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Fleurice Parat François Holtz Miloš René Renat Almeev 《Contributions to Mineralogy and Petrology》2010,159(3):331-347
The equilibrium phase relations of a mafic durbachite (53 wt.% SiO2) from the Třebíč pluton, representative of the Variscan ultrapotassic magmatism of the Bohemian Massif (338–335 Ma), have
been determined as a function of temperature (900–1,100°C), pressure (100–200 MPa), and H2O activity (1.1–6.1 wt.% H2O in the melt). Two oxygen fugacity ranges were investigated: close to the Ni–NiO (NNO) buffer and 2.6 log unit above NNO
buffer (∆NNO + 2.6). At 1,100°C, olivine is the liquidus phase and co-crystallized with phlogopite and augite at 1,000°C for
the whole range of investigated pressure and water content in the melt. At 900°C, the mineral assemblage consists of augite
and phlogopite, whereas olivine is not stable. The stability field of both alkali feldspar and plagioclase is restricted to
low pressure (100 MPa) at nearly water-saturated conditions (<3–4 wt.% H2O) and T < 900°C. A comparison between experimental products and natural minerals indicates that mafic durbachites have a near-liquidus
assemblage of olivine, augite, Ti-rich phlogopite, apatite and zircon, followed by alkali feldspar and plagioclase, similar
to the mineral assemblage of minette magma. Natural amphibole, diopside and orthopyroxene were not reproduced experimentally
and probably result from sub-solidus reactions, whereas biotite re-equilibrated at low temperature. The crystallization sequence
olivine followed by phlogopite and augite reproduces the sequence inferred in many mica-lamprophyre rocks. The similar fractionation
trends observed for durbachites and minettes indicate that mafic durbachites are probably the plutonic equivalents of minettes
and that K- and Mg-rich magmas in the Bohemian Massif may have been generated from partial melting of a phlogopite–clinopyroxene-bearing
metasomatized peridotite. Experimental melt compositions also suggest that felsic durbachites can be generated by simple fractionation
of a more mafic parent and mixing with mantle-derived components at mid crustal pressures. 相似文献
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Evidence of multiple evaporite recycling processes in a salt‐tectonic context,Sivas Basin,Turkey 
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下载免费PDF全文 Alexandre Pichat Guilhem Hoareau Jean‐Paul Callot Etienne Legeay Kaan Sevki Kavak Sidonie Révillon Corinne Parat Jean‐Claude Ringenbach 《地学学报》2018,30(1):40-49
The isotopic composition of evaporites can shed light on their environment of precipitation and their subsequent recycling processes. In this study, we performed Sr, O and S isotopic analyses on evaporitic sulphates in the halokinetic Sivas Basin. The main objectives were to decipher the age and origin of the evaporites responsible for the salt tectonics, and to test whether diapir dissolution acts as the source of younger evaporitic layers in continental mini‐basins. The Sr isotopes demonstrate that the first evaporites precipitated from seawater during the Middle–Late Eocene. The similar isotopic values measured in the halokinetic domain confirm that the Eocene evaporites triggered the salt tectonics and were continuously recycled in Oligo‐Miocene mini‐basins as lacustrine to sabkha evaporites. Modern halite precipitates suggest that the dissolution and recycling of diapiric halite is ongoing. This study demonstrates the efficiency of isotopic analyses in constraining evaporite recycling processes in continental halokinetic domains. 相似文献
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帕拉提·阿布都卡迪尔 《地球科学》1999,24(3):278-281
新疆萨勒布尔山上志留统克克雄参数表明其物源为布鲁克碎屑浊积岩。该组的ＲＥＥ,主元素地化学参数表明其物源为布鲁克其组的岛弧型火山主沙尔布尔组的岩浆弧建造,其形成的构造环境为大洋岛弧至活动大陆边缘之间,代表着由大洋向活动大陆转变的趋势。 相似文献
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西昆仑北缘钾镁煌斑岩及超镁铁岩地质特征 总被引：5，自引：1，他引：4
帕拉提·阿布都卡迪尔 《新疆地质》2000,18(2):163-166
