The Nanling region in South China contains widespread granites of variable ages. Large-scale W and Sn mineralization were closely associated with Yanshan granites, but the mineralization related to granites of other ages has been little studied. Understanding the metallogenic significance of Indosinian granites is crucial for refining exploration models, as recent discoveries suggest they may have played a greater role than previously recognized. The weighted mean zircon U-Pb age of the biotite granite from the eastern part of the Dupangling pluton is 224.7 f 4.8 Ma, while the cassiterite U-Pb age from the Babanqiao Sn-polymetallic deposit is 223.6 f 4.0 Ma. These results indicate that the Babanqiao deposit formed contemporaneously with late Indosinian granitic magmatism, suggesting that the deposit was likely associated with granitic activity during the late Indosinian period. Fluid inclusion data reveal the initial ore-forming fluids were part of a NaCl-H2O system with high to moderate temperatures and salinities, which contained CH4 f N2. Homogenization temperatures ranged from 182.1 degrees C to 381.5 degrees C in the early mineralization stage and decreased to 145.4 degrees C to 279.8 degrees C in the main mineralization stage, with corresponding salinities of 13.62-25.15 wt% NaCl equiv. and 7.45-19.76 wt% NaCl equiv., respectively. These values indicate that ore deposition occurred under reducing conditions, with a progressive decrease in temperature and salinity as meteoric water mixed with the magmatic fluids. delta 18O and delta D values show that the ore-forming fluids were magmatic waters that gradually transitioned to meteoric waters. This progressive dilution likely influenced metal transport. Integrated analysis indicates that during the Indosinian period, Sn-bearing magmatic-hydrothermal fluids migrated into closely spaced microfractures and joints, where localized boiling may have occurred, producing limited precipitation. The fluids then ascended along these structures and mixed with infiltrating meteoric water, destabilizing Sn-Cl complexes and precipitating Sn in fault zones to form quartz-vein-type Sn ore. Thus, fluid mixing was the primary mineralization mechanism at Babanqiao. These findings also highlight the exploration potential of Indosinian granites in South China as hosts of previously unrecognized W-Sn systems.

ABSTRACTGreat breakthroughs have been made in the Indosinian W–Sn ore exploration in the Nanling region of China in recent years, but there is still relatively little research on its metallogenic mechanism. Nanzhuhe Sn polymetallic deposit is located on the southeast side of Dupangling complex in the western part of Nanling and is a typical altered fracture zone type of Sn polymetallic deposit. The ore body is controlled by the NE‐trending fault and occurs in the Indosinian granite in the Indosinian contact zone and the secondary tension–torsion fault zone. In this article, zircon and cassiterite were selected for U–Pb dating and trace element analysis, and quartz was studied by microthermometry, Laser Raman compositional analysis and H and O isotopes. The results show that the zircon U–Pb age of the biotite granite is 224.2 ± 6.4 Ma (MSWD = 1.5), and the cassiterite U–Pb age is 217.9 ± 7.2 Ma (MSWD = 1.6). The cassiterite is enriched in high‐field‐strength elements such as Nb, Ta, Ti, Sc, V and Hf, which indicates that the deposit was formed by the highly evolved granitic magmatic activity in the late stage of the Indosinian. The fluid inclusions are mainly liquid‐rich two‐phase, and a little gas‐rich two‐phase. The gas component is mainly water vapour. The initial ore‐forming fluid is NaCl–H2O system with medium to high temperatures and medium to low salinity. Hydrogen and oxygen isotopes indicate that about 40% of the atmospheric precipitation is mixed along the extensive fault. The comprehensive study shows that the mixing of magmatic–hydrothermal fluid and meteoric water occurred in the Indosinian period of the Nanzhuhe Sn polymetallic deposit, which led to the continuous decrease of temperature and salinity of the ore‐forming fluid, the increase of oxygen fugacity, the increase of pH value and the decrease of ligand activity, which destroyed the stability of tin complex and caused a large number of tin and other metal ions to break off from the complex carrier, and finally the precipitation of tin and other metals.

