Trace element geochemistry during chemical weathering——As exemplified by the weathered crust of granite, Longnan, Jiangxi

The granite weathering in Longnan, Jiangxi, is represented by mineralogical changes of feldspars → montmorillonite, illite → kaolinite, halloysite f66 bauxite, with Na, Ca, Si, P, V, U and Sr being in a mobile state while Ti, Al, Fe, Sc, Th, Zr and Hf remaining relatively conservative. With the exception of Zr/Hf, Nb/Ta, Th/Sc, Zr/Nd and Sm/Nb, changes are notable in ratios between most of the trace elements. Re-distribution of REE and Y has taken place during the chemical weathering, and the REE patterns of weathered samples in the profile, with original characters of the parent rock still recognizable, has undergone some fractiona-tion. Generally, the extent of chemical weathering is the critical factor determining the mineralogical and chemical characteristics of the profiles and this must be taken into account in any study of tracing the provenance on the basis of mineralogical and trace element characteristics of the sediments.     

Trace element geochemistry during chemical weathering

The granite weathering in Longnan, Jiangxi, is represented by mineralogical changes of feldspars → montmorillonite, illite → kaolinite, halloysite → bauxite, with Na, Ca, Si, P, V, U and Sr being in a mobile state while Ti, Al, Fe, Sc, Th, Zr and Hf remaining relatively conservative. With the exception of Zr/Hf, Nb/Ta, Th/Sc, Zr/Nd and Sm/Nb, changes are notable in ratios between most of the trace elements. Re-distribution of REE and Y has taken place during the chemical weathering, and the REE patterns of weathered samples in the profile, with original characters of the parent rock still recognizable, has undergone some fractionation. Generally, the extent of chemical weathering is the critical factor determining the mineralogical and chemical characteristics of the profiles and this must be taken into account in any study of tracing the provenance on the basis of mineralogical and trace element characteristics of the sediments.     

Reappraisement and refinement of zircon U-Pb isotope and trace element analyses by LA-ICP-MS

A protocol was established for simultaneous measurements of zircon U-Pb ages and trace elements by LA-ICP-MS at spot sizes of 16 32 μm.This was accomplished by introducing N 2 into ICP to increase the sensitivity.The obtained U-Pb ages for zircon standards GJ-1,TEMORA and SK10-2 are consistent with the preferred values within about 1% uncertainty (2σ) by simple external calibration against zircon standard 91500.Different data reduction softwares could yield different uncertainties for calculation of U-Pb ag...     

Microstructure and mechanical properties of the welding joint filled with microalloying 5183 aluminum welding wires

In this study, 7A52 aluminum alloy sheets of 4 mm in thickness were welded by tungsten inert gas welding using microalloying welding wires containing traces of Zr and Er. The influence of rare earth elements Zr and Er on the microstructure and mechanical properties of the welded joints was analyzed by optical microscopy, energy dispersive X-ray spectroscopy, transmission electron microscopy, hardness testing, and tensile mechanical properties testing. Systematic analyses indicate that the addition of trace amounts of Er and Zr leads to the formation of fine Al₃Er, Al₃Zr, and Al₃(Zr,Er) phases that favor significant grain refinement in the weld zone. Besides, the tensile strength and hardness of the welded joints were obviously improved with the addition of Er and Zr, as evidenced by the increase in tensile strength and elongation by 40 MPa and 1.4%, respectively, and by the welding coefficient of 73%.     

Zn含量对Mg-0.6Zr合金力学性能及阻尼性能的影响

采用金相分析、拉伸试验、动态机械热分析等方法研究了不同含量Zn对Mg-0.6Zr合金力学性能及阻尼性能的影响.结果表明,加入微量Zn后,Mg-0.6Zr合金的强度和伸长率都得到提高,且强度随Zn含量的增加而增大,而伸长率而随Zn含量的增加变化不大;阻尼性能有所降低,且随Zn含量的增加而降低,这是由晶粒细化和溶质原子增多所导致的结果.     

