The Lanthanide Tetrad Effect in Argillic Alteration: An Example from the Jizvan District, Northern Iran

Intrusion of quartz-monzodioritic igneous bodies of Oligocene age into Eocene lithic crystal tufts and trachy-basalts resulted in the occurrence of a widespread argillic alteration zone in the Jizvan district （northern Iran）. Mineralogically, the argillie alteration zone includes minerals such as kaolinite, quartz, smectite, pyrophyllite, muscovite-illite, alunite, rutile, calcite, feldspar, chlorite, hematite and goethite. Therefore, the non-CHARAC behaviour for trace elements in the argillic samples is reflected in the non-chondritic Y/Ho and Zr/Hf ratios and the irregular REE patterns, which appear related to the tetrad effect phenomenon. The chondrite-normalized REE distribution patterns indicate both concave （W-shaped） and convex （M-shaped） tetrad effects in the argillic samples. Based on the field evidence and the results from geochemical studies, it can be concluded that the samples from the argillic alteration zone having high fourth tetrad effect values （〉0.30） were developed in the fault and breccia zones. The results indicate that factors such as preferential scavenging by Mn-oxides, crystallization of clay minerals, fluid-rock interaction, overprint of hypogene mineral assemblage by supergene ones, and the structural control, have all played an important role in the occurrence of tetrad effects in samples of the argillic zone in the Jizvan district.

REE Tetrad Effect as a Powerful Indicator of Formation Conditions of Karst Bauxites: A Case Study of the Shahindezh Deposit, NW Iran

Study of the concentration of major,trace,and rare earth elements(REE)in the Shahindezh karst bauxite deposit,northwestern Iran clarifies the relationship of the tetrad effect with geochemical parameters in the bauxite ores.The existence of irregular curves in the chondrite-normalized REE patterns as well as non-CHARAC behavior of geochemically isovalent pairs(Y/Ho)are related to the tetrad effect.The meaningful positive correlation between the sizes of the calculated T3 tetrad effect and some geochemical factors such as Y/Ho,ΣREE,La/Y,(La/Yb)N,and(LREE/HREE)N as well as some major oxides-based parameters like Al2O3+LOI/SiO2+Fe2O3,Al2O3/Fe2O3,Al2O3+LOI,IOL,and SiO2+Fe2O3indicate that the studied bauxite horizon was likely deposited by different(acidic and/or alkalic)solutions at different stages.The lower part of the studied horizon with a thickness of^4.7 m displays alkali characteristics whereas the upper parts of the horizon with a thickness of^5.3 m are characterized by more acidic conditions.These results are fully supported by the co-occurrence of convex-concave tetrad effect curves in the chondrite-normalized REE patterns.Therefore,the tetrad effect phenomenon used in this study has proved to be a good and reliable geochemical proxy to assess the conditions of the depositional environment in the Shahindezh bauxite ores.

Petrology, REE Geochemistry and Tetrad Effect of Some Muscovite Granites at Wadi El Gemal Area, South Eastern Desert, Egypt

The muscovite granites at the study area are being emplaced into biotite granites and ophiolitic mélange settings. They occur in four exposures namely;Umm Seleimat, Sikait, Umm El Kheran and Umm Addebaa exposure. The presence of garnet and muscovite flakes may reflect the peraluminous nature of the studied muscovite granites. Petrographically, the studied granites are mostly subsolvus and consist of plagioclase, K-feldspars, quartz, muscovite and biotite. Garnet, zircon, allanite and opaques are accessories. The textural features of these granites are expressed by bent plagioclase lamellae, distorted microcline twinning, deformed mica flakes and development of myrmekite and recrystallization of feldspars into fine-grained aggregates. Umm Seleimat and Sikait exposures are more differentiated due to the presence of high content of K-feldspar and LREEs. The REE budget decreased from Umm Seleimat-Sikait exposures to Umm El Kheran-Umm Addebaa exposures as (514.5 - 495.6) to (195.9 - 197.7), respectively. Umm Seleimat-Sikait exposures have lower HREE/LREE (0.12 - 0.67), relative to Umm El Kheran-Umm Addebaa exposures (0.99 - 2.06). The studied granites revealed that the chondrite normalized REE patterns are the normal M-type of tetrad effect, where TE1,3 tetrad effect is higher than 1 in all samples which implies that there was an interaction between melt and water-haloid-rich fluid when these granites are crystallized from magma. Spectrometric values of Umm Seleimat and Umm Addebaa indicate that U content is more than Th content. Applying the U mobilization equation proved that the studied granites have been originated from a late magmatic phase of magma very rich in radioelements, also the majority of measurements lie above the zero line indicating that the studied granites affected with hydrothermal solutions rich in uranium than thorium which indicates uranium addition.

