際際滷shows by User: micaellua1 / http://www.slideshare.net/images/logo.gif 際際滷shows by User: micaellua1 / Fri, 31 May 2013 12:59:06 GMT 際際滷Share feed for 際際滷shows by User: micaellua1 Paleoenvironmental interpretations of Middle Pleistocene from benthic foraminifera of Santos basin, Brazil https://pt.slideshare.net/slideshow/bergamaschi-2012-22255828/22255828 bergamaschi2012-130531125906-phpapp02
Pleistocene (2.58 million years to 12,000 years ago) was a very dynamic period in geologic history of Earth, characterized by large climatic fluctuations that changed the conditions of the environments on the planet and regulated the distribution of marine biodiversity. Foraminifera are protists mostly marine, very sensitive to environmental changes, and widely used in paleoecological studies. The present study aims to examine the benthic foraminiferal associations from the core BS-A, in order to contribute to knowledge about the paleoecological and paleoenvironmental characteristics of Middle Pleistocene. The core examined was collected at a depth of 2,141 m on the continental slope of the Santos basin and has continues recovery of 20.65 m of sediment. Were selected 25 samples belonging to Middle Pleistocene, processed within the standard methodology for calcareous microfossils. We identified 26,629 specimes, distributed in 64 genera and 147 species of benthic foraminifera, however three showed a consistent pattern of abundance and distribution (Epistominella exigua, Alabaminella weddellensis and Cassidulina californica). Using data distribution of fauna and regression analysis it was possible to subdivide the interval studied in three subintervals. The subintervals A (oldest, between 2,037 and 1,946 cm) and C (latest, between ~1,509 and 849 cm), had moments of dominance with high E. exigua abundance, high density of foraminifera specimens per gram of sediment (ind/g) and low diversity. The species E. exigua is opportunistic and able to reproduce rapidly, in response to seasonal phytodetritus deposits. This suggests that in these two moments have occurred considerable influx of phytodetritic organic matter to the seafloor and a consequent increase in the abundance of E. exigua, which conditioned a fauna with high dominance and low diversity. Already the subinterval B, intermediate chronostratigraphically (between 1.910 and ~1.529 cm), presented a more diverse community of foraminifera, with high abundance of infaunal morphotypes, low density and low abundance of E. exigua. This data suggest a moment of greater environmental stability, and the absence of considerable phytodetritical organic matter flow to the seafloor, enabling an increase of diversity in the community of foraminifera. The species C. californica, in spite of being the most present infaunal species in the core, has no statistical relationship with the abundance of this morphotype, and presented its highest values in subintervals A and B, suggesting that other paleoenvironmental factors have controlling their populations, usually associated with the presence of large amounts of total organic carbon in sediment-water interface. An opposition abundance of A. weddellensis with E. exigua indicates moments that suffered different types of phytodetritc flow deposited in seasonal pulses (subintervals A and C) and interspersed with periods where the deposition of organic matter occurred mo]]>
Pleistocene (2.58 million years to 12,000 years ago) was a very dynamic period in geologic history of Earth, characterized by large climatic fluctuations that changed the conditions of the environments on the planet and regulated the distribution of marine biodiversity. Foraminifera are protists mostly marine, very sensitive to environmental changes, and widely used in paleoecological studies. The present study aims to examine the benthic foraminiferal associations from the core BS-A, in order to contribute to knowledge about the paleoecological and paleoenvironmental characteristics of Middle Pleistocene. The core examined was collected at a depth of 2,141 m on the continental slope of the Santos basin and has continues recovery of 20.65 m of sediment. Were selected 25 samples belonging to Middle Pleistocene, processed within the standard methodology for calcareous microfossils. We identified 26,629 specimes, distributed in 64 genera and 147 species of benthic foraminifera, however three showed a consistent pattern of abundance and distribution (Epistominella exigua, Alabaminella weddellensis and Cassidulina californica). Using data distribution of fauna and regression analysis it was possible to subdivide the interval studied