radiolaria - Marum

Radiolaria 14 Bibliography - 1991
open ocean sites. The combined marine pollen and radiolarian
records indicate changes in the Sea of Okhotsk's physical
oceanographic conditions and surrounding vegetation during the late
glaciaI which were associated with this region's response to global
climate change.
Motoyama, I. 1991. 3-2 Radiolaria. In: Preliminary
results on Tansei-maru Cruise KT90-9 in Forearc Areas off
Northern Tohoku and Hokkaido, and Sagami Bay, Japan.
(Tsukawaki, S. & Nemoto, N., Eds.), vol. 38/1. Sci. Rep.
Hirosaki Univ., pp. 61-62.
Nagai, H. & Mizutani, S. 1991. Jurassic Radiolarians
from Tsuzuya, Minokamo City, Central Japan. Bull. Nagoya
Univ. Furukawa Mus., 7, 1-13. (in Japanese)
Jurassic radiolarians extracted from siliceous shale exposed at
Tsuzuya, Minokamo City, Gifu Prefecture. are briefly described. They
range in age from the middle Jurassic to the lower part of the upper
Jurassic, and are partly correlative with those of the Dictyomitrella
(?) kamoensis-Pantanellium foveatum assemblage commonly found
in the Mino terrane, central Japan. Geologically, however, it is worthy
to note that the siliceous shale of the study area is much thicker
than the other areas so far described despite of the same
biostratigraphic horizon. This implies 1) the siliceous shale of the
study area is more or less different in its sedimentary facies from
that of the other areas, and is truly well developed and thicker, or 2)
the siliceous shale is duplicated or triplicated owing to the structural
deformation after the deposition. The present study is carried out to
find a relationship between the radiolarian assemblage and the
sedimentary facies or geological structures, and it describes
common species of the radiolarians found in the siliceous shale of
the Mino terrane.
Nakae, S. 1991. Latest Jurassic radiolarians from the
Miyama area in the Tamba Terrane and their significance. J.
geol. Soc. Japan, 97/5, 385-387. (in Japanese)
Nelson, D.M., Ahern, J.A. & Herlihy, L.J. 1991.
Cycling of biogenic silica within the upper water column of
the Ross Sea. Marine Chem., 35, 461-476.
We determined the distributions of biogenic particulate silica
and dissolved silicic acid in the upper 80 m over the continental
shelf of the southern Ross Sea, Antarctica, during two occupations
of an east-west transect at 76°30'S in mid-January and early
February 1990. There was a persistent (at least 3.5 weeks in
duration) diatom bloom within a surface meltwater lens extending
100-150 km seaward from the edge of the receding pack ice, with
biogenic silica concentrations frequently exceeding 20 µmol l -1 in
the upper 15 m. There were also other significant maxima in biogenic
silica, with concentrations greater than 7 µmol l -1 at distances of
250-500 km seaward of the ice edge. These maxima were
apparently unrelated to meltwater effects.
30
Si tracer experiments to measure the production and
dissolution rates of biogenic silica as a function of depth within the
upper 50 m at three stations within the ice-edge diatom bloom
indicate that the specific production rate (i.e. the rate per unit of
biogenic silica present) ranged from 0.05 to 0.12 day- 1 (0.07-0.17
doublings day -1 ). The resulting vertically integrated silica production
rates ranged from 27 to 50 mmol m -2 day -1 , with a mean of 34.
Vertically integrated rates of biogenic silica dissolution ranged from
16 to 28 mmol m -2 day -1 , with a mean of 22, or 64% of the mean
silica production rate. The mean resulting net rate of biogenic silica
production within the bloom, 12 mmol m -2 day -1, leads to an
estimated net annual silica production rate of 1.0 mol m -2 in the
upper 50 m of the southwestern Ross Sea. A revised silica budget
for the western Ross Sea, incorporating the most recent estimates
of production, redissolution, accumulation in the sediments and
efflux from the sea-- bed, indicates that virtually all silica exported
from the upper 50 m must reach the sea-floor unless advective
transport from the east is significant.
Nigrini, C. 1991. Composition and biostratigraphy of
radiolarian assemblages from an area of upwelling
(Northestern Arabian Sea, Leg 117). In: Proceedings of the
Ocean Drilling Program, Scientific Results. (Prell, W.J.,
Nitsuma, N. et al., Eds.), vol. 117. College Station, TX
(Ocean Drilling Program), pp. 89-126.
