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1.
We have analyzed the chemical composition and boron isotope composition of tourmaline from tourmalinites, granite and a quartz-tourmaline
vein from the Deri ore zone and from a pegmatitic band in the Rampura-Agucha ore body. These two Proterozoic massive sulfide
deposits occur in the Aravalli-Delhi orogenic belt, Rajasthan, northwest India. Tourmaline from stratiform tourmalinites closely
associated with the massive sulfides in the Deri deposit have preserved their original chemical compositions despite regional
and thermal metamorphism in the area. These tourmalines have low Fe/(Fe + Mg) ratios (0.19–0.30; mean 0.26) that suggest formation
close to the sediment-sea water interface. The δ11B values (−15.5 and −16.4‰) are compatible with boron derived from leaching of argillaceous sediments and/or felsic volcanics
underlying the original massive sulfide deposit during its formation. Boron isotope compositions measured in tourmaline from
a post-ore granite and quartz-tourmaline vein in the Deri deposit indicate that boron in these tourmalines was derived from
the tourmalinites produced during ore formation. The boron isotope systematics of a coarse brown tourmaline crystal from a
pegmatitic band on the hanging wall contact of the Rampura-Agucha deposit indicate that 45 ± 25% of the boron within the original
tourmaline was lost during upper amphibolite facies regional metamorphism.
Received: 3 April 1996 / Accepted: 11 April 1996 相似文献
2.
Summary
Quartz-tourmaline vein-hosting rocks of the Okote area belong to the Neoproterozoic Adola Belt. Metasomatic auriferous quartz-tourmaline
veins occur in ductile N–S trending, sinistral shear zones. These veins commonly contain quartz, carbonates, and tourmaline,
with minor pyrite, and accessory chalcopyrite, pyrrhotite, and gold. Tourmaline forms isolated euhedral crystals in the fracture
surfaces of quartz carbonate veins. Many of the tourmaline crystals are optically zoned with a bluish core and a bluish to
brown rim. Electron microprobe analyses show that the tourmalines comprise an intermediate dravite-schorl solid solution with
a mean FeO/(FeO + MgO) = 0.47. Abrupt transitions between the colour zones within single tourmaline crystals are accompanied
by relative variations in the FeO/(FeO + MgO) ratios. The tourmaline separates indicate that the tourmalines contain highly
variable average contents of trace elements. Chondrite-normalized rare earth element (REE) abundances of tourmaline separates
from auriferous veins show LREE-enriched to LREE-depleted patterns with negative to positive Eu anomalies and a flat, near-chondritic
HREE pattern. The auriferous quartz-tourmaline veins have LREE-enriched patterns without a Eu anomaly and a flat HREE pattern,
but tourmaline-free gold-quartz veins have very low REE contents and LREE-depleted patterns also without Eu anomalies. The
FeO/(FeO + MgO) ratios, major and trace element compositions, and the types of wall-rock alteration are used to suggest that
the sources of boron are dominantly metamorphic (dehydration and devolatilization processes), but do not totally exclude the
possibility of a magmatic source. The occurrences of high-grade gold associated with tourmaline make tourmaline a valuable
prospecting guide for hydrothermal gold mineralization in the Adola Belt, southern Ethiopia.
Received November 17, 1999; revised version accepted July 23, 2001 相似文献
3.
4.
广西大厂地区笼箱盖黑云母花岗岩与区内晚白垩世锡多金属成矿作用在时空上密切相关。岩相学特征表明,笼箱盖黑云母花岗岩中的电气石可以分为三类:1)浸染状电气石; 2)石英-电气石囊; 3)电气石-石英脉。本文利用电子探针和激光剥蚀等离子体质谱系统测定三种不同产状电气石的化学组成。分析结果显示,三种产状的电气石均具有高的Fe/(Fe+Mg)和Na/(Na+Ca)比值,主体属于碱基亚类铁电气石。浸染状电气石为岩浆晚期结晶,其Fe/(Fe+Mg)比值变化于0. 85～0. 94,随着岩浆分异,电气石逐渐富集Li、F、Fe和Sn等元素。与浸染状电气石相比,石英-电气石囊中早阶段电气石具有低的Fe/(Fe+Mg)比值,高的V、Co和Sr含量,可能反映了岩浆演化晚期出现的不混溶富硼熔/流体对早期黑云母和长石的交代作用,从而使囊中早阶段电气石继承部分被交代矿物的化学组成特征;石英-电气石囊中晚阶段电气石的化学组成变化较大(如Li、F、Mg、Al、V、Fe和Zn),与热液成因电气石的推论一致。与浸染状和囊状电气石相比,石英脉中的电气石具有高的Fe/(Fe+Mg)和Na/(Na+Ca)比值;微量元素组成与囊状电气石相似。就成矿元素锡而言,三种产状的电气石均具有相对高的锡含量,与其他地区锡成矿花岗岩中电气石的成分特征相似。但是,从岩浆晚期到热液阶段,大厂地区电气石的锡含量并没有显著升高,可能反映了早期岩浆热液流体对熔体锡有限的萃取作用。 相似文献
5.
