New-type metasedimentary rock-hosted stratiform Cu deposits occur in the Jianglang Dome. They are hosted by the Late Neoproterozoic Liwu Group and were unusually induced by an epigenetic magmatic-hydrothermal system. However, the source characteristics of fluids and metals remain poorly understood. Here, we employed Re-Os dating and He-Ar-S-Pb isotopes to determine their mineralization age and origin. Chalcopyrite Re-Os isotopic dating defines an isochron age of 162.7 +/- 3.2 Ma and a crust-like initial Os-187/Os-188 ratio of 1.421 +/- 0.021 (n = 4). Sulphide He-Ar isotope (n = 20) yields low R/Ra ratios of 0.052-0.144, high Ar-40/Ar-36 ratios of 479-2463 and low Ar-40*/He-4 ratios of 0.013-0.804, with calculated He-mantle values of 0.69-2.20 wt.%. In situ chalcopyrite sulphur isotope exhibits positive delta S-34(V-CDT) values of 3.87-9.50 parts per thousand (n = 72). Together with similar lead isotope data of chalcopyrite separates (n = 40) and ca. 164 Ma granites (n = 4), as well as low residual gravity anomalies in this region, our integrated data indicate an epigenetic magmatic-hydrothermal mineralization at ca. 163 Ma. The ore-forming fluids were dominantly crust-derived, with minor air-saturated water and negligible mantle input (0.69-2.20 wt.%). This is most likely attributed to the low proportion (total <5 vol%) of sandwiched metabasic rocks in the metalliferous Liwu Group. All the investigated orebodies show source homogeneity, in contrast to classic sediment-hosted stratiform Cu deposits with isotopic heterogeneity. Further, our findings imply significant mineral exploration potential in the Jianglang Dome and analogous domes in the eastern Songpan-Ganze Orogen.

High-grade Cu deposits in the Jianglang Dome have recently been interpreted as a new type of granite-related and sediment-hosted stratiform Cu deposits, yet the magmatic-hydrothermal fluid pathway remains an enigma. Here we employ major elements, rare earth elements (REE) and Sm-Nd chronometer to decode the genetic mechanism of two contrasting garnets in these deposits. Specifically, Grt1 is fine-grained, deformed (parallel to S2 foliation) and chalcopyrite-free, whereas Grt2 is coarse-grained, undeformed (cross-cutting S2 foliation) and cupriferous. They both occur within the Neoproterozoic metamorphic rocks and are almandinerich (63.58-87.33 wt%), thereby indicating a metamorphic origin. Their associated fluids are reduced, nearly neutral and Cl-poor, with diverse temperatures (average 505 degrees C vs. 559 degrees C) and pressures (average 5.6 kbar vs. 3.6 kbar). Significantly, Sm-Nd isotopic dating yields isochron ages of 190.3 +/- 8.3 Ma for Grt1 (2 sigma, MSWD = 0.86, n = 4) and 162.6 +/- 8.0 Ma for Grt2 (2 sigma, MSWD = 0.71, n = 4). These ages match regional ca. 204-190 Ma peak metamorphism and ca. 164-160 Ma magmatic-hydrothermal mineralization. As such, magmatichydrothermal overprint on primary metamorphic Grt2 accounts for its distinct geological, geochemical and age features relative to Grt1. Further, our garnet Sm-Nd dating results, with geological significances, imply that almandine Sm-Nd closure temperature is far below 725 degrees C as previously estimated. Combined with exploration practices, we advocate that the unique and incompetent Grt2-bearing layers, dominated by mechanically soft chlorite schist, served as a lateral pathway for epigenetic magmatic-hydrothermal fluids in the Jianglang Dome. This means that mineralization potential is likely limited beneath these characteristic zones in the lower Liwu Group.

