Abreu, Vitor dos Santos and Haddad, Geoffrey A. (1998): Glacioeustatic fluctuations; the mechanism linking stable isotope events and sequence stratigraphy from the early Oligocene to middle Miocene

ODP 120
DSDP 73 522
DSDP 74 529
DSDP 82 563
DSDP 94 608
ODP 120 747

Abreu, Vitor dos Santos
Petrobras Research Center, Rio de Janeiro, Brazil

Haddad, Geoffrey A.
Exxon Production Research, United States

Glacioeustatic fluctuations; the mechanism linking stable isotope events and sequence stratigraphy from the early Oligocene to middle Miocene
In: de Graciansky, Pierre-Charles (editor), Hardenbol, Jan (editor), Jacquin, Thierry (editor), Vail, Peter R. (editor), Mesozoic and Cenozoic sequence stratigraphy of European basins
Society for Sedimentary Geology (SEPM), Tulsa, OK, United States
One of the most difficult challenges of sequence stratigraphy is the establishment of synchrony between events observed in widely separated depositional basins. Problems arise primarily because the chronostratigraphic control in most passive margins is not adequate to constrain the ages of sequence boundaries to better than plus or minus a few million years. This resolution is often insufficient for the correlation of third-order sequences. Furthermore, unless a common mechanism affecting eustasy is assumed, such as variations in the volume of ice on the planet, there is no a priori reason to expect that sequences of similar age in widely separated basins are indeed synchronous. The stable oxygen isotope composition (delta (super 18) O) of marine carbonates is an independent proxy for ice volume (sea level) which has been under utilized in sequence stratigraphic analyses. This is somewhat surprising given the number of studies that have established a good relationship between foraminifera delta (super 18) O and ice volume in Pliocene to Pleistocene units. This paper builds on the work of Miller et al. (1987, 1991) and Abreu and Savini (1994) in identifying major Oligocene to middle Miocene isotope events and correlating them to sequence stratigraphic events. Identification of isotope events is based on delta (super 18) O data from DSDP sites 522, 529, 563, and 608, and ODP Site 747, drilled in abyssal water depths in the Atlantic and Indian oceans. These isotope records were used by Miller et al. (1991) to define Oligocene and Miocene oxygen isotope zones. In addition to the DSDP/ODP sites, we present oxygen and carbon isotope data from Petrobras Well A drilled in bathyal water depths in the Campos Basin on the Brazilian passive continental margin. Detailed biostratigraphy indicates that this well contains a fairly complete Oligocene to middle Miocene record. Ages of common isotope events in DSDP and ODP sites and Well A correspond remarkably well with the ages of Oligocene to middle Miocene sequence boundaries identified by Hardenbol et al. (this volume) and Vakarcs et al. (this volume) and correlated to the new time scale of Berggren et al. (1995). Because of the good correlation between the isotope and sequence stratigraphic records, we reconfirm that ice-volume change is the common mechanism driving both oxygen isotope and sea-level fluctuations from Oligocene to present time. We propose four previously unidentified early Oligocene to middle Miocene heavy oxygen isotope events that correlate with sequence boundaries identified in the Pannonian Basin (Vakarcs et al., this volume) and presented in the new cycle chart of Hardenbol et al. (this volume). Additionally, we suggest new chronostratigraphic positions for most of the heavy oxygen isotope zonal boundaries observed previously by Miller et al. (1991). We also present the chronostratigraphic positions for minimum ice-volume events (maximum flooding surfaces) determined from the isotopic record.
Coverage:Geographic coordinates:
West:-80.0000East: 147.0000

Stratigraphy; Isotope geochemistry; Atlantic Ocean; biostratigraphy; C-13/C-12; carbon; Cenozoic; chemostratigraphy; chronostratigraphy; correlation; Deep Sea Drilling Project; depositional environment; DSDP Site 522; DSDP Site 529; DSDP Site 563; DSDP Site 608; eustacy; fluctuations; glacial environment; glaciation; glaciomarine environment; Indian Ocean; IPOD; isotope ratios; isotopes; Leg 120; Leg 73; Leg 74; Leg 82; Leg 94; lower Oligocene; marine environment; middle Miocene; Miocene; Neogene; O-18/O-16; Ocean Drilling Program; ODP Site 747; Oligocene; oxygen; paleoclimatology; paleoenvironment; Paleogene; sea-level changes; sequence stratigraphy; stable isotopes; Tertiary;