甘肃阿干煤矸石的矿物组成与演变

煤矸石因对环境污染受到人们的关注。选择甘肃阿干煤矿煤矸石作为研究对象,运用X射线粉晶衍射(XRD)、X射线荧光光谱(XRF)及电感耦合等离子质谱(ICPMS)等现代测试技术和地球化学理论,结果发现:样品表面与内部矿物种类有一定差别。新鲜部分含有铜镍硫化物矿物(铜蓝、黑硫铜镍矿、锑镍铜矿等);表面风化部位则多见斜蓝铜矿、高岭石和利蛇纹石等次生矿物。表明煤矸石在表生条件下一些组成矿物发生风化淋滤演变。化学分析结果发现:新鲜样品具有含量较高的w(SiO_2)(22.51%),w(Al2O3)(9.40%),w(Cr)(385.95×10~(-6)),w(Th)(38.27×10~(-6)),w(U)(12.74×10~(-6))和较低含量w(MgO)(2.49%),w(CaO)(5.28%),w(Sr)(220.44×10~(-6)),w(Ba)(531.76×10~(-6))。其中Cr,Cs元素为地壳丰度值的10倍,Co,Ni,Pb,Th,U和REE等达3倍~5倍。风化样品则贫w(SiO_2)(6.75%),w(Al_2O_3)(1.16%)和w(Cr)(160.71×10~(-6)),w(Th)(13.21×10~(-6)),w(U)(5.10×10~(-6)),富w(MgO)(7.70%),w(CaO)(23.04%)和w(Sr)(814.72×10~(-6)),w(Ba)(1 067.37×10~(-6)),Pb元素亏损至地壳平均值的1/10。表明经过风化淋滤,除Mg,Ca相对富集外,Al,Na,K,Fe,Ti和P均有不同程度的流失,Cu,Fe,Zn,Cr,Ni,Rb,Th,U和REE等微量元素也出现不同程度亏损。流失和亏损的元素往往随降水进入地表水和地下水中,对环境或生态系统造成不同程度的危害。研究结果对于抑制有害元素淋滤富集,环境污染有效预防、治理修复及稀土资源的综合利用等具有理论和现实意义。     

内蒙古霍林河地区晚石炭世本巴图组火山岩年代学、地球化学特征及构造背景

在内蒙古东部霍林河地区晚古生代地层中厘定出一套火山岩,其LA-ICPMS锆石U-Pb年龄为(313.7±3.5)Ma,时代归属晚石炭世。岩石学、岩石地球化学特征表明:研究区本巴图组火山岩主要由安山岩、玄武安山岩组成,属准铝质碱性系列岩石,SiO2含量52.83%～54.76%,具较高的Al2O3含量(17.43%～20.79%),Ti O2含量(0.97%～1.41%)较低,Na2O(3.74%～4.21%)K2O(2.37%～3.02%)。稀土总量(ΣREE)较高,为46.78×10-6～124.36×10-6,轻稀土(LREE)富集(42.57×10-6～109.06×10-6),重稀土(HREE)较富(4.21×10-6～15.30×10-6);LREE/HREE值为6.04～10.43,轻、重稀土分馏较强,(La/Yb)N值为6.32～14.56,在球粒陨石标准化稀土元素配分图上呈现出左高右低的右倾型分配模式;富集大离子亲石元素(Rb、Ba、K、Pb、Sr)和轻稀土元素,亏损高场强元素(Nb、Ta、Ti)和重稀土元素。岩浆来源于俯冲流体交代的地幔楔部分熔融;具岛弧及大陆边缘弧构造环境的特征,形成于板块边缘的消减带,主要与古亚洲洋板块的俯冲作用有关。     

