Fluoride is commonly found in geofluids and is thought to enhance metal transport through fluoride complex formation. However, its strong tendency to associate with hydrogen to form HF(aq) may limit the availability of free fluoride. Due to the lack of investigation into the dissociation behavior of HF(aq) in hydrothermal fluids, its role in metal transportation remains poorly understood. To address this gap, we developed a Density Functional Theory based deep-potential (DP) model for the HF-H2O system using the SCAN functional. This model, along with enhanced sampling techniques, allowed extensive simulations of HF(aq) dissociation at temperatures up to 1000 degrees C and pressures of 100 kbar, generating the first dataset on HF(aq) dissociation constants at high temperature and pressure. The water self-ionization constants (pKw) were also calculated with the DP model, showing overall agreement with previously published data. Our DP molecular dynamics (DPMD) calculated HF(aq) dissociation constants (logKd) at ambient and high-temperature vapor pressures closely align with previously reported experimental values. Our findings indicate that HF(aq) dissociation is more pronounced in high-density fluids than previously recognized, with free fluoride ions remaining stable across a wider pH range. Using tungsten as an example, we demonstrate that the increased availability of free fluoride ions may potentially enhance metal transport in hydrothermal fluids by forming metal-fluoride complexes. Similar results can also be applied to other metal elements. These findings may advance our understanding of deep-earth geochemical processes by clarifying how fluoride complexes dictate element mobility in the high-pressure hydrothermal fluids of subduction zones.

The ‘Strangelove ocean’ (a state of ocean, almost devoid of living organisms) documented in the early Cambrian strata in South China, has been thought to be driven by an extraterrestrial impact, but this viewpoint has been doubted for emerging geochemical evidence. Volcanism may be a trigger for the oceanic crisis. However, such a linkage has not yet been established. Here, we conduct an investigation into the timing and origin of the early Cambrian K-bentonites (a type of clay rock formed from volcanic ash) of the Yangtze and Baoshan blocks. The results suggest that the K-bentonites may represent early Cambrian explosive super-eruptions occurred in the north-western margin of Gondwana. The eruptions might trigger the anoxia of the contemporaneous ocean and coincided temporally with a bio-crisis preceding the summit of the Cambrian explosion. We propose that they may have initiated the ‘Strangelove ocean’ and delayed the climax of the Cambrian bio-radiation. The ‘Strangelove Ocean’, with severely reduced biological activity before the summit of the Cambrian explosion, may have been triggered by super-eruptions in the north-western margin of Gondwana, according to analysis of geological samples from Southern China.

Understanding the origin of volcanic material at times of environmental change and evolutionary development may help aid investigation of causal linkages between the changes and volcanic activity. One such episode of environmental change of interest is the Ediacaran-Cambrian boundary (ECB), which follows the emergence of the Ediacaran fauna, and precedes the Cambrian explosion. Owing to recent developments in geochronology, a number of K-bentonites of ECB age have been identified in strata from South China, but systematic research on their origin has not been performed. Here, we carried out mineralogical, whole-rock, and zircon geochemical studies on ECB-age K-bentonites from the middle Zhujiaqing Formation at Meishucun and the topmost Liuchapo Formation at Pingyin in South China to investigate the origin of the K-bentonites. Whole-rock major- and traceelement data, and trace-element data of volcanic zircons in the K-bentonites indicate the source magmas are felsic, whilst Hf-isotope compositions of the volcanic zircons indicate the primary source magmas likely originated from the depleted mantle, with a minor contribution of ancient crustal material. Whole-rock data and trace-element data of volcanic zircons in the K-bentonites further indicate the source volcanoes were located in a subduction-related tectonic setting. By combining our findings with previous studies of Gondwanan tectonics, we suggest the source volcanoes were most probably located in a magmatic arc setting formed by subduction of the Proto-Tethys oceanic crust towards the Iran terrane in the northwestern margin of Gondwana. Thus, the Kbentonites represent episodes of intense felsic explosive volcanism along the northwestern margin of Gondwana during the Ediacaran-Cambrian transition and have likely been transported 1000 km to the studied sites. Largescale felsic explosive volcanism played an important role in influencing the atmospheric and oceanic environments throughout Earth's history, and the volcanic activity documented here is contemporaneous with eruptions elsewhere in the world. The tight temporal link between this activity and the dramatic environmental fluctuations and the turnover of early life evolution during the Ediacaran-Cambrian transition, leads us to propose that volcanism may have played a role in the environmental and evolutionary events of the ECB.

