A moderately diversified, well preserved, low frequency nannofossil assemblage with over twenty species is recorded from one (S-13) calcareous marl sample of the Ariyalur Formation situated north of the village Aladi. The assemblage includes the latest Maastrichtian index species Micula prinsii. Preservation is good and although specimens are overgrown, no dissolution effects are apparent. The assemblage is of late Maastrichtian age CC 26b (Perch-Nielsen, 1985) correlative with UC 20dTP (Burnett, 1998). The range of Micula prinsii, a low latitude marker, is indicative of the latest Maastrichtian magnetochron C29r below the K/T boundary that spans approximately the last 500,000 years of the Maastrichtian. In addition, high abundance of Petrobrasiella? bownii in both very small and large sizes (3-4 ?m to 10 im diameter) along with Ceratolithoides aculeus, C. kamptneri, Arkhangelskiella maastrichtiana, Calculites obscurus attests to this zonal placement. The high latitude Maastrichtian genus Nephrolithus, represented by N. miniporus, is also present in the assemblage and indicates a cold water current in the southeastern part of India during latest Maastrichtian. Reworked Campanian species represented by Nannoconnus spp. and Haqius circumradiatus are also present in the assemblage. Further study of this locality may provide a record of the K/T boundary.
Terminal Maastrichtian Age Calcareous Nannofossils Preceding K/T Mass Extinction from Aladi Formation, Vridhachalam Area, South India
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A moderately diversified, well preserved, low frequency nannofossil assemblage with over twenty species is recorded from one (S-13) calcareous marl sample of the Ariyalur Formation situated north of the village Aladi. The assemblage includes the latest Maastrichtian index species Micula prinsii. Preservation is good and although specimens are overgrown, no dissolution effects are apparent. The assemblage is of late Maastrichtian age CC 26b (Perch-Nielsen, 1985) correlative with UC 20dTP (Burnett, 1998). The range of Micula prinsii, a low latitude marker, is indicative of the latest Maastrichtian magnetochron C29r below the K/T boundary that spans approximately the last 500,000 years of the Maastrichtian. In addition, high abundance of Petrobrasiella? bownii in both very small and large sizes (3-4 ?m to 10 im diameter) along with Ceratolithoides aculeus, C. kamptneri, Arkhangelskiella maastrichtiana, Calculites obscurus attests to this zonal placement. The high latitude Maastrichtian genus Nephrolithus, represented by N. miniporus, is also present in the assemblage and indicates a cold water current in the southeastern part of India during latest Maastrichtian. Reworked Campanian species represented by Nannoconnus spp. and Haqius circumradiatus are also present in the assemblage. Further study of this locality may provide a record of the K/T boundary.
Publication Mode |
Online |
---|---|
Publication Author |
Jyotsana Rai |
Publication Language |
English |
Publication Type |
Conference Paper |
Publication Year |
2013 |
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