colonies occur. Upsection these communities are replaced
by a bed of framework forming, massive, dome-shaped
corals (58), succeeded by grain- and rudstones with toppled
and fragmented corals, coralline algal crusts (Neogonioli-
thon, Spongites, Sporolithon, Lithoporella) and rhodolites
(Sporolithon, Lithothamnion) (Fig.
10
c; 59–61). Frequent
gastropod casts are related to Cassis, Ampullinopsis and
Globolaria (Harzhauser
2004
).
Zefreh section
Zefreh section is a composite of two section tracts with Ze-
freh A (Fig.
6
) covering the lower and Zefreh B (Fig.
7
) the
upper segment of the complete section. In Zefreh A (Fig.
6
)
shallow marine deposits of the Qom Fm. unconformably rest
on continental siliciclastics (red conglomerates and green or
yellow siltstones) of the Lower Red Fm. (1–3).
The Qom Fm. starts with a unit of predominantly green
and brown marls (4–11). At its base interbeds of cross-
bedded sandstones and siltstones occur (6, 9, 10). The
marls contain a rich fauna dominated by bivalves (e.g.,
large oysters, Amussiopecten labadyei, A. subpleuronectes)
and gastropods (mainly turritellids and strombids) that are
often enriched within coquinas, and a planktic foraminif-
eral assemblage including Globigerina cf. ciperoensis,
Globoturborotalia woodi, Globigerinoides trilobus, Gs.
immaturus,
Gs.
quadrilobatus,
Globigerinella
obesa,
Globoquadrina cf. dehiscens, and Paragloborotalia cf.
semivera.
Upsection follows a unit of limestones (rud- and grain-
stones with bryozoans), and partly laminated siltstones
(12–14). It is topped by a marl succession with abundant
mollusks, which is, in turn, terminated by a bed of large
oysters (20).
Above follow conglomeratic sandstones and conglom-
erates
(21–23).
These
grade
into
a
succession
of
siliciclastics and marls that show a vertical change in color
from red to green (24–29). Intercalated are thin layers of
bright-green volcanic ashes. The fauna is characterized by
mollusks (turritellids, strombids, oysters) while in the
upper part branching bryozoans become abundant (26).
Pectinid bivalves (Amussiopecten labadyei, A. subpleuro-
nectes) are present as well. Foraminifers are represented by
lepidocyclinids [Lepidocyclina (Eulepidina) dilatata, L.
(E.) aff. favosa, L. (Nephrolepidina) of morgani-type],
Fig. 5
Lithological aspects of
the Qom Formation. a Marl with
lepidocyclinids from section
Abadeh (44). The relatively
small size of lepidocyclinid tests
indicates a relatively shallow
water environment. b Massive
colony of a Porites coral from
the Porites-Faviidae assemblage
from Abadeh section (31). The
developed microatoll
documents that the coral grew
near the sea-surface and was
exposed at lowest tides. c Dense
in situ population of the
teredinid bivalve Kuphus
melitensis. F-Member of section
Chalheghareh (102); hammer
for scale. d Sandstone with
oscillation ripples and trough
cross-bedding from the
d-Member in the Qom section
(34). e Laminated gypsum of
the Qom section (37); hammer
for scale. f Paleokarst cavities
filled with red continental
siliciclastics of the Upper Red
Formation. Top of the
f-Member limestones at section
Chalheghareh; hammer for scale
Int J Earth Sci (Geol Rundsch)
123
Operculina complanata, heterosteginids, and few mio-
gypsinids. Besides, sirenian bones occur sporadically. The
marl at its top is intercalated with beds of sandstone and
siltstone (27, 28). A coral build-up constructed mainly by
Tarbellastraea with thickly branching colonies and Porites
with thick platy growth forms follows above (30). It is
capped by a package of skeletal limestones (31, 32) com-
posed of corallinaceans and larger benthic foraminifers
(lepidocyclinids, heterosteginids, Operculina). A unit of
argillaceous limestones with abundant bryozoans follows
(33), topped by a coral build-up constructed by Leptoseris
and Porites with platy growth forms (34). The marly
interstitial sediment contains abundant bryozoans and lep-
idocyclinids with large discoid tests. A thick package of
carbonates forms the upper part of the Zefreh A section
(35–58) with bioclastic floatstones prevailing. Interbedded
are bioclastic pack- and rudstones. At the base of this
depositional unit, argillaceous limestones with large dis-
coid lepidocyclinids occur (36–38). Upsection the amount
of fine-grained matrix decreases. The fauna is here repre-
sented by foraminifers (lepidocyclinids, miogypsinids,
heterosteginids, Operculina, Amphistegina, Austrotrillina,
Borelis, Elphidium ortenburgense, E. matzenense), bivalves
(e.g., pectinids, oysters), abundant corallinaceans, as well
as gastropods, echinoids, and bryozoans. Some beds con-
tain coral rubble (42, 52) or in situ corals (platy Porites; 51,
40). The topmost layers of the carbonatic unit (58) contain
Kuphus tubes in growth position (Fig.