The concentration and transport of metals (e.g., Sn) in granitic melts is key processes for magmatic-hydrothermal tin mineralization. The Sn-bearing Dupangling batholith located in the western Nanling Mountains of South China hosts a number of Sn deposits. The enrichment and transport processes of Sn in granitic melts remain poorly known. This study focuses on geochemical, mineralogical, and isotopic analyses in order to assess the role of magmatim in Sn enrichment of granites in the Dawan area of the northern Dupangling Batholith. Results show that the Dawan granites were emplaced at 224-232 Ma, and are both temporally and spatially correlating with Sn mineralization. Zircon epsilon Hf(t) values (-9.47 - -0.21) and corresponding T-DM2 ages (1.28-1.87 Ga) suggest that their parental magmas originated mainly from partial melting of Proterozoic basement rocks. The magmas were highly fractional, characterized by high temperatures (similar to 819.5 degrees C) and reduced oxygen fugacities (an average Delta FMQ of -0.15). Therefore, it appears that a combination of high-melting temperature, and highly-evolved and reduced granitic melts is the primary condition for Sn enrichment. Furthermore, the compositional zoning of mica and its decreasing of rare metals (e.g., Li, Rb, Cs, Nb, Ta and Sn) and increasing of Fe3+/Fe2+ from core to rim suggests an interaction between magmatically-derived F-bearing hydrothermal fluids and micas after crystallization. Tin mineralization in the Dupangling region is therefore likely associated with the ponding of magmaticallyderived hydrothermal fluids that were capable of concentrating and transporting Sn.

The Banlun magnetite ore cluster area in southeastern Yunnan, located at the junction of Cathaysian, Yangtze and Indosinian plates, is an important part of the Gejiu-Wenshan-Debao skarn type Sn-W polymetallic metallogenic belt. The predecessors have carried out a small amount of research work on the geological characteristics and genesis of the skarn type magnetite deposit in this area, but there is still no systematic study on the genesis of the skarn, which seriously restricts the further understanding of the genesis of skarns and the accurate evaluation of magnetite prospecting potential in this magnetite ore cluster area. This paper focus on the skarns and related rocks from the most typical Kunhong and Dongha magnetite deposits in Banlun magnetite ore cluster area. Based on the detailed study of the field geological characteristics and petrography of the skarns and related rocks, their geochemical and mineralogical characteristics are systematically studied by LA-ICP-MS and EPMA. The results show that the diagenetic and metallogenic evolution of skarns can be divided into three stages: early progressive metamorphic skarn stage, late degenerative metamorphic skarn stage and sulfide-carbonate stage; There are significant differences between siliceous rock bands of (magmatic-) hydrothermal origin and Late Permian OIB type basic complexs (namely "Banwa type" pluton) in primitive mantle-normalized spider diagrams and chondrite-normalized REE pattern diagrams; However, they are relatively similar to the model curves between siliceous rock bands of (magmatic-) hydrothermal origin and Middle Triassic island arc type intermediate-basic complexs (namely "Anding type" pluton), showing the characteristics of obvious depletion of Nb, Ta, P and Ti elements; The model curves of skarns are also similar to that of siliceous rock bands, and ore-bearing skarns are very close to siliceous rock bands than ore free skarns in terms of trace element contents and model curves. The research results of mineral chemistry show that the first generation garnets belongs to the series of Andradite-Almandite-Grossularite (And80-83Alm9-11Gro5-7), and containing more Grossularite (Gro); The second generation garnets belongs to the series of Andradite-Almandite (And86-93Alm6-12), and basically contains no or only a small amount of Grossularite (Gro); From early pyroxene to late pyroxene, the proportion of hedenbergite is relatively reduced, while the content of diopside is significantly increased in the end member component of pyroxene. Comprehensive analysis shows that the hydrothermal fluid forming skarns mainly come from Middle Triassic island arc type intermediate-basic complexs; The diagenetic and metallogenic environment of skarn type magnetite deposits has at least experienced a transformation process from the relative reduction environment in the early stage of progressive metamorphic skarn stage to the relative oxidation environment in the late stage of progressive metamorphic skarn stage and degenerative metamorphic skarn stage to the relative reduction environment in the late sulfide-carbonate stage.

