By means of the analysis methods of linear regression,climate tendency rate,integral humidity index and dry-wet index,precipitation,agricultural water demand and drought degree were analyzed systematically.The results...By means of the analysis methods of linear regression,climate tendency rate,integral humidity index and dry-wet index,precipitation,agricultural water demand and drought degree were analyzed systematically.The results showed that precipitation tendency rate in crop growing season was-19.983 mm/10 a in recent 50 years,and precipitation reduced by around 100 mm.60%-70% years had basically satisfactory precipitation and the satisfaction degree of natural precipitation towards agricultural water demand decreased by 23%.Due to precipitation decrease,climatic type changed from semi-humid and relative drought to moderate drought.The average water deficit was 56 mm in growth season and 36% years were affected by drought.Spring drought was the most serious with the probability of 64%,followed by autumn drought with the probability of 58%,and summer drought was the lightest with the probability of 24%.The drought probability from planting to seedling emergence in May was 70%,which had the greatest effect on agriculture production.展开更多
Situated at the foot of Yuelu Mountain in Changsha,is the cradle ofnonferrous metal scientific workers—Central.South University of Tech-nology,Professor Chen Xinmin has been working here for nearly
A continuous sedimentation at the Xinmin Section, Anshun, Guihzou Province, with the Upper Permian Talung Formation dominated by bedded siliceous rocks, and the Lower Triassic Luolou Formation consisting mudstones and...A continuous sedimentation at the Xinmin Section, Anshun, Guihzou Province, with the Upper Permian Talung Formation dominated by bedded siliceous rocks, and the Lower Triassic Luolou Formation consisting mudstones and marls as well as siliceous mudstones at its basal part indicates that it represents a deeper-water basinal facies across the Permian-Triassic boundary. Based on a systematic conodont biostratigraphic work, nine conodont species belong to two genera have been identified in this study. It enable us to establish five conodont zones at this section, in ascending order, they are： Clarkina changxingensis Zone（beds 1-3-4-2）, Clarkina yini Zone（beds 4-3-5-1-1）, Clarkina meishanensis Zone（beds 5-1-2-5-2）, Hindeodus changxingensis Zone（beds 5-3-1-5-3-2） and Hindeodus parvus Zone（beds 5-3-3-5-3-4）, respectively. According to the first occurrence of Hindeodus parvus in bed 5-3-3, the Permian-Triassic boundary is placed at the base of bed 5-3-3. This conodont zonation of the Xinmin Section provides precise biostratigraphic framework for further investigations on the geological events across the Permian-Triassic boundary at this section. In addition, the new conodont data also reveals that several siliceous beds occurred at the basal Triassic. It provides an exception of Early Triassic Chert Gap.展开更多
文摘By means of the analysis methods of linear regression,climate tendency rate,integral humidity index and dry-wet index,precipitation,agricultural water demand and drought degree were analyzed systematically.The results showed that precipitation tendency rate in crop growing season was-19.983 mm/10 a in recent 50 years,and precipitation reduced by around 100 mm.60%-70% years had basically satisfactory precipitation and the satisfaction degree of natural precipitation towards agricultural water demand decreased by 23%.Due to precipitation decrease,climatic type changed from semi-humid and relative drought to moderate drought.The average water deficit was 56 mm in growth season and 36% years were affected by drought.Spring drought was the most serious with the probability of 64%,followed by autumn drought with the probability of 58%,and summer drought was the lightest with the probability of 24%.The drought probability from planting to seedling emergence in May was 70%,which had the greatest effect on agriculture production.
文摘Situated at the foot of Yuelu Mountain in Changsha,is the cradle ofnonferrous metal scientific workers—Central.South University of Tech-nology,Professor Chen Xinmin has been working here for nearly
基金supported by the Natural Science Foundation of China (Nos. 41372039, 41272044, 41172024)the ‘Fundamental Research Funds for the Central Universities, China University of Geosciences (Wuhan)’
文摘A continuous sedimentation at the Xinmin Section, Anshun, Guihzou Province, with the Upper Permian Talung Formation dominated by bedded siliceous rocks, and the Lower Triassic Luolou Formation consisting mudstones and marls as well as siliceous mudstones at its basal part indicates that it represents a deeper-water basinal facies across the Permian-Triassic boundary. Based on a systematic conodont biostratigraphic work, nine conodont species belong to two genera have been identified in this study. It enable us to establish five conodont zones at this section, in ascending order, they are： Clarkina changxingensis Zone（beds 1-3-4-2）, Clarkina yini Zone（beds 4-3-5-1-1）, Clarkina meishanensis Zone（beds 5-1-2-5-2）, Hindeodus changxingensis Zone（beds 5-3-1-5-3-2） and Hindeodus parvus Zone（beds 5-3-3-5-3-4）, respectively. According to the first occurrence of Hindeodus parvus in bed 5-3-3, the Permian-Triassic boundary is placed at the base of bed 5-3-3. This conodont zonation of the Xinmin Section provides precise biostratigraphic framework for further investigations on the geological events across the Permian-Triassic boundary at this section. In addition, the new conodont data also reveals that several siliceous beds occurred at the basal Triassic. It provides an exception of Early Triassic Chert Gap.