Tourmaline in the central Swedish ore district 总被引：2，自引：0，他引：2
More than 40 recently discovered tourmaline occurrences have been investigated in the Mid-Proterozoic Bergslagen ore district of central Sweden. Some are spatially associated with ores, others with zones of leaching, remobilization and migmatization. Among the tourmaline-bearing ore deposits are the Dammberg ZnPb-Fe sulphide deposit, the Sala Pb-Zn-Ag deposit, the Dalkarlsberg, Pershyttan and Håksberg Fe oxide deposits, the Leja Cu deposit, and the Zinkgruvan Zn-Pb-Ag deposit. Tourmaline has been recorded a) as tourmalinites and tourmaline-bearing chemical sediments; b) in tourmaline-bearing skarns; c) in tourmaline-quartz veins; d) as disseminations along the foliation in schists; e) in tourmaline pegmatites; f) in tourmalinized haloes in metavolcanites along tourmaline pegmatites; and g) in late joints. Tourmalinites, tourmaline-bearing chemical sediments and tourmaline-bearing skarns are spatially associated with sulphide and oxide mineralizations. The dravite components in these tourmalines are proportional to the size of Zn-Pb sulphide mineralizations. Tourmalines from quartz veins close to and within ore deposits contain high Zr and Cr contents. With increasing distance away from these deposits, the Zr and Cr contents fall significantly. Tourmalines from pegmatites have inherited a number of trace element enrichments through partial melting and assimilation of volcaniclastic sediments into granitic melts. Despite magmatic homogenization, Zn contents in these tourmalines reflect the proximity of Zn-Pb-sulphide deposits, decreasing away from them. Tourmalines from late joints with Zn contents above the 100 ppm level are also indicative for the proximity of Zn-Pb sulphide mineralizations. Thus, some trace elements in these tourmalines may represent suitable exploration tools. 相似文献
6.
Diopside-rich, skarn-hosted, copper–gold ore derived primarily from carbonaceous metapelites at Mount Elliott forms a distinctive
member of the spectrum of Cu–Au–(Fe oxide) deposit styles in the Cloncurry district of the Paleoproterozoic to Mesoproterozoic
Mount Isa Block. The mine sequence is a package of carbonaceous metapelites and metagreywackes containing amphibolites derived
from tholeiitic basic rocks. A 40Ar–39Ar age spectrum with an extensive plateau-like segment at 1,510 ± 3 Ma from an actinolite associated with sulfides is taken
to represent the age of mineralization and is identical within error to the ages of most of the nearby batholithic granitoids.
The mine sequence is locally intruded by 1- to 10-m-thick late- to post-tectonic trachyandesite dykes, which were emplaced
during the hydrothermal activity that created the orebodies and have affinities with the regional high potassium “Eureka”
supersuite granitoids. Stable isotope data are consistent with dominantly magmatic fluids during mineralization and the regionally
distinctive skarn (Ca–Mg) and Cu–Au–Ni–Co–Te–Se (low Pb–Zn–Ag–Sb) chalcophile element associations may reflect a primitive
magmatic fluid source and/or leaching of these elements from country rocks. Mount Elliott is an unusual skarn deposit characterized
by pronounced early albitization (K–Fe–Mg depletion) of the host rocks succeeded by predominantly open-space deposition of
sodic diopside ± actinolite ± scapolite ± andradite ± magnetite ± sulfides ± apatite ± allanite ± tourmaline ± calcite. The
Ca–Fe–Mg(–Na)-rich (manganese-poor) chemistry was imposed from the fluid phase in the absence of carbonate-rich protoliths.
Immobile trace element (Ti, Zr, Nb) geochemistry shows that Mount Elliott skarns formed in both metasedimentary and mafic
metavolcanic host rocks, but the former are the main hosts of ore in upper and lower ore zones that represent most of the
resource. Banded skarns derived from a distinct calc-silicate/marble package at the nearby SWAN prospect have higher Nb/TiO2 and Zr/TiO2 ratios than the Mount Elliott metasediment-derived skarns, consistent with different provenance of the detrital components
in the two sequences. Medium- to coarse-grained massive skarn and skarn breccia in the Mount Elliott lower ore zone formed
in pelites and the trachyandesite dykes are the only intrusive rocks that could be genetically related to the mineralization
in the immediate vicinity of the orebodies.
