correlation from shelf areas to the deep sea part of the basin. In our age assignment
of the main interpreted horizons and seismic sequences we have taken the advantage of the petroleum exploration wells drilled in numerous part of the Black Sea
shelf area (Fig. 6.1) and recently in the deep part of the basin by a few frontier
exploration wells targeting the Mio-Pliocene biogenic gas play or the deep Paleogene plays (see also Bega and Ionescu 2009; Georgiev 2012; Tari et al. 2009). The
results of these new wells are partially disclosed such as those drilled offshore
Turkey, like Sinop-1, Yassihoyuk-1 and Kastamonu-1 wells (Aydemir and Demirer
2013; Korucu et al. 2013; S ¸en 2013; Tari et al. 2011) and are facilitating in part the
correlation of the sequences encounter on the shelf with their deep water equivalents. Of course the calibration is still punctual, the wells being drilled on the
uplifted areas (Fig. 6.1), and it will be probably revised with the results of other
wells being gradually disclosed or of future drilling.
Notwithstanding this, the combination of existing wells and regional seismic
data provide a good age constrain along the WBS for the sequences above the Base
Oligocene, which we call in our study the main unconformity, and a more challenging one for the sequences below and above the WBS basin basement, oceanic
or continental in origin (Fig. 6.1). The above mentioned issues are related in part
with the numerous basin scale unconformities, such as the Messinian, Serravallian,
Base Oligocene, Intra Eocene, Base Eocene and Paleocene (see also, Dinu et al.
2005; Finetti et al. 1988; Robinson et al. 1995; Sinclair et al. 1997) that are effecting
the basin margins; and in part of the difficulty in assessing the age and geometry of
the oceanic crust in the WBS, with the inferred age ranging from Middle Cretaceous
to Upper Cretaceous or Paleocene (Belousov et al. 1988; Galushkin et al. 2007;
Golmshtok et al. 1992; Munteanu et al. 2013; Nikishin et al. 2015b; Spadini et al.
1996).
As we have mentioned above the main unconformity splits our age correlation
into two main units (Figs. 6.3 and 6.4). The age of the main unconformity is better
constrained by the wells drilled offshore Romania and Bulgaria that had encountered Oligocene deposits on top of older series from the basement to Mesozoic with
the youngest one being Upper Eocene in age, hence the unconformity marks the
base of Oligocene deposits (Dinu et al. 2005; Georgiev 2012; Ionescu 1999;
Robinson et al. 1995; Tambrea et al. 2002b). The age of the prograding sequence
observed offshore Turkey is still problematic (Fig. 6.7 BS03). In our interpretation
we include it within the Oligocene sequence representing most probably early
lowstand deposits, which makes our interpretation different from those of Nikishin
et al. (2015a). We base our interpretation on the observation that the Upper Eocene
shallow water carbonatic deposits drilled onshore Romania have a HST prograding
geometry with a clear erosional upper limit on which the Oligocene deposits are
gradually onlaping (Ionescu 1999; Tambrea et al. 2002a, b). Another observation is
that the Yassihoyuk-1 well (Fig. 6.7 BS03 line) drilled Middle Eocene shallow
water carbonates below the main unconformity which suggest that if there were any
Upper Eocene deposit they have been removed and transported in the deep sea part
during Early Oligocene times (Aydemir and Demirer 2013; Korucu et al. 2013).
100
I. Munteanu et al.
of the main interpreted horizons and seismic sequences we have taken the advantage of the petroleum exploration wells drilled in numerous part of the Black Sea
shelf area (Fig. 6.1) and recently in the deep part of the basin by a few frontier
exploration wells targeting the Mio-Pliocene biogenic gas play or the deep Paleogene plays (see also Bega and Ionescu 2009; Georgiev 2012; Tari et al. 2009). The
results of these new wells are partially disclosed such as those drilled offshore
Turkey, like Sinop-1, Yassihoyuk-1 and Kastamonu-1 wells (Aydemir and Demirer
2013; Korucu et al. 2013; S ¸en 2013; Tari et al. 2011) and are facilitating in part the
correlation of the sequences encounter on the shelf with their deep water equivalents. Of course the calibration is still punctual, the wells being drilled on the
uplifted areas (Fig. 6.1), and it will be probably revised with the results of other
wells being gradually disclosed or of future drilling.
Notwithstanding this, the combination of existing wells and regional seismic
data provide a good age constrain along the WBS for the sequences above the Base
Oligocene, which we call in our study the main unconformity, and a more challenging one for the sequences below and above the WBS basin basement, oceanic
or continental in origin (Fig. 6.1). The above mentioned issues are related in part
with the numerous basin scale unconformities, such as the Messinian, Serravallian,
Base Oligocene, Intra Eocene, Base Eocene and Paleocene (see also, Dinu et al.
2005; Finetti et al. 1988; Robinson et al. 1995; Sinclair et al. 1997) that are effecting
the basin margins; and in part of the difficulty in assessing the age and geometry of
the oceanic crust in the WBS, with the inferred age ranging from Middle Cretaceous
to Upper Cretaceous or Paleocene (Belousov et al. 1988; Galushkin et al. 2007;
Golmshtok et al. 1992; Munteanu et al. 2013; Nikishin et al. 2015b; Spadini et al.
1996).
As we have mentioned above the main unconformity splits our age correlation
into two main units (Figs. 6.3 and 6.4). The age of the main unconformity is better
constrained by the wells drilled offshore Romania and Bulgaria that had encountered Oligocene deposits on top of older series from the basement to Mesozoic with
the youngest one being Upper Eocene in age, hence the unconformity marks the
base of Oligocene deposits (Dinu et al. 2005; Georgiev 2012; Ionescu 1999;
Robinson et al. 1995; Tambrea et al. 2002b). The age of the prograding sequence
observed offshore Turkey is still problematic (Fig. 6.7 BS03). In our interpretation
we include it within the Oligocene sequence representing most probably early
lowstand deposits, which makes our interpretation different from those of Nikishin
et al. (2015a). We base our interpretation on the observation that the Upper Eocene
shallow water carbonatic deposits drilled onshore Romania have a HST prograding
geometry with a clear erosional upper limit on which the Oligocene deposits are
gradually onlaping (Ionescu 1999; Tambrea et al. 2002a, b). Another observation is
that the Yassihoyuk-1 well (Fig. 6.7 BS03 line) drilled Middle Eocene shallow
water carbonates below the main unconformity which suggest that if there were any
Upper Eocene deposit they have been removed and transported in the deep sea part
during Early Oligocene times (Aydemir and Demirer 2013; Korucu et al. 2013).
100
I. Munteanu et al.