South Hunan Research Articles

Differentiating Jurassic Cu-, W-, and Sn (—W)-bearing plutons in the Nanling Range (South China): An integrated apatite study

The Nanling mineralization belt, South China, is well-known for widespread W-, Sn (—W), and Cu-polymetallic ore deposits. At present, how to better trace their magma sources and constrain their magmatic processes is currently a conundrum. As a resistant mineral, apatite has shown great potential in metallogenic studies. In this study, we present a comprehensive investigation of apatite from the Baoshan (BS) and Tongshanling (TSL) Cu-bearing granites, the Wangxianling (WXL) W-bearing granite, and the Qitianling (QTL) Sn-bearing granite in South Hunan, to trace the nature of parental magma and to establish apatite discrimination criteria to be used in regional prospecting. The U-Pb age dating of apatite indicates that these different types of ore-bearing granites were all formed in the Middle-Late Jurassic. The εNd(t) values results suggest that (1) Cu-bearing granites in the Nanling Range were formed by melting of meta-igneous rocks in the deep crust, (2) W-bearing granitic magmas were generated by melting of old continental crust, while (3) Sn-bearing granitic magmas were produced by melting of crust material with various input of mantle-derived components. Apatite from the BS and TSL plutons exhibits lower F/Cl ratios compared to those from WXL, and QTL plutons, with higher Cl contents in the BS and TSL plutons, implying that the crustal basement of the suture zone was metasomatized by a Cl-enriched fluid. We used a partial least squares discriminant analysis (PLS-DA) of trace element data in apatite to differentiate Cu-, W-, and Sn (—W)-bearing plutons. We find that the most influential elements for classification are Sr, Eu, Ga, Nd, and Li. Trace elements differences reveal distinguished degrees of fractionation, and redox conditions for different types of ore-bearing granites. A comparative study of apatite from different ore-bearing granites indicates that, apatite can be a useful mineral exploration tool to differentiate Cu-, W-, and Sn (—W)-bearing plutons in the Nanling Range and South China.

The strong evidence that mantle-derived magma continued to provide heat to magma reservoir: Example from the petrogenesis of MME in the Jiuyishan granitic batholith in South Hunan Province

The strong evidence that mantle-derived magma continued to provide heat to magma reservoir: Example from the petrogenesis of MME in the Jiuyishan granitic batholith in South Hunan Province

Hydrogeochemistry and Formation of Low Temperature Geothermal Waters in South Hunan, China

Hydrogeochemistry and Formation of Low Temperature Geothermal Waters in South Hunan, China

Changes and relationship of climate and late-rice yield in chenzhou city of south hunan province of CHINA

The changes and relationship of climate parameters and late-rice yield per unit area during the growth periods of late-rice from 2010 to 2019 were quantitatively analyzed in order to provide scientific guidance for countermeasures against climate change and sustainable production of late-rice. The climate parameters include cumulative daily sunshine hours (S), mean daily temperature (T), cumulative daily precipitation (P), mean daily relative humidity (H), daily highest and lowest temperatures (Th and Tl), days of high temperatures (DT ≥ 30℃ and DTh ≥ 35℃) and low temperature (DTl < 15℃). Results showed that: (i) Late-rice yield was significantly increased quadratically from 5621.33 kg hm2 in 2010 to 6333.65 kg hm2 in 2019 with a mean of 5959.2 kg hm2. (ii ) According to the suitable climate conditions for growth of late-rice, T and P were low but H was suitable in the whole field growth period of late-rice, T was suitable in the transplanting-tillering stage, but was low in the booting-heading and milk ripening-mature stage. DT ≥ 30℃, DTh ≥ 35℃ and DTl < 15℃ was meanly 7.7, 7.5 and 6.4 d, respectively, which showed possible occurrence of the damages to late-rice due to high and low temperatures. iii) Only T, Th and Tl in the booting-heading stage showed significant positive correlation with year, and the optimal regression models were in quadratic and exponential types. The climate parameters of S, T and Th in the boot-heading stage were significantly positively correlated with late-rice yield, and the optimal regression models were all in quadratic types. Daily highest temperature (Th) affected late-rice yield most (61.04%), followed by T (36.50%), and S affected least (2.46%). Considering the current conflict in the field planting periods between tobacco and late-rice, late rice varieties needs to be bred with short growth period and high tolerance to both high and low temperatures. Bangladesh J. Bot. 52(2): 639-647, 2023 (June) Special