The Liwu large scale of Cu-rich poly-metallic deposit is located in the Jianglang tectonic dome, Western China. The main ore-bodies of these deposits are stratiform-like. There exist two episodes of copper poly-metallic mineralization in the deposit, i.e., an early episode with deformed banded mineralization and a late episode with undeformed massive-veined mineralization. Previous studies mainly focus on the massive-veined miner-alization, however, geological features, geochronology and metallogenesis of the deformed banded mineraliza-tion are poorly understood. Here we present thermal ionization mass spectrometry (TIMS) Re-Os geochronological and Pb isotopic data for chalcopyrite from this type of ore, to precisely constrain the ages and origins of the early metallogenic event. In addition, the zircon U-Pb geochronological and TIMS Pb isotopic data are also presented for the ore-hosting metamorphic rocks of the Liwu Group, to better constrain its origin and the correlation with the Liwu deposit. Our new studies indicate that the deformed banded copper poly-metallic mineralization was initiated in the Early Carboniferous (ca. 343 Ma), and derived from the Neo-Proterozoic (541-544 Ma) metamorphic rocks, coeval with the opening of Paleo-Tethys Ocean. The Carboniferous miner-alization was superimposed by the Yanshanian (ca. 151 Ma) massive-veined copper poly-metallic mineralization. This study is beneficial to understand the stratiform deposit especially the metamorphic rock-hosting Cu (-Co) deposit.

江浪穹隆位于松潘-甘孜造山带东南缘,其核部产出的里伍式富铜矿床主要金属硫化物为磁黄铁矿、黄铜矿和闪锌矿.为了查明磁黄铁矿的化学组成和结晶条件,研究针对里伍铜矿致密块状和条带状矿石中的磁黄铁矿开展了显微观察与电子探针成分分析.结果显示这些磁黄铁矿:①主要元素组成为Fe和S,前者含量 62.30％～59.13％,平均 60.14％,后者含量 39.33％～37.36％,平均38.59％,计算平均化学式Fe0.891S;②具有极高的Co元素含量,介于0.79％～0.21％,平均0.49％,可能与Fe呈类质同象的形式存在;③属于高温六方晶系,结晶温度300～556℃,平均411℃;④产于较低的硫逸度环境,计算获得lg f(S2)介于-2.88～-11.50,平均-7.11.结合过去的成果资料,认为里伍式富铜矿床形成于中-高温热液作用,且低硫逸度条件可能更有利于富钴磁黄铁矿的形成.研究首次报道了里伍矿田磁黄铁矿富含战略性关键矿产之一的Co元素,对后续勘查找矿和综合评价具有重要指导意义.

江浪穹窿二叠纪大理岩之中发育一套变玄武岩夹层,其主要成分为角闪石(约75％)和斜长石(约25％).本文进行了锆石U-Pb年代学与地球化学研究,旨在修定原岩的形成年代与探究其成因.定年数据显示,变玄武岩中发育2453.7～258.9Ma的捕获锆石.这一结果表明,变玄武岩的原岩最有可能形成于晚二叠世,并且具有古老变质基底(2453.7～2125.0Ma锆石)、Rodinia超大陆会聚—裂解事件(1144.5～853.5Ma锆石)和加里东期岩浆活动(430.4～427.1Ma锆石)的地质记录.主微量元素分析数据显示,变玄武岩具有低的SiO2含量(45.53％～40.94％)与高的 Mg#值(78.4～70.6)、Cr(1670 × 10-6～1310 × 10-6)含量,其稀土((La/Yb)N=3.07～1.15)与微量元素配分型式平坦,表明原岩岩浆很可能起源于高度部分熔融的亏损地幔源区.岩石的La/Sm(2.34～1.16)、(Th/Yb)PM(1.95～1.23)、(Th/Ta)PM(0.74～0.43)和(La/Nb)PM(1.44～0.27)比值很低,表明岩浆演化过程中地壳物质的混染程度微弱.微量元素比值及构造环境判别图解表明,变玄武岩的化学构成同MORB相当,暗示原岩大概在古特提斯洋成熟的弧后盆地背景下形成.另外成分对比显示,江浪穹窿的二叠纪变玄武岩与峨眉山大火成岩省玄武岩浆活动无关.