The ecological vulnerability in the southwestern karst region is significant, and the protection of biodiversity (BD) and ecosystem services (ES) is of great significance for coordinating ecological protection and sustainable development. However, most studies focus on single targets of BD or ES, while neglecting to identify protected areas by merging them. Therefore, this article quantifies the spatial distribution of BD and ES from 2000 to 2019 using the revised universal soil loss equation model, constructs a biodiversity index, and other methods. The ordered weighted average method and superposition analysis method are further used to determine the southwest karst priority ecological protection area based on dual objectives. The results indicate that setting up priority protection areas in karst areas with better hydrothermal conditions can better protect ES and BD. The priority protected area accounts for 34.76 % of the total karst area in Southwest China, with a relatively small biodiversity protection area (15.59 %) and a relatively large ecosystem service protection area (19.17 %). Nature reserves account for 28.72 % of the BD priority conservation area and 30.89% of the ES priority conservation area. However, in the adjacent areas of Yunnan, Guizhou, and Guangxi provinces, as well as in the central regions of Guizhou, Guangxi, and Hunan, compared with the designated nature reserves in China, the existing protected areas do not provide high protection for the ecosystem services in these areas. Taking into account the dual goals of protecting BD and ES in the protected area, the results can provide reference for the development and utilization of natural resources, sustainable development, and the expansion of the protected area.

近期在燕山期岩浆活动缺乏的黔西南地区发现了罗悃二长花岗斑岩,为厘定其形成年龄,明确黔西南地区燕山期岩浆岩活动机制,本文对其进行了激光剥蚀电感耦合等离子质谱仪(LA-ICP-MS)锆石U-Pb定年,Hf同位素和主、微量元素分析.结果表明,18颗柱状锆石年龄为(157.8±0.4)Ma(MSWD=1.4),代表二长花岗斑岩的侵位年代为晚侏罗世;锆石的176Hf/177Hf值(0.282 390～0.282 478)和εHf(t)(均值为-8.17)表明二长花岗斑岩的岩浆源区主要以富集地幔为主;岩石的SiO2 含量为 65.91％,CaO 为 1.44％,Al2O3 为 15.67％,MgO 为 0.57％,TFe2O3 为 4.23％,K2O 为 4.19％,Na2O 为 5.72％,σ 为3.76～4.98,A/CNK为0.93～0.96,显示富碱、准铝质的特征,应为I型花岗岩类;岩石的∑ REE(323.57×10-6～369.50×10-6)含量中等,LaN/YbN(7.84～9.30)显示为轻重稀土分馏,δEu(0.79～0.83)略微铕负异常,总体表现出右倾稀土配分曲线;明显富集Rb、Ba、Th、K、Nd,而强烈亏损Nb、Ta、P、Ti等元素.元素和同位素特征表明,罗悃二长花岗斑岩是富集岩石圈地幔部分熔融的产物,岩浆经历了分离结晶演化过程,并受到部分地壳物质的混染,形成于板内伸展环境.罗悃二长花岗斑岩晚侏罗世成岩时代的厘定,说明该时期黔西南地区处于岩石圈伸展-减薄阶段.

