16. Radiolaria - Deep Sea Drilling Project

M. G. PETRUSHEVSKAYA, G. E. KOZLOVA
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radiolarian assemblage in a sample. For the characterization
of the total assemblage, the same letters "a", "c", "f" and
"r" are applied. The preservation of the skeletons is
506
classified as "good - g" (all specimens are preserved),
"moderate - m" (some specimens are destroyed, in fragments,
nassellarians without heads) and "poor - p" (nearly
all specimens are destroyed or dissolved).
Site 138 (25° 55.37'N, 25° 33.70'W; water depth 5288
meters)
Rare radiolarians occur at about 52 to 61 meters
below the sea floor (1-CC); they apparently belong in
the Calocycletta veneris Zone. Frequent radiolarians of
moderate preservation occur from 110 to 113 meters
below the sea floor (Core 2). Radiolarians from the
upper part of this core seem to belong in the upper
part of the Calocycletta tuberosa Zone. The lower
part of Core 2 seems to belong in the lower part
of the Calocycletta tuberosa Zone. Paleocene?
radiolarians from Core 4 were not studied. Lower
than 332 meters below the sea floor, Cretaceous
radiolarians of poor preservation occur (see "Cretaceous
Occurrences").
Site 139 (23° 31.14'N, 18° 42.26'W; water depth 3047
meters)
Radiolarians, if present, were of good preservation, and
the assemblages are rich in species and in individuals.
Radiolarians are common and even abundant from 114
to 123 meters below the sea floor (Core 1). These samples
seem to belong no lower than the Pterocanium prismatium
Zone.
Radiolarians are frequent and even common from 345 to
576 meters below the sea floor (Core 3). Sample 3-CC
contains a Middle Miocene assemblage. It is difficult to
determine the zone it belongs in, but it may be in the
lowest Cannartus petterssoni Zone. Samples 4-CC, 5-CC and
139-SW1 seem to belong in the Calocycletta costata Zone.
Core 7 (576 to 665 meters below the sea floor) is poor in
radiolarians; it apparently belongs in the Calocycletta
veneris Zone. Sample 7-CC is abundant in radiolarians; it
belongs in the lowest part of the Calocycletta veneris Zone.
Site 140 (21 C
meters)
44.97'N, 21° 47.52'W; water depth 4483
Hole 140
Well-preserved radiolarians are common from about 201
meters below the sea floor (Core 2). The samples from the
upper part of this core seem to belong in the lower part of
the Dorcadospyris alata Zone. The middle part of this core
(Section 2 and 4) appear to belong in the Calocycletta
costata Zone. The lower part of Core 2 and Sample 2-CC
apparently belong in the Calocycletta veneris Zone, but the
slide marked as 2-CC contains an abundance of wellpreserved
Late Eocene radiolarians. It apparently belongs in
the upper part of the Thyrsocyrtis bromia Zone.
Well-preserved (but many fragmented) radiolarians are
common in Core 3 (311 to 318 meters below the sea floor).
These samples seem to belong in the Lampterium goetheana
Zone.
Poorly preserved skeletons (infilled with silt) are
abundant in Core 4 (368 to 374 meters below the sea
floor). Apparently it belongs in the Low Eocene (similar to
the samples described by C. Nigrini, 1970).