The Liwu stratiform copper deposit is located in the northwestern Jianglang dome, western China. Current studies mainly focus on the genetic type and mineralization of this deposit. Detailed fluid inclusion characteristics of metallogenic period quartz veins were studied to reveal the ore-forming fluid features. Laser Raman analysis indicates that the ore-forming fluids is a H2O-NaCl-CH4 (-CO2) system. Fluid inclusions microthermometry shows a homogenization temperature of 181-375 & DEG;C and a salinity of 5.26%- 16.99% for the disseminated-banded Cu-Zn mineralization; but a homogenization temperature of 142-343 & DEG;C and a salinity of 5.41%-21.19% for the massive-veined Cu-Zn mineralization. These features suggest a medium-high temperature and a medium salinity for the ore-forming fluids. H-O isotopic data indicates that the ore-forming fluids were mainly from the metamorphic and magmatic water, plus minor formation water. And sulfur isotopic data indicates that sulfur was mainly derived from the formation and magmatic rocks. Metallogenesis of the disseminated-banded mineralization was mainly correlated with fluid mixing and water-rock reaction; whereas that of the massive-veined mineralization was mainly correlated with fluid boiling. The genetic type of the deposit is a medium-high temperature hydrothermal deposit related to magmatism and controlled by shear zones. This study is beneficial to understand the stratiform copper deposit. & COPY;2023 China Geology Editorial Office.

The Wenjiaping granite, as one of the few Late Jurassic granites in the Songpan–Garzê fold belt (SGFB), can provide an important clue for comprehensively recognizing the tectonic evolution and mineralization of this belt. In this contribution, we present new age and geochemical data for this pluton to better constrain its petrogenesis and discuss the tectonic and metallogenic implications. LA‐ICP‐MS zircon U–Pb dating shows that the Wenjiaping pluton was emplaced at ~159 Ma. The granite contains minor amphibole, and exhibits slightly peraluminous characteristics (A/CNK = 1.03–1.10) and lower initial Sr–Pb isotope ratios than those of the Liwu Group, which excludes the possibility that the Wenjiaping granite was derived from partial melting of the metasedimentary rock‐dominated Liwu Group as previously suggested. Significantly, high Sr/Y (40.93–54.30), La N /Yb N (39.64–56.64), and K 2 O/NaO (0.77–1.11) ratios, low MgO (0.47%–0.86%) and Cr (25.1–41.3 ppm) contents, and relatively enriched Sr–Nd–Pb–Hf isotope compositions of the Wenjiaping granite are comparable to those of the Late Triassic adakitic rocks in the SGFB, indicating that they probably share a similar source. Combined with previous researches, we propose that large‐scale detachment of the Jianglang dome caused by post‐collisional lithospheric extension in the SGFB‐induced decompressional partial melting of the Precambrian basement rocks can account for the generation of the Late Jurassic Wenjiaping pluton. In addition, our results also suggest that the Wenjiaping pluton probably cannot supply abundant metal elements for the Liwu‐type Cu‐polymetallic deposits in the Jianglang dome, SGFB.

里伍铜矿田位于江浪变质核杂岩穹隆的构造结构中,目前已经发现了很多中小型的铜矿床,包括里伍,黑牛洞等,也被作为是西缘地区铜矿的集中产地.其中中深层次的江浪变质核杂岩是该矿区的主体构造.本文我们通过对里伍铜矿的地质特点,控矿因素及构造特征进行深入分析,说明了里伍铜矿田和区域的找矿方向.

The Pennsylvanian to lower Permian succession at Madiyi, South China, represents a nearshore mixed siliciclastic‐carbonate system characterized by cyclic sedimentation patterns along a depth gradient from continental siliciclastics to marine open platform carbonates. Various palaeokarst features related to subaerial exposure are widely distributed. Additionally, pedogenesis was pervasive. The identification of twenty‐eight sedimentary cycles grouped into five sequences allows the reconstruction of a relative sea‐level curve. The cycles represent higher frequency changes superimposed on the long‐term evolution. After the initial transgression, the sea level remained relatively low in the late Bashkirian to early Moscovian. Then, it rose stepwise until a major drop occurred in the late Moscovian. Afterwards, the sea level rose again, but marine sedimentation ceased during at least the early Kasimovian. The area was flooded in the late Kasimovian, and the sea level rose until a late Gzhelian sea‐level drop. The subsequent marine sequence contains uppermost Gzhelian to upper Asselian deposits, which are capped by lower Permian continental facies associated with a major regional regression.Shallow to deeper marine sedimentary settings recorded high‐frequency sea‐level changes throughout South China during the late Bashkirian to Asselian. The main transgression–regression cycles are clearly associated with different depositional settings during several time intervals. Furthermore, the good correlations among South China, Ukraine, and the U.S. Mid‐continent are rooted in the impact of Gondwanan glaciations on the global sedimentation patterns. However, not all changes at Madiyi are the result of glacio‐eustatic sea‐level fluctuations; some are related to the local subsidence history and the rise of the Xuefeng Uplift.

