南天山拜城县波孜果尔A型花岗岩类锆石U-Pb定年及其Lu-Hf同位素组成

新疆拜城县波孜果尔A型花岗岩类岩体位于塔里木地台北缘及邻区的近东西向碱性侵入岩带上,主要岩石类型为霓石钠闪石英碱长正长岩、霓石钠闪碱长花岗岩、黑云母碱长正长岩。全岩SiO₂=68.97%~74.14%,Na₂O+K₂O=9.67%~11.19%,Al₂O₃=13.72%~15.26%,Fe₂O₃=0.18%~1.41%,FeO=0.91%~1.51%,CaO=0.35%~0.63%。稀土元素总量较高,ΣREE=298×10^-6~1286×10^-6,平均706×10^-6,轻稀土富集,重稀土亏损,强烈的Eu负异常,呈“右倾海鸥型”的稀土元素配分模式。富Nb、Ta、Zr、Hf等高场强元素,亏损Ba、K、Sr等大离子亲石元素,Zr+Nb+Ce+Y=936×10^-6~3684×10^-6,平均1813×10^-6。为A1型花岗岩。岩体形成于早二叠纪。锆石LA-ICP-MS U-Pb年龄为287.7~291.6Ma,平均289.8Ma,岩体形成后,在279.1~282Ma左右经历了后期热液流体的改造。锆石ε_Hf（t）值为-6.3~9.0,两阶段模式年龄（t_DM2）跨越古元古代晚期-新元古代中期,主要集中在中元古代。岩浆平均温度832~839℃,形成于非造山的板内构造环境,且具高温、无水、低氧逸度的成岩特点。该岩体具有壳幔混源的特点。     

全吉地块金泉山—化石沟一带古生代 花岗质岩体地球化学及其构造意义

柴达木盆地北缘之全吉地块花岗质岩体大量发育,具多期次多阶段特征。通过对全吉地块金泉山—化石沟一带古生代花岗质岩体岩石学、岩石化学特征及单颗粒锆石U-Pb同位素定年,发现该区花岗岩有4次侵入,侵入时代分别为早奥陶世(471~476Ma)、中奥陶世(459±5Ma)、早志留世(423±4Ma)和中泥盆世(366±2Ma)。岩石地球化学研究显示,该4期花岗岩均具典型的钙碱性特征,轻稀土富集、重稀土轻度亏损、Eu轻微负异常—正异常,大离子亲石元素K2O、Rb、Ba、Th等相对强烈富集,高场强元素Nb、Ta、Hf、Zr及Yb明显亏损,除第4期岩体即具I型,又具S花岗岩特征外,其它各期次均属I型花岗岩,总体显示岩体具壳源特征,为板块碰撞前消减地区花岗岩,研究推测,金泉山—化石沟一带古生代花岗质岩体第1、2组年龄为全吉地块与柴达木陆块碰撞的时代,第3组年龄反映了深俯冲地下的板块由于拆沉而折返的时代,第4组年龄为碰撞隆起后造山带伸展、滑塌的时代。     

Silicate melt inclusions in the Qiushuwan granitoids,northern Qinling belt,China: Implications for the formation of a porphyry Cu–Mo deposit as a reduced magmatic system

Melt inclusions (MIs) in quartz from granitoids in the northern Qinling belt were studied using microthermometry and laser Raman spectroscopy. The total homogenization of melt inclusions occurs in a mean range between 1050 and 1100 °C. Laser Raman experiments reveal H₂O, C₂H₆, C₄H₆ and CH₄ as the dominant volatile compounds. Our results provide insights into the temperatures of magma crystallization and the dominantly reducing environment during the early magmatic stage. Based on ore mineralogy, and on the volatile species content in the MIs, we evidence firstly that the Qiushuwan porphyry Cu–Mo deposit in the Qinling–Dabie–Sulu orogenic belt was derived from a reduced magmatic system, emplaced at relatively deep domains more than 10 km deep, and secondly, that the magmas that are responsible for the generation of Qiushuwan were either derived from an inherently reduced source, or reduced during ascent and emplacement. The mechanism might have involved the assimilation of sedimentary material with minimal crustal interaction. The parental magmas likely underwent reduction essentially by loss of all of their SO₂ by degassing, as evidenced by the low S content in melt inclusions. These reduced materials provided adequate sulfur source for the formation of the porphyry Cu–Mo deposits with obvious zonation, which plays a key role in the mineralization; finally, we conclude that the reduced environment and the relatively deep domain of magma emplacement probably limited the extent of mineralization, generating only a relatively small Cu–Mo deposit in Qiushuwan, located within the northern Qinling accretionary belt.     

Paleozoic granitoid magmatism of the eastern part of the Central Asian Fold Belt and formation of large ore deposits

Evidence on the Paleozoic granitoids of the eastern part of the Central Asian Fold Belt (CAFB) was analyzed. A tectonic chart of orogenic belts was compiled. Sketch maps were constructed for the geodynamic settings of the formation of Paleozoic granitoids and the extensiveness of their occurrence. Two types of deep controlling structures were distinguished: zones of lithospheric faults and plumes, including the newly recognized Jiamusi-Bureya plume. It was sown that the distribution of large and superlarge Paleozoic ore deposits is related to these structures, primarily to plumes. Sites promising for large and superlarge deposits related to the Paleozoic granitoid magmatism were determined in the Russian Far East.     

