* Denotes speaker other than senior author.

SUESS, ERWIN, GERHARD BOHRMANN*, and JENS GREINERT, GEOMAR Research Center, Kiel; ALEXANDER DERKACHEV, RUSLAN KULINICH, and ANATOLIY OBZHIROV, Pacific Oceanological Institute, Vladivostok; and GISELA WINCKLER, Institut fur Umweltphysik der Universitat Heidelberg

Abstract: Giant Cold Vents and Barite Mineralization in the Derugin Basin

Since the early 1980s barite-carbonate mineral associations had been known from a structural high of the Derugin Basin in the Sea of Okhotsk. The porous fabric of dredged lithologies appeared to have formed from fluids emanating at the seafloor. The origin, age, source, and mechanism of possible fluid venting remained unresolved.

We recently documented for the first time by video-survey and sampled by dredging and coring barite chimneys several meters high, travertine-like boulders, blocks, and mounds consisting of pure barite, barite sand and barite silt turbidites. Live bivalves commonly associated with cold seeps were recovered (Calyptogena sp., Solemya sp.) and colonies of these and of gastropods observed around the barite structures. The area of venting is at least several sq km and so far appears confined to the deepest part of the Derugin Basin. Methane anomalies with concentrations exceeding 2000 nl/L were measured decreasing to 30 nl/L as far as 12 km away. The lower water column is depleted in oxygen and enriched in nutrients. Pore waters extracted from the barite turbidites show Cl-depletions. This evidence together with dissolved Ba in the pore fluids and bottom water, He- and C-isotopes isotopes in the lower water column unequivocally prove the existence of giant cold vent fields in the Derugin Basin.

AAPG Search and Discovery Article #90920©1999 AAPG Pacific Section Meeting, Monterey, California