Received: 1 September 1999 / Accepted: 28 September 2000 相似文献
7.
A microprobe study has been carried out on the chemical composition of tourmaline from the Yindongzi and Tongmugou stratabound Pb-Zn ore deposits, eastern Qinling, China. Tourmaline was analysed from a variety of rock types representative of its various occurrences associated with the ore bodies. All the tourmalines studied here belong to the schorl-dravite series. Most are of hydrothermal origin with Mg > Fe and Na > Ca. Some detrital cores of tourmaline have been recognized from their geometry and chemistry, with Fe > Mg. The chemical trends from core to rim in zoned grains suggest a multi-stage model for the growth of tourmaline and genesis of the ore bodies. The first stage was represented by a more Mg-rich hydrothermal fluid in the submarine hydrothermal system, producing Mg-rich tourmalines by selective replacement of clay-rich sediments close to the sediment-water interface. The second stage was dominated by Fe-rich hydrothermal fluid and resulted in overgrowth of Fe-rich tourmaline rims. This stage also led to the nucleation and growth of new tourmaline crystals and was responsible for the formation of the main massive sulphide orebodies. Finally, a further period of hydrothermal activity or a metamorphic event led to the formation of an additional rim of Mg-rich tourmaline. 相似文献
8.
Mineral chemistry and chemical zoning in tourmalines, Pampa del Tamboreo, San Luis, Argentina 总被引：2，自引：0，他引：2
Tourmalinites that are distally associated with tungsten deposits of the Pampa del Tamboreo area, San Luis, Argentina, contain tourmalines retaining evidence for its origin and evolution. Tourmaline grains uncommonly contain small grains of detrital tourmaline. Analysis of a single detrital tourmaline grain reveals that it is a Ca-rich “oxy-dravite”. Proximal to the detrital cores there are inner domains of asymmetric tourmaline overgrowths that developed during low grade metamorphism. Volumetrically dominant tourmaline overgrowths in the outer domain are concentrically zoned aluminous dravite and “oxy-dravite” with Al/(Al + Fe + Mg) = 0.71–0.74 and Mg/(Mg + Fe) = 0.64–0.71. Variability of Al is primarily controlled by the deprotonation substitution R + OH− = Al + O2− (where R = Fe + Mg), and is a function of the activity of H2O. A likely evolutionary scenario is one in which volcanogenic material is altered by hydrothermal fluids in the sea floor resulting in an aluminous and magnesian residuum. With further hydrothermal circulation and incipient metamorphism, boron-rich fluids are expelled from metasedimentary and metavolcanic basement rocks and develop Mg-rich tourmalinites in the aluminous, magnesian host rocks. The tourmalinization process occurs over a range of metamorphic conditions and with fluids of variable activity of H2O. 相似文献
9.
Discriminant diagrams for iron oxide trace element fingerprinting of mineral deposit types 总被引：19，自引：0，他引：19
Magnetite and hematite are common minerals in a range of mineral deposit types. These minerals form partial to complete solid
solutions with magnetite, chromite, and spinel series, and ulvospinel as a result of divalent, trivalent, and tetravalent
cation substitutions. Electron microprobe analyses of minor and trace elements in magnetite and hematite from a range of mineral
deposit types (iron oxide-copper-gold (IOCG), Kiruna apatite–magnetite, banded iron formation (BIF), porphyry Cu, Fe-Cu skarn,
Fe-Ti, V, Cr, Ni-Cu-PGE, Cu-Zn-Pb volcanogenic massive sulfide (VMS) and Archean Au-Cu porphyry and Opemiska Cu veins) show
compositional differences that can be related to deposit types, and are used to construct discriminant diagrams that separate
different styles of mineralization. The Ni + Cr vs. Si + Mg diagram can be used to isolate Ni-Cu-PGE, and Cr deposits from
other deposit types. Similarly, the Al/(Zn + Ca) vs. Cu/(Si + Ca) diagram can be used to separate Cu-Zn-Pb VMS deposits from
other deposit types. Samples plotting outside the Ni-Cu-PGE and Cu-Zn-Pb VMS fields are discriminated using the Ni/(Cr + Mn)
vs. Ti + V or Ca + Al + Mn vs. Ti + V diagrams that discriminate for IOCG, Kiruna, porphyry Cu, BIF, skarn, Fe-Ti, and V deposits. 相似文献
10.