Significant numbers of radiolarians ranging in age from late
middle Miocene to Recent were recovered from six sites drilled on
the Oman margin and Owen Ridge. Sparse faunas were recovered
from five additional sites on the Oman margin and one site on the
Indus Fan. Detailed range charts and biozonations are presented for
most sites. The radiolarian assemblages are peculiar in that
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numerous common tropical forms, some of which are biomarkers, are
absent or very rare. In addition, some species not usually found in
tropical assemblages are present. These forms, indicative of
upwelling conditions, fall into three categories: (I) endemic upwelling:
species endemic to upwelling and not previously described from the
Indian Ocean; (2) displaced temperate: temperate forms not usually
found in tropical waters; and (3) enhanced tropical: tropical forms
which are more abundant and/or robust in areas of upwelling.
Comparison of the Oman margin/Owen Ridge fauna with that
recovered from the Peru margin upwelling area (ODP Leg 112)
suggests that the assemblage may be globally diagnostic of
upwelling conditions.
The onset of upwelling is marked by the appearance of siliceous
biota at about 11.9 Ma, and there is some indication of a decrease in
the strength of the upwelling signal at about 9.6 Ma. A strong pulse
in, or strengthening of, the upwelling mechanism is indicated by a
marked fauna change at 4.7 Ma. There is a weaker signal, implying a
change in upwelling conditions, at about 1.5 Ma.
Nöthig, E.M. & Gowing, M.M. 1991. Late winter
abundance and distribution of phaeodarian radiolarians, other
large protozooplankton, and copepod nauplii in the weddell
Sea, Antarctica. Marine Biol., 111, 473-484.
Large protozooplankton ( 400 µm) phaeodarian radiolarians;. contributed more than
98 % of the carbon h the large protozooplankton fraction; large
protozooplankton were approximately 38 % of the total
protozooplankton carbon during the late winter under the close pack
ice in the upper 250 m. This indicates that large protozooplankton
may be an important food source for small particle-feeding
zooplankton in the upper 250m, and a modest food source down to
l000m.
Phaeodarian species distributions showed a distinct vertical
pattern: Challengeron bicorne, Protocystis tridens, Phaeodina
antarctica and Cannosphaera antarctica were most abundant in the
upper water column; Protocystis micropelecus. Protocystis
triangularis, and the families Aulacanthidae, Aulosphaeridae, and
Coelodendridae were most abundant between 100 and 500 m; and
Protocystis harstoni, Euphysetta sp., and Porospathis sp. were
dominant in the deeper water. Except for spumellarian and
nassellarian radiolarians all other protozooplankton (foraminiferans,
thecate dinoflagellates, tintinnids) were most abundant in the upper
250 m. This vertical pattern changed slightly from west to east. The
horizontal variation showed a western, central and eastern pattern
most probably due to the differing regional hydrography.
Feeding ecology of the dominant species of phaeodarians was
examined using transmission electron microscopy of contents of
feeding vacuoles. The 58 specimens were trophic generalists, having
consumed a variety of detrital material, autotrophic and
heterotrophic protozoans, and bacteria. Silica fragments and
amorphous material dominated vacuole contents. Several lines of
evidence, including the similarity of vacuole contents of specimens
from 3 depth zones, suggest that phaeodarians in late winter may
have fed on organic aggregates.
Okada, H., Tarduno, J.A., Nakaseko, K.,
Nishimura, A. & Sliter, W.V. 1991. Reexamination of
the age of the uppermost sequence of the Sorachi Group in its
type area, Hokkaido, Japan. Mem. Fac. Sci., Kyushu Univ.,
Series D (Earth planet. Sci.), 27/1, 1-13.
The Sorachi Group of central Hokkaido is characterized by
hemipelagic sediments and ophiolitic rock associations. To
determine the precise age of the upper Sorachi Group, a key unit in
the geotectonic evolution of Hokkaido, radiolarian fossil
assemblages have been studied. The results indicate that the upper
Sorachi Group may be Albian in age, much younger than previously
believed. This age is similar to that obtained for the youngest
pelagites of the Nikoro Group of the Tokoro Belt, eastern Hokkaido,
although the paleoenvironmental and paleogeographic settings of the
two groups may well have differed.
Queguiner, B., Treguer, P. & Nelson, D.M. 1991.
The production of biogeneic silica in the Weddell and Scotia
Seas. Marine Chem., 35, 449-459.