radiolaria - Marum

Radiolaria 14 Bibliography - 1991
overlying the Coast Range ophilite, Stanley Mountain,
Southern California Coast Range. Ph.D. Thesis. Programs in
Geoscience, University of Texas at Dallas, 696 p.
(unpublished)
Ishida, K. & Hashimoto, H. 1991. The problem on
radiolarian shells reworking into the Lower Cretaceous
molluscan facies in Chichibu Terrane, eastern Shikoku. J.
sedimentol. Soc. Japan, 34, 15-20. (in Japanese)
Some Middle-Late Jurassic radiolarian shells were detected
associated with Early Cretaceous autochthonous radiolarian and
anmmonite assemblages from the Lower Cretaceous formations of
molluscan facies in eastern Shikoku.
The modes of occurrence on these Middle-Late Jurassic
radiolarian shells were summarized as follows: 1) Specific diversity
of associate Middle-Late Jurassic radiolarians are restricted within
several species of Tricolocapa and Stichocapsa genera. 2) Most of
these Jurassic radiolarians are subspherical with closed distal end in
shape. 3) Their sizes are limited to 100-150 µm in length and 80-
100 µm in diameter. 4) Lithologically, they are contained in
laminated sandy mudstones and sandy siltstones. 5) Among these
older radiolarians, Tricolocapsa plicarum, T. conexa, T. fusiformis ?,
Stichocapsa convexa and S. naradaniensis are the index species of
Middle to early Late Jurassic age. But the other species whose final
appearances are known within Earliest Cretaceous such as
Cinguloturris carpatica, Pseudodictyomitra primitiva and
Eucyffidiellum pyramis have possibility that their ranges reach into
Barremian age. 6) All these Jurassic elements are yielded from the
first transgressive sediments successively just above the Lower
Cretaceous nonmarine formations in the Northern and the Middle
Chichibu Terranes. 7) These ammonites and radiolarians bearing
Lower Cretaceous formations are the continental shelf or upper
submarine terrace sediments, because they construct cyclothem
together with the coal-bearing and blackish sediments which
unconformably overlie both the melange type Jurassic formations in
the Northern Chichibu Terrane and the molluscan facies Middle-Late
Jurassic formations in the Middle Chichibu Terrane.
The above-mentioned evidences showed that these Jurassic
radiolarian shells are the reworked fossils in the same manner as
other detrital clastics in the Cretaceous sediments, probably derived
from the Pre-Cretaceous basement similar to the Northern and the
Middle Chichibu Terranes. Therefore, it is necessary to consider the
problem of reworking and mixing by older materials when we deal
with the microfossil biostratigraphy at nearshore sediments on such
continental shelf and/or upper submarine terrace.
Ishida, K. & Hashimoto, H. 1991. Radiolarian
assemblages from the Lower Cretaceous formation of the
Chichibu Terrane in eastern Shikoku and their ammonite
ages. J. Sci., Univ. Tokushima, 25, 23-67. (in Japanese)
Lower Cretaceous radiolarian biostratigraphy is studied in the
molluscan facies strata of the Chichibu Terrane in eastern Shikoku.
Chronological order of each assemblage obtained from 14 localities
is estimated statistically on the basis of known specific ranges.
Three radiolarian assemblage zones are newly proposed and are tied
to chronostratigraphy by means of coexisting ammonites. They are
Archaeodictyomitra pseudoscalaris Assemblage Zone of Barremian
age, Stichomitra communis Assemblage Zone of middle Aptian age,
and Pseudodictyomitra pentacolaensis Assemblage Zone of Late
Albian age. Among the 65 species, identified, listed and figured, the
first appearances of 10 species and the final appearances of 15
species are newly ascertained. The proposed zones are correlated
with those of proposed by other authors in pelagic and non shallowmarine
facies.
Ishiga, H. 1991. "Dimorphic pairs" of Albaillellaria (late
Paleozoic Radiolaria), Japan. Mem. Fac. Sci., Shimane
Univ., 25, 119-129.
Ishiga, H. 1991. Description of a new Follicullus species
from southwest Japan. Mem. Fac. Sci., Shimane Univ., 25,
107-118.
Johnson, L.E., P., F., Taylor, B., Silk, M.,
Jones, D.L., Sliter, W.V., Itaya, T. & Ishii, T.
1991. New evidence for crustal accretion in the outer Mariana
fore arc: Cretaceous radiolarian cherts and mid-ocean ridge
basalt-like lavas. Geology, 19, 811-814.
New age determinations on radio1arian cherts, foraminifers,
and volcanic rocks document the presence of allochthonous
fragments of Cretaceous oceanic plate, suggesting accreted
terrane, in the outer Mariana fore arc, more than 50 km from the
- 65 -
trench. Three dredges, from a 3 km 2 area along a steep scarp,
recovered a diverse assemblage of rocks representing an ophiolite
suite (chert, mafic and intermediate lavas and intrusive rocks).