Several K-bentonite beds have been discovered in the upper part of the Ediacaran system in South China. Existing researches mainly focus on the zircon U-Pb geochronology of the K-bentonites. However, the nature of the primary magmas of the K-bentonites, the tectonic setting of their source volcanoes, the significance of their geochemical correlation, and their potential implications to evolution of late Ediacaran life have not been unraveled. Here, whole-rock and zircon geochemical studies have been carried out on the K-bentonites in the top of the Miaohe Member from the Jiuqunao section, and in the basal Liuchapo Formation and the lower Dengying Formation from the Fanglong section. The major and trace element contents of the K-bentonites and the trace element contents of volcanic zircons in the K-bentonites suggest that the nature of the primary magmas of the Kbentonites from the Fanglong and Jiuqunao sections is trachyandesitic. The oxygen isotope compositions of the volcanic zircons in the K-bentonites suggest that the source magmas of the K-bentonites from the two sections are mainly from the crust. The whole-rock Y-Nb, Ta/Yb-Th/Yb, Yb-Th/Ta, and Ta/Hf-Th/Hf diagrams, and the volcanic zircon Hf-U/Yb, Y-U/Yb, Th/U-Nb/Hf, and Th/Nb-Hf/Th diagrams of the K-bentonites show that the tectonic setting of source volcanoes of the K-bentonites was a convergent environment, which may be the result of the assembly of Gondwana during late Ediacaran. The geochemical results suggest that the K-bentonites in the basal Liuchapo Formation at the Fanglong section are correlative with the K-bentonite in the top of the Miaohe Member at the Jiuqunao section. Therefore, the geochemical correlation of the K-bentonites indicate that the age of 550.5 +/- 1.0 Ma for the K-bentonite in the top of the Miaohe Member may be too young to be used as the end time of the Doushantuo negative carbon isotope excursion (DOUNCE), and that the end time of this event should be older than the age 557 +/- 3 Ma of the K-bentonite in the lower part of the Dengying Formation at the Fanglong section. Thus, the termination of the DOUNCE and the Shuram carbon isotope excursion (terminated at 567.3 +/- 3.0 Ma) may be isochronous. As volcanic ashfall events are known to supply nutrients to the oceans, we hypothesise that the widespread volcanism of the late Ediacaran may have enhanced oceanic productivity and play a role in the evolution of life at this time.

华南下寒武统牛蹄塘组底部及其相当地层发育一层Ni-Mo多金属层,被当作华南下寒武统区域对比的标志层.然而,目前华南部分重要剖面的Ni-Mo多金属层位置依然没有明确,妨碍了基于精确地层对比的寒武纪早期海洋环境信息的揭示.本研究中,我们对云南梅树村剖面和贵州平引剖面地层进行采样,采用电感耦合等离子质谱仪(ICP-MS)对样品微量元素含量进行分析,以确定这两条剖面的Ni-Mo多金属层位置.在此基础上,进一步对平引剖面牛蹄塘组底部样品进行Fe组分分析,结合前人数据,初步揭示华南下寒武统Ni-Mo多金属层沉积时期(～521 Ma)南华盆地海水的氧化还原信息.微量元素含量结果显示,梅树村剖面玉案山组底界之上3 m的地层(Ni:135×10-6,Mo:583×10-6)和平引剖面牛蹄塘组底界之上2.5 m的地层(Ni:2480×10-6,Mo:16341×10-6)记录了各自剖面的Ni、Mo、As、Tl等元素含量的峰值.因此,我们认为梅树村剖面Ni-Mo多金属层应位于该剖面玉案山组底界之上3 m层位,平引剖面Ni-Mo多金属层应位于该剖面牛蹄塘组底界之上2.5 m层位.平引剖面牛蹄塘组底部样品Fe组分数据表明,该剖面Ni-Mo多金属层及其附近地层记录了海水硫化信息(FeHR/FeT＞0.38,Fepy/FeHR＞0.80).结合已有的华南其他代表性剖面Ni-Mo多金属层及其附近层位(或相当层位)的Fe组分数据,我们对南华盆地(包括台地带、斜坡带和盆地带)Ni-Mo多金属层沉积时期的海水氧化还原状态进行重建,结果表明该时期南华盆地发生了一次深层海水硫化扩张事件.这一事件可能对寒武纪生命幕式辐射产生了重要影响.

