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Regional patterns of hydrothermal alteration of sediments as interpreted from seafloor reflection coefficients, Middle Valley, Juan De Fuca Ridge
Author(s) -
Rohr Kristin M. M.,
Schmidt Ulrike,
GroschelBecker Henrike
Publication year - 1993
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/93gl00564
Subject(s) - seafloor spreading , geology , hydrothermal circulation , reflection (computer programming) , ridge , drilling , geochemistry , seismology , geomorphology , mineralogy , paleontology , materials science , metallurgy , computer science , programming language
Reflection coefficients of the seafloor have been calculated from three multi‐channel seismic reflection profiles across Middle Valley of the Juan de Fuca ridge. Seafloor reflection coefficients in this sedimented rift valley are high over an active hydrothermal vent and adjacent to major offset faults. Comparison of our measurements to drilling results from Leg 139 shows that high reflection coefficients over an active vent mound are produced by cemented sediments. Large reflection coefficients adjacent to major faults may have a similar origin and indicate that ongoing faulting creates pathways for hydrothermal fluids which alter the sediments and result in higher densities and velocities. Since 30 Hz seismic energy responds to the top 50 m of sediments, we are looking at the integrated response of hydrothermal alteration over tens of thousands of years. This is the first time seafloor reflection coefficients have been used to identify highly altered sediments in a region of deep‐water hydrothermal activity.