zn含量对Mg一0．6Zr合金力学性能及阻尼性能的影响

采用金相分析、拉伸试验、动态机械热分析等方法研究了不同含量zn对Mg一0．6Zr合金力学性能及阻尼性能的影响．结果表明,加入微量zn后,Mg一0．6Zr合金的强度和伸长率都得到提高,且强度随zn含量的增加而增大,而伸长率而随zn含量的增加变化不大;阻尼性能有所降低,且随zn含量的增加而降低,这是由晶粒细化和溶质原子增多所导致的结果．     

西藏雄村铜金矿床Ⅰ号矿体成矿构造背景与成矿物质来源探讨

西藏雄村铜金矿是近年来在冈底斯成矿带新发现的大型斑岩型铜金矿床。通过对Ⅰ号矿体富矿围岩、成矿期前侵入岩、成矿期侵入岩的岩石学、常量与微量元素以及金属硫化物的硫、铅同位素研究表明,Ⅰ号矿体火山岩和侵入岩具有一致的微量元素组成,均强烈亏损Nb、Zr、Ti,相对富集Rb、Ta、Hf、Y。Mg#介于7.9~34.4,平均为19.8。黄铁矿的铅同位素具有地幔铅和地壳铅混合特征,金属硫化物硫同位素组成与地幔硫接近。Ⅰ号矿体形成于中侏罗世早期特提斯洋向北俯冲的岛弧环境,岩浆起源于部分熔融的地幔,并混染有壳源物质,成矿金属来源于岩浆。     

南秦岭岚皋基性火山岩的地质学 、地球化学及其构造意义

为了研究南秦岭岚皋地区基性火山岩的岩石成因和区域构造背景, 选择岚皋县境内的玄武岩和火山角砾岩进行岩相学、常量元素、微量元素和稀土元素的分析。通过分析发现, 它们同属于碱性玄武岩系列, 轻重稀土分异明显, Rb, K 相对Th, Hf 亏损, 不具 Nb, Ta, Zr, Ti 负异常, 整体表现出与 OIB( 洋岛玄武岩) 高度一致的稀土图谱和微量元素特征。岩石成因分析表明, 它们为同源岩浆演化序列, 其原始岩浆起源于尖晶石-石榴石二辉橄榄岩和石榴石二辉橄榄岩地幔源区的低度部分熔融, 在上升过程中基本未受地壳混染的影响。岩浆演化过程中主要经历了单斜辉石、少量斜长石的分离结晶作用。综合区域地质学和微量元素特征, 该组火山岩最有可能形成于洋盆台地或大洋岛构造环境。     

贵州中北部铝土矿若干微量元素特征及其成因意义

根据贵州中，北部若干铝土矿床中各类铝土矿石，粘土岩和下伏及上覆岩石中微量元素Ｓｒ，Ｂａ，Ｇａ，Ｖ，Ｚｒ的定量分析资料与Ｓｒ／Ｂａ，Ｂ／Ｇａ，Ｖ／Ｚｒ比值和比值曲线，以及由硼的含量算出的校正硼，相当硼一和含盐度，结合区域地质背景及含矿岩系剖面，讨论了铝土矿带的形成环境，指出修文铝土矿带和遵义铝土矿带在微量元素方面的差别，反映了二者在沉积成矿环境上的差异，前者形成于淡化泻湖一滨海沼泽环境，后者形成了滨     

貉被毛中微量元素的ICP-AES分析

采用低温干灰化法制备样品, 用电感耦合等离子体原子发射光谱(ICP-AES）法同时分析毛皮动物貉的被毛组织中多种微量元素. Ba,Be,Cd,Si,Y,Zn的测定下限为1.0～9.0 ng/g级,B,Fe,La,Mg,Mo,Ni,Ti,Co,Cr,Cu,Sr,V,Zr的测定下限为0.01～0.09 μg/g级, In,Th,P,Pb的测定下限为0.13～0.23 μg/g级, Nb为1.08 μg/g级. 经国家人发标准物质(GBW07601)验证, 测得该方法相对误差为083%～959%, 相对标准偏差为081%～520%, 各项检测指标均能满足生物样品检测要求. 分别测得健康种貉、自咬症轻重病貉被毛中的22种微量元素, 健康貉的B,Co,Cr,Ni微量元素含量明显高于病貉,而Al,Ba,Be,Cd,Mo,Pb,Sr,Ti,Zr元素含量较低.