50 research outputs found
Deciphering the origin of the Cenozoic intracontinental rifting and volcanism in eastern China using integrated evidence from the Jianghan Basin
Intracontinental rifting and low-volume volcanism are a globally common phenomenon, yet the underlying driving mechanisms and whether they can be explained through classic plate tectonic concepts, remain hotly debated. A prominent example is the Cenozoic rift and volcanic province in eastern China. Using an integration of geological, geophysical and geochemical data, we unravel the spatial and temporal variations of the rifting and volcanism in the Jianghan Basin. Both rifting and volcanism in the Jianghan Basin show two intense-to-weak cycles (65ā50 Ma and 50ā26 Ma, respectively) with significant enhancement in activity during the late rift phase. Moreover, rifting and depocentres progressively migrated eastward. The Jianghan basalts all share an asthenospheric origin while the source of the late phase basalts is slightly more enriched and heterogenous in Nd-Hf isotopes than that of the early phase basalts. The late phase basalts also display a smaller extent of partial melting even under a thinner lithosphere, likely indicating a significant decrease of volatile content in the mantle source. Based on regional tectonic correlations, the main stages of tectonic evolution of the Jianghan Basin and eastern China are not synchronous with changes in Pacific plate motion, while they are coincident with India-Asia collision processes. These observations lead us to propose that the asthenospheric flow driven by India-Asia collision rather than the rollback of the subducted Pacific slab has caused the widespread rifting and volcanism in eastern China. The variations of rifting and volcanism in the Jianghan Basin suggest a multiphase and eastward asthenospheric flow beneath eastern China driven by India-Asia collision, with an intense upwelling when passing through the North-South Gravity Lineament (NSGL). The much more intense rifting and volcanism during the late rift phase may indicate a much larger scale of volatile-poor asthenospheric flow than the early rift phase which could result in a more intense erosion of ancient enriched lithospheric mantle and the volatile content in the mantle source dropping sharply. This study provides an improved model based on our multidisciplinary observations for asthenospheric flow which may be an alternative driving mechanism for intracontinental rifting and low-volume volcanism in the regions where there are step changes in lithospheric thickness globally
CRESt ā Copilot for Real-world Experimental Scientist
Autonomous laboratories were previously controlled mainly by scripting languages such as Python, limiting their usage among experimentalists. The recent release of OpenAI\u27s ChatGPT API\u27s function calling feature has enabled seamless integration and execution of Python subroutines in experimental workflows using voice commands. We have developed a system of Copilot for Real-world Experimental Scientist (CRESt) system, with a demonstration shown on YouTube. Large language models (LLMs) empower all research group members, regardless of coding experience, to leverage the robotic platform for their own projects, simply by talking with CRESt
Age and Tectonic Setting of Layered LeadāZinc Ore Bodies in the Xiaohongshilazi Deposit: Constraints from Geochronology and Geochemistry of the Volcanic Rocks in Central Jilin Province, NE China
The newly discovered Xiaohongshilazi deposit located in Panshi City, central Jilin Province, NE China, is a medium-scale PbāZnā(Ag) deposit. The PbāZnā(Ag) orebodies are divided into layered and vein-type orebodies, which have different ore geneses. The layered PbāZn orebodies are mainly hosted within and spatially controlled by the volcanic rocks. To constrain the age and tectonic setting of the layered PbāZn mineralization, we completed laser-ablationāICPāMS zircon UāPb dating and whole-rock major and trace element analyses of the ore-bearing volcanic rocks. The dacite samples were confirmed as belonging to the Daheshen Formation and were the main ore-bearing volcanic rocks for the layered orebodies. They yielded concordia UāPb ages of 278.1 Ā± 1.8 Ma and 278.3 Ā± 1.8 Ma, respectively, indicating that the volcanic rocks from the Daheshen Formation and related layered PbāZn mineralization were formed in the early Permian. The andesite and rhyolite located above the layered orebodies yielded concordia UāPb ages of 225.0 Ā± 1.1 Ma, 225.3 Ā± 1.5 Ma, and 224.7 Ā± 1.2 Ma, respectively; these substances are considered to be of the Sihetun Formation and were first reported in the area. The dacite samples associated with layered PbāZn mineralization were high in SiO2 (62.54ā65.02 wt.