REE Tetrad Effects in Rare-metal Granites

Described in this paper are the characteristics of tetrad effects of REE in rare-metal granites.Based on the analytical data and experimental geochemical data available,it is pointed out that the tetrad effects of REE in the granites are produced in the metal-fluid system.Intense fractional crystallization of granitic melt(containing REE accessary minerals)and its interaction with volatile-rich(F,Cl)fluid are the major factors leading to the tetrad effects of REE.From this,this paper presents a composite genetic model for high-degree fractional crystallization-volatile-rich fluid metasomatism of rare-metal granites.With the model,quantitative calculations have been made.Meanwhile,it is pointed out that the tetrad effects of REE can be used as an important indicator to distinguish mineralized granites from barren ones.

Mineralogy,M-type tetrad effect and radioactivity of altered granites at the G.Abu Garadi shear zone,central Eastern Desert,Egypt

The G. Abu Garadi area is covered mainly by metasediments, alkali feldspar granites and stream sediments. The alkali feldspar granite is traversed by a major strike-slip fault trending in an N-S direction as well as two subordinate sets of faults trending NW to WNW for the first one and NE for the second one. These faults represent the shear zones affected by magmatic (syngenetic) as well as hydrothermal (epigenetic) activities causing alteration of the granitic rocks. The most common alteration features are albitization, greisenization and koalinitization. The mass balance calculations of the studied altered samples show enrichments in Zr, Y, Ni, U, Th and Ga and depletions in Zn, Sr, Nb, Ba, Pb, Cu and V. Only the greisenized samples exhibit a significant enrichment in Nb, ∑REE budget and pronounced lanthanide tetrad effect (M-type), especially TE1,4, while weakly expressed tetrad effects are for the other albitized and koalinitized samples. Mineralogically, the common accessory minerals in the altered samples include samarskite-(Y), betafite, uranothorite, zircon, fluorite and cassiterite. The greisenized granites contain high eU and eTh than the other altered types, where they are characterized by an assemblage of the radioactive minerals; samarskite-(Y), betafite, uranothorite in addition to zircon. The inter-element relationships between U and Th and also their ratios illustrate that the radioelement distribution in these granites is mainly governed by magmatic processes, in addition to post-magmatic ones. The distribution of chemical elements and the fractionation of some isovalents within the shear zone are largely controlled by the newly formed mineral phases. With respect to uranium mobilization, uranium migrated from the host alkali feldspar granites of G. Abu Garadi, while the shear zones acted as traps for the migrated uranium. Moreover, U migrated in the shear zone during greisenization and albitization, and migrated out during koalinitization.

The Hizeh-Jan Kaolin Deposit of NW Iran:the Tetrad Effect in REE Distribution Patterns

The Hizeh-Jan kaolin deposit(northwest of Varzeghan, East-Azarbaidjan Province, NW Iran) is a product of the alteration of Eocene andesitic rocks. Based on mineralogical examinations, kaolinite, quartz, smectite, pyrophyllite, muscovite-illite, alunite, calcite, diaspore, goethite and hematite are the most abundant mineral phases in this deposit. The geochemical indicators, such as Y/Ho and Zr/Hf, indicate the non-CHARAC(non-Charge-radius control) behavior of these pairs, which are likely to be due to the occurrence of the tetrad effect phenomenon in this deposit. Simultaneous concave and convex shapes in the chondrite-normalized REE distribution patterns are a remarkable feature of the kaolin samples. Bivariate diagrams of the size of the third tetrad effect(T_3) versus geochemical parameters such as Y/Ho, Nb/Ta and Zr/Hf ratios display two distinct populations for the kaolin samples. The first population is characterized by high T_3 values(>0.13), which are near or on the fault zone. The second population is characterized by low T_3 values(<0.13), and are farther from the fault zone. The obtained results from the geochemical data have furnished compelling evidence that fluidrock interaction, overprint of hypogene processes by supergene ones, and structural control, are key controlling factors for the occurrence of tetrad effects in REE distribution patterns in the Hizeh-Jan kaolin deposit.

