江西上饶广丰白花岩明代二十四诸天壁画初探

二十四诸天的图像组合,是佛教美术题材中常见的艺术表达。留存的遗迹多以雕塑、壁画的形式展现。江西省上饶市广丰区白花岩下的广福寺,其大雄宝殿有两铺古代壁画,表现的内容正是二十四诸天。而两铺壁画无文献记载,无题榜落款;浏览图像,其人物无背光、无头光、无坐骑、无胁侍、无台座及脚踩物;同时,还因年久失修坏掉了两位人物画像。通过考究文化背景、文献记载,结合图像学研究,对这两铺壁画的二十四诸天做出具体辨识,考证其创作年代为明代中后期,并分析两铺壁画的构图方式、色彩特点、笔法技巧等,为中国二十四诸天古代壁画遗存图像志增加一处实例。

中祁连东段白花沟岩体地球化学特征及年代学意义

为了研究中祁连东段白花沟岩体的地球化学特征,通过LA-ICP-MS方法测得花岗闪长岩同位素年龄为(922±16)Ma(MSWD=2.0),侵位时代为新元古代。岩石中SiO_2含量为64.4%~75%,Al_2O_3含量为12.98%~15.75%,MgO含量为0.34%~2.25%,Na_2O/K_2O>1,总体显示为过铝质花岗岩类;微量元素方面,Sr含量较低,属于低Sr花岗岩,Ba,Sr,Nb,Eu表示出明显的负异常;轻稀土表现出强烈富集的特征,δEu<1(0.36~0.82),具有明显的负异常。白花沟岩体形成于晋宁运动前期的一次碰撞造山运动,为古老陆壳的重融,其源岩为贫粘土、富斜长石的砂屑岩。

青海岩黄芪属(Hedysarum)一新变型

发表黄芪属一新变型

似梦人间 铜钹山

1铜钹山传奇 总有这样的时刻，梦想找到一个地方：清秀的山水间鸟雀欢歌，落满松针枯叶的山路两旁，野草张扬地铺展，山涧明净，幽兰吐香，还有竹林、野果、游鱼和蹦跳的小兔、松鼠……古朴的村落，木屋楼板吱嘎作响，老式农具斜倚于幽静的墙角。溢满树脂香味的柴棚里，偶尔闪过老乡憨厚的笑脸……

Origin of Early Creceouscalc-alkaline granite, Taxkorgan: Implications for evolution of Tethys evolution in central Pamir

The Pamir plateau may have been a westward continuation of Tibet plateau.Meanwhile,the Rushan-Pshart suture is correlative to the Bangong-Nujiang suture of Tibet,and the Central Pamir is the lateral equivalent of the Qiangtang Block.We present the first detailed LA-ICPMS zircon U-Pb chronology,major and trace element,and Lu-Hf isotope geochemistry of Taxkorgan two-mica monzogranite to illuminate the Tethys evolution in central Pamir.LA-ICPMS zircon U-Pb dating shows that two-mica monzogranite is emplaced in the Cretaceous(118 Ma).Its geochemical features are similar to S-type granite,with enrichment in LREEs and negative Ba,Sr,Zr and Ti anomalies.All the samples show negative zirconεHf(t)values ranging from 17.0 to 12.5(mean 14.5),corresponding to crustal Hf model(TDM2)ages of 1906 to 2169 Ma.It is inferred that these granitoids are derived from partial melting of peliticmetasedimentary rocks analogous to the Paleoproterozoic Bulunkuole Group,predominantly with muscovite schists component.Based on the petrological and geochemical data presented above,together with the regional geology,this work provides new insights that Bangong Nujiang Ocean closed in Early Cretaceous(120114 Ma).

Muscovite 40Ar-39Ar age and its geological significance in Zhuxi W（Cu） deposit, northeastern Jiangxi

The Zhuxi W(Cu)skarn deposit,the world’s largest tungsten deposit is newly discovered in Jingdezhen city,northeastern Jiangxi province,China.It mainly occurs near the contact zone between the Yanshanian granites and the Late Paleozoic carbonate rocks.Three types of mineralization including skarn type,altered granite type and quartz vein veinlet type orebodies have been observed.In this study,the 40Ar 39Ar age of hydrothermal muscovite coexisting with copper mineralization in the altered granite type orebody formed near the unconformity interface is determined by step-heating technology using CO2 laser.The plateau age,isochron age,and inverse isochron age of muscovite are(147.39±0.94)Ma,(147.2±1.5)Ma,and(147.1±1.5)Ma,respectively.These ages are almost identical to the ages of ore-related granite and other mineralization types in the Zhuxi W(Cu)deposit,indicating that the Cu mineralizations occurred at the shallow depth and near the unconformity interface are contemporaneous during the Late Jurassic.This further suggested that the acompanied W and Cu mineralization in the Zhuxi W(Cu)deposit which may be controlled by the magma source is enriched in both W and Cu.