%), enriched in LREEs and LILEs (e.g., Rb, Ba, and K), and showed depletion in HFSEs (e.g., P and Ti). It showed slightly negative Eu anomalies (Ī“Eu = 0.60ā0.65) and negative Nb anomalies, with Th/Nb (1.12ā1.21) and La/Nb (2.8ā4.7) ratios, presenting subduction-related arc magma affinity formed in an active continental margin setting. In agreement with previous studies on zircon Hf isotopes (ĪµHf (t) = +0.23~ +10.60) of the volcanic rocks from the Daheshen Formation, we infer that they were derived from the partial melting of the depleted lower crust. In conclusion, mineralization characteristics, geochronological data, geochemical features, and regional tectonic evolution suggest that two PbāZnā(Ag) mineralization stages from the Xiaohongshilazi deposit occurred: the layered VMS-type PbāZn mineralization associated with the marine volcanic rocks from the early Permian Daheshen Formation, which was induced by the subduction of the Paleo-Asian oceanic plate beneath the northern margin of the North China Craton, and the vein-type PbāZnā(Ag) mineralization caused by the subduction of the Paleo-Pacific Plate in the early Jurassic. Considering this, along with the mineralization characteristics of the same-type polymetallic deposits in this region, we propose that the early Permian marine volcanic rocks have great prospecting potential for the VMS-type PbāZn polymetallic deposits
Ore Genesis of the Toudaochuan Gold Deposit in Central Jilin Province, NE China: Constraints from Fluid Inclusions and C–H–O–S–Pb Isotopes
The Toudaochuan gold deposit is a recently discovered lode gold deposit in Central Jilin Province. Gold ore bodies are dominantly controlled by NE-trending fault. The major hydrothermal period can be further divided into the quartz–pyrite stage (stage I), quartz–gold–polymetallic sulfides stage (stage II, major gold mineralization stage), and quartz–carbonate stage (stage III). Primary fluid inclusions (FIs) identified in quartz at different hydrothermal stages include liquid-rich aqueous FIs (L-type), CO2 FIs (C-type, including CO2-bearing C1-type FIs and CO2-rich C2-type FIs), and minor vapor-rich aqueous FIs (V-type). Microthermometry studies on different fluid inclusions indicate that the original ore-forming fluids belonged to the CO2–H2O–NaCl system characterized by a moderate–low temperature and low salinity in stages I and II, and they finally evolved into a H2O–NaCl system characterized by low temperature and low salinity in stage III. Fluid immiscibility is considered to be the key ore-forming mechanism. The initial ore-forming fluid was originated from magmatic water and was mixed with meteoric water in the later stage. The S and Pb isotope data suggest that the ore metal materials were derived from the mixed source of mantle and crust. Based on all the above data, therefore, it can be proposed that the Toudaochuan gold deposit is a mesothermal magmatic–hydrothermal gold deposit
Preparation of Mn2O3-Co3O4 and its xylene removal by oxidation
Xylene is one of the main components of volatile organic compounds (VOCs), the catalytic oxidation of xylene has been studied. In this work, the manganese-cobalt mixed oxide catalysts for the xylene removal have been prepared by one step direct decomposition method with the aid of glucose. The physicochemical properties of the catalysts were characterized by TG, XRD, TEM, BET, TPR and XPS. The catalytic experiments results show that the Mn-Co catalysts are composite oxides composed of Mn2O3 and Co3O4. The Mn1Co1.4Ox catalyst with the molar ratio of Mn to Co of 1:1.4 has excellent oxidation removal performance of xylene. At the space velocity of 20000 mL (gĀ·h)ā1 and the concentration xylene of 500 ppm, the temperature of complete conversion of xylene is 210 Ā°C, which is related to the developed pore structure, high specific surface area, excellent reduction performance, abundant adsorbed oxygen species, coexistence and interaction of polyvalent species. The space structure and competitive adsorption of reactants make the oxidation performance of low polarity p-xylene better. The participation of water vapor reduced the catalytic performance of the reaction system by 12-19%, which is related to the ads-desorption of water molecules and the decomposition of active components