产于塔里木地台铁克力克隆起内的钾镁煌夺岩石化学成分与亚洲钾煌斑岩的平均岩这成分接近,与澳大利亚西后利地区钾镁煌斑岩一致。稀土元素、微量元素组成与世界已 知钾镁煌斑岩具有相同特征。铁克力克隆起南缘柯岗－塔伦深断裂南阔绰人串珠状分布的超镁铁岩体,与钾镁煌斑岩具有相同的地质背景。该深断裂与西昆仑北缘深断裂交汇处是寻找含矿钾镁煌斑岩的有利部位。 相似文献
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Crystallization experiments at 400 MPa, oxidized condition (logfO2= NNO + 1, where NNO is nickel–nickel oxide buffer) andover a range of temperatures (850–950°C) and fluidcomposition (XH2Oin = 0·3–1) have been carriedout to constrain the storage conditions of the sulphur-richmagma of the Huerto Andesite (an anhydrite, pyrrhotite, andS-rich apatite-bearing, post-Fish Canyon Tuff mafic lava). Theresults are used to evaluate the role of fluids released fromthe crystallization of magmas such as the Huerto Andesite onthe remobilization of the largely crystallized dacitic FishCanyon magma body. Experiments were performed using the naturalandesitic bulk composition with and without added sulphur. Thepresence of sulphur slightly affects the phase equilibria bychanging the phase proportions, stability fields of plagioclase,pyroxenes and ilmenite, and also affects the plagioclase composition.Phase equilibria and mineral composition data indicate thatthe magma may have contained 4·5 wt % water in the meltand that the pre-eruptive temperature was 875 ± 25°C.Assuming that the magma was in equilibrium with a fluid phase,the CO2 concentration of the melt is estimated to be in therange 2000–4000 ppm (at 400 MPa). Before eruption, theandesite had an oxidation state very close to, or slightly within,the co-stability field of anhydrite–pyrrhotite at NNO+ 1·1. At these conditions, the sulphur content in themelt is 500 ppm. Assuming open-system degassing resulting fromcontinuing crystallization at depth, most of the CO2 dissolvedin the andesitic melt should be released after the crystallizationof <10 vol. % of the magma, corresponding to a cooling from875 to 825–850°C. Thus, the fluids released owingto crystallization processes should be mainly composed of waterat temperatures below 825°C. KEY WORDS: experimental study; andesite; volatile; Fish Canyon Tuff; Huerto Andesite 相似文献
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通过对北秦岭丹凤地区早古生代花岗岩的Ph、Sr、Nd同位素地球化学特征的系统研究,结合元素地球化学特征,证明早古生代具成分极性的枣园、黄柏岔、石门花岗岩是由于秦岭群斜长角闪岩和黑云斜长片麻岩部分熔融,近俯冲带以熔体与熔体的混合、远离俯冲带是前者产生的熔体与后者熔融后的残留相以不同比例混合形成的。 相似文献
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新疆某地红宝石和蓝宝石矿物学研究 总被引：1，自引：0，他引：1
本文系统地研究了新疆某地红宝石和蓝宝石矿床,查明该矿床中红宝石和蓝宝石的粒度、形态、双晶、裂纹,包裹体形态和成分,硬度、密度、多色性、吸收性、Ne和No值,晶胞参数及化学成分等特征,从而为该类矿床的开发利用提供了重要信息。同时,根据这些宝石的物理性质和化学成分上的区别,进一步探讨了呈色机理。 相似文献
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Sulfur partition coefficient between apatite and rhyolite: the role of bulk S content 总被引：2，自引：1，他引：1
Fleurice?ParatEmail author Fran?ois?Holtz 《Contributions to Mineralogy and Petrology》2005,150(6):643-651
Experimental studies have been performed to constrain sulfur behavior during apatite crystallization and to determine sulfur
partition coefficient between apatite and melt (KdSapatite/melt) at oxidizing conditions. Crystallization experiments have been conducted with a hydrous rhyolitic melt and different bulk
sulfur contents (0.15 to 2 wt.% S) at 900 and 1,000°C, 200 MPa and Δlog =NNO+3.6. The sulfur content in the glass increases with increasing amount of added S. Anhydrite crystallizes for S added = 0.75 wt.%
(0.10 and 0.13 wt.% SO3 in glass at 900 and 1,000°C, respectively). The amount of anhydrite increases and the amount of apatite decreases with increasing
amount of added sulfur. The sulfur exchange reaction in apatite is influenced by the bulk composition of the melt (e.g., P
content). However, changing melt composition has only little effect on KdSapatite/melt for the investigated rhyolitic composition. The KdSapatite/melt does not depend directly on temperature, decreases from 14.2 to 2.7 with increasing S content in glass from SO3=0.03 to 0.19 wt.%, respectively, and can be predicted from the following equation: ln Kd = −0.0025×S in melt (in ppm)+2.9178.