Jianglang dome is located in southeastern Songpan-Ganzi orogen,western Yangtze block.The LA-ICP-MS detrital zircon U-Pb study on biotite schists from Jianglang group shows that they are mainly dated from 537-2925 Ma.Comparative analyses reveal that the sources of these sedimentary rocks are mainly from Neo-proterozoic strata of Yangtze block.These zircons were mainly derived from magmatic events at about 548 Ma,810 Ma and 2479 Ma,whereas the metamorphic events mainly occurred at about 918 Ma,608 Ma and 100 Ma.The oldest age ranging from 2 925 to 2 462 Ma indicates that the Paleo-proterozoic even Archean basement exists in Songpan-Ganzi area.In addition,six younger zircons yielded ages of 537-559 Ma with a mean of (548 ± 9) Ma (MSWD =1.4,2σ).Thus,we propose that the Jianglang Formation belongs to Proterozoic Liwu group.

通过对柏香林铜矿床变沉积岩和变基性火山岩围岩稀土、微量元素分析显示,二云石英片岩稀土配分型为右倾型,具有较强的Eu负异常(Eu/Eu*=0.43～0.30,平均0.38),富集大离子亲石元素(Rb、Ba和U等),亏损高场强元素(Nb、Ta和Hf),与大陆地壳基本一致;黑云绿泥透闪岩的稀土、微量配分较为平坦,(La/Yb)N平均1.57,无明显Ce(Ce/Ce*平均0.88)与Eu异常(Eu/Eu*平均1.01).综合分析认为,里伍岩群变沉积岩与变基性火山岩很可能形成于统一的弧后盆地构造背景,弧后盆地岩浆活动在其沉积过程中携带来丰富的金属元素,为江浪穹窿富铜矿床的发育奠定了物质条件.

Jianglang Dome is located in the southwestern Songpan-Ganzi Orogen (SGO) in western Sichuan.A series of copper polymetallic deposits such as Liwu, Zhongzui, Sunyelin, Baixianglin, Wajingou and Heiniudong occur around the waist of the dome.All of these deposits occur as stratiform in the Mesoproterozoic strata of the Liwu Group.But their genesis is still unknown.With ore-bearing quartztourmaline from the Liwu and Heiniudong ore deposits as study objects, this paper performed boron isotopic analyses using LA-MC-ICPMS and electron microprobe methods to understand the origin of ore-forming material of the deposits.The BSE and micrographic images reveal that these tourmalines were possibly derived from a single hydrothermal source, and electronic probe results indicate these tourmalines can be grouped into magnesium tourmaline.Boron isotopic results suggest that δ11B values of tourmaline from two deposits are-15.47‰ ± 0.83‰ to-13.06‰ ±0.77‰(n=10) and-13.19‰ ±0.57‰ to-5.91‰ ± 0.67‰(n=16), respectively, both of which are consistent to that of granite, indicating that the two deposits belong to post-magmatic hydrothermal deposits.Comparison study further shows that an NE-SW trending metallogenic belt, i.e.the Songpan-Ganzi copper polymetallic metallogenic belt(SGCPMB), occurs likely within the Songpan-Ganzi orogenic belt.In summary, this study will not only be beneficial to supplement the metallogenic theory of stratiform deposits, but also significant for the copper exploration in other domes in the SGO area in future.

本文提出多元线性回归计算矿石体重的优化方法,并以某铜锌矿为例,采用优化方法计算出体重值与矿石品位之间的方程关系.结果表明,铜锌矿的矿石体重与铜(Cu)、硫(Sp)品位之间线性关系明显,线性方程的拟合效果极好.预测体重与实际体重之间平均误差＜5％,可以直接利用于实际生产.

江浪穹窿位于扬子陆块西缘,核部地层为里伍岩群变质岩系,针对里伍岩群的成岩物质来源及构造背景研究所进行的岩石地球化学分析显示:(1)岩石具有高的SiO2(其质量分数为80.32％～71.76％)与Al2 O3(其质量分数为12.85％～8.40％);(2)稀土元素配分型式显示为右倾型((La/Yb)N=12.9～7.65),具有明显的Eu负异常(Eu/Eu*=0.73～0.49);(3)富集大离子亲石元素(如Rb,Ba和U等),亏损高场强元素(如Nb,Ta,P和Ti).原岩恢复结果表明,里伍岩群变质岩原岩均为沉积岩.综合分析认为里伍岩群变质岩的原岩物源区主要为大陆上地壳,很可能形成于Gondwana超大陆聚合之后的弧后盆地环境.弧后盆地岩浆活动带来丰富的成矿物质并形成里伍式富铜矿床初始的矿源层,同时接受陆源碎屑物质沉积形成碎屑岩系.

