Constraints on the proposed Marie Byrd Land-Bellingshausen Plate Boundary from seismic reflection data

• Published in: Journal of Geophysical Research: Solid Earth
• Main Authors: Heinemann, J., Stock, J., Clayton, R. W., Hafner, K., Cande, S., Raymond, C.
• Format: Article in Journal/Newspaper
• Language: English
• Published: American Geophysical Union 1999
• Subjects: Byrd; Marie Byrd Land; West Antarctica; Antarc*; Antarctica
• Online Access: https://authors.library.caltech.edu/34919/; https://authors.library.caltech.edu/34919/1/Heinemann1999.pdf; https://resolver.caltech.edu/CaltechAUTHORS:20121016-104022644

Single-channel and multichannel marine seismic data off the coast of West Antarctica collected during two Nathaniel B. Palmer cruises (NP92-8 and NP96-2) in the vicinity of 65°S to 71°S, 220°E to 250°E, reveal a NNW trending graben. We interpret this graben to be part of the paleodivergent plate boundary between the Marie Byrd Land and Bellingshausen plates. This graben coincides with a −520 nT magnetic anomaly to the NNW and a −720 nT anomaly to the SSE, as well as a 20 mGal negative gravity anomaly. Seismic profiles subparallel to the graben (22 km/Ma half-spreading rate) reveal greater seafloor roughness to the NE, where seafloor spreading was slower, than to the SW (27 km/Ma half-spreading rate). These data allow the position of the Marie Byrd Land-Bellingshausen plate boundary to be constrained more precisely than has previously been possible, with a trend of N17°W from 68.52°S, 233.65°E to 68.41°S, 233.56°E. The sediment-filled graben has normal separation of sedimentary layers varying from 740±30 m to 580±20 m imaged in seafloor of age A33y (74 Ma).