桂东北冷源伟晶岩型铷矿成矿地质特征及邻区找矿潜力研究

冷源铷矿是桂东北地区目前发现的规模最大的伟晶岩型铷矿床,产于越城岭岩体西侧加里东期花岗岩体内部的韧性剪切带内。赋矿伟晶岩脉从中心到边缘出现明显岩相分带,依次对称发育浅肉红色硅化钾长石伟晶岩→紫色萤石化钾长石伟晶岩→绿色绢云母化钾长石伟晶岩→白色钾长石伟晶岩。伟晶岩的主要造岩矿物为钾长石、石英和绢云母,在地球化学特征上以高硅[w(SiO2)63.36%]、高铝[w(Al2O314.36%)和富碱[w (K2O+Na2O)11.50%]为特征,归属于碱性过铝质花岗岩类。伟晶岩中的稀有金属成矿元素主要为Rb,典型样品含量介于1883×10-6～2355×10-6,平均含量(2117×10-6)达到铷矿工业品位2倍。伟晶岩中Rb元素含量与K元素含量正相关(r=0.9),指示Rb主要赋存于富钾矿物中(钾长石和绢云母)。在与冷源邻近的同禾、瓜里等伟晶岩脉密集区,伟晶岩中Rb元素含量大多都超过了圈定铷矿的边界品位,甚至部分伟晶岩脉中Rb含量达到了铷矿的工业品位,指示在桂东北越城岭西侧一带均有继续寻找伟晶岩型铷矿的良好找矿潜力。     

东天山博格达晚石炭世双峰式火山岩地球化学特征及意义

东天山博格达造山带晚石炭世柳树沟组为一套由玄武岩和流纹岩组成的双峰式火山岩,形成于晚石炭世,其Si O_2含量介于46.18%～46.56%和76.06%～76.25%之间,具有明显的Daly成分间断。其中,玄武岩具富Na贫K特征,Ti O_2、Al_2O_3、Ca O和MgO含量均较高,∑REE为75.54×10~(-6)～80.22×10~(-6),LREE/HREE值为3.00～3.12,以富集Ba、Rb等大离子亲石元素(LILE)和不相容元素(P、K),相对亏损Ti、Ta、Nb等高场强元素(HFSE)和不相容元素(U、Th)为特征;流纹岩Na_2O/K_2O值为0.32～0.36,属低Ti、低Mg类流纹岩,∑REE为520.72×10~(-6)～595.26×10~(-6),LREE/HREE值为5.60～6.53,具有Rb、Th、K、La、Ce、Zr、Hf、Sm等元素的富集以及Ba、U、Ta、Nb、Sr、P和Ti元素的亏损特征。柳树沟组双峰式火山岩形成于大陆裂谷环境,具板内成因特征,玄武岩可能为亏损尖晶石相地幔橄榄岩向石榴石相地幔橄榄岩过渡相较高程度部分熔融的产物,受到地壳物质混染;流纹岩具典型的A型花岗岩的地球化学特征。     

陕西洛南县石家湾钼矿相关花岗斑岩的年代学及岩石成因：锆石U-Pb年龄及Hf同位素制 约

石家湾钼矿床位于东秦岭钼成矿带的西部黄龙铺地区,矿体主要分布于石家湾花岗斑岩外接触带的围岩中,呈细脉-网脉浸染状产出,属斑岩型矿床。花岗斑岩岩石呈斑状结构,斑晶与基质成分相同,主要矿物包括钾长石、石英、斜长石和黑云母。锆石的LA-ICP-MSU-Pb年代学研究表明,花岗斑岩的年龄为139.9～145.6Ma,加权平均年龄为(141.4±0.6)Ma(MSDW=1.00),侵位于早白垩世,与辉钼矿的Re-Os同位素年龄138Ma相近。岩石地球化学分析表明,石家湾花岗斑岩具有高硅〔w(SiO2)70.52%～73.04%〕、富碱〔w(Na2O)+w(K2O)为8.13%～9.12%〕、准铝质特征(A/CNK为0.99～1.13);稀土元素总量中等偏低(∑REE为145.27×10-6～156.97×10-6),富集轻稀土元素(∑LREE为135.38×10-6～145.97×10-6),中等Eu亏损(δEu0.65～0.71),标准化曲线呈右倾;微量元素以富集Rb、Ba、U而亏损P、Ti、Ta、Nb元素为特征。岩石具有较高的Sr初始比值(0.7073～0.7077)及较低的εNd(t)值(-14.8～-16.0)...     