P -T paths from anatectic pelites 总被引：2，自引：1，他引：1
Frank S. Spear Matthew J. Kohn John T. Cheney 《Contributions to Mineralogy and Petrology》1999,134(1):17-32
A relatively simple petrogenetic grid for partial melting of pelitic rocks in the NCKFMASH system is presented based on the
assumption that the only H2O available for melting is through dehydration reactions. The grid includes both discontinuous and continuous Fe-Mg reactions;
contours of Fe/(Fe+Mg) for continuous reactions define P-T vectors along which continuous melting will occur. For biotite-bearing assemblages (garnet+biotite + sillimanite + K-feldspar + liquid
and garnet + biotite + cordierite + K-feldspar + liquid), Fe/(Fe+Mg) contours have negative slopes and melting will occur
with increasing temperature or pressure. For biotite-absent assemblages (garnet + cordierite + sillimanite + K-feldspar + liquid
or garnet + cordierite + orthopyroxene + K-feldspar + liquid) Fe/(Fe + Mg) contours have flat slopes and melting will occur
only with increasing pressure. The grid predicts that abundant matrix K-feldspar should only be observed if rocks are heated
at P < 3.8 kbar, that abundant retrograde muscovite should only be observed if rocks are cooled at P > 3.8 kbar, and that generation of late biotite + sillimanite replacing garnet, cordierite, or as selvages around leu- cosomes
should be common in rocks in which melt is not removed. There is also a predicted field for dehydration melting of staurolite
between 5 and 12 kbar. Textures in migmatites from New Hampshire, USA, suggest that prograde dehydration melting reactions
are very nearly completely reversible during cooling and crystallization in rocks in which melt is not removed. Therefore,
many reaction textures in “low grade” migmatites may represent retrograde rather than prograde reactions.
Received: 5 March 1998 / Accepted: 7 August 1998 相似文献
11.
祖母绿是由微量Cr和/或V致色的绿色绿柱石。位于云南省麻栗坡县的大丫口祖母绿矿床是中国重要的祖母绿矿床,近年来取得了一系列的研究进展,但与祖母绿相关的电气石的研究工作还未展开。本文以大丫口矿床含祖母绿矿脉和非矿脉中的电气石为研究对象,在详细的野外调查和岩相学研究基础上,对电气石进行成分测试,旨在探讨电气石成因、查明物质来源和流体演化过程,进一步探究大丫口祖母绿矿床的成矿机制。结果显示:含矿脉电气石单位分子中Na含量为0.62~0.79 apfu,Al含量为5.36~6.17 apfu,Fe/(Fe+Mg)值为0.31~0.41;非矿脉电气石单位分子中Na含量为0.64~0.76 apfu,Al含量为5.66~6.38 apfu,Fe/(Fe+Mg)值为0.14~0.34。大丫口电气石具有富Mg、Y位(Y-site)上呈低Al或无Al的特征,属于碱族镁电气石,但是含矿脉电气石则显示更高的Fe/(Fe+Mg)值。电气石成分的差异可能主要与形成环境有关,电气石的成分差异具有指示祖母绿是否富集的潜力。大丫口电气石具有成分分带且V2O3含量为0.65%~4.76%,其形成与持续的热液流体交代围岩有关。大丫口矿床是一个岩浆起源的动态热液体系,流体通过碱交代作用参与水岩反应萃取围岩中的成矿物质。早期流体的物质组成以源于花岗质熔体的Si、Al、Be、F、P为主,而随着演化的进行,Ca、V等来自地层的成分逐渐增加。研究表明,铍的氟化物或氟铍络合物是大丫口成矿流体中Be的一种重要的迁移方式。萤石、氟磷灰石等含氟矿物的结晶促使铍的氟化物或氟铍络合物分解,流体中氟元素的减少可能是大丫口祖母绿成矿的重要机制之一。 相似文献
12.
Boron recycling in the continental crust of the central Andes from the Palaeozoic to Mesozoic, NW Argentina 总被引：4，自引：2，他引：2
Simone Kasemann Jörg Erzinger Gerhard Franz 《Contributions to Mineralogy and Petrology》2000,140(3):328-343
Whole-rock chemical composition and 11B/10B isotope ratios in tourmaline was investigated to study the geochemical recycling of boron during the evolution of the Andean
basement from the Palaeozoic to Mesozoic. In the basement (Cambrian to Ordovician high-grade paragneisses, migmatites and
orthogneisses, the Eocambrian Puncoviscana Formation, and Paleozoic-Mesozoic granitoid igneous rocks) whole-rock B contents
are generally below 100 ppm, but B contents of ˜1 wt% are found in cogenetic aplite and pegmatite dikes and in tourmaline–quartz
rocks. In the metasedimentary rocks, no systematic variation in B content because of metamorphic grade and no correlation
of B with other incompatible elements are apparent. Tourmalines from the high-grade metamorphic basement yield δ11B values ranging from −11.2 to −6.8‰ and isotope fractionation during migmatisation was small. Metamorphic tourmalines from
the Puncoviscana Formation have δ11B values between −6.3 and −5.8‰. The calculated (corrected for fractionation) δ11B values of −6 to −2‰ for the sedimentary protolith of the metamorphic basement indicate a continental B source with subordinate
marine input. Tourmalines from Palaeozoic and Mesozoic granitoids display an identical range of δ11B values from −12 to −5.3‰ and indicate a similarly homogeneous B source throughout time. Tourmalines from pegmatites and
tourmaline–quartz rocks record the average δ11B values of the parental granitic magma. We assume that B in the Palaeozoic and Mesozoic granitoids is derived from the local
metamorphic basement supporting the hypothesis that recycling of the lower Palaeozoic crust is the dominant process in granitic
magma formation from Palaeozoic to Mesozoic.
