5 Ma On the basis of Q-mode factor analysis we recognized four d

5 Ma. On the basis of Q-mode factor analysis we recognized four distinct faunal assemblages at this site ( Figure 5) and attempted to give their expected environmental preferences ( Table 3). U. proboscidea

is the single dominant species of this assemblage, having click here a high positive score of factor 1. U. proboscidea is associated with the high organic carbon flux rates due to increased surface productivity and low oxygen levels resulting from organic matter oxidation ( Gupta and Srinivasan, 1992, Rai and Srinivasan, 1994, Wells et al., 1994 and Murgese and Deckker, 2007). Thus, the U. proboscidea assemblage has been considered as an indicator of past periods of enhanced surface productivity ( Table 3). Species of this assemblage have a distinct positive score of factor 2 comprising C. lobatulus, O. umbonatus, Cibicides kullenbergi and G. cibaoensis. C. lobatulus is an epiphyte species ( Gaudant et al. 2010). O. umbonatus is a long-ranging species which lives in various environments ( Miao & Thunell 1993, Schmiedl & Mackensen 1997, Gupta & Thomas 1999). It is reported to reflect a well-oxygenated, low organic carbon environment ( Mackensen et al., 1985 and Miao RG7204 solubility dmso and Thunell, 1993). According to Rathburn & Corliss (1994) it can use

limited amounts of food. C. kullenbergi prefers a deep-sea environment with a low organic carbon content below the low surface productivity regions ( Burke et al., 1993 and Nomura, 1995).

The vertical distribution of C. kullenbergi is confined to the oxygen-rich and nutrient poor NADW ( Schmiedl et al. 1997). G. cibaoensis is broadly distributed in the deep-sea environment with intermediate oxygen, and a variable temperature and food supply ( De & Gupta 2010). This faunal assemblage is suggestive of an oxygenated deep-sea environment with a low organic flux ( Table 3). C. wuellerstorfi, Ehrenbergina carinata, B. alazanensis, and G. cibaoensis are TCL the major species of this assemblage, with a high positive score of factor 3. As a suspension feeder and elevated epibiont, C. wuellerstorfi does not require high organic carbon levels and can withstand active bottom water currents ( Linke and Lutze, 1993 and Gupta and Thomas, 1999). E. carinata thrives in a warm deep sea with low oxygen and variable organic carbon levels ( Nomura, 1995 and Gupta and Satapathy, 2000). E. carinata is also reported from regions with an intermediate to high flux of organic matter and low oxygen conditions in the central Indian Ocean ( Gupta et al. 2006). B. alazanensis is an infaunal species which thrives in a less well oxygenated deep sea with a high continuous food supply ( Corliss and Chen, 1988 and Gupta and Thomas, 1999). It is thus inferred that this faunal assemblage broadly reflects a low to intermediate flux of organic matter and oxygenated deep water with active currents ( Table 3).

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