Nanling is located in central South China and contains the most important area of W-Sn polymetallic deposits worldwide. However, a lack of geochronological data hinders our understanding of the timing and mechanisms of W-Sn mineralization in the Dupangling area of western Nanling. The Maoershi Sn polymetallic deposit is located in the western body of Dupangling complex pluton, and is a significant hydrothermal vein deposit. Cassiterite U-Pb dating shows that the Maoershi Sn mineralization occurred during the Late Triassic (206.2 +/- 2.6 Ma). This age is different from the age of granite in the western Dupangling pluton and similar to the age of the eastern Dupangling pluton. The cassiterite is enriched in Sc (4.5105-18.4049 ppm), V (37.2267-88.9671 ppm), Nb (62.0104-194.1846 ppm), Ta (11.1965-85.6881 ppm), Hf (22.0511-30.7650 ppm), U (2.8870-17.9187 ppm), Th (0.0005-0.0908 ppm), Ti (3873-6170 ppm), and other high-field-strength elements. Based on Nb/Ta and Y/Ho ratios, and the W-Fe discriminant diagram, Sn and the other mineralizing materials were mainly derived from hidden Indosinian granitic rocks. Tungsten-Sn mineralization in the Dupangling pluton exhibits a clear spatial-temporal relationship with Indosinian granitic magmatism, and occurred in an extensional setting after the continent-continent collision that marked the late Indosinian Orogeny.

Rapakivi-type granites not only document magmatic processes but also archive subsolidus interactions between granitic rock and fluid, and thereby provide crucial information about fluid infiltration in the Earth's crust. However, the key process to generate rapakivi texture is still debated. Here, we report comprehensive mineralogical, geochemical and Hf isotopic compositions of the Dupangling rapakivi granites (210.4-214.9 Ma) in the South China Block to investigate the effect of fluid-rock interaction on the origin of rapakivi feldspar. Dupangling rapakivi granites have high SiO2 (72.63-78.21 wt%) and alkali contents (Na2O + K2O = 6.14-9.06 wt%) with high K2O/Na2O ratios (1.37-2.64), characteristic of weakly peraluminous (A/CNK = 1.04-1.10) high-K calcalkaline granites. Samples have weakly fractionated REE patterns with negative Eu anomalies (delta Eu = 0.05-0.38). They have negative whole-rock epsilon Nd(t) (-8.45 to -7.91), variable zircon epsilon Hf(t) (-9.7 to -1.0) and two-stage Hf isotope model ages (1.32-1.84 Ga), due to their derivation from a major early Mesoproterozoic crustal source with a subordinate late Paleoproterozoic component. Rapakivi feldspars in Dupangling granites are composed of an alkali-feldspar core and a plagioclase mantle. Fractures, pores and secondary inclusions (biotite, sericite, epidote and hematite) are closely associated with the mantles and oligoclase patches within alkali-feldspar cores. These pervasive microtextural features and variations of Be, Rb, Ba, Sr and LREE within rapakivi feldspars are interpreted to have formed through subsolidus fluid-induced dissolution-reprecipitation replacement processes. This study highlights that fluid-rock interaction plays an important role in generating rapakivi texture.