Theoretical probe into universal tetrad effect for complexation discrepancy between lanthanide elements and organophosphoric extractant diethyl phosphoric acid

The deep understanding of 4f-correlated electron motion behavior is experimentally limited due to similar physicochemical properties of rare earth elements(REEs).While the solvent extraction behavior originating from the continuous occupation of 4f electrons along the lanthanide family provides a particular platform to probe the 4f electrons motion behavior and its correlations to their versatile functions.Herein,the complexation between REEs and the prototypical extractant of diethyl phosphoric acid(DEP)was substantially studied based on quantum mechanical calculation.The results firstly show that the average bond lengths between Ln and six coordinated oxygen atoms are consistent with lanthanide contraction phenomenon,and gadolinium break effect is also obviously observed.Secondly,the"tetrad effect"is figured out based on the subtle discrepancy of 4f electrons occupation,namely La-Nd,Sm-Eu,Gd-Dy and Ho-Lu.Specifically,the main composition is 4f5d6p for La-Nd,while the discrepancy is due to the increasing electrons in the 5d shell,while it is 4f5d for Pm-Eu.For Gd-Dy,their 4f orbitals accept little electrons and the donating electrons flow into 6s5d subshells due to the half-filled stability and the enhancement of shielding effect.The electrons donate into 5d6p subshells due to multiply electrons occupation of 4f orbitals for Ho-Lu.These detailed analyses obviously clarify the"tetrad effect"along the lanthanide family due to the different variation of 4f orbital occupation.It is expected that these microscopic understandings provide important guidance for the separation of REEs and the design of new extractants.

A peculiar composite M-and W-type REE tetrad effect:Evidence from the Shuiquangou alkaline syenite complex,Hebei Province,China

A new type of REE tetrad effect,a composite M-and W-type,was recognized in the K-feldsparthized and silicificated Shuiquangou alkaline syenites,Dongping,Hebei Province.Different analytical methods such as ICP-MS and isotopic dilution thermal ion mass spectrometer were exploited to verify the REE concentrations of the samples in three laboratories in China,France and Korea.The results are reliable and consistent within errors.In situ quantitative analysis of REE concentrations of individual zircons and apatites extracted from the very same sample has shown that fractional crystallization of magma and the superimposed hydrothermal alteration might have taken place in at least two-stage hydrothermal activities to generate the composite M-and W-type REE tetrad effect.The coexisting melt and aqueous phases,the superimposed alteration by volatile(Cl,CO2) -and Si,K, Al-enriched high temperature hydrothermal fluids might be the important facts for this new MW-type of REE tetrad effect.In addition,the peculiar MW-type tetrad effect might be an indicator for Au mineralization of reworked plutons.

Petrology, geochemistry, radioactivity, and M–W type rare earth element tetrads of El Sela altered granites, south eastern desert,Egypt