夹皮沟片麻杂岩对吉林南部地区太古宙地壳演化的制约——来自岩相学、地球化学、锆石U-Pb年代学方面的证据

吉林南部地区是华北克拉通北缘重要的太古宇出露区。为探讨华北克拉通新太古代构造-岩浆热事件的性质及早前寒武地壳的形成与演化,选择吉林南部夹皮沟TTG片麻杂岩进行研究。研究表明这套岩石高Al(Al2O3=14.97%~16.28%),富Na(Na2O=3.73%~4.54%)、低Mg(MgO=1.96%~2.56%)且平均镁指数为43;富集LREE,亏损HREE,Eu异常并不明显;富集Sr(358×10~(-6)~1114×10~(-6))、Ba(613×10~(-6)~1200×10~(-6))等大离子亲石元素,亏损Nb(6.39×10~(-6)~11.2×10~(-6))、Ta(0.384×10~(-6)~0.679×10~(-6))等高场强元素;Yb(1.17×10~(-6)~1.89×10~(-6))和Y(9.93×10~(-6)~19.3×10~(-6))含量也很低,Sr/Y比值很高(36.0~57.7),以上地球化学特征表明其残留相主要为石榴子石、角闪石和含Ti矿物,没有斜长石,属于高压型TTG岩类。LA-ICPMS锆石U-Pb结果表明其形成于~2509Ma,属于新太古代晚期的产物。结合以往TTG片麻岩类的地球化学研究及Nd模式年龄,这期岩浆事件可能代表古老地壳(~2.8Ga)的重熔。岩相学和锆石形态学研究表明研究区经历了多期变质作用,其中~2509Ma的高级变质事件与岩浆事件几乎同时,可能与地幔柱环境下的岩浆底侵作用有关。     

黔北务-正-道地区铝土矿镓含量特征与赋存状态初探

黔北务(务川)-正(正安)-道(道真)地区铝土矿是贵州铝土矿重要组成部分,对该区瓦厂坪、通塘底和高梁窝3个代表性铝土矿床的镓(Ga)及其一些主要和微量元素进行了分析,结合电子探针研究,初步探讨了ca在本区铝土矿中的赋存状态.结果表明:本区铝土矿及含矿岩系中的铝土质页岩中的Ga含量高,分别为56.1×10-6～131×10-6(平均91.0×10-6)和25.1×10-6～47.6×10-6(平均36.8×10-6),均达到铝土矿中Ga的综合利用指标(20×10-6),具有很高的综合利用价值;铝土矿中的Ga除可能以Al类质同象形式相对富集于Al矿物(主要为-水铝石)外,还有可能在金红石和锆石等重矿物中富集.     

黑龙江滨东地区上石炭统唐家屯组泥质粉砂岩的地球化学特征

报导了滨东地区上石炭统唐家屯组泥质粉砂岩的矿物组成和岩石地球化学特征。矿物组成为石英+钠长石+伊利石±绿泥石±绿泥石/蒙皂石混层±高岭石。全岩主量元素具有高SiO_2(63. 26%)和Al_2O_3(17. 24%)和高钾钠比值(K_2O/Na_2O=3. 35)、低CaO (0. 71%)和MgO (1. 52%)的特点。岩石的成分变化指数ICV平均值0. 77,表明岩石的成分成熟度较低;化学蚀变指数CIA平均值70. 24,反映源区经历了中等程度的化学风化作用。岩石微量元素具V,Ni含量高,Sr,B含量低的特点。B*含量50×10~(-6),Sr含量51. 36×10~(-6)～127. 60×10~(-6),平均值81. 00×10~(-6),B/Ga值0. 10～0. 23,平均值0. 15,1,Sr/Ba值0. 10～0. 25,平均值0. 16,1,V/Ni值2. 22～6. 05,平均值4. 53, 3,V/(V+Ni)值0. 69～0. 86,平均值0. 81, 0. 60。这些特点反映岩石形成于陆相还原环境。轻重稀土元素的分异程度较低,Eu和Ce具负异常。泥质粉砂岩的元素地球化学判别结果表明其形成于大陆岛弧环境,其物质来源可能属于松嫩地块的长英质岩石。     

