radiolaria - Marum

Radiolaria 14 Bibliography - 1991
to the Queen Charlotte Islands taxa, and illustrates some new forms.
One ammonite and J7 radiolarian species are illustrated.
Catalano, R., Di Stefano, P. & Kozur, H. 1991.
Permian circumpacific deep-water faunas from the western
Tethys (Sicily, Italy) - new evidences for the position of the
Permian Tethys. Palaeogeogr. Palaeoclimatol. Palaeoecol.,
87/1-4, 75-108.
Circumpacific deep-water faunas, characterized mainly by
radiolarians, paleopsychrospheric ostracods and conodonts, were
found in the early, middle and late Permian deposits pertaining to the
Sicanian paleogeographic domain of western Sicily, near the western
end of the Eurasiatic Tethys. Similar Permian deep-water faunas are
known from the Phyllite Unit of Crete and from Oman in the latter
area partly above oceanic crust. All these occurrences indicate the
presence of a late Paleozoic Tethys ocean immediately north of
Gondwana.
Caulet, J.P. 1991. Radiolarians from the Kerguelen
Plateau, Leg 119. In: Proceedings of the Ocean Drilling
Program, Scientific Results. (Barron, J., Larsen, B. et al.,
Eds.), vol. 119. College Station, TX (Ocean Drilling
Program), pp. 513-546.
Radiolarians are abundant and well preserved in the Neogene of
the Kerguelen Plateau. They are common and moderately to well
preserved in the Oligocene sequences of Site 738, where the
Eocene/Oligocene boundary was observed for the first time in
subantarctic sediments, and Site 744. Radiolarians are absent from
all glacial sediments from Prydz Bay.
Classical Neogene stratigraphic markers were tabulated at all
sites. Correlations with paleomagnetic ages were made at Sites 745
and 746 for 26 Pliocene-Pleistocene radiolarian events. Many
Miocene to Holocene species are missing from Sites 736 and 737,
which were drilled in shallow water (less than 800 m). The missing
species are considered to be deep-living forms.
Occurrences and relative abundances of morphotypes at six
sites are reported. Two new genera (Eurystomoskevos and
Cymaetron) and 17 new species (Actinomma kerguelenensis, A.
campilacantha, Prunopyle trypopyrena, Stylodictya tainemplekta,
Lithomelissa cheni, L. dupliphysa, Lophophaena(?) thaumasia,
Pseudodictyophimus galeatus, Lamprocyclas inexpectata, L.
prionotocodon, Botryostrobus kerguelensis, B. rednosus, Dictyoprora
physothorax, Eucyrtidium antiquum, E.(?) mariae, Eurystomoskevos
petrushevskaae, and Cymaetron sinolampas) are described from the
middle Eocene to Oligocene sediments at Sites 738 and 744.
Twenty-seven stratigraphic events are recorded in the middle to late
Eocene of Site 738, and 27 additional stratigraphic datums are
recorded, and correlated to paleomagnetic stratigraphy, in the early
Oligocene at Sites 738 and 744. Eight radiolarian events are
recorded in the late Oligocene at Site 744.
New evolutionary lineages are proposed for Calocyclas
semipolita and Prunopyle trypopyrena.
Conti, M. & Marcucci, M. 1991. Radiolarian
assemblage in the Monte Alpe cherts at Ponte di Lagoscuro,
Val Graveglia (eastern Liguria, Italy). Eclogae geol. Helv.,
84/3, 791-817.
The Jurassic formation of Monte Alpe Cherts is the lowest unit
in the sedimentary cover of ophiolites and ophiolite breccias in the
Northern Apennines. A section of this formation has been studied at
Ponte di Lagoscuro, Val Graveglia (Liguria), and an exceptionally rich
radiolarian assemblage of middle Callovian age has been isolated
from chert nodules in its lower part. Several new species are
described in this assemblage
Csontos, L., Dosztály, L. & Pelikán, P. 1991.
Radiolarians from the Bükk Mts. M. All. Földtani Intézet évi
jelentése, 357-381. (in Hungarian)
We investigated radiolarite samples from the Bükk Mts, NE
Hungary. About one third of the samples yielded radiolarians of some
stratigraphic value. The highly silicified samples were macerated
with 4—6% hydrogene fluoride. The fossils were poorly preserved
because of silicification and deformation. However, they gave much
needed information about the different stratigraphic levels of the
two major structural units of the Bükk Mountains.
The stratigraphy of the Bükk Autochtonous has become more
detailed by the radiolarian finds in the borehole Felsotárkány 7. The
black radiolarite is accompanied here by acid volcanites, members of
the Aniso—Ladinian volcanic suite (Szent István-hegy Porphyry). The
radiolarians gave Ladinian age.
