Interpretation of new multichannel seismic reflection data from the Andaman Forearc Basin(AFB) in the northern Indian Ocean is presented here. The highquality multichannel seismic data from the Andaman Forearc region ...Interpretation of new multichannel seismic reflection data from the Andaman Forearc Basin(AFB) in the northern Indian Ocean is presented here. The highquality multichannel seismic data from the Andaman Forearc region enable us to examine the seismic characters and to demarcate seismic sequences bounded by distinct unconformities. Ages of marked seismic horizons have been calibrated with available litholog data from nearby industry boreholes. Seismic interpretation of new data shows that the AFB is filled with * 4.5-s-two way travel time(TWT) thick Neogene to Recent sediments. The entire basin assemblage exhibits two distinct major sequences pertaining to the Neogene and Quaternary times. A large part of the basin is filled with intermittent mass transport deposits(MTD). We infer that the episodic uplift of the Invisible Bank, protuberance of the outerarc and regular deformation through reactivation of preexisting normal faults since the Pleistocene could be attributed as causal mechanisms for the MTDs. Strong bottom simulating reflectors are identified in the Late Miocene and younger sediments of the outerarc and AFB at a depth of * 0.6 s TWT and correspond to the presence of gas hydrates in this region. Our interpretations have significant implications for geodynamic as well as resource exploration in the AFB.展开更多
B Elemental contents of beach rock samples were analyzed using EDXRF.The samples were collected from three locations of Andaman Island.The Al,Ca,K,Fe,Ti,Si,V,Co,Cu,Ba,Zn,Pb,Cd and Mn contents were determined.The geoch...B Elemental contents of beach rock samples were analyzed using EDXRF.The samples were collected from three locations of Andaman Island.The Al,Ca,K,Fe,Ti,Si,V,Co,Cu,Ba,Zn,Pb,Cd and Mn contents were determined.The geochemical behavior of elements in the region is discussed.The elemental contents of beach rock samples from Andaman Island are much below the values of both earth crust and that of Tamilnadu region.However,content of the biogenic element Ca was the highest of all elements.This is due to the typical beach rock formation.展开更多
Species compositions in the mangrove habitats of China and India, especially on Hainan Island （China） and on the Sun- darbans and the Andaman ＆ Nicobar Islands （India）, are of interest, showing several similariti...Species compositions in the mangrove habitats of China and India, especially on Hainan Island （China） and on the Sun- darbans and the Andaman ＆ Nicobar Islands （India）, are of interest, showing several similarities and differences. The total mangrove areas of India cover about 6419 km^2 with 43 species （23 major and 20 minor species）, while the mangrove areas of China cover about 150 km^2 with 26 speices （19 major and 7 minor speices）. We carried out a comparison of mangrove floras in the Indian Sundarbans, Andaman ＆ Nicobar Islands and in Hainan Island. The mangrove areas of the Indian Sundarbans comprise about 66.5% of the total Indian mangroves, presently covering an area of 4267 km^2 with 35 species from 22 genera and 16 families. There are 34 species from 17 genera and l 3 families in the Andaman ＆ Nicobar Islands. Hainan Island is considered a distribution center of mangroves; it has the largest number of mangrove species in China, i.e., 25 species from 15 genera and 12 families, accounting for about 96% of the total number of mangrove species in China. The mangroves of Hainan Island and the Andaman ＆ Nicobar Islands belong to island types, while those of Sundarbans belong to inter-tidal deltaic types. Differences in soil type, rainfall, temperature, tidal fluctuation and other climatic features possibly cause variations in floristic composition of these regions.展开更多
文摘Interpretation of new multichannel seismic reflection data from the Andaman Forearc Basin(AFB) in the northern Indian Ocean is presented here. The highquality multichannel seismic data from the Andaman Forearc region enable us to examine the seismic characters and to demarcate seismic sequences bounded by distinct unconformities. Ages of marked seismic horizons have been calibrated with available litholog data from nearby industry boreholes. Seismic interpretation of new data shows that the AFB is filled with * 4.5-s-two way travel time(TWT) thick Neogene to Recent sediments. The entire basin assemblage exhibits two distinct major sequences pertaining to the Neogene and Quaternary times. A large part of the basin is filled with intermittent mass transport deposits(MTD). We infer that the episodic uplift of the Invisible Bank, protuberance of the outerarc and regular deformation through reactivation of preexisting normal faults since the Pleistocene could be attributed as causal mechanisms for the MTDs. Strong bottom simulating reflectors are identified in the Late Miocene and younger sediments of the outerarc and AFB at a depth of * 0.6 s TWT and correspond to the presence of gas hydrates in this region. Our interpretations have significant implications for geodynamic as well as resource exploration in the AFB.
文摘B Elemental contents of beach rock samples were analyzed using EDXRF.The samples were collected from three locations of Andaman Island.The Al,Ca,K,Fe,Ti,Si,V,Co,Cu,Ba,Zn,Pb,Cd and Mn contents were determined.The geochemical behavior of elements in the region is discussed.The elemental contents of beach rock samples from Andaman Island are much below the values of both earth crust and that of Tamilnadu region.However,content of the biogenic element Ca was the highest of all elements.This is due to the typical beach rock formation.
基金supported by the National Natural Science Foundation of China (Grant No. 40701191)
文摘Species compositions in the mangrove habitats of China and India, especially on Hainan Island （China） and on the Sun- darbans and the Andaman ＆ Nicobar Islands （India）, are of interest, showing several similarities and differences. The total mangrove areas of India cover about 6419 km^2 with 43 species （23 major and 20 minor species）, while the mangrove areas of China cover about 150 km^2 with 26 speices （19 major and 7 minor speices）. We carried out a comparison of mangrove floras in the Indian Sundarbans, Andaman ＆ Nicobar Islands and in Hainan Island. The mangrove areas of the Indian Sundarbans comprise about 66.5% of the total Indian mangroves, presently covering an area of 4267 km^2 with 35 species from 22 genera and 16 families. There are 34 species from 17 genera and l 3 families in the Andaman ＆ Nicobar Islands. Hainan Island is considered a distribution center of mangroves; it has the largest number of mangrove species in China, i.e., 25 species from 15 genera and 12 families, accounting for about 96% of the total number of mangrove species in China. The mangroves of Hainan Island and the Andaman ＆ Nicobar Islands belong to island types, while those of Sundarbans belong to inter-tidal deltaic types. Differences in soil type, rainfall, temperature, tidal fluctuation and other climatic features possibly cause variations in floristic composition of these regions.
