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Hydrothermal discharge zones beneath massive sulfide deposits mapped in the Oman ophiolite

May 14, 1989

The area in the Oman ophiolite containing the volcanic-hosted Bayda and Aarja massive sulfide deposits exposes a cross section of ocean crust and reveals to an unprecedented extent the fossil zones of hydrothermal upwelling that fed these sea-floor deposits. The fossil discharge zones are elongate areas of alteration and mineralization characterized by numerous small (metres to tens of metres in length), linear, discontinuous gossans. The gossans result from oxidation of hydrothermal pyrite replacing primary igneous phases and filling voids and fractures in the altered host rocks. The two deposits have separate discharge zones that appear to be sub-sea-floor extensions of their stockworks. The Bayda zone extends through the volcanic section into the upper sheeted dike complex and is interpreted as having formed on the ridge crest above an axial magma chamber; the Aarja zone terminates against a plagiogranite pluton that intrudes the lower volcanic section and is thought to have formed after Bayda in an off-axis environment. Structural, stratigraphic, and compositional characteristics of the Bayda and Aarja massive sulfide bodies are consistent with this interpretation. The geometry of the discharge zones suggests that in both cases upfiow occurred in broad zones (at least 400-600 m wide) that were elongated along strike (i.e., parallel to the spreading axis).

Publication Year 1989
Title Hydrothermal discharge zones beneath massive sulfide deposits mapped in the Oman ophiolite
DOI 10.1130/0091-7613(1989)017<0531:HDZBMS>2.3.CO;2
Authors R.M. Haymon, Randolph A. Koski, M. J. Abrams
Publication Type Article
Publication Subtype Journal Article
Series Title Geology
Index ID 70210130
Record Source USGS Publications Warehouse
USGS Organization Geology, Minerals, Energy, and Geophysics Science Center