A study of the K-bentonites in the Doushantuo cap dolostones on the Yangtze Platform in South China would facilitate understanding the origin of the Marinoan cap dolostones and testing the snowball Earth hypothesis. To date, sporadic work has been conducted on the whole-rock geochemistry of the K-bentonites from the platform and slope of the Yangtze Platform, to preliminarily understand the genesis of the K-bentonites. However, a study of the whole-rock geochemistry of the K-bentonites from the basin and on zircon geochemistry of the K-bentonites from the entire Yangtze Platform has not been carried out. Therefore, the nature of the primary magmas, source and tectonic setting of the source volcanoes, and the episodes of source volcanic eruptions of the K-bentonites are unknown, which hinders unraveling the possible link between the sedimentary model of the Marinoan cap dolostone and the K-bentonites. Here, we perform a systematic study of the whole-rock and zircon geochemistry of the K-bentonites. The major and trace element concentrations of the K-bentonites and trace element contents in their volcanic zircons suggest that the primary magmas of the K-bentonites from the Jiuqunao and Heyu sections are different in nature. The same geochemical results indicate that the source volcanoes of all the K-bentonites may occur in the extensional setting on the northern margin of the Yangtze Block. Hf isotopic compositions of the volcanic zircons in the K-bentonites imply that the source magmas of the K-bentonites are mainly mantle-derived, and may have mixed with the crustal materials from the northern margin of the Yangtze Block. Based on the difference in whole-rock and zircon geochemistry of the K-bentonites from Heyu and Jiuqunao, two episodes of the source volcanic eruptions of the K-bentonites could be identified. The K-bentonite at Heyu most probably represents the record of the old episode, while that at Jiuqunao represents the record of the young one. The here proposed dual episodic deposition of K-bentonites within the Doushantuo cap carbonates holds potential significance to constrain 1) the duration of the cap carbonate deposition and 2) their genesis in potential slushball or snowball Earth environments.

制约塔里木克拉通下寒武统的精确锆石U-Pb年龄稀少,最近笔者于库鲁克塔格北区下寒武统西山布拉克组底部硅质岩中发现一层10～20 cm厚的凝灰岩夹层,对其锆石斑晶进行LA-ICP-MS U-Pb测年,结果显示该凝灰岩的就位年龄为520.3±2.9 Ma(MSWD=0.11).首次获得塔里木克拉通下寒武统精确锆石U-Pb年龄数据,构建了该区下寒武统以精确锆石U-Pb年龄为基础的时间框架雏形.参考华南下寒武统黑色岩系沉积速率,库鲁克塔格北区且干布拉克达坂剖面下寒武统西山布拉克组可能于532.1±2.9 Ma开始沉积;结合区域地层对比,受西大山运动影响库鲁克塔格北区埃迪卡拉系—寒武系可能存在约50 Ma的沉积间断.

洞穴分布特征及地貌演化研究是洞穴科普活动及洞穴旅游开发与管理的重要支撑.为进一步了解九洞天景区洞穴系统大型串珠式天窗群的分布特征及规律,对溶洞的规模、形态、发育方向及分布高程进行实地考察.将地理学"将今论古"的思想与地理信息系统工具相结合,探讨九洞天洞穴系统的空间展布特征及其地貌演化过程.结果表明:九洞天洞穴系统发育地层以二叠系茅口组地层为主,发育受断层节理和水文条件控制,溶洞发育方向多为北北东、北西和东南方向,与区域构造线基本一致;受第四纪间歇性抬升运动和侵蚀基准面控制的影响,洞穴系统垂向分布大致集中在1150～1220 m、1220～1270 m、1270～1340 m三个海拔范围内,与区内古河道垂向分布具有相似性;九洞天洞穴系统和地貌演化经历油菜河伏流及底纳寨干谷形成期、梯子崖伏流及张家寨干谷形成期、九洞天伏流和大天桥干谷形成期三次大的发育阶段,形成九洞天景区天窗溶洞、明暗流和古河道并存的典型喀斯特格局.