Received: 15 December 1999 / Accepted: 11 July 2000 相似文献
13.
Alteration zoning and primary geochemical dispersion at the Bronzewing lode-gold deposit, Western Australia 总被引：1，自引：0，他引：1
The Late Archaean Bronzewing lode-gold deposit is in the Yandal greenstone belt, Western Australia. It is located in a 500-m-wide,
N–S trending, structural corridor consisting of an anastomosing set of brittle–ductile shear zones and is chiefly hosted by
tholeiitic basalts, which are metamorphosed at mid- to upper-greenschist facies. Syn-peak metamorphic alteration surround
all ore bodies, and alteration extends laterally for ≤80 m from individual mineralised structures. Individual alteration haloes
partially overlap and form a >1.5-km-long and ≤300-m-wide domain. The alteration sequence, studied here at 140 m below the
present undisturbed surface, comprises distal calcite–chlorite–albite–quartz, intermediate calcite–dolomite–chlorite–muscovite–albite–quartz
and proximal ankerite–dolomite–muscovite–albite–quartz–pyrite zones. Mass transfer calculations indicate that chemical changes
during alteration include enrichment of Ag, Au, Ba, Bi, CO2, K, Rb, S, Sb, Te and W, and depletion of Na, Sr and Y. The elements Al, Ca, Cr, Cu, Fe, Mg, Mn, Ni, P, Ti, V, Zn and Zr
are immobile. The degree of chemical change increases with proximity to gold ore zones. In addition, abundant quartz veins
indicate substantial silica mobility during the hydrothermal event, although there is no large relative silica loss or gain
in the host rock. The broadest anomaly surrounding the Bronzewing gold deposit is defined by tellurium (>10 ppb) which, if
it is a hydrothermal anomaly, extends beyond the 400 × 600 m study area. Anomalous values for CO2, K, Rb and Sb also define wider zones than does anomalous gold (>4 ppb), although even the lithogeochemical gold anomaly
extends across strike for as much as 80 m away from ore and >600 m along the N–S strike of the shear zone corridor. Also carbonation
and sericitisation indices outline large exploration targets at the Bronzewing deposit. Sericitisation indices define anomalies
that extend for tens of metres beyond visible potassic alteration, whereas the anomalies defined by the carbonation indices
do not extend beyond visible carbonation. None of the individual alteration indices or pathfinder elements are able to define
consistent gradients towards ore. However, the respective dimensions of individual geochemical anomalies can be used as an
extensive, although stepwise, vector towards ore. This sequence is, from species with broadest dispersion first, as follows:
Te > CO2/Ca ≥ Sb, 3K/Al, Rb/Ti ≥ Au, W > Y/Ti (depletion) > Ag ≥ Bronzewing ore.
Received: 25 October 1999 / Accepted: 11 May 2000 相似文献
14.
R. B. Trumbull M.-S. Krienitz B. Gottesmann M. Wiedenbeck 《Contributions to Mineralogy and Petrology》2008,155(1):1-18
Tourmaline is widespread in metapelites and pegmatites from the Neoproterozoic Damara Belt, which form the basement and potential
source rocks of the Cretaceous Erongo granite. This study traces the B-isotope variations in tourmalines from the basement,
from the Erongo granite and from its hydrothermal stage. Tourmalines from the basement are alkali-deficient schorl-dravites,
with B-isotope ratios typical for continental crust (δ11B average −8.4‰ ± 1.4, n = 11; one sample at −13‰, n = 2). Virtually all tourmaline in the Erongo granite occurs in distinctive tourmaline-quartz orbicules. This “main-stage”
tourmaline is alkali-deficient schorl (20–30% X-site vacancy, Fe/(Fe + Mg) 0.8–1), with uniform B-isotope compositions (δ11B −8.7‰ ± 1.5, n = 49) that are indistinguishable from the basement average, suggesting that boron was derived from anatexis of the local
basement rocks with no significant shift in isotopic composition. Secondary, hydrothermal tourmaline in the granite has a
bimodal B-isotope distribution with one peak at about −9‰, like the main-stage tourmaline, and a second at −2‰. We propose
that the tourmaline-rich orbicules formed late in the crystallization history from an immiscible Na–B–Fe-rich hydrous melt.