Ore Genesis of the Dongping Gold Deposit in the Northern Margin of North China Craton: Constraints from In-Situ Major, Trace Elemental Analysis of Magnetite and Pyrite
The Zhangxuan district in North China, also known as Northwestern Hebei āGolden Triangle,ā develops many intrusion-hosted lode-gold deposits. The Dongping gold deposit in the Zhangxuan district is well known for its unique hosting of rocks and ore mineral assemblages. Magnetite and pyrite are common minerals that widely exist in ores of the Dongping deposit. To get a better understanding of the evolution of the ore-forming fluids responsible for mineralization, we report on an integrated study on the electron microprobe analysis (EMPA) and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) analysis of magnetite and pyrite from the deposit. The major results are as follows: The magnetite grains from the Dongping deposit show a variable content of major and trace elements such as Ti, Al, Si, Fe, Mn, Cr, Na, V, and Co, and the majority of the magnetite contain low Ti contents, revealing potential properties of hydrothermal magnetite. The flat time-resolved signals of LA-ICP-MS imply that the majority of trace elements in magnetite exist in the form of isomorphism, except for some incompatible trace elements. Magnetites from the Dongping deposit have compositional characteristics of hydrothermal origins, and the genetic discriminant diagrams of TiāV, TiāNi/Cr or (Ca + Al + Mn)ā(Ti + V) show that they may be originated from magma differentiated hydrothermal solutions. Co, Ni in pyrite from Dongping mainly enter the lattice via isomorphism, and Cu, Zn, Ag, W, Sn, Au, Pb, and Bi are partitioned into pyrite as micro/nano- mineral inclusions. The Co, Ni content, and the Ni/Co ratios, indicated that the temperature of the ore-forming fluids has decreased from Py-1 to Py-2, and the enrichment of Au in Py-2 may be related to the cooling and boiling of the fluids
Petrogenesis and Tectonic Implication of the Hongtaiping High-Mg Diorite in the Wangqing Area, NE China: Constraints from Geochronology, Geochemistry and Hf Isotopes
This study presents new data from zircon UāPb dating and Hf isotope analysis, as well as whole-rock major- and trace-element compositions of the Hongtaiping high-Mg diorite in the Wangqing area of Yanbian, NE China. Laser ablation inductively coupled plasma mass spectrometry (LAāICPāMS) zircon UāPb dating gives an eruption age of ca. 267 Ma for the high-Mg diorite. These samples have MgO contents of 13.30% to 16.58% and high transition metal element concentrations, classified as sanukite. Their rare earth element (REE) contents range from 45.2 to 68.4 ppm and are characterized by slightly positive Eu anomalies (Eu/Eu* = 1.08ā1.17). They show enrichment in light REEs (LREEs) and depletion in heavy REEs (HREEs), with LREE/HREE ratios = 6.54ā6.97 and (La/Yb)N values = 7.24ā8.08. The Hongtaiping high-Mg diorite is enriched in Rb, U, K, and Sr, but depleted in Th, Nb, and Ta. High MgO contents, Mg# values, and transition metal element concentrations imply that the magma experienced insignificant crystallization fractionation and crustal contamination. Relatively homogenous positive Hf isotopic values indicate that the original magma was generated by the partial melting of a depleted mantle wedge that was metasomatized by subducting slab fluids. The magma was generated by the moderate degree partial melting (20%ā30%) of a garnet lherzolite source. Combined with previous studies, this shows that the high-Mg diorite was formed by the northward subduction of the Paleo-Asian oceanic plate during the Middle Permian
