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| ここには、インド(India、Republic of India)における主に資源(Resource)・地球科学(Earth Science)・環境(Environment)に関連する情報を集めている。 |
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![]() Topographic map of India. |
![]() The University of Texas at AustinのUniversity of Texas Librariesの『Perry-Castaneda(nの頭に〜) Library Map Collection』の中の『India (Shaded Relief) 2001 (273K)』から |
![]() The University of Texas at AustinのUniversity of Texas Librariesの『Perry-Castaneda(nの頭に〜) Library Map Collection』の中の『India - Energy Map from "India: An Energy Sector Overview", 1997, U.S. Energy Information Administration (55K)』から |
![]() 〔応用地質(株)による『地震防災』の中の『インド・グジャラート地震被害調査報告』から〕 |
![]() Figure 2. Map showing the approximate boundaries of the Precambrian cratons making up the Indian shield (e.g., Pandey & Agrawal, 1999; Naqvi & Rogers, 1987), the granulite terrain, the Precambrian structural trends (heavy broken lines), rift zones crossing peninsular India (e.g., Biswas, 1987), and the present outcrop areas of the Deccan and Rajmahal flood basalts. Inset shows the breakup of the Seychelles microcontinent, situated along the northern tip of the Mascarene Plateau (black), from India, soon after the Deccan flood basalt episode (after Norton and Sclater, 1979; Mahoney, 1988). The Koyna and Kuruduvadi “rifts” have been proposed based on gravity surveys and may represent humps of the granitic basement rather than rifts. ![]() Figure 3. Prominent structural-tectonic features of southern Asia and the Indian Ocean basin (based on Mahoney et al., 2002). Abbreviations for localities are: Q, Quetta; Z, Zhob; B, Barmer, M, Mundwara; D, Dhandhuka; B, Bombay; R, Rajahmundry. WG is the Western Ghats region (ages from Venkatesan et al., 1993 and others). ~ 64 Ma age for Rajahmundry basalts is from Baksi (2001a). G, ~ 61 Ma Goa dykes (Widdowson et al., 2000). KK, ~ 90-69 Ma Karnataka-Kerala dykes (e.g., Radhakrishna et al., 1994; Anil Kumar et al., 2001). SMI are the St. Mary's Islands volcanics (85.5 Ma, Pande et al., 2001), part of the Indo-Madagascar CFB which in India is otherwise represented by the KK dykes. The associated flood basalt lavas are not represented or known in India; there are many Precambrian dyke swarms throughout southern India as well. 72-73 Ma ages for Quetta and Zhob rocks and 65 Ma age for Dhandhuka-Botad lavas are from Mahoney et al. (2002), as also the modelled hotspot track showing expected ages in Ma. Note the rift zones underlying the Deccan, and the absence of any triple junction. OFZ, Owen Fracture Zone; MFZ, Mauritius Fracture Zone; VFZ, Vishnu Fracture Zone. In conclusion, a non-plume, plate-tectonic model involving continental breakup and related mantle convection and decompression melting, is suitable for the Deccan. If radial, focused flow of the upper mantle occurs (instead of vertical flow as in the plume model), a potentially unlimited volume of the mantle is available for processing. The plume model was proposed for the Deccan more than 30 years ago, when little was known about the Deccan and about the plume mode of convection. Today we know a lot more about the Deccan, and the plume model becomes less tenable as our knowledge grows. The originators and champions of the plume model had little or no personal knowledge of the Deccan, and their broad generalizations should have been put to critical tests by regional experts on the Deccan. The tendency has been to assume a plume origin and infer the plume properties and characteristics based on whatever is required by the observations, but if volatiles, mantle fertility, continental geology, and dynamic, evolving plates are considered, one no longer needs mantle plumes (Sheth, 2005b). The new voices asking for new explanations (e.g., http://www.mantleplumes.org/Deccan2.html) are a good sign. The plume model for the Deccan has been around for over thirty years, and has failed. A new, scientifically tenable non-plume model for the Deccan could be rapidly developed if only a few of the many Deccan/flood basalt enthusiasts share the task. We live in interesting times. 〔www.MantlePlumes.orgの『India』の中の『Hetu Shet氏によるDeccan Traps: The Deccan beyond the plume hypothesis』から〕 |
![]() ![]() 〔National Water Development Agency (NWDA)の『National Perspective Plan (NPP)』から〕 |