5
d) and articulated
pectinids (Amussiopecten cf. subpleuronectes).
The sedimentary succession continues in section Zefreh
B (Fig.
7
). Its lowermost three beds are composed of lep-
idocyclinid floatstones (1–3). These beds are widely
traceable and allow a correlation with Zefreh A section.
The succeeding part of the section is dominated by ter-
rigenous sandstones and siltstones, while limestone beds
occur rather intermittently. Occasionally, coral debris
composed of branching Porites (8) as well as small Porites
patch reefs (15) are intercalated in the terrigenous deposits.
The limestone beds have a distinct reddish color, contain
varying amounts of terrigenous material, and are predom-
inantly composed of corallinacean algae. Occasionally,
pectinid bivalves (Costellamussiopecten pasini, Oopec-
ten),
Clypeaster
echinoids,
and
larger
foraminifers
(lepidocyclinids, miogypsinids, Heterostegina) signifi-
cantly contribute to carbonate production. Some beds (1,
17) contain Kuphus tubes. The top comprises a succession
of silty marls (28–30). Within their lower part is a bed of
miliolid grainstone intercalated (29). Above this limestone,
the color of the silty marls shifts from gray to red and the
Qom Fm. deposits gradually shift into the continental
redbeds of the Upper Red Formation.
Qom section
At Qom section (Fig.
8
) the underlying Lower Red Fm.
consists of red and green claystones. The onset of the Qom
Fm. is marked by oolithic grainstones and packstones (a-
Member: 1–6). Bioclasts derived from coralline red algae
(Lithothamnion), echinoids, oysters and other bivalves.
Typical is a meter-scaled cross-bedding with intercalated
biolaminites showing wavy lamination at mm- and cm-
scale (1). Upsection follows a lithostratigraphic unit with
silty claystones and marls (b-Member: 7–10). Two inter-
calated packages with cross-bedded, sandy grainstones (8,
10) contain intraclasts (limestone pebbles, clay pebbles,
black pebbles) and glauconite. Scattered shells of Amus-
siopecten labadyei (8) and Pecten tietzei (10) are
represented therein. Foraminiferal assemblages from the
marl below the upper grainstone package (9) include var-
ious planktic (Globigerina praebulloides, Gg. ciperoensis,
Gg. labiacrassata, Gg. anguliofficinalis, Gg. ouachitaen-
sis, Globigerinella obesa, Globigerinoides primordius,
Paragloborotalia? pseudocontinuosa, Cassigerinella chi-
polensis)
and
benthic
forms
(Textularia,
Eggerella,
Vulvulina, Reticulophragmium, Haplophragmoides, Ammo-
nia, Lenticulina, Percultazonaria, Polymorphina, Uvigeri-
na, Bolivina, Orthomorphina, Planulina, Cibicidoides,
Hanzawaia, Nonion). Associated nannoplankton contains
Reticulofenestra abisecta, R. bisecta, and Zygrhablithus
bijugatus.
A thick unit of marl and interbedded limestone beds
follows (c-Member: 11–32). This depositional unit can be
divided into three subunits. The lower subunit is formed by
marls (11). The middle subunit is an alternation of marls
and bioclastic limestones (12–29). Limestones mainly
comprise corallinacean-foraminiferal floatstones (Litho-
thamnion, Neogoniolithon) with echinoids, oysters and
bryozoans (Fig.
10
d). Sporadically bryozoan-dominated
packstones occur (17; Fig.
10
f). The interbedded marls
contain bryozoans, pectinids (Pecten tietzei, Amussiopecten
labadyei, A. subpleuronectes, Costellamussiopecten su-
zannae), sponge spicules and larger foraminifers. The
upper subunit is built up by marls (30), in which bryozoans
locally become very abundant. In addition, nuculid
bivalves, ostracods, benthic (Textularia, Reussella, Loba-
tula, Rosalina, Cibicidoides, Hanzawaia, Ammonia) and
planktic (Globigerina praebulloides, Gg. cf. ciperoen-
sis, Gg. officinalis, Gg. ouachitaensis, Globigerinella
obesa, Globorotalita woodi, Paragloborotalia? pseudo-
continuosa,
Cassigerinella
chipolensis,
Tenuitellinata
angustiumbilicata) foraminifers are very common. All
b
Fig. 8
Qom section; lithological succession, texture, water depth
trend, litho- and chronostratigraphy. Members refer to the lithostrati-
graphic scheme of Furrer and Soder (
1955
); see Fig.
4
for legend
Int J Earth Sci (Geol Rundsch)
123