Power-law patterns appear in a variety of natural systems on the modern Earth;nevertheless,whether such behaviors appeared in the deep-time environment has rarely been studied. Isotopic records in sedimentary rocks, w...Power-law patterns appear in a variety of natural systems on the modern Earth;nevertheless,whether such behaviors appeared in the deep-time environment has rarely been studied. Isotopic records in sedimentary rocks, which are widely used to reconstruct the geological/geochemical conditions in paleoenvironments and the evolutionary trajectories of biogeochemical cycles, offer an opportunity to investigate power laws in ancient geological systems. In this study, I focus on the Phanerozoic sedimentary records of carbon, oxygen, sulfur, and strontium isotopes, which have well documented and extraordinarily comprehensive datasets. I perform statistical analyses on these datasets and show that the variations in the sedimentary records of the four isotopes exhibit power-law behaviors. The exponents of these power laws range between 2.2 and 2.9;this narrow interval indicates that the variations in carbon, oxygen, sulfur, and strontium isotopes likely belong to the same universality class, suggesting that these systematic power-law patterns are governed by universal, scale-free mechanisms. I then derive a general form for these power laws from a minimalistic model based on basic physical principles and geosystem-specific assumptions, which provides an interpretation for the power-law patterns from the perspective of thermodynamics. The fundamental mechanisms regulating such patterns might have been ubiquitous in paleoenvironments, implying that similar power-law behaviors may exist in the sedimentary records of other isotopes.展开更多
While it is critical to accurately understand the sources and transformation of sulfate based on time-series analysis, there are limited studies on temporal variation of sulfate in rivers and on rock weathering by sul...While it is critical to accurately understand the sources and transformation of sulfate based on time-series analysis, there are limited studies on temporal variation of sulfate in rivers and on rock weathering by sulfuric acids.We conducted a monthly sampling campaign in the Beipan, Nanpan, and Hongshui Rivers over the course of one hydrological year. This study examined seasonal variations in riverine sulfate impacted by the monsoon climate in the upper reaches of the Xijiang River basin. In general, the SO_4^(2-) contents in these rivers dropped from relatively high levels to low values during the high-flow season, in response to increasing discharge. The sulfate was generally enriched in heavy isotopes during the low-flow season compared to the high-flow season. The calculated results indicate that the riverine sulfate was mainly derived from sulfide oxidation, but that evaporite dissolution could be an important source during the low-flow season, based on isotopic evidence. Mine drainage is likely an important source of sulfate to these rivers during the high-flow season due to contributions from fast surface flow, which responds to frequent heavy rain in monsoonal climate regions. Arelatively high proportion of HCO_3^- was found to be derived from rock weathering by sulfuric acid during the high-flow season when compared to that observed during the low-flow season. The results suggest that approximately one quarter of the HCO_3^- in the Hongshui River originated from carbonate weathering by sulfuric acid derived from the oxidation of sulfide. Such information on the specific dual isotopic characteristics of riverine sulfate throughout a hydrological year can provide unique evidence for understanding the temporal variability of sulfate concentrations and weathering processes in rivers.展开更多
Mercury mines in Guizhou province are the main base of mercury production and the most important resource base in China.The San-Dan mercury belt in Guizhou province contains a series of important mercury deposits.Howe...Mercury mines in Guizhou province are the main base of mercury production and the most important resource base in China.The San-Dan mercury belt in Guizhou province contains a series of important mercury deposits.However,the source of metallogenic materials and the properties of metallogenic fluid of these mercury deposits have long been a controversial issue.In this study,we used cathode luminescence techniques to distinguish different stages of dolomite and calcite,laser ablation inductively coupled plasma mass spectrometry to analyze the trace elements,and stable isotope mass spectrometry techniques to analyze C-O isotopes compositions of dolomite and calcite in the Sixiangchang mercury deposit in San-Dan mercury belt.We also measured the sulfur isotope composition of cinnabar.Our study showed that dolomite can be divided into two stages,the lumpy dolomite associated with cinnabar in Dol 1 stage and dolomite vein in Dol 2 stage,which is associated with Cal 2 stage calcite vein.With the progress of mineralization,A1,As,Mo,Sb,and Sr elements were gradually enriched in the ore-forming fluid.The rare earth element(REE)partition curve of Dol 1 stage dolomite showed a trend of light REE enrichment.Cal 2 stage calcite and Dol 2 stage dolomite exhibited a flat-type REE partition curve,and Dol 2 stage dolomite showed a strong negative anomaly for Eu.δ^13C of carbonate mineral variation ranges from-6.89 to-2.16‰,whileδ^18O variation ranges from 13.80 to 23.09‰,and theδ34S variation range of cinnabar is 16.51-24.28‰.Carbonate mineral trace elements and C-O isotopes compositions suggested that early ore-forming fluid was reduced,and late ore-forming fluid was oxidized.The oreforming fluid of the Sixiangchang mercury deposit is a mixture of deep crustal fluid and meteoric water in deep thermal circulation,and involved in the oxidation of organic matter.The cinnabarδ^34S results showed that sulfur mainly came from seawater sulfate with the participation of microbial reduction.Sulfur is sedimentary in origin and was derived mainly from the host-rock strata.展开更多
文摘Power-law patterns appear in a variety of natural systems on the modern Earth;nevertheless,whether such behaviors appeared in the deep-time environment has rarely been studied. Isotopic records in sedimentary rocks, which are widely used to reconstruct the geological/geochemical conditions in paleoenvironments and the evolutionary trajectories of biogeochemical cycles, offer an opportunity to investigate power laws in ancient geological systems. In this study, I focus on the Phanerozoic sedimentary records of carbon, oxygen, sulfur, and strontium isotopes, which have well documented and extraordinarily comprehensive datasets. I perform statistical analyses on these datasets and show that the variations in the sedimentary records of the four isotopes exhibit power-law behaviors. The exponents of these power laws range between 2.2 and 2.9;this narrow interval indicates that the variations in carbon, oxygen, sulfur, and strontium isotopes likely belong to the same universality class, suggesting that these systematic power-law patterns are governed by universal, scale-free mechanisms. I then derive a general form for these power laws from a minimalistic model based on basic physical principles and geosystem-specific assumptions, which provides an interpretation for the power-law patterns from the perspective of thermodynamics. The fundamental mechanisms regulating such patterns might have been ubiquitous in paleoenvironments, implying that similar power-law behaviors may exist in the sedimentary records of other isotopes.
