Eocene to Miocene terrigenous inputs and export production: geochemical evidence from ODP Leg 177, Site 1090

Latimer, Jennifer C.; Filippelli, Gabriel M.

doi:10.1016/s0031-0182(01)00493-x

Cited by 99 publications

(88 citation statements)

References 42 publications

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“…However, the calcareous nannofossil record presented here strongly indicates an increased availability of nutrients in the low-latitude surface ocean, adding to the growing number of studies that document an increase in surface ocean productivity directly coincident with the EOT [Anderson and Delaney, 2005;Diester-Haass et al, 1996;Diester-Haass and Zachos, 2003;Latimer and Filippelli, 2002;Ravizza and Paquay, 2008;Salamy and Zachos, 1999]. This discrepancy between surface ocean productivity records and the extent of organic carbon burial across the EOT needs to be addressed and may indicate a widespread decoupling of productivity and carbon burial due to the increased ventilation of the deep ocean.…”

Section: Resultsmentioning

confidence: 55%

“…[4] Evidence for significant increases in primary production through the EOT has been documented at a number of deep-sea sites in the Southern Ocean [Anderson and Delaney, 2005;Diester-Haass et al, 1996;Latimer and Filippelli, 2002;Salamy and Zachos, 1999], probably driven by cooling induced increases in surface-ocean divergence and the associated upwelling of nutrient-rich deep waters and/or enhanced fluxes of weathering derived nutrients during rapid sea level fall [Nilsen et al, 2003;Salamy and Zachos, 1999;Zachos and Kump, 2005]. There is however a lack of comparable paleoproductivity records from the low latitudes [but see Diester-Haass and Zachos, 2003;Nilsen et al, 2003;Ravizza and Paquay, 2008] where quantifying changes in primary carbonate and silica fluxes at many deep-sea sites is hampered by the dramatic deepening of the carbonate compensation depth (CCD) and the associated shift from siliceous to calcareous sediments through the EOT [Nilsen et al, 2003].…”

Section: Introductionmentioning

confidence: 99%

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Major shifts in calcareous phytoplankton assemblages through the Eocene‐Oligocene transition of Tanzania and their implications for low‐latitude primary production

et al. 2008

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A high‐resolution record of exceptionally well preserved calcareous nannofossil assemblages from Tanzania is marked by two key transitions closely related to the climatic events of the Eocene‐Oligocene transition (EOT). The first transition, at ∼34.0 Ma, precedes the first positive shift in δ18O and coincides with a distinct interval of very low nannofossil abundance and a cooling in sea surface temperatures (SST). The second, at ∼33.63 Ma, is immediately above the Eocene‐Oligocene boundary (EOB) and is associated with a significant drop in nannofossil diversity. Both transitions involve significant reductions in the abundance of holococcoliths and other oligotrophic taxa. These changes in calcareous phytoplankton assemblages indicate (1) a widespread and significant perturbation to the low‐latitude surface ocean closely tied to the EOB, (2) a potential role for reduced carbonate primary production at the onset of global cooling, and (3) a significant increase in nutrient availability in the low‐latitude surface ocean through the EOT.

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Section: Resultsmentioning

confidence: 55%

Section: Introductionmentioning

confidence: 99%

Major shifts in calcareous phytoplankton assemblages through the Eocene‐Oligocene transition of Tanzania and their implications for low‐latitude primary production

et al. 2008

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“…While the uncertainty of organic carbon sources and its stability through time limits its use as proxy for lake productivity or paleo-redox conditions, phosphorous concentration is a useful indicator of paleo-productivity (Engstrom and Wright, 1984;Dean and Gorham, 1998;Boyle, 2001). In order to compensate for fluctuations in allochthonous (terrigenous) inputs of sediments to the ria lake, the P to Ti ratio was chosen as productivity indicator (Latimer and Filippelli, 2002;Filippelli et al, 2003). Average P/Ti values vary from 4.20 to 0.66 in suspended sediments of the Xingu River during the dry and wet seasons, respectively.…”

Section: Discussionmentioning

confidence: 99%

“…Seasonal changes in suspended sediments of the Xingu and Tapajós rivers include the increase in the relative amount of P in sediments of the dry season, which is directly related to primary productivity (Engstrom and Wright, 1984;Dean and Gorham, 1998). The P/Ti ratio is an effective proxy to evaluate the sedimentation of phosphorous regardless of terrigenous input and it avoids dilution effects caused by changes in sedimentation rate (Latimer and Filippelli, 2002;Filippelli et al, 2003). Average P/Ti ratios in the Xingu River vary from 0.66 in the wet season to 4.20 in the dry season.…”

Section: Geochemistry Of Suspended and Riverbed Sedimentsmentioning

confidence: 99%

The Fate of Carbon in Sediments of the Xingu and Tapajós Clearwater Rivers, Eastern Amazon

Bertassoli

Sawakuchi

et al. 2017

Front. Mar. Sci.

