radiolaria - Marum

Radiolaria 14 Bibliography - 1992
geological evolution of individual terranes is required before an
integrated model for the entire orogen can be developed.
Aitchison, J.C., Flood, P.G. & Spiller, F.C.O.
1992. Tectonic setting and paleoenvironment of terranes in
the southern New England Orogen, eastern Australia as
constrained by radiolarian biostratigraphy. Palaeogeogr.
Palaeoclimatol. Palaeoecol., 94/1-4, 31-54.
Radiolarians are abundant in the Gamilaroi, Djungati and
Anaiwan terranes of the New England orogen in eastern Australia.
These microfossils present the first age constraints on the timing of
development of hitherto undated lithologies within the various
juxtaposed terranes of the orogen. They give a biostratigraphic
framework for interpreting the history of marine sedimentation in
these terranes and have significant implications for published
tectonic models
Radiolarians also show that the stratigraphically lowermost
rocks or the Gamilaroi terrane are most probably of' Devonian age.
Better stratigraphic resolution permits interpretation of these rocks
as part of an intra-oceanic island arc succession which accreted to
the eastern margin of Australia (Gondwana) around the end of the
Devonian. This intra-oceanic arc is distinct from a younger,
Carboniferous, superposed continental arc sequence which
constitutes a successor basin that developed over the Gamilaroi
terrane subsequent to its accretion to the margin of Australia.
Radiolarians provide the basis for dating siliceous lithologies
which dominate the Djungati terrane and permit a more detailed
analysis of the history of this terrane. During the middle Silurian
through Late Devonian the Djungati terrane was part of an oceanic
basin which was isolated from any source of terrigenous
sedimentation. The Djungati terrane was subsequently influenced by
volcanic island arc activity and was tectonically disrupted during the
latest Devonian to Early Carboniferous. Radiolarian age data show
that age correlations inferred, on the basis of similarities in detrital
sandstone petrography, between lithostratigraphic units in the
Gamilaroi and Djungati terranes, are not always appropriate. Djungati
terrane has been widely interpreted as a subduction complex related
to the Gamilaroi terrane. Radiolarian data now elucidate much of the
structural complexity of this terrane. Significant differences
between the Djungati terrane and the style of well-documented
subduction complexes include the close spacing of zones of
radiolarian chert, the dominance of this lithology over others and the
lateral extent of many of the chert horizons.
The Anaiwan terrane has features which are characteristic of
many well-documented subduction complexes. Radiolarians are
abundant in this terrane and can be used to show that it developed
along the eastern margin of Australia in response to Early
Carboniferous subduction of Late Devonian to Early Carboniferous
oceanic crust. Packages of chert accreted into the subduction
complex are progressively younger towards the northeast indicating
that subduction was directed to the southwest.
Aitchison, J.C. & Murchey, B.L. (Eds) 1992. The
significance and application of Radiolaria to Terrane
Analysis. Special issue of Palaeogeography,
Palaeoclimatology, Palaeoecology, Elsevier Amsterdam.
96, 172 p.
Alexandrovich, J.M. 1992. Radiolarians from Sites 794,
795, 796, and 797 (Japan Sea). In: Proceedings of the Ocean
Drilling Program, Scientific Results. (Tamaki, K., Ingle,
J.C.J. et al., Eds.), vol. 127-128/1. College Station, TX
(Ocean Drilling Program), pp. 291-307.
Japan Sea ODP Leg 127 shipboard radiolarian biostratigraphic
data are compiled and improved. The sequence of biostratigraphic
events determined in sediments above the opal-A/opal-CT transition
is illustrated graphically with depth-depth plots. The absence of
biostratigraphic indicators from the North and subtropical Pacific
and differences between the compositions of the Japan Sea and
Pacific radiolarian assemblages suggest that the planktonic
populations of the Japan Sea have been partially isolated from the
Pacific since the late Miocene. Subtropical fauna in sediments
younger than ~1.8 Ma at Site 797 record the occurrence of a paleo-
Tsushima current. These same fauna record larger volumes of the
paleo-Tsushima current, or warmer intervals during the colder glacial
climate regime at Site 794. The variability of Pleistocene
assemblage composition and preservation shows that radiolarian
dissolution has played a large part in determining what is preserved.
Preliminary taxonomic evaluations are made, and the stratigraphic
and paleoceanographic implications of radiolarian species are
discussed.
