This paper discusses the Cretaceous-Tertiary magnetic polarity sequence of the the Hengyang Basin on the basis of magnetostratigraphic study. The age of each stratigraphic unit has been determined with the magnetic po...This paper discusses the Cretaceous-Tertiary magnetic polarity sequence of the the Hengyang Basin on the basis of magnetostratigraphic study. The age of each stratigraphic unit has been determined with the magnetic polarity time scale combined with 39Ar/40Ar dating, thus providing evidence for determining the geological ages of different formations. The authors assign the age of the Dongjing Formation of the Hengyang Basin to Early Cretaceous, the Shenhuangshan Formation to Early-Late Cretaceous, the Daijiaping Formation to Late Cretaceous, and the Dongtang and Xialiushi formations to Palaeocene.展开更多
Since the coexistence of the Cretaceous and Palaeocene was ascertained in the Hengyang Basin of Hunan in the middle of the 1960's, the Cretaceous and Tertiary boundary has been discussed in several papers, but it ...Since the coexistence of the Cretaceous and Palaeocene was ascertained in the Hengyang Basin of Hunan in the middle of the 1960's, the Cretaceous and Tertiary boundary has been discussed in several papers, but it still remains controversal. The points at issue are the connotation, stratigraphical position and lateral correlation of the Dongtang (or Chejiang) Formation.展开更多
[Objective] The study aimed to assess the vulnerability of agricultural eco-environment of hilly basin area in the middle of Hunan Prov- ince. [ Method] Taking Hengyang basin as an example, we firstly chose 13 indicat...[Objective] The study aimed to assess the vulnerability of agricultural eco-environment of hilly basin area in the middle of Hunan Prov- ince. [ Method] Taking Hengyang basin as an example, we firstly chose 13 indicators from natural, social and economic subsystem to assess the vulnerability of agricultural eco-environment in hilly basin area in the middle of Hunan Province. Afterwards, by using principal component analysis, we calculated the weight of each indicator and the vulnerability of agricultural eco-environment of seven regions, finally analyzed the spatial distribu- tion of agricultural eco-envimnment vulnerability. [ Result] The weight of farmers＇ net income per capita was up to 0.140, followed by forest coverage （0.137）. Among the seven counties, the vulnerability of agricultural eco-environment was primarily moderate, while Hengnan County had the highest vulnerability, followed by Hengyang County, and their vulnerability was extremely serious. In addition, Leiyang City was the minimum fragile region, namely slightly fragile region. In general, the vulnerability of peripheral counties was lower than that of central counties. [ Conclusion] The research could provide scientific references for the restoration and reconstruction of agro-ecological environment as well as the establishment of agri- cultural Dreduction decisions.展开更多
文摘This paper discusses the Cretaceous-Tertiary magnetic polarity sequence of the the Hengyang Basin on the basis of magnetostratigraphic study. The age of each stratigraphic unit has been determined with the magnetic polarity time scale combined with 39Ar/40Ar dating, thus providing evidence for determining the geological ages of different formations. The authors assign the age of the Dongjing Formation of the Hengyang Basin to Early Cretaceous, the Shenhuangshan Formation to Early-Late Cretaceous, the Daijiaping Formation to Late Cretaceous, and the Dongtang and Xialiushi formations to Palaeocene.
文摘Since the coexistence of the Cretaceous and Palaeocene was ascertained in the Hengyang Basin of Hunan in the middle of the 1960's, the Cretaceous and Tertiary boundary has been discussed in several papers, but it still remains controversal. The points at issue are the connotation, stratigraphical position and lateral correlation of the Dongtang (or Chejiang) Formation.
基金Supported by the Cultural Geography Project of Key Subject Construction of Hunan Province,China (05JJ40062)Project of Innovative Team Construction about "Resource and Environmental Management and Regional Sustainable Development" in Higher Education of Hunan Province,China
文摘[Objective] The study aimed to assess the vulnerability of agricultural eco-environment of hilly basin area in the middle of Hunan Prov- ince. [ Method] Taking Hengyang basin as an example, we firstly chose 13 indicators from natural, social and economic subsystem to assess the vulnerability of agricultural eco-environment in hilly basin area in the middle of Hunan Province. Afterwards, by using principal component analysis, we calculated the weight of each indicator and the vulnerability of agricultural eco-environment of seven regions, finally analyzed the spatial distribu- tion of agricultural eco-envimnment vulnerability. [ Result] The weight of farmers＇ net income per capita was up to 0.140, followed by forest coverage （0.137）. Among the seven counties, the vulnerability of agricultural eco-environment was primarily moderate, while Hengnan County had the highest vulnerability, followed by Hengyang County, and their vulnerability was extremely serious. In addition, Leiyang City was the minimum fragile region, namely slightly fragile region. In general, the vulnerability of peripheral counties was lower than that of central counties. [ Conclusion] The research could provide scientific references for the restoration and reconstruction of agro-ecological environment as well as the establishment of agri- cultural Dreduction decisions.