西昆仑赞坎地区古元古代化学沉积岩系的地球化学及微区特征研究

赞坎铁矿是西昆仑地区典型的铁矿床之一,该矿区内存在一套共生的化学沉积岩系"铁矿层和硅质岩"。本研究对该化学沉积岩系的宏观地球化学特征和微观矿物学组构及矿物地球化学特征进行了分析和探讨,研究结果支持赞坎铁矿为遭受了改造的沉积变质型铁矿并形成于类似大陆边缘海相环境。显微镜下,富铁矿石主要包含石英、磁铁矿和硅酸盐矿物并具有明显的条带状构造,而硅质岩则表现为细-微晶石英颗粒构成的紧密堆积结构。矿石富铁条带的XRD和EBSD分析结果表明,该矿石富铁条带内的主要矿物为磁铁矿、辉石和微量磷灰石,磁铁矿颗粒的晶胞参数为a=b=c=8.394A,z=8并吻合沉积变质型铁矿的特征。LA-ICPMS分析结果表明,磁铁矿内杂质元素的氧化物平均含量按照Cr_2O_3(2764×10~(-6))、Al_2O_3(2494×10~(-6))、V_2O_5(1494×10~(-6))、SiO_2(1255×10~(-6))、TiO_2(589.7×10~(-6))、MnO(162.5×10~(-6))、MgO(114.9×10~(-6))依次降低,其地球化学示踪结果吻合沉积变质型铁矿的特征。全岩地球化学分析结果显示,硅质岩的SiO_2含量70.58%~81.78%、Ba含量平均372.4×10~(-6)、U含量平均2.21×10~(-6)、ΣREE值平均97.37×10~(-6),这些特征总体上吻合热水成因,而部分样品偏高的Al_2O_3含量和∑REE值及无明显Eu异常则指示了非热水成因陆源沉积物的贡献;硅质岩的Al/(A1+Fe+Mn)值0.68~0.96、MnO/TiO_2值0.00~0.05、Al/(Al+Fe)值0.74~0.97、Sc/Th值2.22~7.07、U/Th值0.33~0.86、Al_2O_3/TiO_2值平均32.24吻合,这些指标指示其形成于类似大陆边缘海相的沉积环境;硅质岩的Ni/Co平均3.10吻合富氧环境,Sr/Ba值平均0.23指示该硅质岩形成环境的水动力总体偏弱,这说明赞坎地区硅质岩及铁矿的原始形成环境相对富氧且水动力总体偏弱。由于遭受了后期的构造-岩浆事件改造,赞坎铁矿的矿石地球化学特征与典型BIF存在略微的差异,但其岩石学、宏观地球化学和微区矿物学特征均在总体上吻合沉积变质型BIF的特点。综上所述,赞坎铁矿属于早前寒武纪的沉积变质型BIF铁矿,该铁矿形成于类似大陆边缘海相环境并遭受了后期构造-岩浆事件的改造。     

云南省盈江县旧城—姐冒地区土壤和农产品硒地球化学特征及影响因素

基于云南省盈江县旧城—姐冒地区土壤、岩石和农产品采样分析资料,研究了土壤硒地球化学特征及主要影响因素,分析了农产品硒含量特征。结果表明,研究区土壤硒含量范围为0.01×10~(-6)～2.22×10~(-6),平均值为0.23×10~(-6),其中富硒土壤面积为73.41 km~2,占比17.47%;硒主要以残渣态形式存在,而能被农作物有效吸收的水溶态和离子交换态含量仅占总量的3.32%;土壤硒含量主要受成土母质、土壤硅铝铁率、有机质和pH值等因素影响。按照相关评价标准,研究区共有15件咖啡、1件澳洲坚果、2件稻谷和5件甘蔗达到安全富硒食品要求,其安全富硒率分别为100%、10%、1.32%和16.67%,且与富硒土壤集中分布位置基本一致。     