The southern part of the Eastern Desert of Egypt—about 30 km southwest of Abu-Ramad city—is mainly covered by ophiolitic rocks(Sul Hamed), island arc assemblage, younger granites(muscovite granites of Qash Amer and two mica granites of El Sela), and various acidic and basic dikes. Field, petrological, and geochemical studies indicate that the El Sela shear zone has been subject to hydrothermal and supergene alteration such as kaolinization, albitization, sericitization, and hematitization. It is invaded by quartz ENE–WSW veins associated with hydrothermal alteration accompanied by radioactive mineralization. The investigated younger granitic rocks had very low contents of compatible elements, such as Cr, Ni,and Co; and high contents of incompatible elements, such as Zr, and large ion lithophiles, such as Sr, especially in the El Sela shear zone. Major oxide and trace element analyses revealed calc-alkaline affinity and peraluminous character.These highly differentiated granitic rocks' lower Zr/Hf and higher Y/Ho than the normal ratio are consistent with hydrothermal alteration. Most samples had rare earth element(REE)-patterns with an M-type tetrad effect in the first and fourth segments and a W-type tetrad in the third segment. The average ∑REE in the studied granites was lower than the world granite average; the ratio of light to heavy REEs greater. The main radioactive, uranium-bearing, and uraniferous Fe and Mn minerals are uranothorite,autunite, uranophane and autunite as compounds, kasolite,columbite, xenotime, uranophane-bearing zircon and jarosite, silver-bearing pyrite, hematite, and autunite-bearing pyrolusite.

江南造山带中段仁里‒传梓源Li-Cs-Ta型伟晶岩中副矿物的稀土元素四分组效应

Li-Cs-Ta(LCT)型伟晶岩是我国Li、Nb、Ta、Be等关键金属的重要资源类型,其副矿物的稀土元素四分组效应(TE1,3)是表征花岗伟晶质岩浆演化过程和稀有金属成矿效应的重要参数,但其形成机制还存在较大的争议。本文选择江南造山带中段仁里‒传梓源LCT型伟晶岩中的副矿物(独居石、磷灰石、石榴子石和铌钽铁矿)为研究对象,旨在揭示其稀土元素四分组效应的形成机制及其与花岗伟晶质岩浆演化过程的耦合关联。仁里‒传梓源四类LCT型伟晶岩带中副矿物均具有相似的“M”型稀土元素四分组效应,且表现出一致的Eu负异常,表明这些副矿物是从具有“M”型稀土元素四分组效应和强烈Eu亏损的岩浆中同时结晶的。随着微斜长石‒钠长石伟晶岩→钠长石伟晶岩→钠长石‒锂辉石伟晶岩的演化,副矿物的稀土元素含量逐渐降低,Y/Ho和TE1,3值升高,暗示矿物结晶分异与副矿物的稀土元素四分组效应存在一定的联系,但矿物的结晶分异可能并不是副矿物稀土元素四分组效应形成的直接原因。岩浆演化过程中矿物的结晶分异会使熔体富集挥发分,挥发分中的氯与稀土元素的络合作用可能是LCT型伟晶岩中副矿物产生稀土元素四分组效应的根本原因。

贝那鲁肽与四联活菌制剂结合治疗肥胖型2型糖尿病患者的效果

目的分析四联活菌制剂联合贝那鲁肽在肥胖型2型糖尿病(T2DM)中的应用价值。方法以随机数字表法将医院2022年1月至2023年1月接收的104例肥胖型T2DM患者分为对照组、研究组,各52例。对照组接受贝那鲁肽治疗,研究组接受贝那鲁肽联合四联活菌制剂治疗。比较两组疗效、不良反应、治疗前后血糖指标[餐后2 h血糖(2 h PG)、空腹血糖(FBG)、糖化血红蛋白(HbA1c)]、胰岛素抵抗指数(HOMA-IR)、体脂相关指标[空腹C肽(FCP)、瘦素(LEP)、爱帕琳肽13、腹内脂肪含量]、肠道菌群及炎症相关指标[分泌型卷曲相关蛋白-5(SFRP-5)、单核细胞趋化蛋白1(MCP-1)、肿瘤坏死因子α(TNF-α)、蛋白络氨酸磷酸酶-1 B(PTP-1B)]。结果研究组总有效率(96.15%)高于对照组(82.69%)(P<0.05);治疗后研究组2 h PG、FBG、HbA1c、HOMA-IR、LEP、腹内脂肪含量、MCP-1、TNF-α、PTP-1B均低于对照组,FCP、爱帕琳肽13、SFRP-5均高于对照组(P<0.05);治疗后研究组双歧杆菌、乳杆菌数量较对照组高,酵母菌、肠球菌数量较对照组低(P<0.05)。两组不良反应发生率相比,差异无统计学意义(P>0.05)。结论四联活菌制剂联合贝那鲁肽治疗肥胖型T2DM的效果确切,可促进肠道菌群、血糖水平、体脂相关指标改善,减轻机体炎症,促进病情恢复。