Oxygen isotopes in the Cretaceous-Paleogene granites of Primorye and some problems of their genesis

The Cretaceous-Paleogene granites of the Eastern Sikhote Alin volcanic belt (ESAVB) and Late Cretaceous granitoids of the Tatibin Series (Central Sikhote Alin) are subdivided into three groups according to their oxygen isotope composition: group I with δ¹⁸O from +5.5 to +6.5‰, group II with δ¹⁸O from +7.6 to +10.2‰, and group III with less than +4.5‰. Group I rocks are similar in oxygen isotope composition to that of oceanic basalts and can be derived by melting of basaltic crust. Group II (rocks of the Tatibin Series) have higher δ¹⁸O, which suggests that their parental melts were contaminated by sedimentary material. The low ¹⁸O composition of group III rocks can be explained by their derivation from ¹⁸O-depleted rocks or by subsolidus isotopic exchange with low-¹⁸O fluid or meteoric waters. The relatively low δ¹⁸O and ⁸⁷Sr/⁸⁶Sr in the granitoids of Primorye suggest their derivation from rocks with a short-lived crustal history and can result from the following: (1) melting of sedimentary rocks enriched in young volcanic material that was accumulated in the trench along the transform continental margin (granites of the Tatibin Series) and (2) melting of a mixture of abyssal sediments, ocean floor basalts, and upper mantle in the lithospheric plate that subsided beneath the continent in the subduction zone (granites of the ESAVB).     

豫西太山庙花岗岩体特征与多金属矿产的关系

经从岩石学、矿物学、地球化学等方面对燕山期太山庙花岗岩体详细研究,认为该岩体侵入为一重要构造热事件,控制着区内多个多金属矿床的形成与规模。本文着重探讨和阐述太山庙花岗岩体特征及其对周边矿床的控矿关系。     

Late mesozoic A-Type granitoids in se China and paleo-pacific plate subduction and slab rollback北大核心CSCD

This study has reviewed the distribution and pedogenesis of late Mesozoic A-Type granitoids in SE China. These A-Type granitoids belong to four belts ( S Jiangxi-SW Fujian belt, Xiang-Gui-Yue belt, Can-Hang belt and coastal belt) due to their temporal-spatial distribution. Based on the comparative analysis of chronology, geochemistry and magmatic association, this study has discussed the formation of A-Type granitoids and the subduction and slab rollback process of paleo-Pacific plate beneath SE China.     

Apatite Composition of Representative Magnetite‐series and Ilmenite‐series Granitoids in Japan

Apatites of representative magnetite‐series and ilmenite‐series granitoids were studied in the Japanese Islands. Concentrations of the volatile components F, Cl and SO₃ are differently distributed in apatites of these granitoid series. Apatites are always fluoroapatite. They have weakly higher F content in the ilmenite series than in the magnetite series. In contrast, Cl and SO₃, are significantly concentrated in apatites of the magnetite series compared to the ilmenite series. These characteristics reflect the original concentrations of these components in the host granitic magmas. A high fO₂ seems most important for the S‐concentration as sulfate in apatite of the magnetite series. REE and Y are only erratically high in the studied apatites.     

西准噶尔成矿带晚古生代花岗岩类岩浆活动及其构造意义

中亚造山带是晚古生代地壳显著生长与大规模成矿的重要地区。本文采集了中亚造山带西部的西准噶尔成矿带哈图-别鲁阿嘎希及其附近地区11个岩体共33件花岗岩类样品,对其开展了岩石地球化学与同位素示踪等研究,厘定了该地区晚古生代岩浆活动的特点与大地构造环境,并与哈萨克斯坦境内的巴尔喀什成矿带晚古生代岩浆活动进行了对比。研究表明,哈图地区晚石炭世花岗岩类主要为后碰撞伸展构造环境的A型花岗岩类,别鲁阿嘎希等地区存在洋内俯冲与岛弧环境的埃达克岩,显示了西准噶尔晚古生代构造环境时空变化的复杂性。该地区花岗岩类εNd(t)值较高(+4.62~+7.53)、εSr(t)值为(-57.61~+18.21),具有中亚造山带花岗岩类的共同特征,为古生代增生的新生陆壳,其源区与亏损地幔组分具有亲缘关系,这与巴尔喀什成矿带东段的花岗岩类具有一致性。花岗岩的~(206)Pb/~(204)Pb、~(207)Pb/~(204)Pb和~(208)Pb/~(204)Pb比值范围分别为18.2776~19.1677、15.5260~15.5796和38.2080~39.0821,为造山带花岗岩类。     

Integrated approach of using ASTER-derived emissivity and pixel temperature for delineating different granitoids – a case study in parts of Dharwar Craton,India

We have delineated different granitoids based on variation in emissivity and relative surface temperature recorded in thermal bands of Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) sensor of EO-1 satellite. In this regard, we have used emissivity normalization algorithm to derive broadband emissivity from thermal bands of ASTER sensor to delineate different lithounits of the granitoid family. We have compared emissivity and radiance image composites in terms of delineation of different granitoids. We have also used false colour composite (FCC) image derived using two emissivity bands and temperature (derived using emissivity normalisation method) bands to delineate different granitoids. We could differentiate different granitoids in the three-dimensional (3D) data space of ASTER-derived emissivity bands (second and third bands) and temperature bands. Based on the analysis of 3D scatter plot, we also proposed a ternary diagram of emissivity and temperature, which can be used to delineate different granitoids.