广东石岭碱性杂岩的岩石学特征及地质意义   总被引：1，自引：0，他引：1  

肖振宇  杨学明 《矿产与地质》1998,12(3):155-159

广东石岭碱性杂岩体岩石矿物和岩石化学研究表明,杂岩体以霞石角闪正长岩、角闪正长岩为主,黑云母正长岩等岩石组成,为Ａ－型花岗岩分异结晶作用所形成。产于板内引张构造环境,与深大断裂有关。岩体本身已构成霞石正长岩矿床,具有较高的工业利用和经济价值。  相似文献   

Contrasting origin of post-collisional high-K calc-alkaline and shoshonitic versus alkaline and peralkaline granitoids. The use of sliding normalization   总被引：41，自引：0，他引：41  

Jean-Paul Ligeois  Jacques Navez  Jan Hertogen  Russell Black 《Lithos》1998,45(1-4):1-28

Abundant high-K calc-alkaline (HKCA) magmatism appears to be post-collisional and often shifts to shoshonitic or alkaline–peralkaline compositions in the final stages of orogeny. The nature and the causes of this transition are studied on the basis of 308 major element and of 86 unpublished trace element (including REE) analyses of the Pan-African granitoids from the Tuareg shield (Adrar des Iforas, Mali and Aïr, Niger). This database covers a wide variety of magmas from subduction-related to intraplate-type including abundant HKCA batholiths. Literature data from geodynamically well-constrained cases are also included. In addition to a conventional geochemical approach of the studied magmatism, the sliding normalization method is proposed. This tool aims at comparing magmatic series: each studied rock is normalized to the interpolated composition of the reference series that has the same SiO₂ content as the sample. This method amplifies differences in sources and in fractionation processes and allows comparison of rocks from basic to acid composition. Two distinct juvenile sources are proposed: a previously enriched phlogopite-K richterite bearing lithospheric mantle or a lower juvenile crustal equivalent for HKCA-shoshonitic magmas, and a lowest lithospheric-upper asthenospheric OIB-type mantle for alkaline-peralkaline magmatism. The first source is melted only shortly after its generation when the lithosphere was still hot, which restricts HKCA magmatism mainly to post-collisional settings. The second asthenospheric/lowest lithosphere source is by definition close to its melting temperature and can generate magma ubiquitously both in space and time. The main melting triggers are lithospheric major structures which are not only operative in a post-collisional setting but also in other environments such as intraplate setting. Geochemistry thus gives indications about the nature of the source and on geotectonic settings. However, the latter is a second rank information, which is partly model-dependant. The post-collisional period differs from other settings by a propensity to generate large amounts of magma of various kinds, among which HKCA magmatism is volumetrically the most prominent.  相似文献   

13C/12C- und 18O16O-Signaturen von Calcit-Abscheidungen in Drainagesystemen     

M. Dietzel 《洁净——土壤、空气、水》1995,23(4):180-184

¹³C/¹²C- and ¹⁸O/16O-signatures of Calcite Precipitations in Drainage Systems Measurements of drainage waters show two distinct processes of calcite precipitation: 1. reprecipitation of calcium carbonate previously dissolved in groundwaters and 2. absorption of atmospheric CO₂ by alkaline solutions. Both processes may be distinguished by the stable isotopes of oxygen and carbon. Calcite precipitated from carbonate groundwater yields δ¹³C ≈ ?13%₀ (PDB) and δ¹⁸O ≈ 24%₀ (SMOW), whereas calcite produced by CO₂-absorption shows δ¹³C ≈ ?25%₀ (PDB) and δ¹⁸O ≈ 10%₀ (SMOW).  相似文献   

扇贝碱性磷酸酶中Zn的作用     

欧阳培  徐培宁  李碧荣 《热带海洋学报》1991,(2)

以华贵栉孔扇贝Chlamys nobilis(Reeve)为材料,获得聚丙烯酰胺凝胶电泳为单一蛋白区带的酶制剂。用凝胶过滤法测得该酶的分子量为159000,由20种氨基酸组成,共1118个氨基酸残基。每个酶蛋白含有4个Zn原子。将该酶的酶制剂制成脱Zn酶后,与相同浓度过度性两价金属离子作用,其活力回升以Zn最强,Co次之。若向脱Zn酶蛋白分别加入一定量Zn原子或Co原子,根据实验结果初步推测:每个酶蛋白的4个Zn原子中有2个Zn原子先与该酶结合,与酶的催化作用有密切关系;另外2个Zn原子与酶结合,则起维持酶结构的作用,与哺乳动物和Eschericha coli来源的碱性磷酸酶研究结果一致。此外,本实验采用可见吸收光谱和圆二色谱(CD)来确证Co能很好地取代该酶蛋白内的Zn,与Simpon报道相比较,得知当Co原子加入脱Zn酶时,先加2个Co~(2 )离子结合到该酶的结构部位,而后加2个Co~(2 )离子才结合到催化部位。  相似文献   