Amon, E.O. 1992. Some materials to the revision of
Prunobrachium genus (Radiolaria, Sphaerellaria). In:
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Materials on Paleontology and Stratigraphy of the Western
Siberia. (Podobina, V.M., Eds.). Tomsk Univ. Publisher,
Tomsk. pp. 84-87. (in Russian)
Amon, E.O. & Chuvasov, B.I. 1992. Early Permian
radiolarian associations of the type section "Sim" of the
Southern Urals. In: New data on Paleozoic stratigraphy and
lithology of Urals and Middle Asia. Nauka Publisher,
Ekaterinburg. pp. 96-108. (in Russian)
Amon, E.O. & Korovko, A.V. 1992. First data about
late Devonian radiolarian association from Rezhevskaya
structural-facial zone of Eastern Middle Urals. In: New data on
Paleozoic stratigraphy and lithology of Urals and Middle
Asia. Nauka Publisher, Ekaterinburg. pp. 69-77. (in Russian)
Anderson, O.R. & Matsuoka, A. 1992.
Endocytoplasmatic microalgae and bacteroids within the
central capsule of the radiolarian. Symbiosis, 12, 237-247.
Micro-algae (c. 2.5 to 3.5 µm wide x3.8 to 4.5 µm long) occur
abundantly within perialgal vacuoles in the intracapsular cytoplasm
of the radiolarian Dyctyocoryne truncatum, a triangular-shaped,
spongiose skeletal radiolarian. The fine structure of the microalgae
resembles that of yellow-brown pigmented symbionts observed in
larger spongiose skeletal radiolaria of the spongodrymid type. The
density of microalgae in a typical ultrathin section is c. 4/100 µm 2 .
Bacteroids (0.2x0.5 µm) are present throughout the intracapsular
cytoplasm. There is no evidence of a vacuolar membrane enclosing
the bacteroids, but each is surrounded by an electron lucent zone.
The central capsule of radiolaria contains the nucleus and
cytoplasmic organelles and is bounded by a capsular wall. Previously,
algae associated with radiolaria have been observed in the
extracapsulum. The occurrence of intracapsular microalgae in D.
truncatum is of interest since this indicates that the intracapsular
cytoplasm, previously thought to be largely specialized for
metabolism, storage of reserve substances and production of
reproductive swarmers, can also be a site for host-algal
interactions.
Baumgartner, P.O. 1992. Lower Cretaceous radiolarian
biostratigraphy and biogeography off northwestern
Australian (ODP sites 765 and 766 and DSDP site 261), Argo
abyssal plain and lower Exmouth Plateau. In: Proceedings of
the Ocean Drilling Program, Scientific Results. (Gradstein,
F.M., Ludden, J.N. et al., Eds.), vol. 123. College Station,
TX (Ocean Drilling Program), pp. 299-342.
During Leg 123, abundant and well-preserved Neocomian
radiolarians were recovered at Site 765 (Argo Abyssal Plain) and
Site 766 (lower Exmouth Plateau). The assemblages are
characterized by a scarcity or absence of Tethyan taxa. The
Berriasian-early Aptian radiolarian record recovered at Site 765 is
unique in its density of well-preserved samples and in its faunal
contents. Remarkable contrasts exist between radiolarian
assemblages extracted from claystones of Site 765 and reexamined
DSDP Site 261, and faunas recovered from radiolarian sand layers of
Site 765. Clay faunas are unusual in their low diversity of apparently
ecologically tolerant species, whereas sand faunas are dominated by
non-Tethyan species that have never been reported before.
Comparisons with Sites 766 and 261, as well as sedimentological
observations, lead to the conclusion that this faunal contrast results
from a difference in provenance, rather than from hydraulic sorting.
Biostratigraphic dating proved difficult principally because of
the paucity or even absence of (Tethyan) species used in published
zonations. In addition, published zonations are contradictory and do
not reflect total ranges of species.
Radiolarian assemblages recovered from claystones at Sites
765 and 261 in the Argo Basin reflect restricted oceanic conditions
for the latest Jurassic to Barremian time period. Neither the
sedimentary facies nor the faunal associations bear any
resemblance to sediment and radiolarian facies observed in typical
Tethyan sequences. I conclude that the Argo Basin was
paleoceanographically separated from Tethys during the Late
Jurassic and part of the Early Cretaceous by its position at a higher
paleolatitude and by enclosing landmasses, i.e., northeastern India
and the Shillong Block, which were adjacent to the northwestern
Australian margin before the opening.
Assemblages recovered from radiolarian sand layers are
dominated by non-Tethyan species that are interpreted as
circumantarctic. Their sudden appearance in the late
Berriasian/early Valanginian pre-dates the oceanization of the Indo-
Australian break-up (M11, late Valanginian) by about 5 m.y., but
coincides with a sharp increase in margin-derived pelagic turbidites.
The Indo-Australian rift zone and its adjacent margins probably were