Stratigraphy, structure, and origin of the Mendeleev Ridge from bathymetry, controlled source seismic, and gravity observations

Abstract

Multi-channel-seismic (MCS), seismic refraction, and gravity data collected over the Mendeleev Ridge have been processed and interpreted to describe the crustal style of the ridge, as well as the structural and depositional history. These results provide constraints on the origin of the ridge, and the tectonic evolution of the Amerasian Basin. MCS images reveal two primary sediment sequences separated by an unconformity that persists across the entire Mendeleev Ridge. The basement and lower sediment sequence exhibit pervasive normal faulting and the regional unconformity is interpreted to mark the end of extensional deformation. Modeling of the seismic refraction data reveals an upper crustal velocity structure consistent with either a volcanic rifted continental margin, or an oceanic plateau. Gravity anomalies collected along the MCS lines can be reproduced with models containing bathymetry, sediment and basement horizons, and a crust of 2.86 g/cm³. This result is consistent with homogeneous, mafic crust. Comparing the velocity and density structures of the Mendeleev Ridge to the Alpha Ridge suggests they are contiguous and share a common geologic origin. Three tectonic models are presented for the origin of the Alpha Mendeleev Ridge (AMR) that satisfy constraints set by this and previous studies.