988 resultados para WTR (MA-g-WTR)
Resumo:
中国东南部地处太平洋板块与欧亚板块的接合部位,其独特的地理位置和构造运动长期以来引起了地质学家的广泛关注。自印支运动以来,板内构造演化复杂而多样。最引人注目的无疑是燕山期广泛而强烈的构造一岩浆热事件。近年来随着研究的深入,逐渐凸显出两个重要的地质问题需要解决:(1)中国东南部晚中生代构造属性的转变时间及地球动力学演化过程;(2)多金属成矿作用与岩石圈伸展减薄及地壳拉张的关系。基于此,本文以中国东南部福建省的基性脉岩、岩体为研究对象,运用系统的矿物学、岩石学、岩石地球化学、同位素地球化学及同位素年代学证据,详细论述了晚中生代中国东南部板块俯冲、地慢演化、壳幔相互作用及岩石圈伸展减薄的地球动力学过程,探讨了地壳拉张期次在福建省区域构造上的响应。本研究主要获得以下几点认识:1、岱前山辉长岩体沿福建长乐一南澳大断裂带分布,侵位于沿海的绿片岩相和角闪岩相的变质岩中及内陆的中生代火山岩中。岩体的微量元素特征表现为与俯冲作用有关的岛弧特点。岱前山岩体由低程度部分熔融形成(约7%),伴有角闪石、单斜辉石的分离结晶作用和斜长石的堆晶作用。时间上与古太平洋板块低角度一歪斜俯冲、晚中生代的变质事件、平潭一东山变质带抬升和长乐一南澳剪切带运动在时间上基本一致。岩体是受俯冲流体交代的上地慢,经部分熔融沿长乐一南澳断裂一应力转换带侵入。它与中国东南部出露的其它基性岩同源,但未受到地壳的混染作用。2、闽南茅坪一晒鞍角基性侵入体具独特的地球化学属性,表现为高Al2O3、CoO、MnO,低FeOT、MgO、TiO2含量,富集轻稀土元素(LREE)和大离子亲石元素(LILE),并具正的Pb异常和负的Ti异常;Sr-Nd-Pb同位素结果显示,该基性岩有EM2组分的参与。模拟计算表明,该基性岩墙群是尖晶石二辉橄榄岩地慢5-15%部分熔融的产物;微量元素配分模式及理论模拟表明茅坪一晒鞍角基性岩体的地慢源区在熔融前曾受到1%俯冲沉积物熔体的源区混染和5%流体交代作用。基性岩浆在上升过程中还受到10%左右的地壳物质的混染作用,导致该区基性岩富放射成因Sr、Pb同位素。3、福建省晚中生代基性脉岩富Al2O3(14.0-20.4 wt%)、CaO(4.09-12.7wt%)。按地球化学特征可分为两组:第一组脉岩具较低稀土总量(53.8-145.5μg/g)和平缓的稀土配分模式L(La/Yb)n=1.68-4.651,而第二组脉岩的稀土总量较高(63-247μg/g),且轻稀土富集[(La/Yb)n=4.63-19]。在原始地慢标准化图解上,第一组脉岩显示Pb的正异常和Ti负异常,无Nb、Ta异常,而第二组脉岩显示明显的Nb一Ta一Ti负异常和Pb正异常。两组脉岩经历了不同的源区混合和陆壳混染过程,第一组脉岩显示了以陆壳混染为主的地球化学过程,不具有岛弧特点的微量元素配分模式表明该类基性岩的地慢源区可能未受俯冲作用过程影响,第二组脉岩的岛弧地球化学特点暗示该类基性岩地慢源区是经俯冲作用改造过的富集岩石圈地慢。第一组基性脉岩来源于石榴石一尖晶石二辉橄榄岩地慢,而第二组脉岩来源于尖晶石或尖晶石一斜长石二辉橄榄岩地慢。地球化学数据显示,不同类型的地慢存在不均一性,反映了不同程度的交代作用或不同量俯冲沉积物的加入。福建省晚中生代基性脉岩产生于拉张构造背景,与岩石圈的伸展减薄及软流圈的上涌紧密联系;4、福建省基性脉岩的同位素特征显示,第一组脉岩具较高的143Na/144Nd,第二组脉岩的143Nd/144Nd较低;Th/Nd、Ba/La比值及理论模拟结果表明,第二组脉岩可能受到流体交代和俯冲沉积物的源区混合作用,而第一组脉岩基本未受俯冲组分(沉积物+流体)的改造。地壳混染对两组脉岩可能起着重要的作用。EC-AFC理论模拟表明,福建省基性脉岩在上升过程中受到前寒武纪变质岩的影响,这种混染作用在一定程度上改变了同位素组成。因此,福建省晚中生代基性脉岩的地球化学特点是太平洋板块俯冲与壳慢相互作用共同作用的结果;5、K-Ar年龄结果表明,出露于福建省的基性脉岩年龄具周期性分布,表现为五个周期:70-75Ma士,85 Ma士,105-110Ma,125Ma士和135-140Ma。这与前人的研究结果基本一致,表明福建省与中国东南部区域上有相似的地壳拉张期次。K-Ar年龄主要集中分布在14OMa→65Ma之间,这表明:①140M。限定了中国东南部岩石圈伸展作用开始的下限,也就是说中国东南部晚中生代的岩石圈伸展至少开始于140Ma左 右,而并非90Ma;②标志着中国东南部大规模拉张作用的开始,表明构造属性由令挤压为主转变为以拉张作用为主。
Resumo:
Removal of NO by a continuous microwave discharge at atmospheric pressure with the addition of CH4 is reported. The conversion of NO to N-2 is approximately 80%, and the energy efficiency is up to 0.55 g-NO/kWh. The effects of CH4 addition and three discharge modes on NO conversion and energy efficiency are investigated. The dependence of NO conversion on experimental time is also observed.