Ore Genesis of the Dongping Gold Deposit in the Northern Margin of North China Craton: Constraints from In-Situ Major, Trace Elemental Analysis of Magnetite and Pyrite
The Zhangxuan district in North China, also known as Northwestern Hebei “Golden Triangle,” develops many intrusion-hosted lode-gold deposits. The Dongping gold deposit in the Zhangxuan district is well known for its unique hosting of rocks and ore mineral assemblages. Magnetite and pyrite are common minerals that widely exist in ores of the Dongping deposit. To get a better understanding of the evolution of the ore-forming fluids responsible for mineralization, we report on an integrated study on the electron microprobe analysis (EMPA) and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) analysis of magnetite and pyrite from the deposit. The major results are as follows: The magnetite grains from the Dongping deposit show a variable content of major and trace elements such as Ti, Al, Si, Fe, Mn, Cr, Na, V, and Co, and the majority of the magnetite contain low Ti contents, revealing potential properties of hydrothermal magnetite. The flat time-resolved signals of LA-ICP-MS imply that the majority of trace elements in magnetite exist in the form of isomorphism, except for some incompatible trace elements. Magnetites from the Dongping deposit have compositional characteristics of hydrothermal origins, and the genetic discriminant diagrams of Ti–V, Ti–Ni/Cr or (Ca + Al + Mn)–(Ti + V) show that they may be originated from magma differentiated hydrothermal solutions. Co, Ni in pyrite from Dongping mainly enter the lattice via isomorphism, and Cu, Zn, Ag, W, Sn, Au, Pb, and Bi are partitioned into pyrite as micro/nano- mineral inclusions. The Co, Ni content, and the Ni/Co ratios, indicated that the temperature of the ore-forming fluids has decreased from Py-1 to Py-2, and the enrichment of Au in Py-2 may be related to the cooling and boiling of the fluids
Genesis of Metal Sulfides and Its Significance on Graphite Mineralization in the Huangyangshan Graphite Deposit, East Junggar, Xinjiang Province, China
The Huangyangshan super-large graphite deposit is located in the Qitai area of East Junggar in Xinjiang Province, China. This deposit is well known for its distinguishing properties, including the alkaline granite complex that hosts the graphite ore, the dominantly orbicular structure developed in the graphite ore, and the association of graphite with metal sulfides in the orbicular ore. This study aims to determine the genetic relationship between graphite and metal sulfides in order to better understand the graphite mineralization process of the Huangyangshan deposit. The methods applied in the study include X-ray micro-CT scanning and scanning electron microscopy (SEM) analyses of the orbicular graphite ore and in situ inductive laser ablation-coupled plasma mass spectrometry (LA-ICP-MS) trace element analyses of the pyrrhotite and chalcopyrite associated with the graphite. The analytical results show that the graphite ore is composed of crystalline graphite, K-feldspar, albite, quartz, biotite, amphibole, and metal sulfides. The metal sulfides in the orbicular ore include pyrite, pyrrhotite, pentlandite, and chalcopyrite. According to the color, crystalline shape, texture, and occurrence, pyrrhotite can be classified into four types (I, II, III, and IV), and chalcopyrite into two types (I and II), of which types I, II, and III pyrrhotite and type I chalcopyrite have a close genetic relationship with graphite. The granular types (I, II, and III) of pyrrhotite are enriched in Co, Ni, Se, Ge, and Te and are depleted in As, Sb, Ag, and Au; they also have a high value of Co/Ni, indicating that these types of pyrrhotite have a magmatic origin. Low values of Co/Ni suggest that type IV pyrrhotite has a hydrothermal origin. The similar contents of Co and Ni and the values of Co/Ni compared with the chalcopyrite from the magmatic CoāNi sulfide deposits imply that type I chalcopyrite has a magmatic origin. In summary, the metal sulfides of the Huangyangshan deposit are genetically related to graphite mineralization and formed predominantly by magmatic processes