甘孜州东部及与其相邻的阿坝州西南部,是我国伟晶岩型锂辉石矿床的重要分布区域.本文选择处于这一地区的康定甲基卡超大型锂辉石矿和具有重大找矿潜力的九龙打枪沟锂辉石矿作为典型矿床进行解剖,结合区域内已发现的其他同类矿床,归纳总结此区域内伟晶岩型锂辉石矿床的矿床特征,分析其成矿规律,明确其找矿标志,并试图指出本区此类矿床的找矿方向.

江浪穹窿位于扬子陆块西缘,其间的甲坝岩组发育一套顺层产出的角闪岩,主要由角闪石(80％～85％)、斜长石(10％～15％)与少量石英(＜3％)组成.为查明角闪岩的原岩性质、成岩时代及构造背景,对其进行岩石地球化学分析及LA-ICP-MS锆石U-Pb定年研究.主微量元素测试结果表明:(1)角闪岩叫(SiO2)介于48.10％～54.44％,具有较高的Al2O3(平均13.82％)、Fe2O3T(平均10.56％)、MgO(平均8.07％)、CaO(平均9.09％)含量;(2)轻、重稀土元素具中等程度分异 ((La/Yb)N平均3.57),无明显Ce异常与Eu异常;(3)富集大离子亲石元素(如Rb,Th和Sr),亏损高场强元素(如Nb,P,Zr,Hf和Ti),多数微量元素含量与N-MORB相当.原岩恢复及构造背景判别显示,角闪岩原岩可能是弧后盆地玄武岩.锆石U-Pb年代学分析表明,角闪岩中锆石具有清晰的振荡环带及较高的Th/U值(平均0.51),应属岩浆成因;锆石207Pb/206Pb加权平均年龄分为2385Ma及2211Ma两组,前者应为捕获锆石的年龄,后者可以代表原岩结晶年龄.这一结果暗示,至少有部分甲坝岩组地层形成于古元古代.综合分析,江浪穹窿很可能发育古元古代基底,且部分地层时代亟待重新厘定.

The Zhongzui Copper deposit, a medium-sized copper-rich deposit explored in recent years, is hosted to the Jianglang metamorphic core complexes in Jiulong, western Sichuan. The copper ore bodies often occur as stratoids controlled by ductile shear zones, and are laterally extensive. The ore types comprise disseminated, veinlet, brecciated and massive Cu-Zn ores in the Fe-Cu-Zn formations. The metallic minerals contain chalcopyrite, pyrrhotite, sphalerite and galena. The main alterations include garnetization, sericitization, chloritization and biotitization. The ore bodies have higher copper grades, with an average copper grade of 1. 65%. The discovery of the Zhongzui copper deposit is significant to the reassessment of the exploration potential around the Liwu copper deposit.

The Upper Carboniferous-Lower Permian in the Yuanling region along the margins of the Xuefeng ancient land is characterized by limestones interbedded with conglomerates and sandstones, which can be divided into two formations from bottom to top as follows:Dabu Formation and Maping Formation.Abundant compound rugose corals are found in the lower-middle part of Dabu Formation, which are identified as 7 genera with eleven species in total,namely the following:Arachnastraea kaipingensis(Grabau)Yoh,A.crassiseptata King,A.sp.,Antheria sp.,Ivanovia asteroides Zhang,I.yuanlingensis sp.nov.,Lithostrotionella gorskyi Yu,L.planitabulate Yu,Orionastraea yuanlingensis sp.nov.,Protoivanovia intermedia Yu and Protodurhamina kunlunensis Cai(fasciculate rugose coral).In contrast,the solitary ones decline as 4 genera with 4 species,including Axolithophyllum cylindricum Wu and Zhao, Koninckophyllum minor Jing,Neokoninckophyllumsp.,Caniniasp.