radiolaria - Marum

Radiolaria 14 Bibliography - 1989
three sites ranging from highly productive coastal upwelling to
oligotrophic central gyre waters in the northeast Pacific Ocean. Total
radiolarian fluxes and living phaedorian fluxes were generally highest
at the coastal site throughout the water column. There was no
consistent site-specific pattern for fluxes of living polycystine,
polycystine empty skeletons and phaedorian empty skeletons. Living
phaedorians were the only group that showed the same rank order of
sites with respect to flux at both the base of the euphotic zone and
at 2000m. Thus different short-term processes occurring in the
water column (e.g. destructive and non-destructive predation and
midwater addition of living radiolarians) altered radiolarian fluxes.
Neither radiolarian fluxes at the base of the euphotic zone nor fluxes
at 2000 m showed a simple correspondence with primary
production, indicating that short-term measurements did not reveal
long-term patterns. At most depths at all sites, fluxes of living,
skeleton-bearing phaeodorians outnumbered fluxes of empty
phaeodarian skeletons. In contrast, at most depths at all sites,
fluxes of empty polycystine skeletons outnumbered fluxes of living,
skeleton-bearing polycystine. Relatively large, living skeleton-less
phaeodarians were the numerically dominant radiolarian in the
uppermost traps at the oceanic and coastal sites. These
phaeodarians agglutinate siliceous skeletons of other plankton and
contributed 5% of the silicoflagellate flux, 16% of the polycystine
flux, and 2% of the centric diatom flux at these depths. The
resemblance of skeleton-less phaeodarians to faecal pellets may
cause them to be misidentified as faecal material when trap
contents are dried for processing.
Gowing, M.M., Garrison, D.L., Buck, K.R. &
Coale, S.L. 1989. AMERIEZ 1988: winter zooplankton
from the Weddell and Scotia seas. Antarct. J. U. S., 24/5,
160-162.
As part of the Antarctic Marille Ecosystem Research at the Ice-
Edge Zone (AMERIEZ) project, we are studying the distributions,
abundances, and trophic ecology of heterotrophic protozooplankton.
Protozooplankton range in size from microflagellates a few
micrometers in length Up to colonial radiolarians that can reach
meters in size. In this report, we focus on protozooplankton ranging
from 50 to 300 micrometers in their longest dimension. These
include radiolarians, foraminiferans, heliozoans, and some ciliates.
Samples were collected along several transects perpendicular to the
ice edge during the AMERIEZ 88 cruise (see cruise track in Ainley
and Sullivan, Antarctic Journal (this issue) in the austral winler from
9 June to 13 August 1988. We took both quantitative plankton tows
and large-volume (60-litre) water samples; this report discusses
preliminary results based on analysis of water samples from 8 of 17
stations. At each station, 30 litres of water were collected from
each of 10 depths: 5 + 10 meters, 30 + 40) meters, 65 + 85
meters, 115 + 135 meters, and 190 + 21() meters. Samples from
each pair of combined depths were concentrated to 200 millilitres
by reverse-flow filtration (Garrison and Buck 1989) immediately
after collection and preserved with Karnovsky's fixative (Garrison
and Buck 1989). Upon return to our laboratory, samples were
stained with the nuclear fluorochrome DAPI (Coleman 1980),
concentrated in settling chambers, and examined with an inverted
fluorescence microscope. The nuclear stain allowed us to distinguish
between organisms that were alive at the time of capture and empty
skeletons, and also indicated organisms that were undergoing
reproduction. The nuclear stain was also useful for distinguishing
organisms in samples with much detritus.
Gursky, H.-J. & Gursky, M.M. 1989. Thermal
alteration of chert in the ophiolite basement of southern
Central America. In: Siliceous Deposits of the Tethys and
Pacific Regions. (Hein, J.R. & Obradovic, J., Eds.). Springer-
Verlag, New York. pp. 217-233.
Radiolarian chert and volcaniclastic-rich siliceous rocks of the
Nicoya Complex were studied by optical mineralogy, X-ray
diffractometry, and SEM. Various phenomena of thermal alteration
occur due to postdepositional mafic magmatism. Progressive
destruction of sedimentary features is classified into four stages
from weak to complete recrystallization. Increases in quartz
crystallinity reflecting diagenetic to high-grade thermo-metamorphic
conditions parallel the recrystallization noted in thin sections.
Mineral assemblages especially in volcaniclastic-rich rocks help
estimate the metamorphic grade. Chert with smectite and illitesmectite
mixed-layer minerals or heulandite and clinoptilolite,
respectively, indicates low-temperature conditions of less than
200°C. Piemontite, garnet, and diopside reflect low to medium or
high (?) grade, very low-pressure contact metamorphism. Mineral
assemblages with scapolite were found close to igneous contacts
and indicate medium to high grade metamorphism. Secondary
minerals in veins with dominantly barite and zeolites commonly
formed under low temperature conditions of less than 150°C. These
different petrologic changes are discussed as to their usefulness in
defining thermal grades.
