The western Hunan-eastern Guizhou Zn-Pb metallogenic belt is one of the important Zn-Pb mineralization regions in China.The Dadongla deposit,located in the northeast of Guizhou Province,is one of the typical Zn-Pb dep...The western Hunan-eastern Guizhou Zn-Pb metallogenic belt is one of the important Zn-Pb mineralization regions in China.The Dadongla deposit,located in the northeast of Guizhou Province,is one of the typical Zn-Pb deposits in the region and has estimated resources more than 12 million metric tons(Mt)with an average grade of 4.11 wt%Zn+Pb.Its orebodies are hosted in the lower Cambrian Aoxi Formation dolomite,occurring as bedded,para-bedded in shape,and in conformity with the wall rock.The ore mineral assemblage is simple,dominated by sphalerite with minor pyrite and galena,and the gangue minerals are composed of dolomite,calcite with minor bitumen and barite.In view of the lack of geological and geochemical researches,the genesis of Zn-Pb ore is still unclear.Laser ablation-inductively coupled plasma mass spectrometry(LA-ICPMS)spot and mapping analyses were used to obtain sphalerite trace element chemistry in the Dadongla Zn-Pb deposit in Guizhou,China,aiming to constrain its ore genesis.The results show that sphalerite is characterized by the enrichment of Cd,Fe,Ge and Hg,corresponding with that of typical MVT deposits.Four zones were identified in the sphalerite crystal from Dadongla from the center to margin according to the color bands.in which the zone in the center,representing the early ore-stage sphalerite,is characterized by enrichment of Cd relatively,while the zone forming at late ore-stage is enriched in Ge and Hg relatively.The finding was controlled by differential leached metals content in ore-forming fluid from its source rock.Notably,critical element Ge trends to be enriched at the late ore-stage and follows a substitution of 2 Zn^2+(?)Ge^4++□(vacancy).Moreover,the calculated ore-forming temperature ranges from 79.9℃to 177.6℃by the empirical formula,which is similar to that of typical Mississippi Valley-type(MVT)deposits.Compared with the features of trace elements in sphalerite from different types of deposits,together with the geology,the Dadongla deposit belongs to an MVT Zn-Pb deposit.展开更多
Due to the decreasing resources of both inshore and offshore fisheries, many organizations have released fry to enhance their stock in recent years. The discrimination between wild and hatchery-reared individuals must...Due to the decreasing resources of both inshore and offshore fisheries, many organizations have released fry to enhance their stock in recent years. The discrimination between wild and hatchery-reared individuals must be performed to assess the efficiency of the release. Fresh groundwater is generally used by hatchers in southwesternTaiwanto decrease salinity and to promote the growth of larvae prior to feeding;thus, the elemental composition of the otolith may be different in stocks, and this difference may be used for identification. This study used Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICPMS) to analyze the trace elements in the nuclei of otoliths from black porgy Acanthopagrus schlegelii, including six hatchery reared specimens from the Tainan County, three recaptured marked and ten captured unmarked specimens from the Miaoli County in Northwestern coast of Taiwan. Among the six hatchery and three recaptured marked specimens, which ranged from 4.9 to23.4 cmin body length, the nucleus zone (relative to within5 cmin size growth) of the otoliths showed higher magnesium concentrations than that observed on both edges. The distribution was similar to an inverse “V” shape. The otoliths also showed lower manganese concentrations near the nucleus and had higher values near the edges, resulting in a distribution similar to a “U” shape. According to the appeared shape of Mg2+/Ca2+ and Mn2+/Ca2+ ratio in the central area of the nucleus zone, this study determined six specimens which were from hatchery reared and three specimens were from wild among ten unmarked specimens captured from the Northwestern coast of Taiwan. Under the conditions used in this study, the absorption of calcium into the otolith was active and required energy in the seawater and freshwater, while the incorporation of magnesium and manganese was passive and was primarily affected by diffusion.展开更多
基金supported by the National Natural Science Foundation of China(41673056 and U1812402)the Key Program of Guizhou Natural Science Foundation(Qiankehejichu[2017]1421)+1 种基金the State Key Program of National Natural Science Foundation of China(41430315)National Key R&D Program of China(2017YFC0602500)。
文摘The western Hunan-eastern Guizhou Zn-Pb metallogenic belt is one of the important Zn-Pb mineralization regions in China.The Dadongla deposit,located in the northeast of Guizhou Province,is one of the typical Zn-Pb deposits in the region and has estimated resources more than 12 million metric tons(Mt)with an average grade of 4.11 wt%Zn+Pb.Its orebodies are hosted in the lower Cambrian Aoxi Formation dolomite,occurring as bedded,para-bedded in shape,and in conformity with the wall rock.The ore mineral assemblage is simple,dominated by sphalerite with minor pyrite and galena,and the gangue minerals are composed of dolomite,calcite with minor bitumen and barite.In view of the lack of geological and geochemical researches,the genesis of Zn-Pb ore is still unclear.Laser ablation-inductively coupled plasma mass spectrometry(LA-ICPMS)spot and mapping analyses were used to obtain sphalerite trace element chemistry in the Dadongla Zn-Pb deposit in Guizhou,China,aiming to constrain its ore genesis.The results show that sphalerite is characterized by the enrichment of Cd,Fe,Ge and Hg,corresponding with that of typical MVT deposits.Four zones were identified in the sphalerite crystal from Dadongla from the center to margin according to the color bands.in which the zone in the center,representing the early ore-stage sphalerite,is characterized by enrichment of Cd relatively,while the zone forming at late ore-stage is enriched in Ge and Hg relatively.The finding was controlled by differential leached metals content in ore-forming fluid from its source rock.Notably,critical element Ge trends to be enriched at the late ore-stage and follows a substitution of 2 Zn^2+(?)Ge^4++□(vacancy).Moreover,the calculated ore-forming temperature ranges from 79.9℃to 177.6℃by the empirical formula,which is similar to that of typical Mississippi Valley-type(MVT)deposits.Compared with the features of trace elements in sphalerite from different types of deposits,together with the geology,the Dadongla deposit belongs to an MVT Zn-Pb deposit.
文摘Due to the decreasing resources of both inshore and offshore fisheries, many organizations have released fry to enhance their stock in recent years. The discrimination between wild and hatchery-reared individuals must be performed to assess the efficiency of the release. Fresh groundwater is generally used by hatchers in southwesternTaiwanto decrease salinity and to promote the growth of larvae prior to feeding;thus, the elemental composition of the otolith may be different in stocks, and this difference may be used for identification. This study used Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICPMS) to analyze the trace elements in the nuclei of otoliths from black porgy Acanthopagrus schlegelii, including six hatchery reared specimens from the Tainan County, three recaptured marked and ten captured unmarked specimens from the Miaoli County in Northwestern coast of Taiwan. Among the six hatchery and three recaptured marked specimens, which ranged from 4.9 to23.4 cmin body length, the nucleus zone (relative to within5 cmin size growth) of the otoliths showed higher magnesium concentrations than that observed on both edges. The distribution was similar to an inverse “V” shape. The otoliths also showed lower manganese concentrations near the nucleus and had higher values near the edges, resulting in a distribution similar to a “U” shape. According to the appeared shape of Mg2+/Ca2+ and Mn2+/Ca2+ ratio in the central area of the nucleus zone, this study determined six specimens which were from hatchery reared and three specimens were from wild among ten unmarked specimens captured from the Northwestern coast of Taiwan. Under the conditions used in this study, the absorption of calcium into the otolith was active and required energy in the seawater and freshwater, while the incorporation of magnesium and manganese was passive and was primarily affected by diffusion.
