Analyzed in this paper are the influencing factors, characteristics, and mechanism of land-sea interaction for the Taihu Lake Basin. The course of mass movement and energy transformation between land and sea in the Ta...Analyzed in this paper are the influencing factors, characteristics, and mechanism of land-sea interaction for the Taihu Lake Basin. The course of mass movement and energy transformation between land and sea in the Taihu Lake Basin has experienced three different stages, namely, ocean predominance, balance between land and sea, and land predominance. In the paper the process of the formation and the evolution of the Taihu Lake is studied considering the land-sea interaction.展开更多
To understand the thermal evolution of lacustrine sedimentary n-alkane hydrogen isotopic composition(δD),especially bacterially derived n-alkanes,anhydrous thermal simulation experiments were performed with sediments...To understand the thermal evolution of lacustrine sedimentary n-alkane hydrogen isotopic composition(δD),especially bacterially derived n-alkanes,anhydrous thermal simulation experiments were performed with sediments from Lake Gahai(Gannan,China).We analyzed the original and pyrolysis-generated n-alkanes and theirδD values.The results showed that thermal maturity and n-alkane origins significantly affected the distribution of pyrolysis-generated n-alkanes.In immature to post-mature sediments,the bacterial-derived medium-chain n-alkanes generally had depletedδD values.The maximum difference in averageδD values between the bacterial-and herbaceous plant-derived medium-chain n-alkanes was 32‰,and the maximum difference in δD values among individual n-alkanes was 59‰.We found that the averageδD value of pyrolysis-generated n-alkanes from different latitude was significantly different in immature to highly mature sediments,but similar in post-mature ssediments.The hydrogen isotopes of sedimentary n-alkanes can be used as indicators for paleoclimate/paleo-environment conditions only when sediments are immature to highly mature.During thermal evolution,the δD value of generated individual n-alkanes and the averageδD value increased with thermal maturity,indicating that hydrogen isotopes of sedimentary n-alkanes can be used as an index of organic matter maturity.We established mathematical models of average δD values of generated n-alkanes from immature to post-mature sediments using n C_(21)^(-)/nC_(21)^(+)and average chain lengths.These results improve our understanding of the distribution andδD value of sedimentary n-alkanes derived from herbaceous plants in mid-latitude plateau cold regions.展开更多
Taihu Lake is a well-known economic lake in China, and is also a famous scenic lake all over the world (Fig. 1). Scientists have long paid attention to the origin of Taihu Lake and put forward several hypotheses for i...Taihu Lake is a well-known economic lake in China, and is also a famous scenic lake all over the world (Fig. 1). Scientists have long paid attention to the origin of Taihu Lake and put forward several hypotheses for its formation, for example, the river-derivation hypothesis, the tectonic subsidence hypothesis, the lagoon hypothesis etc., and recently the展开更多
The origin of Taihu Lake has attracted the attention of several generations ofChinese geologists. Especially the impact origin hypothesis was put forward by Prof.Pen Zhi-zhong. In the beginning of the 1990s, based on ...The origin of Taihu Lake has attracted the attention of several generations ofChinese geologists. Especially the impact origin hypothesis was put forward by Prof.Pen Zhi-zhong. In the beginning of the 1990s, based on the previous hypotheses, differ-ent views have been advanced one by one. These indicate that research work aboutthe Taihu Lake origin is in a deep-going way.展开更多
Shatter cones are conical fragments of rock characterized by striations that radiate from the apex. In 1905, they were first observed at Steinheim Basin in Germany. In the United States, the well-known occurrence site...Shatter cones are conical fragments of rock characterized by striations that radiate from the apex. In 1905, they were first observed at Steinheim Basin in Germany. In the United States, the well-known occurrence site of shatter cones is Kentland, Indiana. In 1938, when the existence of terrestrial impact crater was still a hypothesis, J. D. Boon had suggested that the structures similar to the Kentland were the products of meteoritic crater. In 1947, when making frequent investigations on Kentland quarry, R. S. Dietz pointed out that the axes of these cones were oriented normal to the bedding, with the apexes pointing toward the top of the bed. Thus, they were formed by giant forces which came from above rather than below. Because except the impact of meteorite, there is not any giant force from space, shatter cones should be 'root' of crater. This argument was proved because of the discovery展开更多
基金This work was financially supported by Science and Technology Innovation Fund of Ministry of Water Resources ofChina (Grant No.SCX2004-03)
文摘Analyzed in this paper are the influencing factors, characteristics, and mechanism of land-sea interaction for the Taihu Lake Basin. The course of mass movement and energy transformation between land and sea in the Taihu Lake Basin has experienced three different stages, namely, ocean predominance, balance between land and sea, and land predominance. In the paper the process of the formation and the evolution of the Taihu Lake is studied considering the land-sea interaction.
