Geology Reference
In-Depth Information
et al. 1988), and again in the latest Albian. In this re-
gion the group becomes extinct in the Middle Cenoma-
nian. The group includes valuable paleoenvironmental
indicators. Orbitolinids lived in shallow warm waters
of normal salinity. They occur in different microfacies
types formed on shallow lagoonal platforms, sometimes
in close association with reefs, and in upper slope set-
tings.
Late Cretaceous
shelf and shelf slope deposits yield
discoidal or lenticular tests of orbitoidacean rotaliinid
foraminifera (Pl. 72/5-10). The
orbitoidaceans
are char-
acterized by radially hyaline and perforated walls, cy-
clically arranged equatorial chambers and regular lat-
eral chambers. Orbitoidacean foraminifera are abun-
dant in Maastrichtian shallow-water shelf carbonates
(see Pl. 72/7-10). This group is used for biostratigraphic
zonations (Berthou 1984; Caus 1988; De Castro 1990).
Planktonic Cretaceous and Cenozoic foraminifera
Planktonic foraminifera (Globigerinacea) are abun-
dant in fine-grained Cretaceous and Cenozoic carbon-
ates deposited at the deep-sea bottom of open-marine
Text continued on p.478
Plate 69 Jurassic Foraminifera
Many benthic Jurassic foraminifera as well as dasyclad calcareous algae (see 10.2.1.7) are facies-diagnostic
fossils and assist in subdividing platform and reefal platform-edge carbonates (Chiocchini et al. 1988). Lituolinid
larger foraminifera with complex inner structures (-> 1, 2, 3, 8) are excellent index fossils (Hottinger 1971,
Septfontaine 1981) and form the basis for a biozonation of lagoonal platform carbonates. The plate displays
some common taxa comprising Textulariina (-> 1-3, 7, 8), porcelaneous Miliolinina (-> 4, 6, 10) as well as
Involutinina (-> 5, 6).
1
Pseudocyclammina lituus
(Yokoyama). Lituolinid larger foraminifer with complex internal structures. Axial section.
Test planspirally enrolled. Note thick honeycombed labyrinthic wall with alveoli and thick septa perforated by large
openings. Species range: Middle Jurassic (Domerian) to Early Cretaceous (Valanginian). Late Jurassic (Tithonian): Ernstbrunn,
Austria.
2
Kurnubia palastinensis
Henson. Lituolinid foraminifera with complex internal structures. Oblique section. Important
criteria are the subepidermal network (arrow) and the central column (CC). Species range: Oxfordian to Tithonian,
abundant in the Oxfordian. Late Jurassic (Kimmeridgian): Central Apennines, Italy.
3
Kurnubia palastinensis
Henson. Transverse section. Diagnostic criteria of the endoskeleton are best shown in sections
like this perpendicular to the coiling axis. Late Jurassic (Kimmeridgian): Western High Atlas Mountains, Morocco.
4
Trocholina alpina
Leupold. Oblique axial sections of conical tests. Common in platform and reef carbonates. Early
Tithonian: Sulzfluh Mountains, Graubünden, Switzerland.
5
Spirillinid foraminifer
. The characteristic feature of the involutinid group Spirillilina, particularly common in Liassic
deep shelf limestones (Blau 1987), are monocrystalline shells (Hohenegger and Piller 1977). Transverse section of the
discoidal test. Late Jurassic (sponge-
Tubiphytes
reef, Tithonian): Altensteig 1 well, western Molasse Basin, southern
Germany.
6
Conicospirillina basiliensis
Moehler. Oblique section of the spirillinid foraminifera. Species range: Tithonian to
Valanginian. Same locality as -> 4.
7
Ammobaculites
Cushman. Textulariina. Lituolacean foraminifera without complex internal structures. Longitudinal sec-
tion. Free, elongated test. Early portion coiled, later rectilinear. Note coarsely agglutinated wall structure. Genus range:
Mississippian to Holocene. Same locality as -> 5.
8
Alveosepta
Hottinger
.
Lituolinid foraminifer with complex internal structures. Section slightly oblique to the coiling
axis. Exoskeleton with subepidermal network lining the entire chamber including the septa (arrow). Genus range: Oxfor-
dian to Kimmeridgian. Same locality as -> 3.
9
Lenticulina
Lamarck. Rotaliina. Oblique section. Involute planispiral test. Wall calcareous, hyaline, finely perforate.
Same locality as -> 5.
10
Protopeneroplis striata
Weynschenk. Involutinina. Test enrolled in about two rapidly enlarging and loosely coiled whorls.
Wall calcareous lamellar. The species is common in Middle and early Late Jurassic carbonates deposited in shelf-margin
and upper slope positions. Same locality as ->4.
11
Frondicularia
Defrance. Miliolina, Nodosariacea. Simple uniserial, elongated test consisting of broad, uniform cham-
bers. Sutures are highly arched to angled at the midline of the test. Same locality as -> 5.
12
Planktonic foraminifera:
'Protoglobigerinid', an informal name for probably the oldest planktonic foraminifera, are
regionally abundant in Callovian and Oxfordian basinal carbonates (Riegraf 1987). Middle Jurassic: Unken, Austria.
-> 8: Hüssner 1985
