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Boersma, Anne (1990): Benthic foraminifera of the central Indian Ocean [dataset publication series]. PANGAEA, https://doi.org/10.1594/PANGAEA.756728, Supplement to: Boersma, A (1990): Late Oligocene to late Pliocene benthic foraminifers from depth traverses in the central Indian Ocean. In: Duncan, RA; Backmann, J; Peterson, LC; et al. (eds.), Proceedings of the Ocean Drilling Program, Scientific Results, College Station, TX (Ocean Drilling Program), 115, 315-379, https://doi.org/10.2973/odp.proc.sr.115.146.1990

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Abstract:
Late Oligocene to late Pliocene vertical water-mass stratification along depth traverses in the northern Indian Ocean is depicted in this paper by benthic foraminifer index faunas. During most of this time, benthic faunas indicate well-oxygenated, bottom-water conditions at all depths except under the southern Indian upwelling and in the Pliocene in the southern Arabian Sea.
Faunas suggest the initiation of lower oxygen conditions at intermediate depths in the northern Indian Ocean beginning in Oligocene Zone P21a. Lower oxygen conditions intensified during primary productivity pulses, possibly related to increased upwelling vigor, in the latest Oligocene and throughout most of the late middle through late Miocene. During times of elevated primary production, there may be more oxygen flux into sedimentary pore waters and the shallow infaunal habitat may become more oxygenated.
One criterion for locating the source of "new" water masses is vertical homogeneity of benthic foraminifer indexes for well-oxygenated water masses from intermediate through abyssal depths. In the northern Mascarene Basin, this type of faunal homogeneity with depth corroborates the proposal that the northern Indian Ocean was an area of sinking well-oxygenated waters through most of the Miocene before Zone N17.
Oxygenated, possibly "new" intermediate-water masses in the low- to middle-latitude Mascarene and Central Indian basins first developed in the late Oligocene. These well-oxygenated waters were probably more fertile than the Antarctic Intermediate Waters (AAIW) that cover intermediate depths in these areas today. Production of intermediate waters more similar to modern AAIW is indicated by the sparse benthic population of epifaunal rotaloid species in the northern Mascarene Basin during middle Miocene Zone N9 and from early through late Pliocene time.
Deep-water characteristics are more difficult to interpret because of the extensive redeposition at the deeper sites. Redeposited intermediate, rather than shallow, water fossils and erosion from north to south in the Mascarene Basin are incompatible with the sluggish circulation from south to north through the western Indian Ocean basins today. Such erosion could result from the vigorous sinking of an intermediate-depth water mass of northern origin.
Before late Oligocene Zone P22, benthic faunas indicate a twofold subdivision of the troposphere, with the boundary between upper and lower well-oxygenated water masses located from 2500-3000 mbsl. No characteristic bottom-water fauna developed before the end of late Oligocene Zone P22.
Deep and abyssal benthic indexes suggest the development of water masses similar to those of the present day in the latest Miocene. Faunas containing deep-water benthic indexes, including the uvigerinids, suggestive of a water mass similar to modern Indian Deep Water (IDW), appeared during the late Miocene in the northern Mascarene and Central Indian basins. In the early Pliocene, this deep-water fauna was found only in the Central Indian Basin, whereas a fauna typical of modern Antarctic Bottom Water (AABW) spread through deep waters at 2800 mbsl in the Mascarene Basin. By late Pliocene Zone N21, however, deep-water faunas similar to their modern analogs were developed in both the eastern and western basins.
Abyssal faunas, studied only in the Mascarene Basin, show more or less similarity to those under modern AABW. Bottom-water faunas containing Nuttallides umbonifera or Epistominella exiguua were first differentiated at the end of Zone P22, then appeared episodically during the early Miocene. These AABW-type faunas reappeared and migrated updepth into deep waters during the glacial episodes at the end of the Miocene and at the beginning of the Pliocene. By late Pliocene Zone N21, however, a bottom-water fauna similar to that under eastern Indian Bottom Water (IBW) developed in the Mascarene Basin. Modern bottom-water characteristics of the Mascarene Basin must have developed after ZoneN21.
Project(s):
Deep Sea Drilling Project (DSDP)
Ocean Drilling Program (ODP)
Coverage:
Median Latitude: -3.330333 * Median Longitude: 70.872176 * South-bound Latitude: -24.877500 * West-bound Longitude: 59.016800 * North-bound Latitude: 9.029200 * East-bound Longitude: 90.538800
Date/Time Start: 1972-02-08T00:00:00 * Date/Time End: 1987-06-28T07:45:00
Event(s):
22-214 * Latitude: -11.336800 * Longitude: 88.718000 * Date/Time: 1972-02-08T00:00:00 * Elevation: -1655.0 m * Penetration: 500 m * Recovery: 340.9 m * Location: Indian Ocean//RIDGE * Campaign: Leg22 * Basis: Glomar Challenger * Method/Device: Drilling/drill rig (DRILL) * Comment: 53 cores; 492.5 m cored; 2.5 m drilled; 69.2 % recovery
22-216 * Latitude: 1.462200 * Longitude: 90.208000 * Date/Time: 1972-02-18T00:00:00 * Elevation: -2237.0 m * Penetration: 477.5 m * Recovery: 169.2 m * Location: Indian Ocean//RIDGE * Campaign: Leg22 * Basis: Glomar Challenger * Method/Device: Drilling/drill rig (DRILL) * Comment: 38 cores; 353 m cored; 0 m drilled; 47.9 % recovery
22-217 * Latitude: 8.926200 * Longitude: 90.538800 * Date/Time: 1972-02-24T00:00:00 * Elevation: -3010.0 m * Penetration: 614.5 m * Recovery: 181.6 m * Location: Indian Ocean//RIDGE * Campaign: Leg22 * Basis: Glomar Challenger * Method/Device: Drilling/drill rig (DRILL) * Comment: 35 cores; 326.5 m cored; 9.5 m drilled; 55.6 % recovery
License:
Creative Commons Attribution 3.0 Unported (CC-BY-3.0)
Size:
18 datasets