海洋沉积物中碱性磷酸酶活力与水体污染的关系   总被引：4，自引：0，他引：4  

薛雄志  洪华生 《台湾海峡》1995,14(3):274-279

厦门西港和香港维多利亚港近岸沉积物中碱笥磷酸酶活力与水体受污染程度的多项指标均表现出一定的相关性，如水体不ＢＯＤ５、无机氮、ＣＯＤ、无机磷等的含量及采样点离陆源排放点的距离等相关性较大，其相关性在水动力条件差的水域尤为显著。  相似文献   

黄海两种典型硅藻的磷胁迫生理研究   总被引：6，自引：0，他引：6       下载免费PDF全文

王丹  黄春秀  黄邦钦  谷体华  黄秋  柳欣  杨听林 《海洋科学》2008,32(5):22-27

在实验室批次培养条件下,研究黄海两种浮游植物优势种玛氏骨条藻(Skeletonema marinoi)和旋链角毛藻(Chaetoceros curvisetus)在低磷条件下的生长特性、环境中不同形态磷浓度的变化以及磷饥饿状态下浮游植物的营养吸收动力学和碱性磷酸酶动力学。结果表明,玛氏骨条藻在磷胁迫情况下可利用自身较高的吸收速率和较小的细胞体积有效摄取环境中的无机磷快速生长并取得优势,而旋链角毛藻在无机磷的利用上并无优势,其比玛氏骨条藻需要更多的细胞颗粒磷去维持细胞活性,而且更容易诱导碱性磷酸酶分解利用有机磷,推测在有机磷丰富的环境下旋链角毛藻会在二者竞争中取得优势。这些生理特性有可能是二者在黄海季节性水华发生过程中大量存在的原因。  相似文献   

Chromium mineralization in the Khibiny alkaline massif (Kola Peninsula,Russia)     

O. S. Yakovleva  I. V. Pekov  I. A. Bryzgalov 《Moscow University Geology Bulletin》2009,64(4):220-229

This paper presents new data on chromium mineralization in a fenitized xenolith in Mt. Kaskasnyunchorr in the Khibiny alkaline massif (Kola Peninsula, Russia) and summarizes data on Cr mineralogy in the Khibiny Mountains. Protolith silicates that contained Cr³⁺ admixture are believed to be the source of this element in the fenite. Cr-bearing (maximum Cr₂O₃ concentrations, wt %, are in parentheses) aegirine (5.8), crichtonite-group minerals (2.1), muscovite (1.3), zirconolite (1.1), titanite (1.0), fluorine-magnesioarfvedsonite (0.8), biotite (0.8), ilmenite (0.6), and aenigmatite (0.6) occur in the fenite. The late-stage spinellides of the FeTi-chromite-CrTi-magnetite series, which are very poor in Mg and Al and which formed after Crrich aegirine and ilmenite, are the richest in Cr (up to 42% Ct₂O₃). Cr concentrations grew with time during the fenitization process. Unlike minerals in the Khibiny ultramafic rocks where Cr is associated with Mg, Al (it is isomorphic with Cr), and with Ca, chromium in the fenites is associated with Fe, Ti, and V (with which Cr³⁺ is isomorphic) and with Na in silicate minerals. Cr³⁺ Mobility of Cr³⁺ and the unique character of chromium mineralization in the examined fenites were caused by high alkalinity of the fluid.  相似文献   

A natron source at Pikrolimni Lake in Greece? Geochemical evidence     

E. Dotsika  D. Poutoukis  I. Tzavidopoulos  Y. Maniatis  D. Ignatiadou  B. Raco 《Journal of Geochemical Exploration》2009,103(2-3):133-143

  相似文献   

Petrology of the Tekirova (Antalya) ophiolite (Southern Turkey): evidence for diverse magma generations and their tectonic implications during Neotethyan-subduction   总被引：1，自引：0，他引：1  

