Plate-Scale Tectonic Events Inferred from Mesozoic and Cenozoic Tectonostratigraphy of the Southeastern Portion of the Arabian Plate

George, Richard P.¹, Bertrand de Monteynard¹, Martine J. Hardy², Nurlan I. Muratov¹, Christopher G. Willan¹, George J. Grabowski¹, John C. Mitchell¹, D. Mark Steinhauff¹, Will B. Maze¹, Keith C. King¹, John K. King¹, Charles R. Beeman¹, James A. Lopez¹, Jean-Christophe Sempere¹, Ron J. Kleist² (1) ExxonMobil Exploration Company, Houston, TX, (2) ExxonMobil Upstream Research Company, Houston, TX

We have integrated the Mesozoic-Cenozoic stratigraphy of the Arabian plate (from north­western Saudi Arabia and southern Iraq to Oman and northern Yemen) into a second- and third-order sequence-stratigraphic framework, from which we infer the following structural and tectonic characteristics:

1. Large regions have low structural dips (typically < 1o; rarely > 5o) that persist withlittle change of dip azimuth for tens to hundreds of km. The low dips contribute to the per­ception that much of the study area was a “stable” platform. Areas of high dips are associ­ated with deformation fronts of the Oman and Zagros Mountains and with mobilized InfraCambrian Hormuz salt.

2. Second-order sequence boundaries in the “stable” platform are low-angle (typically <1o; rarely > 5o ) unconformities. The unconformities are laterally persistent and can have constant direction of increasing downcutting over hundreds of km. Section missing at five tectonically-enhanced unconformities (Hettangian, Toarcian, mid-Tithonian, Turonian, and Maastrichtian) exceeds 300 m over broad areas (> 50,000 km2), belying the platform’s apparent “stability”.

3. The area is tectonically quiet for long intervals (25 to 50 Ma) and tectonically dis­turbed during short intervals (2 to 10 Ma).

4. Map patterns of amount of erosion suggest that broad upwarping (wavelengths > 100km) rather than block-faulting is the major mechanism that created topographic relief dur­ing erosion (Maastrictian event excepted).

We interpret most of the broad upwarps as thermal welts that overlay zones of mantle upwelling associated with rift and drift of other former parts of Gondwana from Arabia.