老挝北部仙诺地区大地构造位置为难河-程逸-沙缴缝合带西侧的景洪-素可泰火山弧带,在该区中三叠世晚期南团组底部发现有一套火山岩组合,通过1∶200剖面测量,在凝灰岩中采集样品进行主量元素、微量元素、稀土元素分析,以及锆石U-Pb定年.SiO2含量为56.13％～74.58％,Al2O3含量为13.9％～25.38％,MgO含量为0.43％～0.86％,Na2O+K2O含量为4.73％～5.74％,属中-酸性系列火山岩(英安质凝灰岩),反映出该火山岩具高铝低镁,典型的碱性-钙碱性岩系列特征.U-Pb测年为(215±1.4) Ma,属晚三叠世诺利期产物,为缅泰马地块与兰坪-思茅地块碰撞时间的确定提供了依据,同时探讨了形成的构造背景.

提通过对且干布拉克地区西山布拉克组泥质岩岩石学、地球化学特征的研究，探讨其物源特征、风化作用以及沉积盆地的构造环境。且干布拉克大坂剖面泥质岩Al2O3/TiO2、Th/Sc、（Gd/Yb）N、(Eu/Eu*)N、ICV、CIA均值分别为24、0.9、1.1、0.6、1.2、70，莫合尔山剖面泥质岩Al2O3/TiO2、Th/Sc、（Gd/Yb）N、(Eu/Eu*)N、ICV、CIA均值分别为10.5、0.2、3.5、1.01、2.8、75。这些特征表明，研究区泥质岩为第一次沉积的沉积物，源区母岩主要以岩浆岩为主。且干布拉克大坂剖面泥质岩的源区母岩主要以南部的花岗岩等长英质岩浆岩为主，沉积于陆内较稳定的构造环境；莫合尔山剖面泥质岩的源区母岩主要以北部玄武岩等中基性岩浆岩为主，沉积于陆内火山岩隆起的构造环境。在诺丁尼亚超大陆裂解的大构造背景下，早寒武世早期莫合尔山的裂解作用比且干布拉克大坂更为强烈。CIA值表明且干布拉克地区泥质岩物源区母岩经历了中等程度的化学风化作用，沉积物沉积时气候较温暖、湿润，早寒武世早期位于30°S左右的低纬度地区。且干布拉克大坂剖面的含钒炭质硅质页岩、莫合尔山剖面的铁质磷质岩的元素地球化学特征暗示了磷、钒等成矿元素与可能来自于震旦纪和寒武纪的中基性火山岩。

The Kuluketage block is the best area for Precambrian geology in north western China, because it contains the most complete Precambrian lithology units. Thus, the study of this ancient basement can improve the understanding of the Precambrian evolution of the Tarim Craton. In this study, we report LA-ICPMS zircon U-Pb ages and Hf isotopes of detrital zircons from a magnetite quartzite from the Shayiti Formation of the Xingditage Group. The 65 zircon ages and Hf isotopes obtained are used not only to constrain the maximum depositional ages of the Shayiti Formation but also to obtain the information about the evolution of regional tectonic-magmatic activities in the Paleoproterozoic of the Kuluketage block. According to the youngest concord Pb-207/Pb-206 zircon age of 1851 +/- 36 Ma in magnetite quartzites and the 1.47 Ga of the diabase sills which intrude into the Shayiti Formation, the most probable depositional age of the Shayiti Formation is between 1.47 Ga and 1.85 Ga. The detrital zircon dates are mainly clustered at 1806 Ma to 1889 Ma, 1898 Ma to 1981 Ma, and 1988 Ma to 2054 Ma, with the most prominent age peak appearing at around 1900 Ma and the subordinate peak age at around 1960 Ma. The magmatic features of Cathodoluminescence (CL) images indicate that two large magmatic tectonic-magmatic activities occurred in this district. The metamorphic rims of magmatic zircons and some baddeleyites also show regional metamorphism in the Paleoproterozoic, which may be related to the amalgamation of the Columbia supercontinent. We obtained two sets of concordant U-Pb ages older than 2.5 Ga, and several sets of two-stage Hf model ages older than 3.0 Ga. Combined with previous data in the literature, we suggest that Meso- to Neo-Archean basement rocks existed in the Kuluketage block, but were strongly reformed by tectonics, magmatism, and metamorphism in the Paleoproterozoic.