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Datasets listed in this publication series

  1. Boersma, A (1990): (Table 4) Ranges of benthic foraminifers from the early Oligocene to the early Miocene in DSDP Hole 22-214. https://doi.org/10.1594/PANGAEA.756701
  2. Boersma, A (1990): (Table 6) Ranges of benthic foraminifers through the Oligocene in DSDP Hole 22-216. https://doi.org/10.1594/PANGAEA.756703
  3. Boersma, A (1990): (Table 8) Ranges of benthic foraminifers through the Oligocene in DSDP Hole 22-217. https://doi.org/10.1594/PANGAEA.756705
  4. Boersma, A (1990): (Table 18) Ranges of benthic foraminifers through the Neogene in DSDP Hole 23-219. https://doi.org/10.1594/PANGAEA.756722
  5. Boersma, A (1990): (Table 10) Ranges of benthic foraminifers through the Oligocene in DSDP Hole 24-238. https://doi.org/10.1594/PANGAEA.756708
  6. Boersma, A (1990): (Table 7) Ranges of benthic foraminifers through the Oligocene in DSDP Hole 26-253. https://doi.org/10.1594/PANGAEA.756704
  7. Boersma, A (1990): (Table 3) Ranges of benthic foraminifers from the late Eocene through the Oligocene in ODP Hole 115-707A. https://doi.org/10.1594/PANGAEA.756698
  8. Boersma, A (1990): (Table 12) Ranges of benthic foraminifers through the Miocene in ODP Hole 115-707A. https://doi.org/10.1594/PANGAEA.756711
  9. Boersma, A (1990): (Table 19) Ranges of benthic foraminifers from the late Neogene through the Pleistocene in ODP Hole 115-707A. https://doi.org/10.1594/PANGAEA.756726
  10. Boersma, A (1990): (Table 15) Ranges of benthic foraminifers through the early-middle Miocene in ODP Hole 115-709A. https://doi.org/10.1594/PANGAEA.756718
  11. Boersma, A (1990): (Table 20) Ranges of benthic foraminifers from the late Neogene through the Pleistocene in ODP Hole 115-709A. https://doi.org/10.1594/PANGAEA.756727
  12. Boersma, A (1990): (Table 11) Ranges of benthic foraminifers through the Oligocene in ODP Hole 115-709C. https://doi.org/10.1594/PANGAEA.756709
  13. Boersma, A (1990): (Table 16) Ranges of benthic foraminifers through the Neogene in ODP Hole 115-710A. https://doi.org/10.1594/PANGAEA.756720
  14. Boersma, A (1990): (Table 9) Ranges of benthic foraminifers through the Oligocene in ODP Hole 115-710A. https://doi.org/10.1594/PANGAEA.756707
  15. Boersma, A (1990): (Table 17) Ranges of benthic foraminifers through the late Neogene in ODP Hole 115-713A. https://doi.org/10.1594/PANGAEA.756721
  16. Boersma, A (1990): (Table 5) Ranges of benthic foraminifers from the late Oligocene to the early Miocene in ODP Hole 115-714A. https://doi.org/10.1594/PANGAEA.756702
  17. Boersma, A (1990): (Table 14) Ranges of benthic foraminifers through the Neogene in ODP Hole 115-714B. https://doi.org/10.1594/PANGAEA.756716
  18. Boersma, A (1990): (Table 13) Ranges of benthic foraminifers through the early to middle Miocene in ODP Hole 115-715A. https://doi.org/10.1594/PANGAEA.756713