高Sr/Y比值二云母花岗岩的形成机制及其构造动力学意义

最近的研究表明,喜马拉雅造山带普遍经历了大于30Ma的高温变质和部分熔融作用,形成了不同规模的混合岩或花岗岩。厘定这些地壳深熔岩浆的地球化学性质及其形成机理对于深化认识大型碰撞造山带的岩浆作用及其构造物理效应具有重要意义。在雅拉香波穹隆核部及其南部发育一系列类似的二云母花岗岩岩体,其中确当花岗岩侵入到二叠纪(?)复理石地层内。全岩地球化学测试结果表明,确当花岗岩具有与雅拉香波花岗岩、打拉花岗岩类似的特征,即①高SiO2(68.2%~69.3%)和铝(Al2O3>15.14%),低铁(TFeO<2.0%)和镁(MgO<1.5%),为富钠过铝质花岗岩;②富集LREE,亏损HREE,平坦的Ho到Lu稀土元素分布样式(Ho/Yb)N=1.2~1.4),无或微弱Eu负异常(Eu/Eu?=0.9~1.0);③较低的Y(<8.1×10-6)和 Yb(<0.7×10-6)含量,较高的Sr/Y(>37.5)和La/Yb(>29.3)比值。这些特征表明,确当花岗岩是以角闪岩为主和变泥质岩为辅组成的源区发生部分熔融的结果。     

河床高差对Y型汇流口螺旋流结构的影响

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。     

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

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.     

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

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.     

浅析沿空留巷技术

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。     

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

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.     

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

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.     

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

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.     

饲料中添加虾青素对血鹦鹉皮肤类胡萝卜素含量和体色三刺激值的影响

为探讨投喂增色剂对鱼类增色效果的定量评价方法,分别用添加0、30、100、300、500、700、900 mg/kg虾青素的饲料饲喂血鹦鹉60 d,测定血鹦鹉皮肤中的总类胡萝卜素含量和鱼体体色的三刺激值。结果显示,血鹦鹉皮肤总类胡萝卜素含量随着虾青素添加量的增加而升高,而三刺激值X、Y、Z则逐渐减小。总类胡萝卜素含量300～900 mg/kg各组显著高于对照组(P<0.05),500、700和900 mg/kg组显著高于0、30、100 mg/kg组(P<0.05),而500、700和900 mg/kg各组间差异不显著(P>0.05)。总类胡萝卜素含量与三刺激值间的相关系数分别为-0.966、-0.932、-0.981,均达到极显著水平(P<0.01)。可见,在饲料中添加虾青素可明显提高血鹦鹉皮肤类胡萝卜素含量,改善血鹦鹉体色,血鹦鹉体色的三刺激值与皮肤总类胡萝卜素含量有极高的相关性,可用测色色差计测定血鹦鹉的三刺激值,并以此来推算鱼体皮肤总类胡萝卜素含量,定量评价血鹦鹉的体色。