Based on the measurement of faulted geomorphic surfaces,large trench logging and systematic chronostratigraphic sampling,we suggest that the total slip amount along the Baying segment of the north margin fault of Fans...Based on the measurement of faulted geomorphic surfaces,large trench logging and systematic chronostratigraphic sampling,we suggest that the total slip amount along the Baying segment of the north margin fault of Fanshan Basin since 90 ka B.P.is 34 m.Nine paleoseismic events occurred in the last 75 ka.Among them,the four events A,B,C,and D revealed by the large trench were dated at 28 ka,14 ka,7.5 ka,and 656 B.P.,respectiv eJy.The model for paleoearthquake recurrence along the segment may have two stages; in the stage from 90 ka to 14 ka B.P.,the "time-predictable model" is suitable,while in the stage from 14 ka B.P.to now,the "displacement-attenuation model" applies.展开更多
REE geochemistry data from the Fanshan alunite deposit indicated that its ore-forming materials came chiefly from the country rocks, with δCe>0 for alunite ores. According to the differences in δEu,the alunite or...REE geochemistry data from the Fanshan alunite deposit indicated that its ore-forming materials came chiefly from the country rocks, with δCe>0 for alunite ores. According to the differences in δEu,the alunite ores were divided into three types: weak negative Eu anomaly, weak positive Eu anomaly and remarkable positive Eu anomaly. The phenomena of Ce-enrichment in the ores indicated that the Fanshan alunite deposit was formed in an oxidizing environment. Variations in fO2 are corresponding to those in δEu: Eu anomaly varies from negative to positive with increasing fO2 . And two other important factors may impact the occurrence of Eu anomalies: the contents of alkaline feldspar and the protolith structure in the mineralization period.展开更多
Laser micro area analysis 40 Ar 39 Ar isochron dating for pure alunite is first reported. Micro area 40 Ar 39 Ar isochron dating results revealed that the metallogenetic epoch of Fanshan superlarge alunite deposit is ...Laser micro area analysis 40 Ar 39 Ar isochron dating for pure alunite is first reported. Micro area 40 Ar 39 Ar isochron dating results revealed that the metallogenetic epoch of Fanshan superlarge alunite deposit is 74.50 Ma, and this age is 10-20 Ma later than that of regional volcanic activity. Moreover, the potential application of micro area analysis 40 Ar 39 Ar isochron dating method in metallogenetic epoch studies for nonmetal deposits is also discussed.展开更多
文摘Based on the measurement of faulted geomorphic surfaces,large trench logging and systematic chronostratigraphic sampling,we suggest that the total slip amount along the Baying segment of the north margin fault of Fanshan Basin since 90 ka B.P.is 34 m.Nine paleoseismic events occurred in the last 75 ka.Among them,the four events A,B,C,and D revealed by the large trench were dated at 28 ka,14 ka,7.5 ka,and 656 B.P.,respectiv eJy.The model for paleoearthquake recurrence along the segment may have two stages; in the stage from 90 ka to 14 ka B.P.,the "time-predictable model" is suitable,while in the stage from 14 ka B.P.to now,the "displacement-attenuation model" applies.
基金This research project was financially supported jointly by the Key Research Project (No. KZCX3-SW-125) of CAS and the National Natural Science Foundation of China (No. 40172037).
文摘REE geochemistry data from the Fanshan alunite deposit indicated that its ore-forming materials came chiefly from the country rocks, with δCe>0 for alunite ores. According to the differences in δEu,the alunite ores were divided into three types: weak negative Eu anomaly, weak positive Eu anomaly and remarkable positive Eu anomaly. The phenomena of Ce-enrichment in the ores indicated that the Fanshan alunite deposit was formed in an oxidizing environment. Variations in fO2 are corresponding to those in δEu: Eu anomaly varies from negative to positive with increasing fO2 . And two other important factors may impact the occurrence of Eu anomalies: the contents of alkaline feldspar and the protolith structure in the mineralization period.
文摘Laser micro area analysis 40 Ar 39 Ar isochron dating for pure alunite is first reported. Micro area 40 Ar 39 Ar isochron dating results revealed that the metallogenetic epoch of Fanshan superlarge alunite deposit is 74.50 Ma, and this age is 10-20 Ma later than that of regional volcanic activity. Moreover, the potential application of micro area analysis 40 Ar 39 Ar isochron dating method in metallogenetic epoch studies for nonmetal deposits is also discussed.
