radiolaria - Marum

Bibliography - 1993 Radiolaria 14
what we know from typical tethyan sequences. We conclude that the
Argo Basin was paleoceanographically separated from the Tethys
during the Late Jurassic and part of the Early Cretaceous by its
position at higher paleolatitudes and/or by enclosing land masses.
Assemblages recovered from radiolarian sand layers are
dominated by non-tethyan species that are interpreted as
circumantarctic. Their first appearance in the late Berriasian-early
Valanginian predates the oceanization of the Indo-Australian
breakup (Ml l, late Valanginian), but coincides with a sharp increase
in margin-derived pelagic turbidites. The Indo-Australian rift zone
and the adjacent margins must have been submerged deeply enough
to allow an intermittent influx of circumantarctic cold water into the
Argo Basin, creating increased bottom current activity. Cold-water
radiolarians carried into the Argo Basin upwelled along the margin,
died, and accumulated in radiolarite layers due to winnowing by
bottom currents. High rates of faunal change and the sharp increase
of bottom current activity are thought to be synchronous with
possible pronounced late Berriasian-early Valanginian lowstands in
sea level. Hypothetically, both phenomena might have been caused
by a tendency to glaciation on the Antarctic-Australian continent,
which was for the first time isolated from the rest of Gondwana by
oceanic seaways as a result of Jurassic-Early Cretaceous sea-floor
spreading.
The absence of most typical tethyan radiolarian species during
the Valanginian-Hauterivian is interpreted as reflecting a time of
strong influx of circumantarctic cold water following oceanization (M
11) and rapid spreading between Southeast India and West
Australia.
The reappearance and gradual abundance/diversity increase of
tethyan taxa, along with the still dominant circumantarctic species
are thought to result from overall more equitable climatic conditions
during the Barremian-early Aptian and from the establishment of an
oceanic connection with the Tethys Ocean during the early Aptian.
Blome, C.D. & Reed, K.M. 1993. Acid processing of
pre-Tertiary radiolarian cherts and its impact on faunal
content and biozonal correlation. Geology, 21/2, 177-180.
The numbers of radiolarians visible in thin sections of chertrich
rocks are commonly an order of magnitude greater than the
numbers observed on the surfaces of fragments etched by
hydrofluoric acid (HF) and typically orders of magnitude greater than
the numbers of individuals found in HF-processed residues.
Destruction of radiolarians during both diagenesis and HF processing
severely reduces faunal abundance and diversity and affects the
taxonomic and biostratigraphic utility of chert residues. The robust
forms that survive the processing represent only a small fraction of
the death assemblage, and delicate skeletal structures used for
species differentiation, commonly preserved in limestone radiolarian
faunas, are either poorly preserved or dissolved in many coeval
chert residues. First and last occurrences of taxa in chert
sequences are likely to be coarse approximations of their true
stratigraphic ranges. Precise correlation is difficult between
biozonations based solely on index species from cherts and those
constructed from limestone faunas. Careful selection of samples in
sequence, use of weaker HF solutions, and study of both chert and
limestone faunas should yield better biostratigraphic information.
Blueford, J. & Murchey, B. 1993. Radiolaria of giant
and subgiant fields in Asia. Nazarov Memorial Volume.
Micropaleontology Press Special Publication, vol. 6.
American Museum of Natural History , 200 p.
Throughout geologic time radiolarians have been major
contributors to world-wide siliceous deposits. Their robust skeletons
make them excellent candidates for preservation. The fact that
radiolarians can be traced in abundance back to the Ordovician with
unique evolutionary sequences, coupled with their planktonic
lifestyles that are indicative of various paleoenvironmental
conditions, make them ideal microfossils for stratigraphy and basin
analysis. In this volume, workers from Russia, China, and Japan
outline the usefulness of rads in stratigraphy, petrography, and
paleoenvironmental interpretations.