The massive precipitation of orbicular tourmaline nearly exhausted the melt in boron and the shift of δ11B to −2‰ in secondary tourmaline can be explained by Rayleigh fractionation after about 90% B-depletion in the residual fluid.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
15.
I. A. Baksheev A. F. Chitalin V. O. Yapaskurt M. F. Vigasina I. A. Bryzgalov V. I. Ustinov 《Moscow University Geology Bulletin》2010,65(1):27-38
Three generations of tourmaline have been identified in propylite in the Vetka porphyry copper-molybdenum deposit of the Chukchi
Peninsula of Russia. Tourmaline-I is characterized by its Fetot/(Fetot + Mg) value, which ranges from 0.33 to 0.49. Tourmaline-II, which crystallizes at a lower temperature, overgrowing tourmaline-I
or occurring as isolated crystals, is distinguished by a higher Fetot/(Fetot + Mg), which varies from 0.46 to 0.72. The Fetot/(Fetot + Mg) ratio in tourmaline-III, which overgrows tourmaline-II is lower (0.35–0.49), and is identical to that of the first
tourmaline generation. This is probably caused by the beginning of sulfide deposition. Tourmalines in the deposit characterized
by complex isomorphic substitutions can be attributed to the intermediate members of the dravite—“hydroxy-uvite”-“oxy-uvite”
and schorl-“hydroxy-feruvite”-“oxy-feruvite” series. Tourmaline starts to crystallize at temperatures above 340°C. The fluid
responsible for the tourmaline deposition was magmatic, with a significant admixture of meteoric water (δ18OH
2O = −0.85 to −0.75‰). The high Fe3+/Fetot ratio (0.50) indicates high oxygen activity when the tourmaline precipitated. It has been established that the isomorphic
substitution Fetot → Al is typomorphic of tourmalines from porphyry copper deposits worldwide. 相似文献
16.
云龙铁厂锡矿位于青藏滇缅"歹"字型构造收缩部位的澜沧江变质带中,属于东南亚锡矿带东支——滇泰锡矿带的北延部分之云龙锡矿带。矿化与燕山晚期—喜马拉雅期细粒二云母花岗岩有关,矿体多产在岩体舌状边缘及外接触带的层间剥离带或混合岩体内的构造裂隙中。矿石类型以锡石-电气石、石英型为主,锡石-硫化物型和锡石-角岩型次之,成因类型为混合岩化-高温热液矿床。以混合岩化、主干断裂及硅化、电气石化为本区重要找矿标志,通过对铁厂锡矿矿床地质特征及找矿标志的研究,对该区寻找同类型矿产具有积极的指导意义。 相似文献
17.
I. A. Baksheev O. Yu. Plotinskaya V. O. Yapaskurt M. F. Vigasina I. A. Bryzgalov E. O. Groznova L. I. Marushchenko 《Geology of Ore Deposits》2012,54(6):458-473
Tourmalines from the Kalinovka porphyry copper deposit with epithermal bismuth-gold-basemetal mineralization and the Michurino gold-silver-base-metal prospect have been studied in the South Urals. Tourmaline from the Kalinovka deposit occurs as pockets and veinlets in quartz-sericite metasomatic rock and propylite. The early schorl-“oxy-schorl” [Fetot/(Fetot + Mg) = 0.66?0.81] enriched in Fe3+ is characterized by the homovalent isomorphic substitution of Fe3+ for Al typical of propylites at porphyry copper deposits. The overgrowing tourmalines of the second and third generations from propylite and quartz-sericite metasomatic rock are intermediate members of the dravite-magnesio-foitite solid solution series [Fetot/(Fetot + Mg) = 0.05?0.46] with homovalent substitution of Mg for Fe2+ and coupled substitution of X ? + YAl for XNa + YMg. These substitutions differ from the coupled substitution of YAl + WO2? for YFe2+ + WOH? in tourmaline from quartz-sericite rocks at porphyry copper deposits. At the Michurino prospect, the tourmaline hosted in the chlorite-pyrite-quartz veins and veinlets with Ag-Au-Cu-Pb-Zn mineralization is an intermediate member of the dravite-magnesio-foitite solid solution series [Fetot/(Fetot + Mg) = 0.20?0.31] with homovalent substitution of Mg for Fe2+ and coupled substitutions of X ? + YAl for XNa + YMg identical to that of late tourmaline at the Kalinovka deposit. Thus, tourmalines of the porphyry and epithermal stages are different in isomorphic substitutions, which allow us to consider tourmaline as an indicator of super- or juxtaposed mineralization. 相似文献
18.
