Geology Reference
In-Depth Information
appears hyaline except in stratigraphically old taxa
which exhibit microgranular, brownish opaque
walls (
Chitinoidella;
Pl. 77/1).
The fossils are studied in thin sections or peels.
Taxonomic differentiation needs sections exhibit-
ing the shape of the test (U- and C-shaped figures),
the type of the collar bordering the oral apertura as
well the shape of the aboral region. These criteria
are shown by longitudinal sections (Pl. 77). Cross
sections are circular and statistically more frequent
(Fig. 10.30). Geometric variations due to different
cutting planes and the possibility of tectonical de-
formation (Remane 1964) must be thoroughly con-
sidered. The length and width of the test are fur-
ther criteria used in discriminating species.
Remane
1971
Grün and Blau 1997
gr. carpathica Pl. 77/2930
gr. hungarica Pl. 77/3435
E
major
Pl. 77/27
darderi
Pl. 77/2526
dadayi
Pl. 77/24
3
murgeanui
Pl. 77/21
D 2
filipescui
Pl. 77/23
oblonga
Pl. 77/16
1
simplex
Pl. 77/15
Significance of calpionellids
Biozonation:
Calpionellids are excellent
index
fossils
enabling the biozonation of Late Jurassic
(Middle Tithonian) to Early Cretaceous (Valan-
ginian) Tethyan pelagic carbonates to be estab-
lished. The current standard calpionellid biozona-
tion is based on studies by Remane (1964,) Le
Hégarat and Remane (1978), Remane et al. (1986),
and Pop (1994).
A revised zonal and subzonal subdivision was
proposed by Grün and Blau (1997; Fig. 10.32).
Calpionellid stratigraphy is generally combined
with biozonations based on calcareous nannoplank-
ton (nannoconids, coccolithophorids) and radiolar-
ians (Weidich and Schairer 1990; Ondrejickova et
al. 1993).
C
cadischiana
Pl. 77/14
elliptica
Pl. 77/8
B
alpina
Pl. 77/67
3
catalanoi
Pl. 77/10
A 2
intermedia
Pl. 77/2
1
remanei
andrusovi
Pl. 77/5
bermudezi
boneti
Pl. 77/1
dobeni
Sediment production:
Calpionellids were rock-
building constituents of Late Jurassic and Early
Cretaceous fine-grained basinal carbonates in a
tropical belt extending from Mexico to eastern In-
donesia. The fossils occur in high abundance typi-
cally in very fine-grained micritic limestones or
marly limestones that are rich in other pelagic mi-
Fig. 10.32.
Calpionellid biozonation
after Grün and Blau (1997).
The zones and subzones reflecting faunal successions and evolu-
tion events are used in worldwide correlations. Many of the spe-
cies used to name the subzones are shown on Plate 77. Note that
the generic assignment of these species must not correspond to
the genera characterizing the major calpionellid zones.
are enclosed within an organic test (lorica) exhibiting
a large oral opening (apertura) and a differentiated abo-
ral pole.
crofossils (coccolithophorids, nannoconids; Pl. 77/23),
and radiolarians). Nannoconids are calcitic conical
nannofossils particularly common in Tethyan pelagic
and hemipelagic limestones ranging from the Late Ju-
rassic (Tithonian) to the Late Cretaceous (Campanian).
They usually co-occur with coccoliths, calpionellids and
radiolarians, but almost purely nannoconid limestones
are also known.
Morphology and thin-section criteria:
Calpionellids
have a bell-shaped, amphora-like or cylindrical, cal-
careous test (lorica) with axial symmetry, and a large
oral opening (aperture) surrounded by a collar of vari-
able shape and construction (Fig. 10.30, Fig. 10.31).
The collar is usually formed by prolongation of the lat-
eral walls, but can also correspond to independent ele-
ments. The aboral pole is rounded, pointed or charac-
terized by a caudal appendix. In thin sections the wall
Other tintinnidlike thinsection fossils
Morphologically similar microfossils characterized
by bell-shaped figures and thought to be tintinnids have
been described from the Paleozoic (Silurian: Hermes