茵栀黄口服液联合双歧杆菌四联活菌治疗新生儿黄疸的效果

目的分析茵栀黄口服液联合双歧杆菌四联活菌应用在新生儿黄疸中的效果。方法选择山东省梁山县人民医院儿科自2021年6月至2023年10月期间收治的80例黄疸儿作为观察对象,依据随机数字表法进行分组,即对照组(40例,双歧杆菌四联活菌)和观察组(40例,茵栀黄口服液联合双歧杆菌四联活菌),对比两组不同治疗方案的作用效果。结果治疗后,其观察组的黄疸消失时间、胆红素及大便恢复正常时间等指标均优于对照组,(P<0.05);观察组治疗总有效率为97.50%显著高于对照组的85.00%,两组间差异明显(P<0.05);比较两组的并发症情况,观察组的并发症例数有2例,占比5.00%,对照组的并发症发生例数有9例,占比22.50%,组间差异显著(P<0.05)。结论茵栀黄口服液联合双歧杆菌四联活菌在新生儿黄疸中均有较高的应用价值,不仅提高了临床治疗效果,还促进其临床症状的改善,其不良反应也有所降低,可加速其康复进度。

双歧杆菌四联活菌片联合蒙脱石散对腹泻患儿肠黏膜屏障及血清炎性因子水平的影响

目的:研究双歧杆菌四联活菌片+蒙脱石散对腹泻患儿肠黏膜屏障及血清炎性因子水平的影响。方法:随机数字表法将该院(2022年3月至2023年3月)确诊的204例腹泻患儿分为研究组、参照组,各102例。参照组行蒙脱石散治疗,研究组在其基础上行双歧杆菌四联活菌片治疗。比较两组临床疗效、肠黏膜屏障功能指标、肿瘤坏死因子-α(Tumor necrosis factor-α,TNF-α)、血管活性肠肽(Vasoactive intestinal polypeptide,VIP)、C反应蛋白(C-reactive protein,CRP)、胃动素(Motilin,MTL)、白细胞介素-10(Interleukin-10,IL-10)、生长抑素(Somatostatin,SS)、γ干扰素(Interferon-γ,IFN-γ)、不良反应发生率。结果:研究组总有效率高于参照组(P<0.05);治疗后研究组D-乳酸、二胺氧化酶、内毒素水平低于参照组(P<0.05);治疗后研究组IL-10、IFN-γ高于参照组,MTL、VIP、SS、TNF-α、CRP低于参照组(P<0.05);治疗后研究组不良反应总发生率与参照组相比,差异无统计学意义(P>0.05)。结论:联合治疗方案疗效显著,可有效改善患儿肠道黏膜,减少炎症反应,且不良反应少,安全性高。

高度演化的黄山A型花岗岩:对扬子克拉通东南部中生代岩石圈减薄的约束?

黄山花岗岩以高硅(SiO2>75%)、低钙(CaO=0.51%～0.86%)、贫镁、相对富碱和高FeO*/MgO比值(8.28～87.20)为特征。微量元素地球化学性质上表现为强烈亏损Ba、Sr、Eu(δEu=0.01～0.13),富集Rb、Th和U,高场强元素Zr、Nb、Y和Ga的含量也较高。主量和微量元素均表现为A-型花岗岩的特征。该花岗岩最奇妙的特征是稀土元素分馏模式表现出罕见的"四素组效应"(tetrad effect),一些微量元素的行为也表现出不受离子电荷和半径的控制(non-CHARAC行为),如异常低的K/Rb和Zr/Hf比值以及醒目的高K/Ba比值,该特征仅见于与热液发生过强烈相互作用的高度演化的岩浆中。与钙碱性的太平岩体相比,高度演化的具A-型花岗岩特征的黄山岩体具有相对较低的87Sr/86Sr初时值(0.707,而太平岩体为0.710)和较高的εNd(t)值(-4.45～-4.87,而太平岩体为-6.21～-6.40),二阶段模式年龄(TDM-2)为1.24～1.33Ga,明显年轻于扬子克拉通内不同时期花岗岩所普遍显示的约2.1Ga的模式年龄值,也小于太平岩体的模式年龄(1.44～1.45Ga),指示黄山岩体的母岩浆中包含有较多新加入的软流圈地幔物质。我们认为,由钙碱性的太平岩体转变为碱性的黄山岩体所指示的是扬子克拉通东南部中生代岩石圈的减薄事件。