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The Xingu and Tapajós rivers in the eastern Amazon are the largest clearwater systems of the Amazon basin. Both rivers have "fluvial rias" (i.e., lake-like channels) in their downstream reaches as they are naturally impounded by the Amazon mainstem. Fluvial rias are widespread in the Amazon landscape and most of the sedimentary load from the major clearwater and blackwater rivers is deposited in these channels. So far, little is known about the role of Amazon rias as a trap and reactor for organic sediments. In this study, we used organic and inorganic geochemistry, magnetic susceptibility, diatom, and pollen analyses in sediments (suspended, riverbed, and downcore) of the Xingu and Tapajós rias to investigate the effects of hydrologic variations on the carbon budget in these clearwater rivers over the Holocene. Ages of sediment deposition (∼100 to 5,500 years) were constrained by optically stimulated luminescence and radiocarbon. Major elements geochemistry and concentration of total organic carbon (TOC) indicate that seasonal hydrologic variations exert a strong influence on riverine productivity and on the input and preservation of organic matter in sediments. Stable carbon isotope data (δ 13 C from −31.04 to −27.49‰) and pollen analysis indicate that most of the carbon buried in rias is derived from forests. In the Xingu River, diatom analysis in bottom sediments revealed 65 infrageneric taxa that are mostly well-adapted to slack oligotrophic and acidic waters. TOC values in sediment cores are similar to values measured in riverbed sediments and indicate suitable conditions for organic matter preservation in sediments of the Xingu and Tapajós rias at least since the mid-Holocene, with carbon burial rates varying from about 84 g m −2 yr −1 to 169 g m −2 yr −1 . However, redox-sensitive elements in sediment core indicate alternation between anoxic/dysoxic and oxic conditions in the water-sediment interface that may be linked to abrupt changes in precipitation. The variation between anoxic/dysoxic and oxic conditions in the water-sediment interface controls organic matter mineralization and methanogenesis. Thus, such changes promoted by hydrological variations significantly affect the capacity of Amazon rias to act either as sources or sinks of carbon.

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“…The timing for this is still controversially discussed. While Latimer and Filippelli (2002) suggest 32.8 Ma, Pfuhl and McCave (2005) argue for the opening of a deep Drake Passage near the Oligocene-Miocene boundary. Nevertheless, this led to a transition to dominantly glacial conditions with formation of bottom-water masses on the shelves and a build-up of large ice masses.…”

Section: Geological and Oceanographic Backgroundmentioning

confidence: 99%

Depositional patterns at Drift 7, Antarctic Peninsula: Along-slope versus down-slope sediment transport as indicators for oceanic currents and climatic conditions

Uenzelmann-Neben

2006

Marine Geology

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Understanding the processes and phases of deep-sea sediment drift formation is essential for a reconstruction of their evolution. This leads to a better understanding of the properties of oceanographic currents active during drift formation and in turn to information on the climatic conditions. A system of sediment drifts at the Antarctic Peninsula Pacific rise has been chosen to learn more about the Neogene evolution of both current systems and palaeo-climate in that area. Drift 7 was extensively surveyed (seismic and sampling), and two ODP Leg 178 sites were drilled there. Using this information, maps of reflectors depth and seismic unit thickness were compiled and interpreted regarding the controlling depositional processes. The depositional model shows an initially major along-slope sediment transport by a SW-setting bottom current (25-15 Ma), which deflected sediment supplied from the continental shelf. Between 15 Ma and 9.5 Ma down-slope transport took over as a result of the growth of the Antarctic Peninsula ice sheet. The SW setting bottom current appears to have broken down. Down-slope transport has decreased since 9.5 Ma, but a re-onset of the bottom current can only be observed since 5.3 Ma. The analysis has further shown that the nucleus of the drift is connected to a basement ridge. It is hence inferred that basement topography played a major role in the formation of this sediment drift.

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Eocene to Miocene terrigenous inputs and export production: geochemical evidence from ODP Leg 177, Site 1090

Cited by 99 publications

References 42 publications

Major shifts in calcareous phytoplankton assemblages through the Eocene‐Oligocene transition of Tanzania and their implications for low‐latitude primary production

Major shifts in calcareous phytoplankton assemblages through the Eocene‐Oligocene transition of Tanzania and their implications for low‐latitude primary production

The Fate of Carbon in Sediments of the Xingu and Tapajós Clearwater Rivers, Eastern Amazon

Depositional patterns at Drift 7, Antarctic Peninsula: Along-slope versus down-slope sediment transport as indicators for oceanic currents and climatic conditions

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