Arabian Orbital Stratigraphy revisited – AROS 2015

Abstract

ABSTRACT ‘Arabian Orbital Stratigraphy’ (AROS) is an R&D program aimed at dating Arabia’s transgressive-regressive (T-R) depositional sequences using the ‘Orbital Scale’ of Matthews and Al-Husseini (2010). The scale consists of time-rock units named ‘orbitons’, ‘dozons’ and ‘stratons’ that are tuned by orbital-forcing of glacio-eustasy. Orbitons have durations of 14.58 million years (Myr), and are bounded by regional sequence boundaries (SB, hiatus, unconformity, disconformity, lowstand deposits). Orbiton 1 was deposited between SB 1 at 16.166 million years before present (Ma) and SB 0 (zero) at 1.586 Ma. The interval between SB 0 and the Precambrian/Cambrian Boundary (PCB) consists of 37 orbitons; at least 30 can be identified in Arabia based on published data. SB 37 is predicted at 541.046 Ma (1.586 + 37 × 14.58 Myr), and correlates to the PCB, calibrated in Oman at 541.0 Ma. An orbiton consists of 36 stratons. Stratons are T-R sequences that tracked the long-eccentricity orbital cycle (E-cycle). The age of base Straton 1 is 0.371 Ma. Their durations can range between about 300 thousand years (Kyr) and 550 Kyr, but average 405 Kyr over several million years. The Phanerozoic Era consists of 1,336 stratons that are typically referred to as 4th-order sequences or cycle sets. Approximately 200 stratons are identified in this paper, and tentatively dated in the Orbital Scale. An orbiton also consists of three dozons, which are generally bounded by regional SBs. Dozons typically consist of 12 stratons (4.86 Myr). Examples of dozons are illustrated in this paper for the Permian–Triassic in Arabia. AROS predicts ages for Arabian and global T-R sequences that are deterministic, and they may be more accurate than those estimated by the Geological Time Scale GTS 2015. The paper proposes that the global T-R sequences should be recast in terms of stratons (E-cycles), and that stratons be used to calibrate biostratigraphy, magneto-stratigraphy and other global stratigraphic markers in future GTSs.