radiolaria - Marum

Radiolaria 14 Bibliography - 1992
& Aita, Y., Eds.), vol. 8 . News of Osaka
Micropaleontologists, special Volume, Osaka. pp. 9-19. (in
Japanese)
Middle Triassic and late Early to early Middle Jurassic
radiolarians are extracted from the rocks in the Khabarovsk
complex, at the outcrops to the south of the railway bridge over the
Amur River near Khabarovsk, eastern Russia. The Khabarovsk
complex is a tectonic melange which includes blocks and slices of
chert, siliceous shale, sandstone, basalt, limestone, and psammitic
and pelitic schists within sheared shale matrices.
Two rock samples of reddish brown bedded chert yield Middle
Triassic radiolarians, such as Triassocampe deweveri,
Pseudostylosphaera cf. japonica and P. cf. tenue. One rock sample of
reddish brown siliceous shale yields late Early Jurassic radiolarians,
such as Hsuum hisuikyoense, Tricolocapsa plicarum and
Eucyrtidiellum sp. A. Another rock sample of reddish brown siliceous
shale yields early Middle Jurassic radiolarians, such as Tricolocapsa
plicarum, T. (?) fusiformis and Stichocapsa japonica. These Jurassic
radiolarian assemblages are almost coeval with the Laxtorum (?)
jurassicum Zone and Tricolocapsa plicarum Zone (MATSUOKA and
YAO, 1986), respectively. Lithology, structure, and ages of the
rocks in the Khabarovsk complex is very similar to those of the
sedimentary complexes in the Mino terrane (central Japan) and in
the Nadanhada region (Northeast China). The evidence suggests that
the complexes of the three regions belong to a single disrupted
terrane in Jurassic to early Cretaceous time.
Wang, Y.J. & Yang, Q. 1992. Neogene and Quaternary
radiolarians from Leg 125. In: Proceedings of the Ocean
Drilling Program, Scientific Results. (Freyer, P., Pearce,
J.A., Stokking, L.B. et al., Eds.), vol. 125. College
Station, TX (Ocean Drilling Program), pp. 95-112.
Radiolarians were recovered from three of the five holes
investigated during Leg 125. Relative abundances are estimated at
Holes 782A and 784A, where preservation is poor to good. Rare,
poorly preserved radiolarians are present in Hole 786A. Seven
radiolarian zones are recognized in the latest early- middle Miocene
to early Pleistocene of Holes 782A and 784A. These zones are
approximately correlated to the zones of Sanfilippo and others
published in 1985.
Welling, L.A., Pisias, N.G. & Roelofs, A.K.
1992. Radiolarian microfauna in the northern California
Current System: indicators of multiple processes controlling
productivity. In: Upwelling Systems: Evolution Since the
Early Miocene. (Summerhayes, C.P., Prell, W.L. & Emeis,
K.C., Eds.), vol. 64. Geological Society of London, special
Publication, London, U. K. pp. 177-194.
Radiolaria. as other plankton, appear to be highly tuned to
specific oceanographic environments. Thus, in a transitional region
such as the eastern North Pacific, where many different water
masses are mixed, Radiolaria provide very sensitive tracers of these
water masses and the currents that carry them. We present the first
two years of radiolarian results from the Multitracers sediment trap
study across the northern California Current System. Three
moorings. positioned along a transect at approximately 130, 280
and 650 km from the coast. sample a wide variety of oceanographic
conditions both spatially and temporally. Selected species or species
groups are presented along with hydrographic data from the region in
order to demonstrate the basic trends in the radiolarian data and
illustrate their relationships to fluctuations in their physical
environment. Multiple linear regression is used to explore the
relationship between radiolarian composition and the export of
carbon from this system.
The most important physical process controlling variability in
the radiolarian composition along this transect is attributed to
variability in the intensity of the southward-flowing California
Current. The seasonality of the California Current is clearly
reflected by changes in the composition of the radiolarian trap
assemblages; very different species dominate this region in summer
as compared to winter. In addition to seasonal trends, evidence in
both the offshore and onshore environments suggests significant
differences between years. This region appears to have been more
strongly influenced by cold. subarctic water during the winter of
1988/1989 than during the previous year. The relationship between
radiolarian species abundances and the fluxe of organic carbon
strongly indicates that a number of different oceanographic
processes contribute to enhanced productivity at these sites. This
has important implications when making inferences from the
geological record about past changes in the intensity of upwelling in
this eastern boundary current system.
White, L.D., Garrison, R.E. & Barron, J.A. 1992.
Miocene intensification of upwelling along the California
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margin as recorded in siliceous facies of the Monterey
Formation and offshore DSDP sites. In: Upwelling Systems:
Evolution Since the Early Miocene. (Summerhayes, C.P.,
Prell, W.L. & Emeis, K.C., Eds.), vol. 64. Geological
Society of London, special Publication, London, U.K. pp.
