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SITE-613
No full textThe general composition of the lithologic units at Site DSDP 613 varies only slightly from those at Site 612, but the style of decomposition is significantly different. Whereas evenbedded hemipelagic deposition prevailed most of the time at Site 612, the section at Site 613 is characterized by the frequent occurrence of slump deposits and conglomeratic, sandy, channel-fill deposits.- from Author
Quaternary benthic foraminifers from DSDP Sites 95-612 and 95-613
No full textThe Quaternary benthic foraminifers from Leg 95 Sites 612 and 613 were examined with respect to paleoceanographic trends. Data from the two sites indicate the presence of markedly different bottom-water masses, during both glacial and interglacial periods. The dominant interglacial species at Site 612 is Uvigerinct peregrina, which is barely present in corresponding intervals at Site 613. Dominant glacial species are Elphidium excavatum and Cassidulina reniforme at Site 612 and Epistominella takayanagii at Site 613
(Table 2) Ostracoda community from DSDP Hole 95-613
No full textSamples 95-613-12X-3,80-84; 95-613-13X-3,80-84; 95-613-18X-3,80-84; and 95-613-9X-3,80-84 barren
(Table 1) Gas molecules, isotopic composition and delta Deuterium in DSDP Holes 95-603D and 95-613
No full textMethane is the major hydrocarbon gas measured in Vacutainer samples from Holes 603D and 613 ( C1/sumCn > 0.999). In Hole 613 the concentration of this dry hydrocarbon gas is highest (7.4 x 10 **5 ppm max.) in the upper 60 to 120 m, then decreases erratically to low trace levels by 261 m sub-bottom (lower Pliocene). No gas accumulations were observed in older sediments. Methane from both holes is strongly depleted in both 13C (d13C, - 75 to -85 per mil) and deuterium (D/H, - 175 to -262 per mil), indicating the biogenic origin of the methane. The C and H isotopic compositions support methanogenesis via the CO2-reduction pathway; this is also corroborated by the dissolved-sulfate and alkalinity minima at these depths. The relationship between D/H of the methane and coexisting interstitial water from Site 613 further show the methanogenesis to be primarily by CO2 reduction
Neogene benthic foraminiferal community and organic carbon at DSDP Holes 95-612 and 95-613
No full textQuantitative study of benthic foraminifers from the upper Miocene to lower Pliocene section at Site 612 (1404 m present water depth) and the Pliocene section at Site 613 (2323 m present water depth) shows no evidence of widespread downslope transport of shallow-water biofacies or reworking of older material in the greater than 150 µm size fraction. In contrast, upper Miocene sediments from Site 604 (2364 m present water depth) show extensive reworking and downslope transport. At Site 612, benthic foraminifers show a succession from an upper Miocene Bolivina alata-Nonionella sp. biofacies, to an uppermost Miocene Bulimina alazanensis biofacies, to a lower Pliocene Cassidulina reflexa biofacies, to an upper Pliocene Melonis barleeanum-Islandiella laevigata biofacies. Evidence suggests that the Pliocene biofacies are in situ, although they could have been transported downslope from the upper-middle bathyal zone. At Site 613, Uvigerina peregrina dominated the "middle" Pliocene, while Globocassidulina subglobosa was dominant in the early and late Pliocene. High abundances of U. peregrina at Site 613 are associated with high values of sedimentary organic carbon
Diatom communities at DSDP Holes 95-612 and 95-613
No full textSamples from Sites 612 and 613 along the New Jersey transect were examined for diatoms, utilizing the processing methods of Abbott (1978) as well as heavy liquid concentrations. The diatom biostratigraphy at these two sites was difficult to interpret because of the apparent frequent reworking into a rare, poorly preserved, indigenous flora and the lack of stratigraphic markers. The actual numbers of specimens found per slide for each species are listed in Tables 1 and 2. Reworked species are indicated with an asterisk and are primarily of Miocene and Eocene age
Ostracoda communities from DSDP Holes 95-612 and 95-613
No full textNinety-three samples from DSDP Leg 95, Sites 612 and 613, were examined for ostracodes to aid in the study of paleoceanography and paleodepth. In total, more than 25 genera were recovered. The most abundant and diverse ostracode assemblages were from the middle Eocene at both sites; lower and upper Eocene and Pliocene-Pleistocene assemblages were less abundant and were dominated by only three or four species.
The middle Eocene assemblages were the most diagnostic of paleoenvironment and suggest water depths of 1000 to 2000 m. These assemblages are similar to other middle Eocene assemblages known from the Caribbean and North Atlantic, and signify a relatively cosmopolitan fauna that inhabited moderately deep but relatively warm bottom waters
Eocene siliceous and calcareous phytoplankton, Deep Sea Drilling Project Holes 95-612 and 95-613
No full textEocene siliceous and calcareous phytoplankton, with emphasis on silicoflagellates, were studied in 62 samples from DSDP Sites 612 and 613 on the continental slope and rise off New Jersey. The mid-latitude assemblages correlate well with assemblages from California, Peru, and offshore of southern Brazil, but are distinctly different from high-latitude cold-water assemblages of the Falkland Plateau off southern Argentina. Coccoliths and silicoflagellates provide evidence for the presence of a fairly complete middle and upper Eocene sequence, represented by a composite of Sites 612 and 613. A major unconformity occurs at the middle Eocene to upper Eocene contact at Site 612.
The genus Bachmannocena Locker is emended and proposed as a replacement for genus Mesocena Ehrenberg for ring silicoflagellates. Six new silicoflagellates and one new diatom are described: Bachmannocena apiculata monolineata Bukry, n. subsp., Corbisema amicula Bukry, n. sp., C. bimucronata elegans Bukry, n. subsp., C. hastata incohata Bukry, n. subsp., C. jerseyensis Bukry, n. sp., Dictyocha acuta Bukry, n. sp., and Coscinodiscus eomonoculus Bukry, n. sp. Also, one new replacement name, B. paulschulzn Bukry, nom. nov., and 24 new combinations are proposed for genus Bachmannocena
(Table 2) Diatom community at DSDP Hole 95-613
No full text# indicates reworked species. Samples examined from Cores 4 to 11 were barren of diatoms except for one specimen of Paralia sulcata (found in Sample 613-6-2, 50-52 cm)
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