Continuous Sea-Floor Spreading in Red Sea: An Alternative Interpretation of Magnetic Anomaly Pattern

摘要

The magnetic anomaly pattern over the Red Sea can be modeled as a continuous system of sea-floor spreading from the early Miocene to the present by using a time-varying process filter. The half spreading rate is approximately 1 cm/yr (0.4 in./yr) since initial rifting. The parameters that determine the process filter and development of the transition zone are the intrusion parameter (a measure of the dispersion of feeder dikes or horizontal strain about the rift axis), a flow parameter (a measure of the average flow width), and the effusion parameter (a measure of volcanic effusion and thickness of layer 2). The interpretation of the anomaly pattern implies that basement within the main trough of the Red Sea is composed of a thick accumulation of volcanic sills and flows deposited during early rifting. Extrusion of the lavas occurred over a wide (up to 60 km or 37 mi) zone of strain distributed about the rift axis. The development of this thickened zone of igneous crust is the second of three successive stages are as follows. (1) An initial stage of crustal stretching or listric faulting in the Oligocene accompanied by probable regional uplift. (2) A period of high volcanic effusion accompanied by the emplacement of stratoid basalts. The stratoid volcanics form overlapping flows and sills with intercalated sediments within the main trough. The spreading center narrowed from the early Miocene to the present. (3) Steady-state sea-floor spreading from Pliocene to present south of a transitional zone near 22 deg S.