湘西沃溪金锑钨矿床中白钨矿的稀土元素地球化学

对湘西沃溪金锑钨矿床进行了研究,结果表明,该矿床中白钨矿的稀土元素(REE)含量相对较高,为40.5～123.6μg/g;且有明显的空间变化趋势,随矿区标高的增加而减少,这可能与流体运移过程中流体的REE浓度不断降低有关。不同产状的白钨矿均以轻稀土元素(LREE)亏损、中稀土元素(MREE)和重稀土元素(HREE)富集为特征;白钨矿样品的REE分布模式均存在着明显的M型四分组效应,暗示白钨矿的形成与流体作用或水/岩反应有关。进一步的研究表明,在沃溪白钨矿的沉淀过程中,成矿流体中的REE发生了明显分异,白钨矿对HREE,特别是MREE,具有明显的优先选择性;REE这种分配行为主要是受晶体化学因素的控制,与白钨矿晶体中Ca位置的大小密切相关,而与成矿流体中REE相对浓度、REE络合物的稳定性关系不大。

贵东花岗杂岩体的稀土元素特征及与铀成矿关系

贵东花岗杂岩体是一个由鲁溪岩体、下庄岩体、帽峰岩体、笋洞岩体、隘子岩体和司前岩体等组成的印支—燕山期复式花岗岩体,不同的岩体不仅在主要元素含量、铝过饱和指数等方面存在差异,而且在一系列稀土元素特征方面,如稀土总量、δEu值以及LREE/HREE、(La/Yb)N、(La/Sm)N、(Gd/Yb)N比值等,也存在很大的不同。铀矿体常常赋存在强过铝质、并且后期发生了强烈的流体-岩石相互作用的花岗岩体中,这些岩体典型的稀土元素特征是稀土总量、δEu、LREE/HREE、(La/Yb)N、(La/Sm)N、(Gd/Yb)N比值等均较低,并具有M型四分组效应。

诸广-下庄铀矿集区成矿过程中水-岩作用的地质地球化学特征

诸广-下庄铀矿集区是我国最大的花岗岩型铀成矿区,本文从岩石蚀变、不同介质中稀土元素的四分组效应、方解石中碳、氧和锶同位素组成等方面系统讨论了诸广-下庄铀矿集区内与铀成矿有关的各种水-岩相互作用的地质地球化学特征,得到以下主要认识:(1)铀矿田范围内成矿的花岗岩大多发生了强烈的蚀变,是水-岩作用的直接表现,晶质铀矿表面发生的溶蚀作用是铀活化的直接证据,裂变径迹特征揭示面型分布的绿泥石化是花岗岩中以类质同像形式存在的铀从花岗岩中活化出来的主要反映;(2)与铀成矿有关的花岗岩具有M型四分组效应,而沥青铀矿、黄铁矿、方解石、绿泥石和伊利石等矿石矿物和脉石矿物则具有W型或W-M混合型四分组效应,这种共轭存在的M型和W型四分组效应表明了流体-花岗岩作用是本区铀成矿作用的关键,沥青铀矿主要是从流体中沉淀成矿的;(3)矿田范围内方解石的δ13C、87Sr/86Sr及δ18O组成特征,及87Sr/86Sr与δ18O之间明显的负相关关系,揭示出本区铀成矿过程中的碳、水和铀来源不同———碳是幔源,铀是壳源,流体中的水至少有一部分是大气降水。