in three subintervals. The subintervals A (oldest, between 2,037 and 1,946 cm) and C (latest, between ~1,509 and 849 cm), had moments of dominance with high E. exigua abundance, high density of foraminifera specimens per gram of sediment (ind/g) and low diversity. The species E. exigua is opportunistic and able to reproduce rapidly, in response to seasonal phytodetritus deposits. This suggests that in these two moments have occurred considerable influx of phytodetritic organic matter to the seafloor and a consequent increase in the abundance of E. exigua, which conditioned a fauna with high dominance and low diversity. Already the subinterval B, intermediate chronostratigraphically (between 1.910 and ~1.529 cm), presented a more diverse community of foraminifera, with high abundance of infaunal morphotypes, low density and low abundance of E. exigua. This data suggest a moment of greater environmental stability, and the absence of considerable phytodetritical organic matter flow to the seafloor, enabling an increase of diversity in the community of foraminifera. The species C. californica, in spite of being the most present infaunal species in the core, has no statistical relationship with the abundance of this morphotype, and presented its highest values in subintervals A and B, suggesting that other paleoenvironmental factors have controlling their populations, usually associated with the presence of large amounts of total organic carbon in sediment-water interface. An opposition abundance of A. weddellensis with E. exigua indicates moments that suffered different types of phytodetritc flow deposited in seasonal pulses (subintervals A and C) and interspersed with periods where the deposition of organic matter occurred mo]]> Fri, 31 May 2013 12:59:06 GMT https://pt.slideshare.net/slideshow/bergamaschi-2012-22255828/22255828 micaellua1@slideshare.net(micaellua1) Paleoenvironmental interpretations of Middle Pleistocene from benthic foraminifera of Santos basin, Brazil micaellua1 Pleistocene (2.58 million years to 12,000 years ago) was a very dynamic period in geologic history of Earth, characterized by large climatic fluctuations that changed the conditions of the environments on the planet and regulated the distribution of marine biodiversity. Foraminifera are protists mostly marine, very sensitive to environmental changes, and widely used in paleoecological studies. The present study aims to examine the benthic foraminiferal associations from the core BS-A, in order to contribute to knowledge about the paleoecological and paleoenvironmental characteristics of Middle Pleistocene. The core examined was collected at a depth of 2,141 m on the continental slope of the Santos basin and has continues recovery of 20.65 m of sediment. Were selected 25 samples belonging to Middle Pleistocene, processed within the standard methodology for calcareous microfossils. We identified 26,629 specimes, distributed in 64 genera and 147 species of benthic foraminifera, however three showed a consistent pattern of abundance and distribution (Epistominella exigua, Alabaminella weddellensis and Cassidulina californica). Using data distribution of fauna and regression analysis it was possible to subdivide the interval studied in three subintervals. The subintervals A (oldest, between 2,037 and 1,946 cm) and C (latest, between ~1,509 and 849 cm), had moments of dominance with high E. exigua abundance, high density of foraminifera specimens per gram of sediment (ind/g) and low diversity. The species E. exigua is opportunistic and able to reproduce rapidly, in response to seasonal phytodetritus deposits. This suggests that in these two moments have occurred considerable influx of phytodetritic organic matter to the seafloor and a consequent increase in the abundance of E. exigua, which conditioned a fauna with high dominance and low diversity. Already the subinterval B, intermediate chronostratigraphically (between 1.910 and ~1.529 cm), presented a more diverse community of foraminifera, with high abundance of infaunal morphotypes, low density and low abundance of E. exigua. This data suggest a moment of greater environmental stability, and the absence of considerable phytodetritical organic matter flow to the seafloor, enabling an increase of diversity in the community of foraminifera. The species C. californica, in spite of being the most present infaunal species in the core, has no statistical relationship with the abundance of this morphotype, and presented its highest values in subintervals A and B, suggesting that other paleoenvironmental factors have controlling their populations, usually