Resumo:
The catalytic behavior of Mo-based zeolite catalysts with different pore structure and size, particularly with 8 membered ring ( M R), 10 M R, coexisted 10 and 12 M R, and 12 M R, was studied in methane aromatization under the conditions of SV=1500 ml/(g.h), p=0.1 MPa and T = 973 K. It was found that the catalytic performance is correlated with the pore structure of the zeolite supports. The zeolites that possess 10 MR or 10 and 12 MR pore structure with a pore diameter equal to or slightly larger than the dynamic diameter of benzene molecule, such as ZSM-5, ZSM-11, ZRP-1 and MCM-22, are fine supports. Among the tested zeolite supports, MCM-22 exhibits the highest activity and selectivity for benzene. A methane conversion of 10.5% with benzene selectivity of 80% was achieved over Mo/MCM-22 catalyst. The Mo/ERS-7 catalyst with 8 MR (0.45 nm) does not show any activity in methane dehydro-aromatization, while Mo/JQX-1 and Mo/SBA-15 catalysts with 12 MR pore exhibit little activity in the reaction. It can be concluded that the zeolites with 10 MR pore or coexisted 10 and 12 MR, having pore size equal to or slightly larger than the dynamic diameter of benzene molecule, are fine supports for methane activation and aromatization.
Resumo:
Manganese-modified mesoporous MCM-41 molecular sieves were synthesized at the absence of alkaline metal ions under mild alkaline condition using cetylpyridinium bromide surfactant as a template, and characterized with X-ray diffraction, N-2 adsorption, transmission electron microscopy, electron spin resonance (ESR), and nuclear magnetic resonance (NMR) spectroscopies. The synthesized MnMCM-41 has a high pore volume of 1.30 cm(3) g(-1) with a corresponding surface area of 1510 m(2) g(-1). The ESR and Si-29 MAS NMR spectra revealed the presence of framework manganese ions in either the as-synthesized or calcined forms. (C) 2002 Elsevier Science B.V. All rights reserved.
Dependence of presence of defect in g-Al2O3 toplayer on structure of support 底膜结构对g-Al2O3顶层缺陷存在的决定作用