Changes and relationship of climate and late-rice yield in chenzhou city of south hunan province of CHINA

The changes and relationship of climate parameters and late-rice yield per unit area during the growth periods of late-rice from 2010 to 2019 were quantitatively analyzed in order to provide scientific guidance for countermeasures against climate change and sustainable production of late-rice. The climate parameters include cumulative daily sunshine hours (S), mean daily temperature (T), cumulative daily precipitation (P), mean daily relative humidity (H), daily highest and lowest temperatures (Th and Tl), days of high temperatures (DT ≥ 30℃ and DTh ≥ 35℃) and low temperature (DTl < 15℃). Results showed that: (i) Late-rice yield was significantly increased quadratically from 5621.33 kg hm2 in 2010 to 6333.65 kg hm2 in 2019 with a mean of 5959.2 kg hm2. (ii ) According to the suitable climate conditions for growth of late-rice, T and P were low but H was suitable in the whole field growth period of late-rice, T was suitable in the transplanting-tillering stage, but was low in the booting-heading and milk ripening-mature stage. DT ≥ 30℃, DTh ≥ 35℃ and DTl < 15℃ was meanly 7.7, 7.5 and 6.4 d, respectively, which showed possible occurrence of the damages to late-rice due to high and low temperatures. iii) Only T, Th and Tl in the booting-heading stage showed significant positive correlation with year, and the optimal regression models were in quadratic and exponential types. The climate parameters of S, T and Th in the boot-heading stage were significantly positively correlated with late-rice yield, and the optimal regression models were all in quadratic types. Daily highest temperature (Th) affected late-rice yield most (61.04%), followed by T (36.50%), and S affected least (2.46%). Considering the current conflict in the field planting periods between tobacco and late-rice, late rice varieties needs to be bred with short growth period and high tolerance to both high and low temperatures. Bangladesh J. Bot. 52(2): 639-647, 2023 (June) Special

Comparing spatial patterns of 11 common cancers in Mainland China

BackgroundA stronger spatial clustering of cancer burden indicates stronger environmental and human behavioral effects. However, which common cancers in China have stronger spatial clustering and knowledge gaps regarding the environmental and human behavioral effects have yet to be investigated. This study aimed to compare the spatial clustering degree and hotspot patterns of 11 common cancers in mainland China and discuss the potential environmental and behavioral risks underlying the patterns.MethodsCancer incidence data recorded at 339 registries in 2014 was obtained from the “China Cancer Registry Annual Report 2017”. We calculated the spatial clustering degree of the common cancers using the global Moran’s Index and identified the hotspot patterns using the hotspot analysis.ResultsWe found that esophagus, stomach and liver cancer have a significantly higher spatial clustering degree (p<0.05) than others. When by sex, female esophagus, male stomach, male esophagus, male liver and female lung cancer had significantly higher spatial clustering degree (p<0.001). The spatial clustering degree of male liver was significantly higher than that of female liver cancer (p<0.001), whereas the spatial clustering degree of female lung was significantly higher than that of male lung cancer (p<0.001). The high-risk areas of esophagus and stomach cancer were mainly in North China, Huai River Basin, Yangtze River Delta and Shaanxi Province. The hotspots for liver and male liver cancer were mainly in Southeast China and south Hunan. Hotspots of female lung cancer were mainly located in the Pearl River Delta, Shandong, North and Northeast China. The Yangtze River Delta and the Pearl River Delta were high-risk areas for multiple cancers.ConclusionsThe top highly clustered cancer types in mainland China included esophagus, stomach and liver cancer and, by sex, female esophagus, male stomach, male esophagus, male liver and female lung cancer. Among them, knowledge of their spatial patterns and environmental and behavioral risk factors is generally limited. Potential factors such as unhealthy diets, water pollution and climate factors have been suggested, and further investigation and validation are urgently needed, particularly for male liver cancer. This study identified the knowledge gap in understanding the spatial pattern of cancer burdens in China and offered insights into targeted cancer monitoring and control.