Utku Bağcı  Osman Parlak 《International Journal of Earth Sciences》2009,98(2):387-405

The SW Antalya Complex is an assemblage of Mesozoic carbonate platform, margin and ophiolitic rocks which record the formation and tectonic emplacement of a small Mesozoic ocean basin. The late Cretaceous ophiolitic rocks are located at two localities, namely the relatively intact Tekirova ophiolite to the east of Kemer zone and the dismembered Gödene ophiolite to the west of Kemer zone. The Tekirova (Antalya) ophiolite comprises harzburgitic tectonites, ultramafic to mafic cumulates, isotropic gabbros and sheeted dikes. Numerous isolated dikes, ranging in thickness from 5 cm to 10 m, intruded the crustal rocks at different structural levels. The isotropic gabbros are represented by gabbro, diorite and quartz diorite rocks with granular to ophitic–subophitic textures. The isolated dikes are characterized by dolerite, diabase and microdiorite with ophitic, intersertal and microgranular textures. These rocks exhibit tholeiitic to alkaline compositions. New geochemical data presented in this paper from the isolated dikes and isotropic gabbros suggest that there are three main types of parental basic magmas that form the oceanic crustal rocks of the Tekirova (Antalya) ophiolite. These are (1) IAT series which can be referred to the Group I isolated dikes and isotropic gabbros; (2) low-Ti boninitic series characterized by the Group II isolated dike and isotropic gabbros; and (3) OIB-type including the Group III isotropic gabbros. The geochemical evidence suggests that the crustal rocks of the Tekirova (Antalya) ophiolite were generated from a progressive source depletion from island arc tholeiites (IAT) to boninites. Therefore, a fore-arc tectonic setting seems likely for the generation of the crustal rocks from the Tekirova (Antalya) ophiolite in the southern branch of Neotethys during the Late Cretaceous. The OIB-type alkaline isotropic gabbros are thought to have resulted from either (1) a late-stage magmatic activity fed by melts that originated within an asthenospheric window due to slab break-off or (2) subduction of a ridge system which generated OIB source across the asthenospheric window that has been no influence of fluids from the subducted slab into the overlying mantle wedge, shortly before the emplacement of the Tekirova (Antalya) ophiolite onto the Tauride platform.  相似文献   

The role of carbonate-fluoride melt immiscibility in shallow REE deposit evolution     

Jindrich Kynicky  Martin P.Smith  Wenlei Song  Anton R.Chakhmouradian  Cheng Xu  Antonin Kopriva  Michaela Vasinova Galiova  Martin Brtnicky 《地学前缘(英文版)》2019,10(2):527-537

The Lugiin Gol nepheline syenite intrusion, Mongolia, hosts a range of carbonatite dikes mineralized in rare-earth elements(REE). Both carbonatites and nepheline syenite-fluorite-calcite veinlets are host to a previously unreported macroscale texture involving pseudo-graphic intergrowths of fluorite and calcite. The inclusions within calcite occur as either pure fluorite, with associated REE minerals within the surrounding calcite, or as mixed calcite-fluorite inclusions, with associated zirconosilicate minerals. Consideration of the nature of the texture, and the proportions of fluorite and calcite present(～29 and 71 mol%,respectively), indicates that these textures most likely formed either through the immiscible separation of carbonate and fluoride melts, or from cotectic crystallization of a carbonatefluoride melt. Laser ablation ICP-MS analyses show the pure fluorite inclusions to be depleted in REE relative to the calcite. A model is proposed, in which a carbonate-fluoride melt phase enriched in Zr and the REE, separated from a phonolitic melt, and then either unmixed or underwent cotectic crystallization to generate an REE-rich carbonate melt and an REE-poor fluoride phase. The separation of the fluoride phase(either solid or melt) may have contributed to the enrichment of the carbonate melt in REE, and ultimately its saturation with REE minerals. Previous data have suggested that carbonate melts separated from silicate melts are relatively depleted in the REE, and thus melt immiscibility cannot result in the formation of REE-enriched carbonatites. The observations presented here provide a mechanism by which this could occur, as under either model the textures imply initial separation of a mixed carbonate-fluoride melt from a silicate magma. The separation of an REEenriched carbonate-fluoride melt from phonolitic magma is a hitherto unrecognized mechanism for REE-enrichment in carbonatites, and may play an important role in the formation of shallow magmatic REE deposits.  相似文献