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A gravity core collected from the upper slope of southwest of Quilon at a water depth of 776 m (Lat: 8°12′263″N, Long: 76°28′281″E)
was analysed for texture (carbonate free), calcium carbonate and organic carbon. Variation in silicic fraction seems to be
controlled by silt, i.e., enrichment from 15 ka BP to 10 ka BP and then constant in Holocene. Below 15 ka BP, the silicic
fraction gets depleted compared to the Holocene section with a minimum around 21 ka BP. Clay content remains nearly constant
except in the Holocene where it shows an enrichment. Carbonate content of less than 63 micron when computed by subtracting
coarse fraction content from the total carbonate suggests that the total carbonates are mainly concentrated in the finer fraction.
All these carbonate phases show an inverse relationship with silicic fraction except in Holocene. Below 15 ka BP, CaCO3 dominates in sediments comprising more than 65%, such an increase is also seen in the coarse fraction. Coarse fraction from
these sections contains abundant nodular type aggregates encrusting small forams. This period is marked by a high sedimentation
rate comparable to Holocene. These parameters suggest that the productivity and precipitation have increased in the Holocene
due to the intensification of the southwest monsoon. During the last glacial maximum and early deglacial period the high sedimentation
rate indicates redeposition of the carbonates from the existing carbonate lithofacies situated between Quilon and Cape Comorin
probably due to the slope instability. 相似文献
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Sohan Singh Rajpurohit Rabindra Kumar Sinha Phalguni Sen Sahendra Singh 《Arabian Journal of Geosciences》2018,11(18):564
Cutting performance of diamond wire saw is a key factor influencing mine planning, production scheduling, and equipment selection for dimension stone quarries. It is normally measured in terms of cutting rate. Rock samples collected from various granite and marble quarries in India were tested in laboratory to determine their physico-mechanical properties. Cutting rate of diamond wire saw was measured in the field studies during the actual cutting process in quarries. Using these laboratory determined properties and the cutting rate, a multiple linear regression model has been developed to predict the cutting rate of diamond wire saw. Physico-mechanical properties of rocks determined in laboratory are used as independent variables and cutting rate as predictor variable in the regression model. The study indicates that the cutting rate increases with a decrease in most of the hardness and strength parameters of rock. The final model is tested for its goodness of fit indicating a significant linear relation between cutting rate and physico-mechanical properties, namely tensile strength, slake durability index, and Cerchar hardness index with regression coefficient of 94%. The resulting model can be used suitably for different types of hard to medium hard and soft dimension stones. The generalized model for estimating the cutting rate becomes a handy tool for mining engineers to work out operating efficiency, expenses, planning etc. of the dimension stone block cutting. 相似文献
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The present study reports the analysis of GPS TEC prior to 3 earthquakes (M > 6.0). The earthquakes are: (1) Loyalty Island (22°36′S, 170°54′E) on 19 January 2009 (M = 6.6), (2) Samoa Island (15°29′S, 172°5′W) on 30 August 2009 (M = 6.6), and (3) Tohoku (38°19′N, 142°22′E) on 11 March 2011 (M = 9.0). In an effort to search for a precursory signature we analysed the land and ocean parameters prior to the earthquakes, namely SLHF (Land) and SST (Ocean). The GPS TEC data indicate an anomalous behaviour from 1–13 days prior to earthquakes. The main purpose of this study was to explore and demonstrate the possibility of any changes in TEC, SST, and SLHF before, during and after the earthquakes which occurred near or beneath an ocean. This study may lead to better understanding of response of land, ocean, and ionosphere parameters prior to seismic activities. 相似文献
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The Kuwaiti oil fires and their associated smoke have led to many speculations and hypotheses by various scientists and the world press. The environmental impact of this phenomenon has yet to be modeled and understood with confidence. Some models predict adverse effects impacting millions of people from Africa to the Indian subcontinent; others predict regional impacts, or do not aggregate to the level of large‐scale and deleterious environmetal consequences. We have initially mapped and delineated the oil fires and attendant smoke palls using Space Shuttle imagery in order to initiate further scientific analyses required to assess this environmental disaster. 相似文献
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