Evaluating the Effect of Window-to-Wall Ratios on Cooling-Energy Demand on a Typical Summer Day.

The window-to-wall ratio (WWR) significantly affects the indoor thermal environment, causing changes in buildings’ energy demands. This research couples the “Envi-met” model and the “TRNSYS” model to predict the impact of the window-to-wall ratio on indoor cooling energy demands in south Hunan. With the coupled model, “Envi-met + TRNSYS”, fixed meteorological parameters around the exterior walls are replaced by varied data provided by Envi-met. This makes TRNSYS predictions more accurate. Six window-to-wall ratios are considered in this research, and in each scenario, the electricity demand for cooling is predicted using “Envi-met + TRNSYS”. Based on the classification of thermal perception in south Hunan, the TRNSYS predictions of the electricity demand start with 30 °C as the threshold of refrigeration. The analytical results reveal that in a 6-storey residential building with 24 households, in order to maintain the air temperature below 30 °C, the electricity required for cooling buildings with 0% WWR, 20% WWR, 40% WWR, 60% WWR, 80% WWR, and 100% WWR are respectively 0 KW·h, 19.6 KW·h, 133.7 KW·h, 273.1 KW·h, 374.5 KW·h, and 461.9 KW·h. This method considers the influence of microclimate on the exterior wall and improves the accuracy of TRNSYS in predicting the energy demand for indoor cooling.

Geological characteristics and metallogenic age of Tengshan'ao Sn deposit in Dayishan of South Hunan and its prospecting significance

The Tengshan'ao Sn deposit, located at the Dayishan ore field, Nanling Range, is one of the recently explored deposits in this region. In this study, LA-MC-ICP-MS cassiterite U–Pb and muscovite 40Ar-39Ar isotopic dating analyses for altered granite-type Sn ores yielded ages of 156.7 ± 4.3 Ma and 151.1 ± 1.5 Ma, respectively. These ages are consistent to the LA-MC-ICP-MS zircon U–Pb age of the fine-grained two-mica monzogranite (158.2 ± 1.6 Ma), indicating a coeval magmatism and mineralization for the Late Jurassic Tengshan'ao Sn deposit. It is further demonstrated that the formation of this deposit is related to the Early Yanshanian (160-150 Ma) large-scale diagenesis and mineralization in Nanling Range. It is suggested that the late-stage fine-grained two-mica (muscovite) granite has an indicative significance for searching the altered granite type Sn polymetallic mineralization.

Genesis of the Huangshaping W–Mo–Cu–Pb–Zn deposit, South China: Role of magmatic water, metasomatized fluids, and basinal brines during intra‐continental extension

