The Lower Miocene deposits have been proven by the wells on the Bulgarian
and Turkey shelf like the Limankoy-1 (Fig. 6.4), while they were not encountered
on the Romanian Shelf, and the Oligocene deposits are unconformable overlaid by
the Middle Miocene deposits (Fig. 6.8, see also Dinu et al. 2005). The Middle
Miocene, Badenian – Lower Sarmatian in local Paratethys scale (Fig. 6.3) has a
reduced thickness as proven by the well drilled on the shelf, and contains another
important basin scale unconformity, of Middle – Upper Sarmatian age, also known
as Serravalian Event which represents the base for the next sequence (see also
Menlikli et al. 2009). The next sequence has a reduced thickness on the basin
margin as it is constrained between two major regional unconformities, Serravallian
and Messinian at the base and top respectively. The Upper Sarmatian – Meotian
age of this sequence is attributed on the base of the Limankoy 1 and 2 wells
(Figs. 6.1 and 6.4) and Yassihoyuk-1 (Figs. 6.1 and 6.7) on the Turkish margin
(Menlikli et al. 2009; Robinson et al. 1995; S ¸en 2013), while on the Romanian
margin it is generally missing (Dinu et al. 2003, 2005) with the exception of one of
the Cobalescu well which seemingly drilled the Upper Sarmatian deposits below
the Lower Pontian ones (Floroiu et al. 2010; Schleder et al. 2016). The presence of
this sequence in the ODP site 380 have been suggested by the Vasiliev et al.
(Vasiliev et al. 2015).
The Messinian Event defines the Miocene-Pliocene limit and is the base for our
last sequence, Pliocene – Quaternary (Figs. 6.3 and 6.4). This event has been
initially described in the deep water settings by the ODP 380 and 381 legs (Ross
et al. 1978). Its precise age and the magnitude of the sea level drop is still a matter of
debate, spanning values such as 1600 m (Hsü and Giovanoli 1979), 1300–1700 m
(Munteanu et al. 2012), 500–600 m (Schleder et al. 2016), 100 m (Tari et al. 2015,
2016) or 50–100 m (Krijgsman et al. 2010). The precise age of this event is not easy
to establish since a large erosion, due to slope failure and gravitational sliding, has
been associated with it on the shelf area, where most of the wells have been drilled,
proving the Midlle Pontian gap (Gillet et al. 2007; Munteanu et al. 2012; Tambrea
2007), while the only largely studied deep-water wells remain the ODP 380 and
381 sites which are on continuous re-evaluation and scrutiny (Suc et al. 2015; Tari
et al. 2016; Vasiliev et al. 2015). Based on our experience of the Romanian shelf,
we have correlated this event with the Middle Pontian gap that is recorded in the
wells, where the Upper Pontian overlies Lower Pontian or older deposits (Dinu
et al. 2002; Tambrea 2007). On the Romanian-Bulgarian margin we picked the
MSC Event unconformity, at the base of the strong amplitude reflectors
representing the Upper Pontian deep sea fans (Figs. 6.4–6.9). We had to make
this decision because of the relatively low resolution of the lines in this area and
hence the ambiguity in picking the base of the mass transport complexes (MTC) of
Middle Pontian age, representing the early lowstand deposits associated with slope
failure as in Munteanu et al. (Munteanu et al. 2012) which would support the role of
the MTC as the base of Pliocene sequence.
The age of the deposits below the main unconformity are seemingly Middle
Eocene- Cretaceous in age resting directly above oceanic or thinned continental
crust (see also Nikishin et al. 2015a). The precise age of these deposits will be
102
I. Munteanu et al.
and Turkey shelf like the Limankoy-1 (Fig. 6.4), while they were not encountered
on the Romanian Shelf, and the Oligocene deposits are unconformable overlaid by
the Middle Miocene deposits (Fig. 6.8, see also Dinu et al. 2005). The Middle
Miocene, Badenian – Lower Sarmatian in local Paratethys scale (Fig. 6.3) has a
reduced thickness as proven by the well drilled on the shelf, and contains another
important basin scale unconformity, of Middle – Upper Sarmatian age, also known
as Serravalian Event which represents the base for the next sequence (see also
Menlikli et al. 2009). The next sequence has a reduced thickness on the basin
margin as it is constrained between two major regional unconformities, Serravallian
and Messinian at the base and top respectively. The Upper Sarmatian – Meotian
age of this sequence is attributed on the base of the Limankoy 1 and 2 wells
(Figs. 6.1 and 6.4) and Yassihoyuk-1 (Figs. 6.1 and 6.7) on the Turkish margin
(Menlikli et al. 2009; Robinson et al. 1995; S ¸en 2013), while on the Romanian
margin it is generally missing (Dinu et al. 2003, 2005) with the exception of one of
the Cobalescu well which seemingly drilled the Upper Sarmatian deposits below
the Lower Pontian ones (Floroiu et al. 2010; Schleder et al. 2016). The presence of
this sequence in the ODP site 380 have been suggested by the Vasiliev et al.
(Vasiliev et al. 2015).
The Messinian Event defines the Miocene-Pliocene limit and is the base for our
last sequence, Pliocene – Quaternary (Figs. 6.3 and 6.4). This event has been
initially described in the deep water settings by the ODP 380 and 381 legs (Ross
et al. 1978). Its precise age and the magnitude of the sea level drop is still a matter of
debate, spanning values such as 1600 m (Hsü and Giovanoli 1979), 1300–1700 m
(Munteanu et al. 2012), 500–600 m (Schleder et al. 2016), 100 m (Tari et al. 2015,
2016) or 50–100 m (Krijgsman et al. 2010). The precise age of this event is not easy
to establish since a large erosion, due to slope failure and gravitational sliding, has
been associated with it on the shelf area, where most of the wells have been drilled,
proving the Midlle Pontian gap (Gillet et al. 2007; Munteanu et al. 2012; Tambrea
2007), while the only largely studied deep-water wells remain the ODP 380 and
381 sites which are on continuous re-evaluation and scrutiny (Suc et al. 2015; Tari
et al. 2016; Vasiliev et al. 2015). Based on our experience of the Romanian shelf,
we have correlated this event with the Middle Pontian gap that is recorded in the
wells, where the Upper Pontian overlies Lower Pontian or older deposits (Dinu
et al. 2002; Tambrea 2007). On the Romanian-Bulgarian margin we picked the
MSC Event unconformity, at the base of the strong amplitude reflectors
representing the Upper Pontian deep sea fans (Figs. 6.4–6.9). We had to make
this decision because of the relatively low resolution of the lines in this area and
hence the ambiguity in picking the base of the mass transport complexes (MTC) of
Middle Pontian age, representing the early lowstand deposits associated with slope
failure as in Munteanu et al. (Munteanu et al. 2012) which would support the role of
the MTC as the base of Pliocene sequence.
The age of the deposits below the main unconformity are seemingly Middle
Eocene- Cretaceous in age resting directly above oceanic or thinned continental
crust (see also Nikishin et al. 2015a). The precise age of these deposits will be
102
I. Munteanu et al.