associated with the presence of large amounts of total organic carbon in sediment-water interface. An opposition abundance of A. weddellensis with E. exigua indicates moments that suffered different types of phytodetritc flow deposited in seasonal pulses (subintervals A and C) and interspersed with periods where the deposition of organic matter occurred mo <img style="border:1px solid #C3E6D8;float:right;" alt="" src="https://cdn.slidesharecdn.com/ss_thumbnails/bergamaschi2012-130531125906-phpapp02-thumbnail.jpg?width=120&amp;height=120&amp;fit=bounds" /><br> Pleistocene (2.58 million years to 12,000 years ago) was a very dynamic period in geologic history of Earth, characterized by large climatic fluctuations that changed the conditions of the environments on the planet and regulated the distribution of marine biodiversity. Foraminifera are protists mostly marine, very sensitive to environmental changes, and widely used in paleoecological studies. The present study aims to examine the benthic foraminiferal associations from the core BS-A, in order to contribute to knowledge about the paleoecological and paleoenvironmental characteristics of Middle Pleistocene. The core examined was collected at a depth of 2,141 m on the continental slope of the Santos basin and has continues recovery of 20.65 m of sediment. Were selected 25 samples belonging to Middle Pleistocene, processed within the standard methodology for calcareous microfossils. We identified 26,629 specimes, distributed in 64 genera and 147 species of benthic foraminifera, however three showed a consistent pattern of abundance and distribution (Epistominella exigua, Alabaminella weddellensis and Cassidulina californica). Using data distribution of fauna and regression analysis it was possible to subdivide the interval studied in three subintervals. The subintervals A (oldest, between 2,037 and 1,946 cm) and C (latest, between ~1,509 and 849 cm), had moments of dominance with high E. exigua abundance, high density of foraminifera specimens per gram of sediment (ind/g) and low diversity. The species E. exigua is opportunistic and able to reproduce rapidly, in response to seasonal phytodetritus deposits. This suggests that in these two moments have occurred considerable influx of phytodetritic organic matter to the seafloor and a consequent increase in the abundance of E. exigua, which conditioned a fauna with high dominance and low diversity. Already the subinterval B, intermediate chronostratigraphically (between 1.910 and ~1.529 cm), presented a more diverse community of foraminifera, with high abundance of infaunal morphotypes, low density and low abundance of E. exigua. This data suggest a moment of greater environmental stability, and the absence of considerable phytodetritical organic matter flow to the seafloor, enabling an increase of diversity in the community of foraminifera. The species C. californica, in spite of being the most present infaunal species in the core, has no statistical relationship with the abundance of this morphotype, and presented its highest values in subintervals A and B, suggesting that other paleoenvironmental factors have controlling their populations, usually associated with the presence of large amounts of total organic carbon in sediment-water interface. An opposition abundance of A. weddellensis with E. exigua indicates moments that suffered different types of phytodetritc flow deposited in seasonal pulses (subintervals A and C) and interspersed with periods where the deposition of organic matter occurred mo
from Micael Lu Bergamaschi
]]> 2123 3 https://cdn.slidesharecdn.com/ss_thumbnails/bergamaschi2012-130531125906-phpapp02-thumbnail.jpg?width=120&height=120&fit=bounds document White http://activitystrea.ms/schema/1.0/post http://activitystrea.ms/schema/1.0/posted 0 https://cdn.slidesharecdn.com/profile-photo-micaellua1-48x48.jpg?cb=1523282304 Graduated in Biological Sciences (BSc) from Universidade do Vale do Rio dos Sinos (UNISINOS). Developed his BSc thesis with benthic foraminifera from Middle Pleistocene of Santos Basin. Scholarship during 4 years (2008-2012) at Institute of Micropaleontology (ITT FOSSIL/UNISINOS), with experience in micropaleontology and studies based on Quaternary foraminifera. Currently working at Research Center of Petrobras (CENPES/PDGEO/BPA) with Quaternary biostratigraphic zonation based on planktonic foraminifera. With experience in micropaleontology, acting on the following topics: planktonic and benthic foraminifera, biostratigraphy, paleoecology and palaeoceanography from Quaternary period. ... http://www.flickr.com/micaellua