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December 02-03, 2019 | Dubai, UAE
Oil & Gas
2
nd
International Conference and Expo on
Journal of Industrial and Environmental Chemistry | Volume 3
Mineralogy of siliceous concretions, cretaceous of Ionian zone, western Greece: Impli-
cation for diagenesis and porosity
Avraam Zelilidis
1
, Nicolina Bourli
1
, Maria Kokkaliari
1
, Ioannis Iliopoulos
1
, Georgia Pe-Piper
2
, David Piper
3
, Angelos
Maravelis
1
1
University of Patras, Greece
2
Mary's University, Greece
3
Bedford Institute of Oceanography, Canada
X
RPD analysis, in selected samples, in both nodules
and siliceous beds, showed the presence of moganite
and Opal-A minerals and introduce mostly an amorphous
silica. The presence of maghemite may be evidence for the
importance of redox-controlled pore-water boundaries in
the initial precipitation of amorphous silica, as maghemite
can form by dehydration and transformation of certain iron
oxyhydroxide minerals.
Results showed different calcite content or the presence/
absence of halite and anhydrite, from different age and
different areas, from both nodules and siliceous beds,
suggesting great differences between areas, due to different
sources, and introduce different tectonic activity between
areas withmore intense tectonic activity in NWPeloponnesus
than in Kastos Island.
The content of calcite in cherts is likely a consequence of
the amount of early amorphous silica precipitation. The
siliceous beds in Gianiskari have a higher calcite content than
nodules of Araxos, both in NW Peloponnesus, suggesting
increased replacement mostly in nodules, whereas in both
areas, there is no difference in calcite content between upper
Cretaceous siliceous bed and nodules. The calcite content
of upper Cretaceous chert is higher in Kastos Island than in
NW Peloponnesus. The major source for Kastos Island was
the Apulian platform whereas for NW Peloponnesus was
the Gavrovo platform, so the physical properties of the two
sediment successions might differ, thus affecting diagenesis.
The clearest evidence for the role of later fluids is the presence
of halite and anhydrite only inNWPeloponnesus, where there
are fault pathways for basinal fluids from underlying Triassic
evaporites that include halite and gypsum. The erosion
of Triassic evaporites, only in the eastern part of the basin,
could be related with intense tectonic activity in this part of
the basin. This difference is because it was influenced by the
first stages of compression (late Eocene to early Oligocene),
situated between Gavrovo and internal Ionian thrusts, that
the western parts of the basin, which influenced by later
stages (late Oligocene-early Miocene), situated between
middle Ionian and Ionian thrusts.
The characteristic presence of dolomite in lower Cretaceous
siliceousbedisinaccordancewiththepresenceofdolomitized
limestones at the lower parts of early Cretaceous Vigla
formation. Either the dolomite replaced calcite before final
growth of the siliceous bed horizons, or chert was replaced by
dolomite. The size and the abundance of nodules was related
with mostly with primary porosity of the hosted deposits
and in relation with the fact that Early Cretaceous nodules
are smaller and in abundance that these of Late Cretaceous
support the idea that the porosity of Late Cretaceous
hosted limestones is greater that in Early Cretaceous hosted
limestones. The fact that now both present equivalent
porosities support the idea that the development of nodules
increased secondarily the porosity of Early Cretaceous
limestones.
Speaker Biography
Avraam Zelilidis was graduate Geologist in 1984 and a PhD in 1988 in the
Department of Geology of the University of Patras. He was appointed
as a lecturer in 1993 and since 2009 as a full professor in the Department
of Geology of the University of Patras. He served as Dean of the Faculty
of Natural Sciences at the University of Patras from 2006 to 2010.
Research deals with the Analysis of Sedimentary Basins, Sequence
Stratigraphy, Seismic Stratigraphy and Petroleum Geology. Have produced
many research projects for oil companies using data in both surface
and subsurface, while he organized many field seminars for foreign oil
companies. He has published more than 100 papers in international
journals, most of which refer to the hydrocarbon potential in Greece and
have been presented in international conferences in an effort to highlight
the issue of existence-exploitation of hydrocarbon fields in Greece.
e:
zelidlisavvaram@patras.grAvraam Zelilidis et al.
, J Ind Environ Chem, Volume:3
DOI: 10.35841/2591-7331-C3-014