Skarn-type tungsten mineralization associated with the Caledonian(Silurian) Niutangjie granite, northern Guangxi, China

The Niutangjie tungsten deposit is a bedded skarn-type scheelite deposit and is located at the junction between Ziyuan and Xingan counties in the north of Guangxi,China.The deposit is genetically related to a fine-grained two-mica granite within the orefield.Zircon LA-ICP-MS U-Pb dating of the granite yielded a Silurian(Caledonian)age of 421.8±2.4 Ma,which is contemporaneous with the adjacent Yuechengling batholith.Mineralization within the skarn is associated with a quartz,garnet,and diopside gangue,and scheelite is present in a number of different mineral assemblages,such as quartz-scheelite and quartz-sulfide-scheelite;these assemblages correspond to oxide and sulfide stages of mineralization.Sm-Nd isotope analysis of scheelite yielded an isochron age of 421±24 Ma.Although the uncertainty on this date is high,this age suggests that the scheelite mineralization formed during the Late Caledonian,at a similar time to the emplacement of the Niutangjie granite.Zircons within the granite have?Hf(t)values and Hf two-stage model ages of?6.5 to?11.6,and 1.79 to 2.11 Ga,respectively.These data suggest that the magma that formed the granite was derived from Mesoproterozoic crustal materials.Scheelite?Nd(t)values range from?13.06 to?13.26,also indicative of derivation from ancient crustal materials.Recent research has identified Caledonian magmatism in the western Nanling Range,indicating that this magmatism may be the source of contemporaneous tungsten mineralization.

Mineralogical feature and geological significance of muscovites from the Longyuanba Indosinian and Yanshannian two-mica granites in the eastern Nanling Range

Emplacement P-T condition estimations using granites are important for understanding metamorphic and erosional processes of orogenic belt.Granites are widespread in South China and a majority of them are peraluminous.Particularly,over 91%of the Indosinian granites exposed in the region are peraluminous in composition.It is extremely hard to determine the pressure of intrusion of these peraluminous granites due to the absence of amphibole,a good mineral barometer commonly identified in metaluminous granites.Muscovite is a common mineral in peraluminous granites,certain kind of it could be used as a mineral barometer to constrain the emplacement pressure of peraluminous granites.In this paper,results of petrographic and geochemical studies of muscovites from the Indosinian and early Yanshanian two-mica granites at the Longyuanba in the eastern Nanling Range are reported.Based on petrographic studies,the primary muscovite can be discriminated from the secondary muscovites.Muscovites from the Indosinian two-mica granites are enriched in Ti,Al,Mg,and Na,and depleted in Fe and Mn.Geochemically,these muscovites were considered as primary,whereas those from the Yanshanian two-mica granites fall into the area of secondary muscovite on discrimination diagrams.Barometer estimations show that pressures calculated for primary muscovites are accurate,but those calculated for secondary muscovites are overestimated.The average pressure of emplacement of the Longyuanba Indosinian two-mica granites is 5.9 kbar,corresponding to^19 km in depth,suggesting that the Indosinian granitic magmas were probably generated by partial melting of a thickened crust root in a compressional tectonic setting.

Petrogenesis of Early Cretaceous adakitic granodiorite: Implication for a crust thickening event within the Cathaysia Block, South China

Adakitic rocks in continental settings are commonly considered to be formed by partial melting of thickened or delaminated lower crust. Investigations on this kind of rocks can provide important information about crustal evolution complementary to information from other rocks. This paper reports adakitic granodiorite of the Lingxi pluton in the interior of the Cathayisa Block. LA-ICP-MS zircon U-Pb dating shows that it was formed in the late Early Cretaceous(100±1 Ma). The granodiorite has geochemical features of adakitic rocks derived from partial melting of the thickened lower crust, e.g., high SiO2(mainly ranging from 64.4 to 68.9 wt.%) and Sr(624–894 ppm) contents, Sr/Y(49.9–60.8) and La/Yb(23.4–42.8) values, low Y(10.3–17.1 ppm), Ni(5.62–11.8 ppm) and MgO(mostly from 0.86 wt.% to 1.57 wt.%) contents and weak Eu anomaly. It has initial 87Sr/86 Sr ratios of 0.7086–0.7091, εNd(t) values of.6.2 to.5.9 and zircon εHf(t) values mostly of.10.1 to.7.6. Based on the geochemical characteristics and simple modelling, it is suggested that the most likely generation mechanism of the Lingxi granodiorite is partial melting of a thickened Proterozoic lower continental crust at a pressure ≥12 kbar(or crust thickness ≥40km), leaving a garnet-bearing amphibolite residue. Combining our results and previous studies of the tectonic evolution of the Cathaysia Block, we propose that the crust was thickened to over 40 km by a compressive event occurring during the late Early Cretaceous, which is supported by the observation that there is an angular unconformity between the Upper Cretaceous Series and the early Lower Cretaceous or the Jurassic rocks. After this event, the Cathaysia Block experienced a lithospheric extension and thinning probably driven by the high-angle paleo-Pacific subduction. With the attenuation of lithosphere, the lower crust was heated to partial melting by upwelling asthenospheric materials, resulting in generation of the Lingxi granodiorite and other coeval granitoids in the Cathaysia Block. This study provides new information on the crustal evolution of the Cathaysia Block during the Early Cretaceous.