Tourmaline occurs as a minor but important mineral in the alteration zc,ne of the Archean orogenic gold deposit of Guddadarangavanahalli （G.R.Halli） in the Chitradurga greenst~ne belt of the western Dharwar craton, southern India. It occurs in the distal alteration halo of the G.R.Halli golcl deposit as （a） clusters of very fine grained aggregates which form a minor constituent in the natrix of the altered metabasalt （AMB tourmaline） and （b） in quartz-carbonate veins （vein tourmaline）. ~[＇he vein tourmaline, based upon the association of specific carbonate minerals, is further grouped as （i） albite-tourmaline-ankerite-quartz veins （vein-1 tourmaline） and （ii） albite-tourmaline-calcite-quartz veins （vein-2 tourmaline）. Both the AMB tourmaline and the vein tourmalines （vein-I and vein-2） belong to the alkali group and are clas- sified under schorl-dravite series. Tourmalines occurring in the veins are zoned while the AMB tour- malines are unzoned. Mineral chemistry and discrimination diagrams 1eveal that cores and rims of the vein tourmalines are distinctly different. Core composition of the ve：n tourmalines is similar to the composition of the AMB tourmaline. The formation of the AMB tourmaline and cores of the vein tour- malines are proposed to be related to the regional D1 deformational event associated with the emplacement of the adjoining ca. 2.61 Ga Chitradurga granite whilst rims of the vein tourmalines vis-a- vis gold mineralization is spatially linked to the juvenile magmatic accretion （2.56-2.50 Ga） east of the studied area in the western part of the eastern Dharwar craton. 相似文献
19.
The origin of the Tongkeng-Changpo tin deposit,Dachang metal district,Guangxi, China: clues from fluid inclusions and He isotope systematics 总被引：6，自引：0，他引：6
Cai Minghai Mao Jingwen Liang Ting Franco Pirajno Huang Huilan 《Mineralium Deposita》2007,42(6):613-626
Tongkeng-Changpo is the largest tin deposit within the giant Dachang polymetallic tin ore field in Guangxi, southern China,
which is part of a large skarn system associated with Cretaceous granitoids. The Tongkeng-Changpo mineralization consists
of veins and stockworks in the upper levels and replacement stratiform orebodies (mantos) at lower levels. Based on textural
relationships, three major mineralizing stages can be recognized: stage I with cassiterite, sulphides, stannite, tourmaline,
and quartz; stage II with cassiterite, sulphides, sulphosalts, quartz, and calcite; and stage III with calcite as the main
phase. The study of fluid inclusions has shown that there are two main fluid types: CO2 and NaCl-H2O. Homogenization temperatures are 270 to 365°C, 210 to 240°C, and 140 to 190°C for stages I, II, and III, respectively. Salinities
range from 1 to 7 wt.% NaCl equiv. in the early ore stage and 3 to 10 wt.% NaCl equiv. in the late stages. Laser Raman Spectroscopy
indicates that the inclusion fluids in stages I and II were of carbono-aqueous composition, with minor amounts of CH4 and H2S, whereas those in stage III were aqueous. Helium isotopic analyses of inclusion fluids indicate that the 3He/4He ratios in the ore veins are in between 1.2 to 2.9 Ra (Ra = 1.4 × 10−6, modern atmospheric ratio), and range from 1.6 to 2.5 Ra in the stratiform orebodies. This range of 3He/4He ratios is significantly higher than that of crustal fluids (0.01–0.05 Ra). The similar characteristics of fluid inclusions
and their He isotopic composition, as well as age constraints, indicate that the ore veins and stratiform orebodies of the
Tongkeng-Changpo deposit formed from the same hydrothermal system, likely related to granite intrusions of the Mesozoic Yanshanian
tectono-thermal event. In addition, the high R/Ra ratios indicate a mantle contribution in the ore fluids. 相似文献
20.
