News

Paper on Early Cretaceous bio- and chemostrat for the Early Cretaceous northern South Atlantic in press

Our paper on "Integrated bio- and chemo-stratigraphy for Early Cretaceous strata offshore Gabon: Additional constraints on the timing of salt deposition and rifting of the South Atlantic", led by my colleague James Eldrett, is now accepted and in press with Marine and Petroleum Geology (reference here).

Abstract:
Early Cretaceous rift basins of the incipient South Atlantic have been the focus of intense hydrocarbon exploration and production activities and host some large oil accumulations in sections predating an interval of major salt deposition, particularly in the central segment of the South Atlantic. Understanding the timing (and associated uncertainties) of source rock and reservoir deposition and their relationship with rift evolution is critical for successful exploration. However, there are still many unresolved issues and data gaps regarding the precise age and duration of salt deposition. Better chronological constraints are particularly needed to the determine the timing of deposition of Pre-Salt reservoirs and the primary evaporites, as well as the secondary phase of halokinensis that resulted in variable reservoir sealing potential. To help address this gap, stable carbon isotope (δ13C) records from bulk organic matter and insoluble kerogen were generated for the Early Cretaceous salt and Pre-Salt intervals from two exploration wells offshore of Gabon. The bulk organic δ13C stratigraphies for the two wells were then integrated with palynological and ostracod biostratigraphy and placed within a sequence stratigraphic and regional tectonic framework, providing new constraints on the timing of rift lake evolution and salt deposition. The good correlation between the offshore Gabon δ13C record with other published sections calibrated to the current Geologic Time Scale as well as other regional sections from NE Brazil, supports the reliability of our new Gabon δ13C record. Several δ13C excursions are identified in the Pre-Salt sequence and are correlated with the Valanginian Weissert event and Early Aptian δ13C event(s). Salt deposition on the Gabon margin is interpreted to have occurred during an interval straddling the Early-Late Aptian boundary (∼118.4–116.8 Ma). These findings are comparable with other published estimates for salt deposition from northeast Brazil but differ from published estimates from the Campos-Santos basins; the latter are critically discussed. This study provides an important stratigraphic dataset for offshore Gabon and contributes to the ongoing debate regarding the timing of rifting and salt deposition in the Early Cretaceous of the South Atlantic passive margin system.

Ocean Transform Paper published in G3

Our paper on "A new model for the evolution of oceanic transform faults based on 3D Broadband Seismic observations from São Tomé and Príncipe in the eastern Gulf of Guinea", led by my colleague Myron Thomas, is now accepted and in press with G-cubed (reference here).

Abstract:
Oceanic Transform faults are one of manifestations of the three major plate boundaries and a key tectonic feature of oceanic crust. They are broadly considered to accommodate strike-slip displacement along simple vertical faults and to be largely without magmatic addition. We present the first observations from broadband 3D seismic of buried, Cretaceous-aged transform faults in the Gulf of Guinea with complex internal architectures including crustal scale detachments and rotated packages of volcanics within oceanic crust. In the study area, several Oceanic Fracture Zones (OFZ) are described from Top Crust to Moho. OFZ scarps are observed to connect at depth with zones of low angle reflectivity which dip into the OFZ and perpendicular to the spreading orientation. At depth they detach onto the Moho, necking the adjacent crust in the manner of extensional shear zones. Thickly stacked and tilted reflectors, interpreted as extrusive lava flows, are common above the shear zones and infill up to 75% of the crustal thickness. The entire OFZ stratigraphy is overlain and sealed by late-stage lavas that are continuous from the abyssal hills of the trailing spreading ridge. These insights demonstrate complexity previously only predicted in numerical simulations. We propose a model with extension at a high angle to the spreading orientation along a low angle shear zone that acts as a conduit for decompression related melt and volcanism. We conclude that oceanic transforms are non-conservative and not simple strike slip fault zones, contradicting the conventional view.

TectonicWaters Blog

For up-to date posts and news, please head over to my TectonicWaters blog on the PaleoEarthLabs wiki.

Nature Communications paper on rift migration is published

Our paper on rift migration and continental margin asymmetry is now available online as open-access through Nature Communications: 10.1038/ncomms5014.

Animations for Geology paper

The following animations accompany our "No Saharan Atlantic ocean"paper in GEOLOGY. The first one is a plate kinematic reconstruction of the region in 1 M.yr. time steps. Further below, you can find the 30 M.yr long animation of the numerical model. Please refer to the paper and the supplementary material (http://www.geosociety.org/pubs/ft2014.htm) for the gory technical details and the data base.

Geology paper on Equatorial Atlantic paper now available

Our paper "Oblique rifting of the Equatorial Atlantic: Why there is no Saharan Atlantic ocean" in GEOLOGY in now available online through the DOI: 10.1130/G35082.1. An official pre-issue publication should follow this week.

Back to Europe

I've relocated back to Europe, now working for Shell International Exploration & Production in The Netherlands.

Equatorial Atlantic paper in press in Geology

Our paper "Oblique rifting of the Equatorial Atlantic: Why there is no Saharan Atlantic ocean" is accepted and in press in GEOLOGY. Check my publication page for updates and the PDF (Expected online publication date is Mid-January 2014)

Successful IODP proposal

I am proponent of a successful IODP proposal 807, led by S. Gallagher from Melbourne Uni, to investigate the history of the Indonesian throughflow and subsidence of the Northwest Australian margin. The cruise is scheduled for 2015 and the full proposal can be accessed on the IODP website: http://iodp.tamu.edu/scienceops/precruise/indonesianthruflow/807-Full_Gallagher.pdf

South Atlantic rift kinematics paper published

The South Atlantic rift kinematics paper is finally published in Solid Earth as of today. Access the paper here

Uplift in SW Australia

Last year, my B.Sc. hons student Nicholas Barnett-Moore has investigated Australian river profiles and what they can tell us about vertical motions of the Australian crust. We have just submitted a paper on this which is available on arXiv under document number 1307.1741. The paper is submitted to Tectonophysics and we will make the associated data available online once we have received feedback from the review process.

South Atlanic Kinematics paper in open online discussion

My South Atlantic paper is now in open online discussion and review at EGU's open access journal Solid Earth Discussions. The direct link to the paper is here http://www.solid-earth-discuss.net/5/41/2013/sed-5-41-2013.html