Integrated fission track and (U-Th)/He analysis is carried out on 6 apatite and 6 zircon samples from a near vertical section in The Tiantangzhai region at the core of the present Dabieshan orogen. The result shows th...Integrated fission track and (U-Th)/He analysis is carried out on 6 apatite and 6 zircon samples from a near vertical section in The Tiantangzhai region at the core of the present Dabieshan orogen. The result shows that the region experienced cooling/exhumation during the Late Cretaceous and Early Tertiary period. Age-elevation relationships for different dating systems and different minerals suggest a pulse of rapid exhumation at ～110 Ma before present, preserved in the structurally highest samples. At lower elevations, ages begin to decrease with decreasing elevation, suggesting lower exhumation rates since 90 Ma. Two periods of different exhumation rates are identified since 90 Ma. The average apparent exhumation rate for the period of 43.4-22.5 is 0.062 km/Ma, whereas that for the period of 76.4-47.4 Ma is 0.039 km/Ma.展开更多
Emmenopterys henryi Oliv. is one of the rare,gymnosperms endemic of China.Its distribution,habitat and community structure in Tiantangzhai of Anhui Province were investigated.The results showed that E.henryi populatio...Emmenopterys henryi Oliv. is one of the rare,gymnosperms endemic of China.Its distribution,habitat and community structure in Tiantangzhai of Anhui Province were investigated.The results showed that E.henryi population is a declining one because of its incomplete age structure.The lower richness,diversity and evenness of the community resulted in a tendency of degeneration,hence,protection for this species must be undertaken.展开更多
基金This work was supposed by the Ministry of Sci—ence and Technology of China(Grant No.G19990646).
文摘Integrated fission track and (U-Th)/He analysis is carried out on 6 apatite and 6 zircon samples from a near vertical section in The Tiantangzhai region at the core of the present Dabieshan orogen. The result shows that the region experienced cooling/exhumation during the Late Cretaceous and Early Tertiary period. Age-elevation relationships for different dating systems and different minerals suggest a pulse of rapid exhumation at ～110 Ma before present, preserved in the structurally highest samples. At lower elevations, ages begin to decrease with decreasing elevation, suggesting lower exhumation rates since 90 Ma. Two periods of different exhumation rates are identified since 90 Ma. The average apparent exhumation rate for the period of 43.4-22.5 is 0.062 km/Ma, whereas that for the period of 76.4-47.4 Ma is 0.039 km/Ma.
文摘Emmenopterys henryi Oliv. is one of the rare,gymnosperms endemic of China.Its distribution,habitat and community structure in Tiantangzhai of Anhui Province were investigated.The results showed that E.henryi population is a declining one because of its incomplete age structure.The lower richness,diversity and evenness of the community resulted in a tendency of degeneration,hence,protection for this species must be undertaken.