Magmatic rocks, deformed structures, and tin–polymetallic deposits are widely distributed in the western Jiangnan Orogenic Belt (JOB) of northern Guangxi Province, China. Magmatism and mineralization are believed to have occurred in the Neoproterozoic stage. Herein, we report the zircon U–Pb dating results of investigations on the Ping’an Pb–Zn–Cu polymetallic veins hosted in gabbro near Ping’an Village. Zircon U–Pb dating of the host gabbro yielded ages of 853.0 ± 7.8, 837.7 ± 7.2, and 450.4 ± 6.7 Ma. The younger age represents the emplacement of gabbros, whereas the older Neoproterozoic age reflects inherited zircons from the wall rocks or source regions. The formation of gabbros (Caledonian) is related to the subduction and collisions of microplates in the western JOB, which are controlled by movements of the Yangtze and Cathaysian plates. We consider that the late Caledonian regional shearing in the western JOB resulted in the fracturing and faulting of rocks (Neoproterozoic and early Caledonian), which provided conduits for the flow of hydrothermal fluids and accommodation for the associated mineralization. Geochemistry investigations show that the Caledonian basic magmatic activity provided a certain material source for the final mineralization. We propose that the tin–polymetallic deposits in the northern Guangx Province, and Neoproterozoic cassiterite crystallization, were subjected to Caledonian shear crushing and hydrothermal transformation with copper, lead, zinc, and other metal elements based on our comprehensive analysis, providing a new ideology for understanding the geology and mineralization in this area.

The Jiangnan orogenic belt is located between the Yangtze and Cathaysia blocks in South China and is one of the largest W–Sn–Nb–Ta ore belts worldwide. Mineralization occurred from the Proterozoic to Mesozoic, but Caledonian Sn mineralization has rarely been reported. The Jialong cassiterite–sulfide deposit is located in the western Jiangnan orogenic belt. It is hosted by the Sibao Group and in contact with the northeastern part of the Yuanbaoshan granite. The deposit was overprinted by the Sirong ductile shear zone. Here, we present cassiterite U–Pb and mylonitic granite muscovite 40Ar/39Ar ages for this deposit. The cassiterite and muscovite yielded concordant U–Pb and 40Ar/39Ar ages of 422–420 Ma, indicating that Sn mineralization occurred during the early Paleozoic and was spatially and temporally related to the ductile shear zone. The cassiterite is depleted in Nb (0.51–5.46 ppm), Ta (0.01–1.09 ppm), Ti (32.84–423.15 ppm), Sc (0.02–1.45 ppm), Hf (0–1.11 ppm), and other high-field-strength elements. Elements, such as Pb (0.01–8.11 ppm) and Sb (9.92–56.45 ppm), are relatively enriched in the cassiterite, which indicate the Jialong deposit was not directly related to magmatism. Shearing along the Sirong ductile shear zone occurred at 419.6 ± 3.8 Ma, concurrent with the formation of the Jialong Sn–Cu deposit. Moreover, cassiterite in the deposit exhibits obvious shear and brittle deformation, and dissolution and regrowth, suggesting that Sn mineralization was closely related to ductile shearing. The Sirong ductile shear zone and secondary shear structures had a key role in controlling the Sn orebody. The heat generated during tectonic deformation in the ductile shear zone may have produced the ore-forming hydrothermal fluids, and NW–SE-trending fractures in the strata provided the space for mineralization. Metamorphic hydrothermal fluids generated by Caledonian shear deformation extracted Sn from Sn-rich strata, which then migrated along interlayer fractures produced by shearing. A decrease in pressure and water–rock reactions led to the mineralization of Sn and other elements. This deposit is the first example of Caledonian and shear zone-related Sn mineralization identified in the Jiuwandashan area of northern Guangxi.

广西环江县平安村铅多金属矿位于江南造山带南缘,区域上先后发现了多个大中型锡多金属矿床.通过对平安村等矿床成因的深入解剖研究,揭示韧性剪切带与锡矿成矿作用的关系,有助于丰富和发展韧性剪切带型矿床的成矿理论.通过对地球化学特征分析认为,平安村铅锌多金属矿物质来源至少有三防岩体、地层都提供了部分物质.其中三防岩体提供了Sn金属物质,同时通过热液提供了部分微量元素.地层提供了Pb、Zn和Cu等金属物质来源.成矿过程中热液系统萃取了地层中的Cu、Pb、Zn等金属元素,同时将周边和深部的金属元素和微小碎裂锡石带入热液.