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Gursky, H.J. 1989. Presencia y origen de rocas
sedimentarias en el basamento ofiolítico de Costa Rica. Rev.
Géol. Amér. Central, 10, 19-66.
Different types of sedimentary rocks intercalated between
basalts of the Nicoya Ophiolite Complex (Jurassic to Lower Tertiary,
Costa Rica and western Panama) were studied using sedimentologic,
petrographic, X-ray diffractional, chemical, and field methods. They
occur as regionally extended sequences up to tens of meters thick,
thin lenses, inter and intrapillow sediment, xenoliths, intrusive jasper
bodies, tectonic blocks, and volcaniclastic material.
Radiolarite sequences containing in places sedimentary
manganese nodules, were formed below the CCD in the eastern
equatorial Pacific Ocean under 02-rich, deep-sea conditions with
little detrital input and very low-energy currents. Lenses of finegrained
tuffite and detritus-rich chert were deposited in local ponds.
Dikes of non-bedded jasper with colloidal structures may represent
hydrothermal mineralizations or thermally mobilized radiolarite
material. Lenses of pelagic foraminiferal limestone are present close
to the top of the Nicoya Complex and were deposited below the CLy.
Volcaniclastic breccias and sandstones represent locally-derived
debris from basalt flows and fault scarps.
The change from siliceous, Jurassic to middle Cretaceous, to
calcareous, upper Cretaceous, sedimentation reflects the late
Mesozoic world-wide lowering of the CCD and variations in regional
igneous and platetectonic morphology. The data make a contribution
to the reconstruction of the geodynamic evolution of the Nicoya
Complex.
Hattori, I. 1989a. Length-Slow Chalcedony in
Sedimentary Rocks of the Mesozoic Allochthonous Terrane
in Central Japan and Its Use for Tectonic Synthesis. In:
Siliceous Deposits of the Tethys and Pacific Regions. (Hein,
J.R. & Obradovic, J., Eds.). Springer-Verlag, New York. pp.
201-215.
Length-slow chalcedony was recently discovered in the
Mesozoic Mino Terrane, Central Japan. Lutecite and quartzine, two
varieties of length-slow chalcedony, occur in exotic limestone, chert,
and dolostone blocks as secondary minerals replacing carbonates or
as vein minerals. Clastic fragments of length-slow chalcedony were
also found in Mesozoic turbidite sandstone in this terrane.
Indigenous rock-formations carrying length-slow chalcedony have
not been recognized in Japan. Length-slow chalcedony is generally
considered to form under geologic environments different from
those for length-fast chalcedony, that is, length-slow chalcedony
tends to form in sedimentary rocks deposited on cratonic margins in
arid, evaporitic environments. Accordingly, it is likely to consider
that the Mino Terrane is composed of tectonic blocks and detritus
from cratonic regions containing much length-slow chalcedony
formed in evaporitic environments. Recent geologic, paleomagnetic,
and paleontologic syntheses of the tectonic evolution of the
Japanese Islands have revealed the allochthonous nature of the Mino
Terrane. I suggest that length-slow chalcedony can be used as a
tracer mineral to identify the provenance of the allochthonous Mino
Terrane.
Hattori, I. 1989b. Jurassic radiolarians from manganese
nodules at three sites in the western Nanjo Massif, Fukui
Prefecture, Central Japan. Memoirs of the Faculty of
Education, Fukui University, 2/29, 47-134. (in Japanese)
A number of manganese nodules occur at three localities in the
Nanjo Massif, Mino Terrane, Central Japan. Generally, they are found
in red shales between lower chert and upper shale and sandstone,
and are considered to be rhodochrossite concretion in red shale.
Abundant well-preserved radiolarians included in them are extracted
and analyzed. They are interpreted to belong to Early to early Middle
Jurassic in age. Accordingly, the manganese nodules in this area are
the oldest manganese nodules in the Mino Terrane so far. For future
researches, a lot of SEM photographs of radiolarians from the
manganese nodules are presented with their distribution charts.
Hattori, I. & Sakamoto, N. 1989. Geology and Jurassic
Radiolarians from manganese nodules of the Kanmuriyama-
Kanakusadake Area in the Nanjo Massif, Fukui Prefecture,
Central Japan. Bull. Fukui municip. Mus. nat. Hist., 36, 25-
79. (in Japanese)
The geology of the Kanmuriyama-Kanakusadake area of the
Nanjo Massif, Mino Terrane, Central Japan, is characterized by Early
Jurassic olistostrome called the Kasugano Facies and Jurassic
chert-sandstone facies called the Koukura Facies. Field observation
suggests that the Koukura Facies structurally overlies the Kasugano
Facies. Sedimentary rocks of the Koukura Facies are refolded; the
fold axis of the older one was primarily of E-W direction, and the
younger axis, of N-S direction. Radiolarian analysis shows that the