The Huangshaping world‐class W–Mo–Cu–Pb–Zn deposit formed during Jurassic intra‐continental extension in the central Nanling region (South Hunan), South China. In order to assess the role of fluids in ore genesis and the origin of polymetallic mineralization, three types of mineralized porphyries (quartz porphyry, granophyre, and granite porphyry) were studied. The multi‐method approach included whole‐rock Sr–Nd isotopic geochemistry and determination of the trace element content and gaseous and aqueous composition of ore minerals from the three stages of intrusion and ore emplacement. Geochemical results show that the Sr–Nd isotopes in these altered porphyries were strongly affected by fluid metasomatism. The 87Sr/86Sr and 147Sm/144Nd ratios for the quartz porphyry and granophyre range from 0.72894 to 0.83093 and 0.1524 to 0.2080, respectively, whereas higher and considerably more variable ratios were determined for the granite porphyry (0.90396 to 1.51943 and 0.2391 to 0.2914). These observations imply that granite porphyry‐associated W–Mo mineralization underwent more intensive fluid–rock interaction. The relatively low REE concentrations and high abundances of CH4 and H2 in the Cu ores associated with the quartz porphyry unambiguously suggest a deep‐sourced magmatic fluid for the Cu mineralization. The high REE concentrations, pronounced negative Eu anomalies, M‐type tetrad effects, and high CO2, H2O, and Ca2+ contents of the W–Mo ores associated with the granite porphyry imply that the W–Mo polymetallic mineralization was formed in a relatively oxidizing, high‐temperature environment with strong metasomatism. In contrast, the slightly negative Eu anomalies, W‐type tetrad effects, low CH4, and high F− and Cl− concentrations of the Pb–Zn ores indicate involvement of a sediment‐derived basinal brine and reducing mineralization conditions. Collectively, a three‐stage genetic model is proposed for the Huangshaping polymetallic deposit. Corresponding to initiation, development, and cessation of Jurassic intra‐continental extension, magmatic water, metasomatized fluids, and basinal brines played key sequential roles in Cu, W–Mo, and Pb–Zn mineralization.

Geochronology, Petrology, and Genesis of Two Granitic Plutons of the Xianghualing Ore Field in South Hunan Province: Constraints from Zircon U–Pb Dating, Geochemistry, and Lu–Hf Isotopic Compositions

Two small-sized granitic plutons, outcropped in Xianghualing ore field, South Hunan (South China), have a close relationship with the super large-scale Sn–W polymetallic mineralization in this ore field. The Laiziling and Jianfengling plutons are composed of medium- to coarse-grained two-mica and coarse-grained biotite granites, respectively, and have zircon U–Pb ages of 156.4 ± 1.4 Ma and 165.2 ± 1.4 Ma, respectively. Both of the Laiziling and Jianfengling granites are characterized by extremely similar elemental and Lu–Hf isotopic compositions with high contents of SiO2, Al2O3, Na2O, K2O, high A/CNK ratios, negative εHf(t) values (ranging from −3.86 to −1.38 and from −5.44 to −3.71, respectively), and old TDMC ages (ranging from 1.30 to 1.47 Ga and from 1.32 to 1.56 Ga, respectively). These features indicate that they both belong to highly fractionated A-type granites, and were formed in an extensional setting and from the same magma chamber originated from the Paleoproterozoic metamorphic basement of South China with a certain amount of mantle-derived magma involved with temperatures of ca. 730 °C and low oxygen fugacity.

南岭地形对湘南降水的影响分析

南岭地形对湘南降水的影响分析

Indium Mineralization in the Yejiwei Sn‐Polymetallic Deposit of the Shizhuyuan Orefield, Southern Hunan, China