广西西部德保县红泥坡酸性岩群岩性以中细粒、细粒(含)黑云二长花岗岩、二长花岗岩、花岗岩、花岗斑岩、石英斑岩为主,呈小岩株、岩脉、岩枝产出,本文报道了其与下泥盆郁江组侵入接触关系的发现.通过岩石地球化学研究,红泥坡酸性岩群具有酸度大、碱质高、钾大于钠、铝过饱和的特点,属于强过铝质高钾钙碱性花岗岩类.稀土元素表现为轻稀土富集,负Eu异常明显,轻重稀土分馏较强.岩浆源区以成熟的泥质岩为主,其中并可能具弱Ce正异常的沉积物参与部分熔融,形成于中浅成相的大陆碰撞挤压构造环境,形成时代晚于早泥盆世,具有较大的Sn成矿潜力.

马塔比矿床位于印度尼西亚北苏门答腊省,是印度尼西亚近年确认的一处世界级高硫浅成低温热液型金-银矿床.文章在梳理前人研究的基础上,对其成矿地质特征与找矿标志进行了总结,以丰富该类型矿床实例,指导找矿实践.该矿床金银矿化呈现典型的高硫型浅成低温热液系统蚀变分带特征,由内而外依次发育硅化带、高级泥化带、泥化带、青磐岩化带.赋矿英安岩的锆石U-Pb定年结果为(3.8±0.5)Ma,热液变质成因明矾石的Ar-Ar坪年龄分别为(3.3±0.11)Ma和(2.14±0.10)Ma,表明成岩与成矿间隔时间较短,且可能存在两期高级泥化蚀变作用.成矿作用既有岩浆热液又有大气水的参与,后期地表风化作用使金和银进一步富集.马塔比矿床具有高硫型浅成低温热液矿床的典型特征,总结其找矿标志包括构造环境标志、岩性标志、蚀变标志和化探标志.

广西融水县南刀坳锡多金属矿位于江南造山带南缘,三防岩体的西南外接触带上,先后发现了多个大中型锡多金属矿床.通过岩石地球化学、矿石元素分析和元素相关性分析等方法,探讨锡矿的成矿物质来源和成矿过程.通过对地球化学特征分析认为,该矿的Sn等成矿物质主要来自三防岩体,Pb和Zn等金属元素可能来自地层萃取.金属元素在岩浆演化过程中从熔浆中分离出来,通过隐伏岩体顶部分馏进入地层,提供了区域锡矿成矿的物质来源.成矿过程基本可以分为4个阶段:第一阶段是高温Sn热液从三防岩体侵位过程中分离、结晶、富集;第二阶段是锡矿的剪切改造;第三阶段是含矿热液携带碎裂锡石就位及锡石重结晶;第四阶段为成矿后热液改造叠加.

不同尺度地球化学填图能否获得稳定的和可追索的地球化学模式,能否真实反映元素含量背景,是检验填图方法是否可行的重要依据.笔者选择印度尼西亚苏门答腊岛巴东—明古鲁地区热带雨林区为研究对象,对比该区1:100万(1个样/100 km2)和1:25万(1个样/4 km2)两种不同比例尺的地球化学采样所获得的地球化学数据和异常分布模式,发现二者获得的元素含量背景值和中位数非常接近,所圈定的地球化学省在形态和变化趋势上非常类似,浓集中心的位置几乎完全重合,证明低密度地球化学填图也能获得稳定的和可追溯的地球化学模式,认为该方法在热带雨林区也是适用的.低密度地球化学填图圈出的地球化学省基本涵盖了研究区大的矿床和花岗岩体,真实的反映了研究区元素的分布情况,在这些地球化学省内开展更大比例尺的地球化学填图工作,能进一步圈定局部异常直接找矿,降低企业勘查投资风险.

