Akademik Veri Yönetim Sistemi
11th International Cretaceous Symposium, Warszawa, Polonya, 22 - 26 Ağustos 2022, ss.392-393
Measured stratigraphical sections (İnişdere-Adıyaman,
Türkoğlu-Kahramanmaraş and Sabunsuyu-Kilis) have enabled us to determine
carbonate platform evolution during the Aptian–Campanian interval in south-east
Turkey. It starts with thin clastics and an overlying alternation of carbonates
and clastics (3–50 m thick Areban Formation; Barremian–Albian) overlying basement
rocks unconformably (Mülayim et al, 2019). A thicker carbonate sequence follows;
the 40–410 m thick Sabunsuyu Formation (Albian–Cenomanian), characterised by
shallow subtidal carbonate facies and thicker dolostones. The Derdere Formation
(Cenomanian) with an average thickness of 50-250 m overlies conformably the
Sabunsuyu Formation and is characterised by cyclic shallow-water facies, while
the platform evolved as a ramp type (Simmons et al, 2020). The 10–180-m-thick Karababa
Formation (Turonian–Santonian) is represented by organic-rich, hemi-pelagic to
pelagic facies below becoming shallower upwards (bioclastic facies). Hardgrounds
at the top of Derdere Formation were recognised by the presence of glauconite
and phosphate at the base of the Karababa Formation. The latter is among the
main source rocks in the region and is overlain by the 10–60-m-thick Karaboğaz
Formation, the a second main source rock in the region (Santonian–Campanian) with
a “drowning” unconformity (Mülayim et al, 2019). The latter comprises organic-rich
clayey limestones with chert nodules, being conformably overlain by shallow-water
platform carbonates with udists, calcareous algae, Actaeonella, sponges and bryozoans in the south or its pelagic
equivalents (Saytepe Member, Campanian) in the north and by an alternation of
pelagic limestone, marl, black shale, clayey limestone and cherty limestone
facies (Sayındere Formation, Campanian–Maastrichtian, around 30–250 m thick). Abundant
macrofossil occurrences in Saytepe and lateral equivalents and the Sayındere
Formation can also be considered as bioevents related to changes in sea
level/depth/nutrients in carbonate platform evolution. The contact between the Saytepe
Member and Sayındere Formation is a drowning unconformity. A hardground surface
is reflected by iron and manganese oxide crusts and a thin layer of sandy
carbonate with abundant glauconite. Aptian–Campanian successions are
characterised by rudists, actaeonellids, benthic and planktic foraminifera and
calcareous algae of biostratigraphical importance (Mülayim et al, 2019). In the
intervals studied, multiple hardgrounds were seen at three levels (Cenomanian,
Turonian/Coniacian–Santonian and Campanian). The sudden changes triggered halts
in platform development, accompanied by regeneration after sudden deepening. Thus,
the platform could not regenerate or partially developed as a small platform on
tectonically elevated areas. However, earlier carbonate generations are well
developed and can be correlated over long distances. Therefore it can concluded
that Cenomanian, Turonian/Coniacian–Santonian and Campanian platform regenerations
can also be associated with collaboration of sea level, palaeoceanographical
changes and tectonics (Yılmaz et al, 2018). Settlement of phosphate and the main
source rocks directly above the hardgrouds can be associated with global
oceanographical events and sea level changes during these time intervals. However,
the last drowning event might have been mostly controlled by tectonics.
This study was financially supported by TÜBİTAK
Project no 118Y425.