Wavelength-dispersive X-ray fluorescence spectrometric determination of Sc, V, Cr, Co, Ni, Cu, Zn, Rb, Sr, Y, Zr, Nb, Ba, Pb, and Th in komatiites

Komatiites are mantle-derived ultramafic volcanic rocks. Komatiites have been discovered in several States of India, notably in Karnataka. Studies on the distribution of trace-elements in the komatiites of India are very few. This paper proposes a simple, accurate, precise, rapid, and non-destructive wavelength-dispersive x-ray fluorescence (WDXRF) spectrometric technique for determining Sc, V, Cr, Co, Ni, Cu, Zn, Rb, Sr, Y, Zr, Nb, Ba, Pb, and Th in komatiites, and discusses the accuracy, precision, limits of detection, x-ray spectral-line interferences, inter-element effects, speed, advantages, and limitations of the technique. The accuracy of the technique is excellent (within 3%) for Sc, V, Cr, Co, Ni, Cu, Zn, Rb, Sr, Zr, Nb, Ba, Pb, and Th and very good (within 4%) for Y. The precision is also excellent (within 3%) for Sc, V, Cr, Co, Ni, Cu, Zn, Rb, Sr, Y, Zr, Nb, Ba, Pb, and Th. The limits of detection are: 1 ppm for Sc and V; 2 ppm for Cr, Co, and Ni; 3 ppm for Cu, Zn, Rb, and Sr; 4 ppm for Y and Zr; 6 ppm for Nb; 10 ppm for Ba; 13 ppm for Pb; and 14 ppm for Th. The time taken for determining Sc, V, Cr, Co, Ni, Cu, Zn, Rb, Sr, Y, Zr, Nb, Ba, Pb, and Th in a batch of 24 samples of komatiites, for a replication of four analyses per sample, by one operator, using a manual WDXRF spectrometer, is only 60 hours.     

高压微波消解法测定醋酸纤维过滤器采集的微尘粒子中的砷镉钴铬铜铁锰镍铅钒锌

最新的流行病学研究表明,空气中较高浓度的悬浮细颗粒可能对人类的健康有不利的影响。根据该项研究显示,由于心脏病、慢性呼吸问题和肺功能指标恶化而导致死亡率的升高与细尘粒子有关。这些研究结果已经促使欧盟于1999年4月出台了限制空气中二氧化硫、二氧化氮、氧化氮、铅和颗粒物含量的法案(1999/30/EC),对各项指标包括对可吸入PM10颗粒的浓度提出了新的限制性指标。PM10颗粒是指可以通过预分级器分离采集的气体动力学直径小于10μm的细颗粒。目前研究的兴趣重点逐步偏向PM2.5这些更细微颗粒物,PM2.5这种颗粒物对健康有明显的不利影响。在欧盟指令2008/50/EC中,对PM10和PM2.5都提     

Isotopic systematics of He,Ar, S,Cu, Ni,Re, Os,Pb, U,Sm, Nd,Rb, Sr,Lu, and Hf in the rocks and ores of the Norilsk deposits

This paper reports the first results of a study of 11 isotope systems (³He/⁴He, ⁴⁰Ar/³⁶Ar, ³⁴S/³²S, ⁶⁵Cu/⁶³Cu, ⁶²Ni/⁶⁰Ni, ⁸⁷Sr/⁸⁶Sr, ¹⁴³Nd/¹⁴⁴Nd, ^206–208Pb/²⁰⁴Pb, Hf–Nd, U–Pb, and Re–Os) in the rocks and ores of the Cu–Ni–PGE deposits of the Norilsk ore district. Almost all the results were obtained at the Center of Isotopic Research of the Karpinskii All-Russia Research Institute of Geology. The use of a number of independent genetic isotopic signatures and comprehensive isotopic knowledge provided a methodic basis for the interpretation of approximately 5000 isotopic analyses of various elements. The presence of materials from two sources, crust and mantle, was detected in the composition of the rocks and ores. The contribution of the crustal source is especially significant in the paleofluids (gas–liquid microinclusions) of the ore-forming medium. Crustal solutions were probably a transport medium during ore formation. Air argon is dominant in the ores, which indicates a connection between the paleofluids and the atmosphere. This suggests intense groundwater circulation during the crystallization of ore minerals. The age of the rocks and ores of the Norilsk deposits was determined. The stage of orebody formation is restricted to a narrow age interval of 250 ± 10 Ma. An isotopic criterion was proposed for the ore-bearing potential of mafic intrusions in the Norilsk–Taimyr region. It includes several interrelated isotopic ratios of various elements: He, Ar, S, and others.     