The combination of experimental data obtained for rhyolitic and andesitic melts reveals that the sulfur partition coefficient
tends toward a value of 2 for high-sulfur content in the glass (>0.2 wt.% SO3). Using S in apatite as proxy for determining S content in melt is promising but additional experimental data are needed
to clarify the individual effects of T, , and P and Ca content in the melt on S partitioning. 相似文献
10.
Experimental study into the petrogenesis of crystal-rich basaltic to andesitic magmas at Arenal volcano 总被引：1，自引：1，他引：0
F. Parat M. J. Streck F. Holtz R. Almeev 《Contributions to Mineralogy and Petrology》2014,168(2):1-18
Arenal volcano is nearly unique among arc volcanoes with its 42 year long (1968–2010) continuous, small-scale activity erupting compositionally monotonous basaltic andesites that also dominate the entire, ~7000 year long, eruptive history. Only mineral zoning records reveal that basaltic andesites are the result of complex, open-system processes deriving minerals from a variety of crystallization environments and including the episodic injections of basalt. The condition of the mafic input as well as the generation of crystal-rich basaltic andesites of the recent, 1968–2010, and earlier eruptions were addressed by an experimental study at 200 MPa, 900–1,050 °C, oxidizing and fluid-saturated conditions with various fluid compositions [H2O/(H2O + CO2) = 0.3–1]. Phase equilibria were determined using a phenocryst-poor (~3 vol%) Arenal-like basalt (50.5?wt% SiO2) from a nearby scoria cone containing olivine (Fo92), plagioclase (An86), clinopyroxene (Mg# = 82) and magnetite (Xulvö = 0.13). Experimental melts generally reproduce observed compositional trends among Arenal samples. Small differences between experimental melts and natural rocks can be explained by open-system processes. At low pressure (200 MPa), the mineral assemblage as well as the mineral compositions of the natural basalt were reproduced at 1,000 °C and high water activity. The residual melt at these conditions is basaltic andesitic (55 wt% SiO2) with 5 wt% H2O. The evolution to more evolved magmas observed at Arenal occurred under fluid-saturated conditions but variable fluid compositions. At 1,000 °C and 200 MPa, a decrease of water content by approximately 1 wt% induces significant changes of the mineral assemblage from olivine + clinopyroxene + plagioclase (5 wt% H2O in the melt) to clinopyroxene + plagioclase + orthopyroxene (4 wt% H2O in the melt). Both assemblages are observed in crystal-rich basalt (15 vol%) and basaltic andesites. Experimental data indicate that the lack of orthopyroxene and the presence of amphibole, also observed in basaltic andesitic tephra units, is due to crystallization at nearly water-saturated conditions and temperatures lower than 950 °C. The enigmatic two compositional groups previously known as low- and high-Al2O3 samples at Arenal volcano may be explained by low- and high-pressure crystallization, respectively. Using high-Al as signal of deeper crystallization, first magmas of the 1968–2010 eruption evolved deep in the crust and ascent was relatively fast leaving little time for significant compositional overprint by shallower level crystallization. 相似文献