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In the higher stratigraphic levels of the Autochtonous mostly
red radiolarites occur in two close horizons: the first between the
diverse Triassic limestones and the black shales, and the second
within the black shales, very close to their base. The radiolarians
from the practically continuous lower horizon (samples Nos 8, 9, 10,
11, 12, 18, 19, 20, 21, 22, 26) and from the lenses within the
black shale (3, 13, 14, 15) indicated the same age: the boundary
between the Middle and Upper Jurassic, more precisely a Callovian—
Oxfordian age.
The strata of the Mónosbél—Szarvasko' nappes yielded
radiolarite lenses and layers from different parts of the proposed
stratigraphic column. Since the sediments of these nappes are the
result of intense reworking, the obtained ages are to be used with
great care.
Samples of the radiolarite lenses coming from the Western
Bükk area, from the close vicinity of the Szarvasko—type mafic
bodies (samples No 1, 2, 5) indicate Middle Jurassic or younger
ages. The layered black radiolarites found supposedly over this
stratigraphic level (4, 6, 7) show a Callovian—Oxfordian age.
The other samples are derived from the same nappe units but
from the Southeastern Bükk area. The radiolarite lens found in a
shale containing also limestone lenses yielded fossils of Bathonian—
Callovian age. The thick black chert (layered radiolarite and/or
sedimentary radiolarite breccia; samples No 24, 25) covering the
Bükkzsérc allodapic oolithic limestone of Late Dogger—Early
Malmian age, gave radiolarians of the same age.
We have a problematic sample (23) taken from an allodapic
limestone bed previously supposed to be of Late Liassic age, based
on foram finds. This black chert nodule gave badly preserved
radiolarians of Late Jurassic age. If this age is ascertained by
further work, we have to reevaluate the significance of the
foraminiferal ages and the model stratigraphic column of the
Mónosbél—Szarvasko nappes.
The recent radiolarian finds and works of MATSUOKA and YAO
(1986) and of AITA (1987) enable us to revaluate the stratigraphic
position of the Unuma echinatus zone. The fossils previously
described from the Bükk mountains (KOZUR 1984) belong to the
Tricolocapsa plicarum (= Ununa echinatus) zone, but unlike KOZUR
(1984), GRILL and KOZUR (1986), we think that the age of the zone
is Bathonian—Callovian. This stratigraphic position corresponds
much better to the reevaluated position of the zone by AITA (1987)
and to the fossils found now.
De Master, D.J., Nelson, T.M., Harden, S.L. &
Nittrouer, C.A. 1991. The cycling and accumulation of
biogenic silica and organic carbon in Antarctic deep-sea and
continental margin environments. Marine Chem., 35, 489-
502.
Rates of biogenic silica and organic carbon accumulation are
reported for Antarctic deep-sea and continental margin deposits.
Naturally occurring radionuclides ( 226 Ra, 231 Pa, and 230 Th) were
used to establish rates of sediment accumulation in the rapidly
accumulating siliceous deposits beneath the Antarctic Polar Front.
The rates were as high as 20-180 cm ka -1 , and when coupled with
biogenic silica and organic carbon measurements, yield accumulation
rates as high as 35 mg cm -2 year -1 for silica and 0.3 mg cm -2 year -1
for organic carbon. SiO2 /organic C weight ratios in Polar Front
sediments are typically about 100, although values as high as 300
were measured. Considering that the SiO2 /organic C ratio in Polar
Front plankton ranges from 0.5 to 2, the high ratios observed in
Polar Front sediments indicate that during settling and burial an
enrichment of 50-600-fold occurs in biogenic silica relative to
organic carbon.
Rates of sediment accumulation were determined for the
continental margin deposits of the Bransfield Strait and the Ross Sea
using 210 Pb and 14 C chronologies. Accumulation rates ranged from
0.02 to 0.5 cm year -1 . Based on these data and measurements of
biogenic silica and organic carbon content, typical rates of
accumulation on the continental margin are of the order of 3-12 mg
cm -2 year -1 for silica and 0.1-0.8 mg cm -2 year -1 for organic carbon.
The SiO 2 /organic C weight ratios in these continental margin
sediments range from 3 to 32. Comparing the accumulation rate
data with estimates of annual silica and organic carbon production
rates indicates that approximately 25-50% of the gross silica
production in surface waters is preserved in the sea-bed, in contrast
to less than 5% of the organic carbon. In some of the continental
margin environments, lateral transport of biogenic material can
create local areas where the rate of silica accumulation is equal to
as much as 70% of the production in the overlying water column. In
the Southern Ocean environments examined in this study, biogenic
silica is preferentially preserved in the sedimentary record relative
to organic carbon. This trend is consistent with the greater role of
Southern Ocean deposits in the global silica cycle as compared with
the organic carbon cycle.