Click to view page image in pdf format.
7th Middle East Geosciences Conference and Exhibition
Manama, Bahrain
March 27-29, 2006
Sequence
Stratigraphy
: Potential Consequences for Global Chronostratigraphy
Neftex
Petroleum Consultants Ltd, 80A Milton Park, Oxford, OX14 4RY, United Kingdom, phone: 44 1235 442699,
[email protected]
Sharland et al. (2001; 2004) have described 65 Phanerozoic maximum flooding surfaces (MFS) that can be identified and
correlated across the Arabian Plate, providing a framework for understanding the regional lithostratigraphy and placing key
petroleum elements into a predictive
sequence
stratigraphic model. Ongoing work has demonstrated that these MFS, plus
many newly identified additional MFS, can be readily identified in the coeval
stratigraphy
of North Africa, along with
intervening
sequence
boundaries (SB) and their correlative conformities. It can be demonstrated across the region that the
majority of these surfaces occur within the same biozone, and are coincident with surfaces independently recognised in
other (largely passive margin) sedimentary basins (e.g. NW Europe – Hardenbol et al. (1998); West Siberia (Sahagian et
al., 1996); Baltica (Nielsen, 2004). This suggests that there is strong eustatic control on sedimentary sequences and that a
global
sequence
stratigraphic model is a reality.
The chronostratigraphy community is currently in the process of defining GSSPs (Global boundary Stratotype Sections and Points) for each Phanerozoic stage. At the time of writing 46 of the 90+ stages have a ratified GSSP. Of these, a number continue to be the cause of dispute, and many of those yet-to-be-defined appear problematic.
Since the evidence for eustatic control on sedimentation is strong, then
sequence
stratigraphic concepts can assist the
definition of GSSPs. Because MFS and SBs relate to changing sea-level, they have associated changes in fossil
assemblages making them readily recognisable and correlatable. Therefore SBs provide “natural” boundaries to stages.
Indeed many stage boundaries, as currently perceived from their historical stratotypes, lie close to
sequence
boundaries
dated in their correlative conformity position in a basin. It is now possible to envisage the conjugation of the global
sequence
stratigraphic model with the chronostratigraphic timescale.