硅酸盐中铁、锰、钛、钙、钾、磷、硅、铝、镁、钠、锶、铷、钡的X-射线荧光光谱定量测定

本文介绍样品经四硼酸锂熔融制成玻璃小饼。采用Lachance模式和理论a系数来校正元素间的效应,由3080E型X-射线荧光谱仪和DF-350B数据处理系统完成硅酸盐中十三个项目的测定。     

硅酸盐类样品中硅、铁、铝、钛、锰、钙、镁、钾、钠和磷的x射线荧光光谱测定

本文拟定了一种以熔融法制备样片,用X射线荧光光谱测定硅酸盐类样品中Si、Fe、Al、Tj、Mn、Ca、Mg、K、Na、P等元素的分析方法。在对不同靶材X光管和分光晶体实验对比的基础上,选择了最佳的测量条件。该法具有快速、准确,测量范围广,检测限低,价格便宜等优点。经过近百个各种类型标样或管理样品的分析对比表明,本法不仅适用于硅酸盐类岩石样品的分析,还适用于铁矿、铝土矿、碳酸盐类岩矿样品以及水泥、耐火材料等样品的分析。     

Viscous, cohesive, non-Newtonian, depositing, radial slurry flow

Mining induced subsidence can significantly affect mining costs where major surface facilities and natural environment need to be protected. Overburden grout injection is a technology used to control coal mine subsidence by injecting the mine waste material extracted from the coal back into the inter-burden rock during longwall mining. The flowing slurry is here categorised as a nonlinear viscous cohesive (Bingham plastic) fluid. During longwall mining the grout slurry is pumped into the separated beds of the rock mass through a central vertical borehole, which is drilled deep into the inter-burden rock strata above the coal seam. However, a blockage can occur in the injection system when the slurry velocity falls below a certain critical threshold velocity, indicating a material phase change from cohesive-viscous to cohesive-frictional. In situ field injection tests through boreholes have been simulated at a smaller scale at the CSIRO laboratory in Brisbane by pumping the slurry through a radial disk (gap = 4 mm) from its centre. Laboratory experiments indicate a general, nonlinear, cohesive, viscous, frictional model for shear behaviour of the slurry, in which the material shear parameters are functions of the disk radial distance. Complete dimensional and dimensionless analytical solutions have been developed based on an approach related to Bingham–Herschel–Bulkley fluid mechanics. The derived formulae include relations for minimum pump pressure, local pressure and pressure gradient, wall shear stress, volume rate, velocity and velocity gradient. The theoretical results match the experimental measurements. The experiments covered slurries with maximum particle sizes of 0.5 to 2 mm with about 50% being larger than 100 µm. The viscosities at the various solids concentrations were measured with a standard torsion viscometer. This study differs from the previous research in several distinct aspects, namely, consideration of the variable shear parameters rather than fixed values, inclusion of total nonlinear behaviour, and implementation of a friction function to mimic behaviour of the deposited and consolidating stiff slurry, which can cause a significant pressure rise as a result of the increased shear resistance.     