湖南骑田岭花岗岩与锡成矿的关系

骑田岭花岗岩是燕山早期深源浅成的高钾钙碱性复式花岗岩岩体。最晚的细粒花岗岩 Rb-Sr等时线年龄为 ( 15 1± 5 )Ma,低温蚀变和矿化的时代约为 13 6Ma。锡矿化分布于外接触带矽卡岩和岩体内部隐爆角砾岩充填的断裂中 ,细粒花岗岩岩浆作用与蚀变和矿化作用在空间上紧密伴生 ,成因上密切相关。骑田岭花岗岩具有花岗岩岩浆作用与矿化作用密切相关的直接证据——岩浆 -热液过渡阶段典型的地质地球化学特征 :1结构构造变化大 ,出现许多不平衡的结构构造 ,如斑状结构、蠕虫结构、连续不等粒结构、文象结构、花斑结构、细晶结构、环带结构、伟晶岩壳和晶洞构造 ;2石英中含有熔体包裹体和熔体—流体包裹体 ,并与 CO2 流体包裹体和高盐度流体包裹体共存 ;3蚀变广泛 ,特别是存在高温自交代蚀变钠长石化和条纹长石的微斜长石化。这种高温蚀变的花岗岩具有四重效应 ,表现出惰性元素的活动性 ,w( K) /w ( Rb)、w ( Sr) /w( Eu)、w( Y) /w( Ho)和 w( Zr) /w( Hf)等值大大偏离球粒陨石中的值。这些特征反映了富挥发分的晚期花岗岩岩浆由于高位减压“过冷”及淬火从而导致挥发分出溶、顶盖沿构造薄弱带隐爆垮塌以及出溶流体与正在结晶的花岗岩间的流—岩相互作用。岩体冷却及其高热产率驱动长期的热液循环 ,形成广泛的?

滇西含绿柱石伟晶岩锆石U-Pb年代学及其地质意义

对腾冲—梁河地区含绿柱石伟晶岩进行了锆石LA-ICP-MS U-Pb定年和地球化学分析。结果表明：含绿柱石伟晶岩的形成时代为（48.1±0.8）Ma（MSWD=4.0）,锆石形态特征和微量元素特征显示,伟晶岩锆石受到热液的改造。含绿柱石伟晶岩与55-52 Ma的白云母花岗岩在主量元素、微量元素及稀土元素方面表现出极其相似的特征,为钙碱性系列,过铝质花岗岩,表现出强烈的Eu亏损,δEu为0.074-0.083,相对富集HREE,（La/Yb）N=1.61-1.92,总体表现出典型的＂M＂型稀土元素四分组效应。含绿柱石伟晶岩是白云母花岗岩浆高度演化的结果,伟晶岩结晶温度为581℃,代表了印度—欧亚板块碰撞导致地壳加厚的构造背景。

大兴安岭中段晚三叠世四分组效应花岗岩的厘定及其地质意义

布敦化岩体位于中亚造山带东段大兴安岭地区的科尔沁右翼中旗,该岩体由中细粒二云母花岗岩和斑状中细粒白云母花岗岩组成。LA-MC-ICP-MS锆石U-Pb同位素年龄测试显示布敦化岩体形成于晚三叠世早期。地球化学分析表明,该岩体为弱过铝质-过铝质、高钾钙碱性系列,主量元素表现出高硅（73.73%-78.33%）、富碱（Na2O＋K2O=7.07%-9.06%）、低钙（Ca O=0.01%-0.87%）、贫镁（Mg O=0.12%-0.52%）的特征;稀土元素具有明显的Eu负异常和M型四分组效应配分型式。岩石学和地球化学特征显示布敦化岩体为高分异I型花岗岩。Lu-Hf同位素研究显示其εHf（t）值为7.0-12.4,二阶段Hf模式年龄（tDM2）为812-473Ma。结合邻区晚三叠世地质资料可知,布敦化岩体是在古亚洲洋闭合造山后伸展的构造背景下产生的,是晚元古代-早古生代地壳物质熔融的产物。布敦化地区的四分组效应花岗岩的稀土元素总量高、岩浆侵位后经历了强烈的分异演化,暗示布敦化地区可能具有较好的稀有金属矿的找矿前景。