The nature of the crust under Cayman Trough from gravity
ten Brink, Uri S.
Coleman, Dwight F.
Dillon, William P.
MetadataShow full item record
KeywordCaribbean plate; Cayman trough; Continental margins; Gravity anomalies; Serpentinized peridotite; Slow spreading
Considerable crustal thickness variations are inferred along Cayman Trough, a slow-spreading ocean basin in the Caribbean Sea, from modeling of the gravity field. The crust to a distance of 50 km from the spreading center is only 2–3 km thick in agreement with dredge and dive results. Crustal thickness increases to ∼5.5 km at distances between 100 and 430 km west of the spreading center and to 3.5–6 km at distances between 60 and 370 km east of the spreading center. The increase in thickness is interpreted to represent serpentinization of the uppermost mantle lithosphere, rather than a true increase in the volume of accreted ocean crust. Serpentinized peridotite rocks have indeed been dredged from the base of escarpments of oceanic crust rocks in Cayman Trough. Laboratory-measured density and P-wave speed of peridotite with 40–50% serpentine are similar to the observed speed in published refraction results and to the inferred density from the model. Crustal thickness gradually increases to 7–8 km at the far ends of the trough partially in areas where sea floor magnetic anomalies were identified. Basement depth becomes gradually shallower starting 250 km west of the rise and 340 km east of the rise, in contrast to the predicted trend of increasing depth to basement from cooling models of the oceanic lithosphere. The gradual increase in apparent crustal thickness and the shallowing trend of basement depth are interpreted to indicate that the deep distal parts of Cayman Trough are underlain by highly attenuated crust, not by a continuously accreted oceanic crust.
This paper is not subject to U.S. copyright. The definitive version was published in Marine and Petroleum Geology 19 (2002): 971-987, doi:10.1016/S0264-8172(02)00132-0.
Suggested CitationMarine and Petroleum Geology 19 (2002): 971-987
Showing items related by title, author, creator and subject.
The origin of hydrothermal chlorite- and anhydrite-rich sediments in the middle Okinawa Trough, East China Sea Shao, Hebin; Yang, Shouye; Humphris, Susan E.; Cai, Di; Cai, Feng; Li, Jiangtao; Li, Qing (2017-05-18)During the Integrated Ocean Drilling Program (IODP) Expedition 331, five sites were drilled into the Iheya North Knoll hydrothermal system in the Okinawa Trough (OT) — a back-arc basin characterized by thick terrigenous ...
Lohman, Rowena B.; McGuire, Jeffrey J. (American Geophysical Union, 2007-04-10)In late August 2005, a swarm of more than a thousand earthquakes between magnitudes 1 and 5.1 occurred at the Obsidian Buttes, near the southern San Andreas Fault. This swarm provides the best opportunity to date to assess ...
A record of eruption and intrusion at a fast spreading ridge axis : axial summit trough of the East Pacific Rise at 9–10°N Soule, Samuel A.; Escartin, Javier E.; Fornari, Daniel J. (American Geophysical Union, 2009-10-22)High-resolution side-scan sonar, near-bottom multibeam bathymetry, and deep-sea photo and bathymetry traverses are used to map the axial summit trough (AST) at the East Pacific Rise between 9 and 10°N. We define three ridge ...