Summary. ?Ca-tourmaline has been synthesized hydrothermally in the presence of Ca(OH)2 and CaCl2-bearing solutions of different concentration at T = 300–700 °C at a constant fluid pressure of 200 MPa in the system CaO-MgO-Al2O3-SiO2-B2O3-H2O-HCl. Synthesis of tourmaline was possible at 400 °C, but only above 500 °C considerable amounts of tourmaline formed. Electron
microprobe analysis and X-ray powder data indicate that the synthetic tourmalines are essentially solid solutions between
oxy-uvite, CaMg3- Al6(Si6O18)(BO3)3(OH)3O, and oxy-Mg-foitite, □(MgAl2)Al6(Si6O18)(BO3)3(OH)3O. The amount of Ca ranges from 0.36 to 0.88 Ca pfu and increases with synthesis temperature as well as with bulk Ca-concentration
in the starting mixture. No hydroxy-uvite, CaMg3(MgAl5)(Si6O18)(BO3)3(OH)3(OH), could be synthesized. All tourmalines have < 3 Mg and > 6 Al pfu. The Al/(Al + Mg)-ratio decreases from 0.80 to 0.70
with increasing Ca content. Al is coupled with Mg and Ca via the substitutions Al2□Mg−2Ca−1 and AlMg−1H−1. No single phase tourmaline could be synthesized. Anorthite ( + quartz in most runs) has been found coexisting with tourmaline.
Other phases are chlorite, tremolite, enstatite or cordierite.
Between solid and fluid, Ca is strongly fractionated into tourmaline ( + anorthite). The concentration ratio D = Ca(fluid)/Ca(tur) increases from 0.20 at 500 °C up to 0.31 at 700 °C. For the assemblage turmaline + anorthite + quartz + chlorite or tremolite
or cordierite, the relationship between Ca content in tourmaline and in fluid with temperature can be described by the equation
(whereby T = temperature in °C, Ca(tur) = amount of Ca on the X-site in tourmaline, Ca( fluid) = concentration of Ca2+ in the fluid in mol/l). The investigations may serve as a first guideline to evaluate the possibility to use tourmaline as
an indicator for the fluid composition.
Received July 24, 1998;/revised version accepted October 21, 1999 相似文献
Zusammenfassung. ?Synthese von Ca-Turmelin im System CaO-MgO-Al 2 O 3 -SiO 2 -B 2 O 3 -H 2 O-HCl Im System CaO-MgO-Al2O3-SiO2-B2O3-H2O-HCl wurde Ca-Turmalin hydrothermal aus Ca(OH)2 and CaCl2-haltigen L?sungen bei T = 300–700 °C und einem konstanten Fluiddruck von 200 MPa synthetisiert. Die Synthese von Turmalin war m?glich ab 400 °C, aber nur oberhalb von 500 °C bildeten sich deutliche Mengen an Turmalin. Elektronenstrahl-Mikrosondenanalysen und R?ntgenpulveraufnahmen zeigen, da? Mischkristalle der Reihe Oxy-Uvit, CaMg3Al6(Si6O18)(BO3)3(OH)3O, und Oxy-Mg-Foitit, □(MgAl2)Al6(Si6O18)(BO3)3(OH)3O gebildet wurden. Der Anteil an Ca variiert zwischen 0.36 und 0.88 Ca pfu und nimmt mit zunehmender Synthesetemperatur und zunehmender Ca-Konzentration im System zu. Hydroxy-Uvit, CaMg3(MgAl5) (Si6O18)(BO3)3(OH)3(OH), konnte nicht synthetisiert werden. Alle Turmaline haben < 3 Mg und > 6 Al pfu. Dabei nimmt das Al/(Al + Mg)- Verh?ltnis mit zunehmendem Ca-Gehalt von 0.80 auf 0.70 ab. Al ist gekoppelt mit Mg und Ca über die Substitutionen Al2□Mg−2Ca−1 und AlMg−1H−1. Einphasiger Turmalin konnte nicht synthetisiert werden. Anorthit (+ Quarz in den meisten F?llen) koexistiert mit Turmalin. Andere Phasen sind Chlorit, Tremolit, Enstatit oder Cordierit. Ca zeigt eine deutliche Fraktionierung in den Festk?rpern Turmalin (+ Anorthit). Das Konzentrationsverh?ltnis D = Ca(fluid)/Ca(tur) nimmt von 0.20 bei 500 °C auf 0.31 bei 700 °C zu. Für die Paragenese Turmalin + Anorthit + Quarz mit Chlorit oder Tremolit oder Cordierit gilt folgende Beziehung zwischen Ca-Gehalt in Turmalin und Fluid und der Temperatur: (wobei T = Temperatur in °C, Ca(tur) = Anteil an Ca auf der X-Position in Turmalin, Ca(fluid) = Konzentration von Ca2+ im Fluid in mol/l). Die Untersuchungen dienen zur ersten Absch?tzung, ob Turmalin als Fluidindikator petrologisch nutzbar ist.
Received July 24, 1998;/revised version accepted October 21, 1999 相似文献