Trace element patterns of the lavas suggest at least three tectonic
associations (island arc, ocean island, and oceanic plate). The cherts
contain two deep-water assemblages of radiolaria of middle to late
Valanginian (131-138 Ma) and Albian (97-112 Ma) age.
Foraminifers recovered with the chert are Aptian to Albian in age.
The lavas record a wide range of K-Ar ages, 85 Ma for a metabasalt
with trace-element signatures of mid-ocean ridge basalt, 71 Ma for
a highly metamorphosed alkalic basalt, and 39 Ma for a fresh glassy
boninite. These ages imply multiple volcanic events and at least two
tectonic settings for magma genesis. The cherts and metabasalts
are too old to have formed in situ or to be part of trapped West
Philippine Basin crust. The mix of old oceanic plate with younger arc
rocks requires complex tectonic relations. We suggest that one or
more fragments of Cretaceous oceanic plate (chert, mid-ocean ridge
basalt, and alkalic lavas) were accreted to the Mariana fore arc and
have been extensively faulted and probably intruded by arc lava
(island-arc tholeiite and boninite).
Jud, R. 1991. Bichronology and systematics of Early
Cretaceous Radiolarian of the Western Tethys. Ph.D. Thesis.
University of Lausanne, 147 p. (unpublished)
About 500 samples of Uppermost Jurassic to Lowermost
Aptian cherty limestones, most of them in the Maiolica facies, were
studied for their contents in radiolarians in order to make a
comprehensive inventory of radiolarian assemblages and to
establish a radiolarian biochronology calibrated and correlated to the
magnetostratigraphy established in the same sections and to
biozonations of other fossil groups. The samples were collected from
26 land sections in Switzerland, Italy and Oman. Of several hundred
morphotypes recorded in 245 well preserved samples from only 13
sections of the 26 examined, 175 radiolarian taxa were selected,
and species occurrences were calculated with the computer program
"BIOGRAPH" (Savary & Guex, 1990). This resulted in 35 successive
Unitary Associations (U.A.) that could be grouped into 11 biozones
whose terminology follows and continues that of Baumgartner
(1984b). A protoreferential or "range chart" based on U.A. was
finally synthetised for all species selected between the interval of
the Middle Tithonian and the Lowermost Aptian.
The 11 radiolarian zones (C1-G2) were correlated to magnetic
polarity chrons, calpionellid zones and nannofossil events
established by previous workers on the investigated sections.
Diachrony in correlating the radiolarian zones is probably caused by
several reasons among which lithostratigraphy, species definition
and abundance, calibration with magnetic chrons and definition of
these chrons are among the most important.
Although the studied sections belong to several distinct
paleogeographic areas with basinal and seamount facies: Prealpine
Nappes (Northern Tethys), Southern Alps and Umbria Marche
Apennines (Apulian Plate, Southern Tethys) and Hawasina Complex
(distal Arabian Margin), the radiolarian Unitary Associations have
proved to be a useful tool for correlation.
Precise correlation of the new radiolarian zonation, based on
the co-existence of several species within one zone, to most of the
previous radiolarian zonations is impossible or very difficult,
because most of them were defined by first or last appearances of
one or two "marker" species, which may greatly differ from section
to section.
The time span covered by the new radiolarian biozones is
variable. Zone E2 has a duration of less than I million years whereas
zone E1b spans about 4 million years. Zone E2 is located in the
Middle Valanginian at the base of the magnetic polarity zone M11
and corresponds, in the Southern Alps, to a time of elevated ∂ 13 C
values (Weissert & Lini, 1991). During this characteristic period,
explained by the authors as an episode of greenhouse climate, pelitic
intervals, elevated bioturbation and cyclic sedimentation occurred.
The same interval (Zones E2 and F1 corresponding to the Middle and
the Upper Valanginian) is also characterized by the abundance of
some taxa in the samples of the Fiume Bosso section.
All the 175 taxa investigated, of which 1 new subspecies, 61
new species and 2 new genera, are described and illustrated in the
systematic part of the thesis.
Kamata, Y., Sashida, K. & Igo, H. 1991. Geology of
the Cretaceous Masutomi Group exposed in the southwestern
part of the Kanto Mountains, central Japan. J. geol. Soc.
Japan, 97/2, 157-169. (in Japanese)
The stratigraphy and ages of the Masutomi Group are discussed
based on recent fossil findings The Masutomi Group is subdivided
into the following three formations from north to south, the Albian to
Maastrichtian Takatoyasan Formation; the late Campanian to early
Maastrichtian Mikado Formation; and the late Albian to