AbstractThe Yejiwei deposit, which is located in the southern Hunan W–Sn–Pb–Zn Metallogenic Belt in south China, is a large‐scale porphyry–skarn–veinlet‐type deposit containing 806 t In. Mineralization occurs as porphyry‐type Sn (stockworks), skarn‐type Sn–Cu, marble‐hosted‐type Sn–Cu (veinlet), and vein‐type Pb–Zn ores. Thirty‐five ore samples were collected from the Yejiwei deposit for bulk and mineral chemical composition, microscopic observation and electron microprobe analyses. The porphyry‐type Sn ores contain variable amounts of In (2.3–76 ppm; mean of 17.4 ppm) with local In enrichment (226 ppm) and 1000 × In/Zn values are 3.8–52.4. The skarn‐type Cu–Sn ore is richest in In (12.3–214 ppm; mean of 114 ppm), and 1000 × In/Zn values are 2.4–117. In contrast, the In content of the marble‐hosted‐type Cu–Sn ores is relatively low (7.4–34.9 ppm; mean of 20.3 ppm), and 1000 × In/Zn is in the range of 0.61–5.5, and the vein‐type Pb–Zn ores in the external zone contain the lowest In contents (7.2–17.0 ppm; mean of 12.1 ppm) with 1000 × In/Zn values of 0.07–0.09. The ore minerals in the deposit include pyrite, pyrrhotite, cassiterite, and In‐bearing minerals of sphalerite, chalcopyrite, and stannite. Although only trace amounts of sphalerite are hosted in the porphyry ores, the sphalerite contains the highest In content (0.27–10.1 wt.% In) in the deposit. We observed the highest In contents of all In‐bearing sphalerite reported in China. The In contents of sphalerite in the skarn‐type ore range from 0.15 to 0.56 wt.%, whereas the marble‐hosted‐, and vein‐type ores have lower In contents (0.00–0.04, and 0.03–0.06 wt.%, respectively). The In resources of the Yejiwei deposit are mainly hosted in skarn ores of the No. 31 and No. 32 orebodies. The genesis of In in the Yejiwei deposit was closely related to the shallow intrusive environment of related igneous rocks. As W–Sn–Mo–Bi–Cu–Pb–Zn–Ag mineralization is widespread in south Hunan, this study would suggest a focus on skarn‐type Sn–Zn deposits for the future prospecting of In resources.

A Test Analysis into Summertime Human Settlement of Traditional Villages in South Hunan

In order to understand the status quo of traditional villages human settlement in the district of South China, this thesis, with typical Banliang Village as a research subject, in combination with case investigation and on-site test, analyzes the factors influencing the human settlement of traditional villages from three perspectives as the space of street-lane, the layout of functional space, and the construction of enclosure structure. After arranging and analyzing results, it was found that: there is the "cold lane” phenomenon in traditional villages, where the narrower the lane way is, the faster the wind speed, and the more obvious the valley effect; the open-type climate buffer zone like the central room of peopleple‘s residence can weaken the influence of natural climate on the main space; the thermal environment of traditional villages is superior than that of common modern residence.

Diversity hotspots and conservation gaps for the Chinese endemic seed flora

The flora in China is highly endemic. Decisions about conservation and management of biodiversity based on hotspots and conservation gaps of endemic seed plant species diversity in China are essential. In this paper, based on a species distribution data set with 12,824 Chinese endemic plants, we measured Chinese endemic seed plant diversity using five indices: endemic species richness (ER), weighted endemism (WE), phylogenetic diversity (PD), phylogenetic endemism (PE), and biogeographically weighted evolutionary distinctiveness (BED). Five percent of China's total land area with the highest biodiversity was used to identify hotspots for each index. In total, 19 hotspots covering 7.96% of China's total land area were identified. Most hotspots are located in mountainous areas, mainly in the Qinling Mountains and further south or in the Hengduan Mountains and to the east in China. Nine hotspots are identified with all five indices. These hotspots include the Hengduan Mountains, the Xishuangbanna Region, the Qinling Mountains, southwest Chongqing, and five mountainous areas (located in east Chongqing and west Hubei; in east Yunnan and west Guangxi; in north Guangxi, southeast Guizhou and southwest Hunan; in north Guangdong and south Hunan; and in southeast Tibet, respectively). Furthermore, we detected conservation gaps for hotspots of Chinese endemic seed flora by overlaying national nature reserves with the identified hotspots, and we designated priority conservation gaps for hotspots by overlaying global biodiversity hotspots with conservation gaps for hotspots. Most hotspots for Chinese endemic seed plant species are badly protected. Only 26.48% of the hotspot areas of Chinese endemic seed plant species were covered by nature reserves. We suggest that it is essential to pay more attention to herbaceous plants in biodiversity conservation, and to promote a network function of nature reserves within these hotspots in China.