Mountains,nations, parks,and conservation

Between 1985 and 1991, two new mountain protected areas (MTNPA) covering more than 35,000 km² and based on participatory management models — the Makalu-Barun National Park and Conservation Area, Nepal, and Qomolangma Nature Preserve, Tibet Autonomous Region — were successfully established through the collaborative efforts of Woodlands Mountain Institute and conservationists in China and Nepal. Characteristics common to both projects include the importance of establishing (1) effective rationales, (2) local support constituencies, (3) a senior advisory group, (4) a task force, (5) linkages between conservation and development, and (6) fund raising mechanisms. The lessons derived from the experiences of Woodlands Mountain Institute are of significant value to others in preserving MTNPA. Increased collaboration and communication between all interested in conservation, however, will remain a critical component for expanding mountain protected area coverage to throughout the world.     

岩石密度和超高压岩石折返速率

在常温常压条件下对中国大陆科学钻CCSD主孔100-3000米岩心样品进行了密度测量,建立了密度连续剖面,并界定了不同超高压岩石的密度值。通过对比高温高压物性实验资料,岩石密度随着退变程度增强而降低,榴辉岩密度变化序列为3.52g/cm3→3.49g/cm3→3.07g/cm3→2.93g/cm3。超高压长英质岩石密度变化序列为3.00g/cm→2.80g/cm3→2.65g/cm3。上述实验资料是讨论不同折返阶段岩石所受浮力的基础,为研究折返速率大小提供了基本参数。本文通过折返板块运动平衡时,上浮力与粘滞力平衡这一关系式,定量研究了大陆俯冲板块的折返速率,认为密度差产生上浮力从而引起折返,温度对板块折返速率的影响最为显著;密度差大小、折返角度、折返板块大小对折返速率也有直接的影响。定量模拟分析表明,在温度高于850℃时,板块的折返速率可以超过100mm/a;当温度降至700℃时,折返速率则低于1.5mm/a。作者认为在折返早期,温度较高,板块快速折返至60-70km榴辉岩相深度;随着传导散热,温度降低,板块以较慢的速率折返至中下地壳。折返速率的估算表明,浮力是板块折返第一阶段(从>100km深部折返至<40km的中下地壳)的主要驱动力。     

Regional distribution of Al,B, Ba,Ca, K,La, Mg,Mn, Na,P, Rb,Si, Sr,Th, U and Y in terrestrial moss within a 188,000 km2 area of the central Barents region: influence of geology,seaspray and human activity

Five hundred and ninety-eight samples of terrestrial moss (Hylocomium splendens and Pleurozium schreberi) collected from a 188,000 km² area of the central Barents region (NE Norway, N Finland, NW Russia) were analysed by ICP-AES and ICP-MS. Analytical results for Al, B, Ba, Ca, K, La, Mg, Mn, Na, P, Rb, Si, Sr, Th, U and Y concentrations are reported here. Graphical methods of data analysis, such as geochemical maps, cumulative frequency diagrams, boxplots and scatterplots, are used to interpret the origin of the patterns for these elements. None of the elements reported here are emitted in significant amounts from the smelting industry on the Kola Peninsula. Despite the conventional view that moss chemistry reflects atmospheric element input, the nature of the underlying mineral substrate (regolith or bedrock) is found to have a considerable influence on moss composition for several elements. This influence of the chemistry of the mineral substrate can take place in a variety of ways. (1) It can be completely natural, reflecting the ability of higher plants to take up elements from deep soil horizons and shed them with litterfall onto the surface. (2) It can result from naturally increased soil dust input where vegetation is scarce due to harsh climatic conditions for instance. Alternatively, substrate influence can be enhanced by human activity, such as open-cast mining, creation of ‘technogenic deserts’, or handling, transport and storage of ore and ore products, all of which magnify the natural elemental flux from bedrock to ground vegetation. Seaspray is another natural process affecting moss composition in the area (Mg, Na), and this is most visible in the Norwegian part of the study area. Presence or absence of some plant species, e.g., lichens, seems to influence moss chemistry. This is shown by the low concentrations of B or K in moss on the Finnish and Norwegian side of the (fenced) border with Russia, contrasting with high concentrations on the other side (intensive reindeer husbandry west of the border has selectively depleted the lichen population).