基金financially supported by the Ministry of Science and Technology of China through Grant Nos.2016YFA0601000 and 2013CB956700National Natural Science Foundation of China(Grant Nos.41422303,41130536 and 41625006)
文摘While it is critical to accurately understand the sources and transformation of sulfate based on time-series analysis, there are limited studies on temporal variation of sulfate in rivers and on rock weathering by sulfuric acids.We conducted a monthly sampling campaign in the Beipan, Nanpan, and Hongshui Rivers over the course of one hydrological year. This study examined seasonal variations in riverine sulfate impacted by the monsoon climate in the upper reaches of the Xijiang River basin. In general, the SO_4^(2-) contents in these rivers dropped from relatively high levels to low values during the high-flow season, in response to increasing discharge. The sulfate was generally enriched in heavy isotopes during the low-flow season compared to the high-flow season. The calculated results indicate that the riverine sulfate was mainly derived from sulfide oxidation, but that evaporite dissolution could be an important source during the low-flow season, based on isotopic evidence. Mine drainage is likely an important source of sulfate to these rivers during the high-flow season due to contributions from fast surface flow, which responds to frequent heavy rain in monsoonal climate regions. Arelatively high proportion of HCO_3^- was found to be derived from rock weathering by sulfuric acid during the high-flow season when compared to that observed during the low-flow season. The results suggest that approximately one quarter of the HCO_3^- in the Hongshui River originated from carbonate weathering by sulfuric acid derived from the oxidation of sulfide. Such information on the specific dual isotopic characteristics of riverine sulfate throughout a hydrological year can provide unique evidence for understanding the temporal variability of sulfate concentrations and weathering processes in rivers.
基金funded by the National 973 Program of China (2014CB440906)the key project of the National Natural Science Foundation of China (41230316)
文摘Mercury mines in Guizhou province are the main base of mercury production and the most important resource base in China.The San-Dan mercury belt in Guizhou province contains a series of important mercury deposits.However,the source of metallogenic materials and the properties of metallogenic fluid of these mercury deposits have long been a controversial issue.In this study,we used cathode luminescence techniques to distinguish different stages of dolomite and calcite,laser ablation inductively coupled plasma mass spectrometry to analyze the trace elements,and stable isotope mass spectrometry techniques to analyze C-O isotopes compositions of dolomite and calcite in the Sixiangchang mercury deposit in San-Dan mercury belt.We also measured the sulfur isotope composition of cinnabar.Our study showed that dolomite can be divided into two stages,the lumpy dolomite associated with cinnabar in Dol 1 stage and dolomite vein in Dol 2 stage,which is associated with Cal 2 stage calcite vein.With the progress of mineralization,A1,As,Mo,Sb,and Sr elements were gradually enriched in the ore-forming fluid.The rare earth element(REE)partition curve of Dol 1 stage dolomite showed a trend of light REE enrichment.Cal 2 stage calcite and Dol 2 stage dolomite exhibited a flat-type REE partition curve,and Dol 2 stage dolomite showed a strong negative anomaly for Eu.δ^13C of carbonate mineral variation ranges from-6.89 to-2.16‰,whileδ^18O variation ranges from 13.80 to 23.09‰,and theδ34S variation range of cinnabar is 16.51-24.28‰.Carbonate mineral trace elements and C-O isotopes compositions suggested that early ore-forming fluid was reduced,and late ore-forming fluid was oxidized.The oreforming fluid of the Sixiangchang mercury deposit is a mixture of deep crustal fluid and meteoric water in deep thermal circulation,and involved in the oxidation of organic matter.The cinnabarδ^34S results showed that sulfur mainly came from seawater sulfate with the participation of microbial reduction.Sulfur is sedimentary in origin and was derived mainly from the host-rock strata.