基金supported by the National Natural Science Foundation of China(Grant Nos.41772108 and 41972110)。
文摘To understand the thermal evolution of lacustrine sedimentary n-alkane hydrogen isotopic composition(δD),especially bacterially derived n-alkanes,anhydrous thermal simulation experiments were performed with sediments from Lake Gahai(Gannan,China).We analyzed the original and pyrolysis-generated n-alkanes and theirδD values.The results showed that thermal maturity and n-alkane origins significantly affected the distribution of pyrolysis-generated n-alkanes.In immature to post-mature sediments,the bacterial-derived medium-chain n-alkanes generally had depletedδD values.The maximum difference in averageδD values between the bacterial-and herbaceous plant-derived medium-chain n-alkanes was 32‰,and the maximum difference in δD values among individual n-alkanes was 59‰.We found that the averageδD value of pyrolysis-generated n-alkanes from different latitude was significantly different in immature to highly mature sediments,but similar in post-mature ssediments.The hydrogen isotopes of sedimentary n-alkanes can be used as indicators for paleoclimate/paleo-environment conditions only when sediments are immature to highly mature.During thermal evolution,the δD value of generated individual n-alkanes and the averageδD value increased with thermal maturity,indicating that hydrogen isotopes of sedimentary n-alkanes can be used as an index of organic matter maturity.We established mathematical models of average δD values of generated n-alkanes from immature to post-mature sediments using n C_(21)^(-)/nC_(21)^(+)and average chain lengths.These results improve our understanding of the distribution andδD value of sedimentary n-alkanes derived from herbaceous plants in mid-latitude plateau cold regions.
基金Project supported by the National Natural Science Foundation of China.
文摘Taihu Lake is a well-known economic lake in China, and is also a famous scenic lake all over the world (Fig. 1). Scientists have long paid attention to the origin of Taihu Lake and put forward several hypotheses for its formation, for example, the river-derivation hypothesis, the tectonic subsidence hypothesis, the lagoon hypothesis etc., and recently the
基金Project supported by the National Natural Science Foundation of China.
文摘The origin of Taihu Lake has attracted the attention of several generations ofChinese geologists. Especially the impact origin hypothesis was put forward by Prof.Pen Zhi-zhong. In the beginning of the 1990s, based on the previous hypotheses, differ-ent views have been advanced one by one. These indicate that research work aboutthe Taihu Lake origin is in a deep-going way.
基金Project supported by the National Natural Science Foundation of China
文摘Shatter cones are conical fragments of rock characterized by striations that radiate from the apex. In 1905, they were first observed at Steinheim Basin in Germany. In the United States, the well-known occurrence site of shatter cones is Kentland, Indiana. In 1938, when the existence of terrestrial impact crater was still a hypothesis, J. D. Boon had suggested that the structures similar to the Kentland were the products of meteoritic crater. In 1947, when making frequent investigations on Kentland quarry, R. S. Dietz pointed out that the axes of these cones were oriented normal to the bedding, with the apexes pointing toward the top of the bed. Thus, they were formed by giant forces which came from above rather than below. Because except the impact of meteorite, there is not any giant force from space, shatter cones should be 'root' of crater. This argument was proved because of the discovery