通过对西山布拉克组第一岩性段硅质岩岩石学、地球化学特征研究，探讨其沉积环境和成因，推测其与库鲁克塔格早古生代地壳演化关系。研究区硅质岩夹泥质硅岩、流纹质晶屑凝灰岩的岩石组合，硅质岩的Al/（Al+Fe）值（~0.6）、Ce/Ce*值（~0.57）、（La/Yb）n值（~0.66）等特征指示为欠补偿、缺氧的深水盆地沉积环境。其Fe/Ti值（~29.2），Al/（Al+Fe+Mn）值（~0.54），（Fe+Mn）/Ti值（~31.3），富集Ag，As，Sb，Ba元素等特征，表明该区硅质岩为热水和海水混合成因，形成过程中海水有较高的生产力。硅质岩∑REE在剖面底部为14.9×10-6，向上减小为8.6×10-6，至顶部增加到105.6×10-6，表明剖面底部到顶部热水活动强度呈减弱趋势。早寒武世硅质岩岩石学、地球化学特征表明，硅质岩形成于裂陷槽盆地中，是上升洋流将海底热水物质带至沉积地点与海水发生不同程度混合的产物，为库鲁克塔格早寒武世早期处于拉张裂解环境提供了岩石学和地球化学证据。

顶苏地区晒瓦组以灰色、深灰色薄—中厚层泥质岩屑粉砂岩为主,基本层序由细砂岩—粉砂岩—粘土岩组成,向上粒径变细,层理变薄.在顶苏—小革么—带晒瓦组底发育砾岩层,为晚二叠世沿中二叠统侵蚀面上发育的一套河流相碎屑岩沉积.砾岩层之下灰岩中产牙形石Neogondolella granti Barskov et koroleva,同时根据晒瓦组假整合于峨眉山玄武岩之上,因此晒瓦组为晚二叠世产物.

本文对海马谷地区金矿进行调查,在贵州安龙海马谷发现北东向陡倾角断层控制金矿体,其围岩为二叠系茅口组生物灰岩,矿石为硅化灰岩角砾岩.根据本次调查及收集已有勘查研究成果,建立了该区的成矿模式,认为该区北东向陡倾角断层是下一步该区重要的找矿目标.

We report the petrology, whole-rock geochemistry, zircon LA-ICP-MS U-Pb chronology and zircon Hf isotopic data of Daxigou granitoids (western part of the Kuluketage Block, NW China) to evaluate their likely petrogenesis and tectonic setting. Zircons from syenogranite can be divided into two groups: 1) those that display oscillatory zoning and high Th/U ratios (average = 1.38), implying their magmatic origin and 2) those that exhibit weak zoning and extremely high U and Pb contents but low Th/U ratios (average = 0.35), resembling zircons that experienced hydrothermal alteration. The zircon LA-ICP-MS U-Pb dating of the two groups of zircons yielded weighted mean ages of 1830 +/- 12 Ma (MSWD = 0.78) and 1798 +/- 21 Ma (MSWD = 1.6) respectively.The Daxigou granitoids belong mostly to normal-K and sodium-rich metaluminous calc-alkaline type, systematically enriched in LREE and large ion lithophile elements (LILE, e.g., K, Ba and Rb), but significantly depleted in high field strength elements (HFSE, e.g., Ti, P, Nb, Ta and U). Their epsilon Hf(t) values and two-stage Hf model ages range from -7.16 to -5.03 and 2.69 to 2.76 Ga, respectively. Taken together, it is suggested that Daxigou granitoids are of I-type affinity and that they were derived by partial melting of a Neoarchaean TTG (e.g., Tuoge Complex) rocks in a continental-arc environment. These new data, combined with previous regional geological studies, demonstrate that a series of Palaeoproterozoic (c. 2.0-1.8 Ga) tectono-magmatic events occurred in Kuluketage Block during the assembly of Columbia.

主要针对岑巩注溪钒矿床矿体“多金属层”地质特征进行描述,结合岩矿石中钒、镍、钼、铀等多金属特征元素及地球化学分析,结果表明:“多金属层”形成于缺氧环境,物质主要来源于陆源碎屑.