Late Triassic orogenic collapse and Palaeo‐Pacific slab roll‐back beneath central South China: constraints from mafic granulite xenoliths and structural features

East Asia suffered an important transformation from the Tethys to the Pacific tectonic domain during the early Mesozoic. Moreover, the South China Block (SCB) in East Asia has an obvious change from an Indosinian syn‐orogenic compression to a post‐orogenic extensional tectonic setting. The dynamic evolution of the SCB that caused this change is still unclear. Here, we combine the petrology and whole‐rock geochemistry of the Daoxian mafic granulite xenoliths in basalts from South Hunan Province and the structural features of the Xuefengshan tectonic belt, to propose a late Triassic tectonic model in the central SCB. The Daoxian region is located in the eastern part of the Xuefengshan basement uplift belt. The Daoxian mafic granulite xenoliths, forming in the late Triassic, have high Mg# value, high MgO and low SiO2 contents. They have flat REE patterns with a positive Eu anomaly, enriched in Rb, Ba, and depleted in Th, U, Nb, Zr and Hf. These xenoliths are the product of pyroxene and plagioclase accumulation of the mafic melts. The mafic melts originated from the asthenosphere and then underplated to the bottom of the lower crust. In the Xuefengshan belt, it is observed that the unconformities during the Late Triassic changed from high‐angle unconformity, through low‐angle unconformity and para‐unconformity, to conformity, from the central to western parts of the SCB. The detachment layer beneath the Xuefengshan belt displaying NW‐trending thrusts cross‐cuts the late Palaeozoic strata. We suggest that orogenic collapse happened beneath the central SCB during the Late Triassic, which was accompanied by lithospheric extension and asthenospheric upwelling. These dynamic processes induced different effects on the SCB. Beneath the central SCB, the mantle‐derived melt underplated the lower crust, and subsequently influenced the deep crust. From central to western SCB, the regular westward change of the stratal unconformities is related to the weakening of the lithospheric extension. In the central and eastern SCB, the orogenic collapse and the subsequent asthenosphere upwelling could have contributed to the mantle disturbance to enhance the roll‐back of the Palaeo‐Pacific slab. Copyright © 2016 John Wiley &amp; Sons, Ltd.

A Preliminary Review of Metallogenic Regularity of Tungsten Deposits in China

AbstractTungsten ore resources are abundant in China with relatively complete types of deposits. Skarn type and quartz vein type deposits are dominated in the tungsten resources, whereas quartz vein type wolframite deposits are most important in terms of exploitation and utilization. Skarn type tungsten deposits are concentratedly distributed in the central Nanling region, such as South Hunan, South Anhui and the eastern Qinling region, while quartz vein type tungsten deposits occur mainly in South China, such as West Fujian, South Jiangxi, North Guangdong and South Hunan. The most important metallogenic epoch of tungsten is the Mesozoic, while the metallogenic tectonic setting is featured by an intracontinental environment after orogeny with sever tectonic movements, deep‐seated faults and frequent magmatic activities, especially Mesozoic granitoids closely related to tungsten‐tin mineralization. 22 metallogenic series of ore deposits characterized by or significantly related to tungsten were defined based on precise statistic information of 1199 tungsten mining areas and thorough the summary of metallogenic regularities. Based on studies of the metallogenic regularity of tungsten deposits, skarn type (or greisen type), quartz vein type and massif‐type of tungsten deposits are thought to be the key prediction types. 65 tungsten‐forming belts and 22 key ore concentration areas were ascertained and a distribution map of tungsten‐forming belts of China was compiled, which provided a theoretical basis for evaluation and prediction of potential tungsten resources.

