Understanding carbonate ramp dynamics using δ13C profiles:: examples from the Neoproterozoic Buah Formation of Oman

The Late Neoproterozoic Buah Formation (Nafun Group, Oman) is a carbonate unit outcropping in the Jabal Akhdar and Huqf areas. It is composed mostly of shallow-water carbonates deposited on a distally steepened carbonate ramp. Correlation of two delta(13)C isotope shifts shows that in the Jabal Akhdar ramp differentiation into fast and slow subsiding areas was followed by lateral progradation. In the Huqf area, however, a uniform scenario of upward shallowing of the facies and lateral progradation is demonstrated by chemostratigraphic timelines cross-cutting the facies belts. The chemostratigraphic profiles show that the Buah Formation was deposited during sea-level highstand conditions and that ramp differentiation was due to synsedimentary tectonics. High-resolution correlation of delta(13)C profiles from the same lithostratigraphic unit (whether Precambrian or Phanerozoic in age) lacking biostratigraphic data can shed light on carbonate systems dynamics, tectonic vs. eustatic controls on depositional sequences and basin subsidence.