领薅组在运用的过程中因各种原因出现了3种写法——领薅组、领组和领好组.这是一种同一名称的同一地层单位,出现用字不同的现象,称为同名异字.文章提出以中国地层委员会确立的地层单位命名的优先权原则作为处理同名异字问题的基本原则.

The Dairi Pb-Zn ore concentration area, hosted by shale and displaying Sedex-type Pb-Zn mineralization of giant scale, is located in northwestern Sumatra, Indonesia.Systematic analysis of fluid inclusions and H, O, S and Pb isotopes was performed to probe its genesis.The results show that (1) the homogenization temperatures range from 189 to 315℃, with a peak at 220-240℃, indicating medium temperature for mineralization; (2)values of δ18OV-SMOW vary from +5.9‰ to +19.5‰, with an average of +16.6‰, implying a magma water-dominated mineralization fluid with minor addition of shallow water; (3)pyrites have positive δ34SCDT values from +25.49‰ to +26.36‰; (4)lead isotopes possess high μ values of 9.92-10.17(averaging 10.04) and ω values of 38.06-40.51 (averaging 39.26).It is indicated that the ores from Dairi formed at medium temperatures, having a fluid source dominated by magma water with minor addition of shallow water, a sulfur source comparable to ocean water and a single lead source from the crust.

Late Triassic A-type granites are identified in this study in Sarudik, SW Sumatra. We present new data on zircon U-Pb geochronology, whole-rock major and trace elements and Sr-Nd-Hf isotope geochemistry, aiming to study their petrogenesis and tectonic implications. LA-ICP-MS U-Pb dating of zircon separated from one biotite monzogranite sample yields a concordia age of 222.6 +/- 1.0 Ma, indicating a Late Triassic magmatic event. The studied granites are classified as weakly peralumious, high-K calc-alkaline granites. They exhibit high SiO2, K2O + Na2O, FeO/(FeO + MgO) and Ga/Al ratios and low Al2O3, CaO, MgO, P2O5 and TiO2 contents, with enrichment of Rb, Th and U and depletion of Ba, Sr, P and Eu, showing the features of A-type granites. The granites have zircon epsilon(Hf)(t) values from -4.6 to -0.4 and whole-rock epsilon(Nd)(t) values from -5.51 to -4.98, with Mesoproterozoic T-DM2 ages (1278-1544 Ma) for both Hf and Nd isotopes. Geochemical and isotopic data suggest that the source of these A-type granites is the Mesoproterozoic continental crust, without significant incorporation of mantle-derived component, and their formation is controlled by subsequent fractional crystallization. The Sarudik A-type granites are further assigned to A2-type formed in post-collisional environment. Combined with previous knowledge on the western SE Asia tectonic evolution, we conclude that the formation of the Late Triassic A-type granites is related to the post-collisional extension induced by the crustal thickening, gravitational collapse, and asthenosphere upwelling following the collision between the Sibumasu and the East Malaya Block.

应用"三步式"矿产资源定量评价方法,在对苏门答腊岛典型斑岩型铜(钼)矿床成矿特征进行分析基础上,构建该类铜(钼)矿床的描述性模型,认为该区斑岩型铜(钼)矿床与苏门答腊岛弧新生代中酸性次火山岩系关系密切,NW向苏门答腊断裂及其次级断裂起到控岩控矿的作用;结合该区已知铜(钼)矿床(点)分布及1:100万低密度地球化学测量成果,圈定了4处铜(钼)成矿远景区;根据密度模型公式估算出该区在90％、50％和10％预测概率下的矿床数;利用蒙特卡洛模拟方法预测该区斑岩型铜(钼)矿产在不同预测概率下的铜(钼)资源量,结果显示苏门答腊岛斑岩型铜(钼)矿产资源潜力巨大.