A Preliminary Review of Metallogenic Regularity of Tin Deposits in China

China is rich in tin resources, and contains many types of tin deposits. Among the tin deposit types, the cassiterite‐sulfide type, skarn type and quartz vein type occupy a large proportion of tin resources and reserves. From the aspect of exploitation and utilization, the most important types are cassiterite‐sulfide type and quartz vein type. The cassiterite‐sulfide type tin deposits are mainly located in Northern Guangxi and Eastern Yunnan, skarn type deposits are mainly distributed in the ore‐concentration areas of South Hunan in Middle Nanling, and the quartz vein type tin deposits are mainly distributed in South China, such as Western Fujian, Middle Jiangxi, Northern Guangzhou and Southern Hunan. The most important metallogenic epoch for tin deposits is the Mesozoic era. The metallogenic geotectonic background is mainly continental environments after orogeny process, with strong tectonic changes, interlaced deep fracture and frequent magmatism. And the most distinctive feature is the well developed Mesozoic granites, which have a close relationship with tin mineralization. Based on the detailed study of the data from 873 tin deposits in China, this paper summarized the metallogenic regularity of tin deposits, classified 20 important metallogenic series of tin or tin‐associated deposits, and inferred that the cassiterite‐sulfide type, skarn type, quartz vein type and greisen type are the main prediction types of tin resources. Forty‐four tin‐mineralization belts were divided, among which, 19 belts are the most important. In addition, a series of maps about tin metallogenic belts and tin metallogenic regularity were compiled, aiming to provide theoretical basis for potential estimation and prediction of tin mineral resources.

Geological Characteristics and Re‐Os Geochronology of Tongshanling Polymetallic Ore Field, South Hunan, China

Geological Characteristics and Re‐Os Geochronology of Tongshanling Polymetallic Ore Field, South Hunan, China

Geochemistry of A-type granites in the Huangshaping polymetallic deposit (South Hunan, China): Implications for granite evolution and associated mineralization

The Huangshaping granites in Hunan Province, South China were investigated for their geochemical characteristics. Three types of granites have been petrographically identified: quartz porphyry, granophyre, and granite porphyry. Whole rock geochemistry suggests that the Huangshaping granites, especially the granite porphyry, exhibit typical A-type granite characteristics with their enrichment in Si, Rb, U, Th, and Nb and significant depletion in Ba, Sr, Ti, Eu, and P. Based on the Al, Y and Zr contents as well as the REE patterns of the rocks investigated, the quartz porphyry and the granophyre are classified as A1 type alkaline granites whereas the granite porphyry is considered as A2 type aluminous granite. Whole rock and quartz/feldspar O isotope data yields a wide range of δ18OSMOW values (11.09–26.32‰). The granites are characterized by high radiogenic Pb isotopic composition. The present-day whole rock Pb isotopic ratios are 206Pb/204Pb=18.706–19.155, 207Pb/204Pb=15.616–15.711 and 208Pb/204Pb=38.734–39.296. Combining the O–Pb isotope compositions with major, trace and REE geochemistry and regional geology characteristics, the Huangshaping granites were determined to resemble within-plate granites that were mainly derived from a felsic infracrustal source related to continental extension. The magma source of the quartz porphyry and the granophyre may have been generated from deeper depths, and then ascended rapidly with limited water content and low oxygen fugacity, which contributed to Cu, Pb and Zn mineralization. On the other hand, the magma that generated the granite porphyry may have ascended relatively slower and experienced pronounced crystal fractionation, upper-crustal basement rock contamination (assimilation) and wall–rock interaction, producing the Sn- and W-rich granite porphyry. This study reveals the crustal extension process and associated magmatic–metallogenic activities during 180–150Ma in South Hunan.

Magnolia denudata var. glabrata var. nov. (Magnoliaceae) from Hunan, China

Magnolia denudata var. glabrata Y. L. Wang et S. Z. Zhang var. nov. is described and illustrated from Hunan, China. The variety occurs mainly in semi‐evergreen forest of south Hunan at altitudes between 700 and 1260 m a.s.l. It differs from M. denudata var. denudata by its green and glabrous twigs and leaves which are glabrous above and have some white pubescence underneath. With its white flowers consisting of mostly 9 tepals, it differs from M. sprengeri Pamp. which mainly has 12 tepals in various shades of red/pink to white. The new variety is rare and considered endangered due to habitat destruction.