This book highlights the radiolarians found in important
hydrocarbon basins in the East Eurasian continent. Many of the
papers reflect an English summary of years of work by the authors
of this book. Originally this book was proposed as a collection of
papers in honor of Dr. Boris Nazarov, a pioneer in using Paleozoic
radiolarians. However, the recent opening of the former Soviet Union
to the outside put an urgency on obtaining information about these
basins. We then decided to weave a story about how radiolarians are
not only important in determining stratigraphy but also in evaluating
the paleoenvironments of these important hydrocarbon yielding
basins.
Blueford, J.R. & Amon, E.O. 1993. Comparing
elongated Spongodiscoidea (Radiolaria) from early Eocene
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deposits of Turgay, Russia, with present world-wide
distribution. In: Radiolaria of giant and subgiant fields in
Asia. Nazarov Memorial Volume. (Blueford, J.R. & Murchey,
B.L., Eds.), Micropaleontology, special Publication vol. 6.
Micropaleontology Press, American Museum of Natural
History, New York. pp. 72-89.
Radiolarians can be reliable paleoceanographic indicators.
"Spongy" radiolarians can be used to determine the environment of
deposition of the early Eocene Tassaranskaya Formation in the
northern Turgay area of Russia when compared to their present day
distribution. The Turgay fauna shows similarities with faunas from
other northern deposits during the Late Cretaceous through
Paleogene. Of particular interest are the abundant elongated
spongodiscoids found in the Tassaranskaya Formation. If recent
studies on spongodiscoid distribution are accurate analogous to
paleoenvironmental interpretation, the presence of these forms
indicate a shallow, wind driven upwelling system with periods of
warm water invasions. Elongated spongy radiolarians are helpful in
reconstructing the depositional history of paleobasins. This paper
taxonomically defines the early Eocene elongated spongodiscoids in
the Turgay region so researchers can more easily compare data from
this area. This study is an example of how paleoceanographic and
paleoenvironmental information can be derived when spongy
radiolarians are found.
Blueford, J.R. & Gonzales, J. 1993. Selected
sedimentary basins on the eastern Eurasian continent. In:
Radiolaria of giant and subgiant fields in Asia. Nazarov
Memorial Volume. (Blueford, J.R. & Murchey, B.L., Eds.),
Micropaleontology, special Publication vol. 6 .
Micropaleontology Press, American Museum of Natural
History, New York. pp. 3-8.
The eastern Eurasian continent has experienced several
tectonic events throughout geologic time. The sedimentary basins
that were formed as a consequence of plate interactions range in
size, form, content and sedimentary evolution. The ages range from
the Proterozoic to the Neogene and represent sedimentary basin fill
from clastics, reefal, deep sea carbonates and silicates, to shallow
water silicates. This area is a vast territory that includes Russia,
China, Japan, India and other Far East countries. This area has been
neglected in the English literature, but it is key to reconstructing
global paleoceanographic patterns. The purpose of this paper is to
summarize those basins that are mentioned in the volume and to
provide geologic background. Since radiolarians are present in many
of the evolving basins of the Phanerozoic, they are of great
importance to understanding the depositional histories of many
Eurasian basins.
Boltovskoy, D., Alder, V.A. & Abelmann, A.
1993. Annual flux of Radiolaria and other shelled plankters in
the eastern equatorial Atlantic at 853 m: seasonal variations
and Polycystine species-specific response. Deep-Sea Res.
Part A, oceanogr. Res. Pap., 40/9, 1863-1895.
Polycystine radiolarians, phaeodarians, tintinnids, tintinnid
cysts and molluscs (chiefly pteropod protoconchae) were counted in
20 time-series sediment trap samples retrieved in the eastern
equatorial Atlantic (01 47.5'N, 11 07.6'W) at 853 m, between 1
March 1989 and 16 March 1990. In addition, polycystine species
were identified. Mean annual flux rates, in ind./m 2 /day, were:
polycystines: 28,446, tintinnids: 27,275, foraminifers: 17,816,
tintinnid cysts: 14,632, phaeodarians: 1370, and molluscs: 1192.
These yields are noticeably higher than most previous data from
various areas of the World Ocean, which in part is attributed to the
coverage of particles