本文通过对广西环江县九逢锡矿锡石的赋存形式、碎裂特征、热液迁移及剪切变形相关性分析,认为该锡矿床中锡石矿物主要赋存于石英脉、蚀变砂岩及云英岩中.其中云英岩上、下盘石英脉中的锡石为主要赋存形式,且至少经历了自形结晶→矿物破碎→热液短距离迁移→快速冷凝结晶阶段.锡石主要以粗粒(>100μm)、细粒(10～100μm)和微细颗粒(＜10μm)三种状态存在.根据锡石内裂隙构造特征,认为碎裂锡石矿物的作用前期为左行剪切,以脆性碎裂为主,后期以韧性碎裂溶蚀为主,具有右行和左行特征,且携带锡石的热液在受到后期的韧性剪切有一定的改造作用.

对靖西地区出露的晚古生代基性-超基性岩进行了全岩主量、微量元素等地球化学研究,结果表明:基性岩主要为辉绿岩,超基性岩则为苦橄岩;基性岩具有较低的SiO 2 （51.34%～53.17%）和较高的MgO（4.67%～6.12%）含量,（K 2 O+Na 2 O）在5.03%～8.06%,具有典型碱性玄武岩特征;超基性岩则具有更低的SiO 2 （39.76%）和极高的MgO（23.97%）,二者均落入碱性玄武岩系列。基性-超基性岩∑REE在（45.47～128.95）×10 -6 ,（La/Yb） N 值在6.67～10.75,δEu值为0.96～1.08,稀土特征总体显示为轻稀土相对富集,重稀土相对亏损的右倾型式,具有与OIB相似的配分趋势,指示源区相对富集;基性-超基性岩不相容元素含量整体偏低,略亏损高场强元素（HREE、 Nb、 Ti等）,指示源区部分熔融程度较低。结合前人研究及岩石沉积背景特征,认为靖西基性-超基性岩为右江盆地早期演化的产物,形成于局部拉张的构造环境,与裂谷作用相关,推测该区域晚古生代受金沙江-哀牢山特提斯洋的打开和演化的影响,右江盆地局部拉张裂解,一系列深大断裂沿北西向展开,早期在局部形成与裂谷作用相关的岩浆活动。晚古生代后期右江盆地可能已演变为弧后盆地属性。

The Jiufeng Sn deposit is located in the outer contact zone southwest of the Neoproterozoic Motianling granitic pluton, in northern Guangxi, South China. The deposit is characterized by a NNE-striking, 30-200-m-wide ductile shear zone, named the Jiufeng ductile shear zone. Majority of the Sn orebodies, including four large ones, are hosted by the shear zone. Field and microstructural observations, electron backscatter diffraction measurements, and magnetic fabric analyses show that the shear zone is characterized by sinistral thrust shearing. The shear zone has also slightly modified the Sn orebodies. Quartz in the shear zone exhibits core-mantle structure and undulose extinction. Quartz has experienced significant sub-grain rotation and grain-boundary migration recrystallization. Lattice preferred orientation analysis reveals primarily basal , rhomb , and prism slips. Cassiterite grains in the shear zone, however, demonstrate brittle deformation. Therefore, the deformation temperature during the ductile shearing is estimated lower than 650 degrees C and below U-Pb closure temperature of cassiterite. As such, the U-Pb isotopic composition of the cassiterite was not disturbed by the shearing and the U-Pb age of the cassiterite could be used for the age of the Sn mineralization. LA-ICP-MS U-Pb dating of cassiterite grains selected from a cassiterite-bearing tourmalinite sample performed in this study yielded a Tera-Wasserburg U-Pb lower intercept age of 832.3 +/- 5.3 Ma. This age is consistent within error with that of the neighboring Neoproterozoic Motianling granitic pluton, which suggests a close genetic relationship between the Sn mineralization and the granitic magmatism. Studies show that the Jiufeng ductile shear zone was produced by a widespread Caledonian (or Kwangsian) tectonic event in South China, indicating that the shearing was much later than the Sn mineralization and has no generic relationship to the Sn deposit.