429-442.
Diatomaceous sediments and their diagenetic equivalents in the
Monterey Formation record a variable history of upwelling along the
California margin. Distinctive dark opal-CT and quartz cherts found
in distal basins of the Monterey Formation are the result of burial
diagenesis of pure biosiliceous oozes (biosiliceous oozes without
significant admixtures of clay) and arc therefore evidence of
intensified coastal upwelling during the early middle Miocene. Dating
of six sections of the Monterey Formation, Iargely by diatom
biostratigraphy, suggests that at the Point Reyes and Point Año
Nuevo sections in north-central California. the age of the earliest
chert intervals is between 13.8 and 15.0 Ma. and 14.3 and 14.8
Ma. respectively. In south-central California. ages from the Shell
Beach, Mussel Rock. and Lions Head sections imply that the age of
the base of the chert intervals is between 12.7 and 13.3 Ma. Both
ages correlate to an early middle Miocene high latitude cooling step
that resulted in more vigorous surface water circulation. upwelling of
nutrient-rich waters, and increased biosiliceous sedimentation in the
North Pacific. The north-south difference in age of the base of the
chert interval probably reflects a progressive intensification of the
California Current from 15.0 to 12.7 Ma.
The age of the onset of biosiliceous sedimentation at DSDP
sites of the northeastern Pacific is also generally younger at the
more southern sites; however, these particular DSDP sites were
located some distance from the centres of coastal upwelling and arc
not as reliable indicators of the intensification of upwelling along the
California margin.
Widz, D. 1992. Datation par les radiolaires des radiolarites
jurassiques de l'Unité de Grajcarek (Zone des Klippes de
Pieniny, Carpathes occidentales, Pologne). Bull. pol. Acad.
Sci. (Earth Sci.), 40/2, 115-124.
The present study of the radiolarian fauna collected from the
Grajcarek Unit provides evidence for the presence of Upper Jurassic
Unitary Associations: U.A. 7-8 (Kimmeridgian), U.A. 8 (Upper
Oxfordian), U.A. 9 (Kimmeridgian). A correlation between eastern
and western parts of the Grajcarek Unit has been established. The
biostratigraphic age determination suggests the synchronous
disappearance of radiolarites (Kimmeridgian) and distinctive
diachronism of lithofacies within them
Wu, H.R. & Pan, Z.P. 1992. Paleozoic sedimentary
sequences and their tectonic setting discrimination in
Western Junggar, Xingjiang, China. Adv. Geosci., 2, 246-
274.
In west Junggar. there are large areas of Paleozoic marine
volcanic-sedimentary clastic sequence associated with ophiolite
melange. Usually a normal sedimentary sequence is in fault-contact
with an older ophiolitic complex. Petrographic sedimentary features
indicate that they are deep-sea turbidites. Mineral and geochemical
evidences. including QFL and QmFLT plots, SiO2 vs K2O/Na2O and
SiO2 /AI2O 3 vs K2O/Na2O plots. TiO2 % ,AI2O 3 /SiO2 , K2O/Na2O, Al2O3 /(CaO/Na2O) vs +MgO% plots, and Th-Sc-Zr. Th-Co-
Zr, La-Th-Sc, Ti/Zr-La/Sc plots. indicate the volcanic arc provenance
for the clastic sequences and the sedimentary basins relating to
oceanic island are . continental island are and active continental
margin. It is clear that during the Paleozoic time there was a west
Junggar ocean characterized by the complicated island arcs and
deep water basins. This ocean might be a part of paleo-ocean
between the Sibirian plate. Kazakhstan plate and Tarim plate. The
variation from the Ordovician-Silurian oceanic island arc or
undissected and transitional arc to the Devonian-Carboniferous
continental island arc or dissected and transitional arc shows the
moving of west Junggar ocean from pelagic environment toward
continental margin.
Yamamoto, K. 1992. Composition and diversity of
radiolarian fossil assemblages: Case study on Upper
Cretaceous Futakawa Formation, Sotoizumi Group. In:
Proceedings of the Third Radiolarian Symposium. (Sakai, T.
& Aita, Y., Eds.), vol. 8 . News of Osaka
Micropaleontologists, special Volume, Osaka. pp. 77-88. (in
Japanese)
Radiolarian fossil assemblages from the Upper Cretaceous
Futakawa Formation, Sotoizumi Group, Southwest Japan were
preliminary studied in order to clarify their composition, diversity
and dominant species. Some methods of quantitative analysis for
radiolarian assemblages are used herein. Through this study, the
assemblages from the Futakawa Formation were characterized by a