Ya. Bogdanov et al., RELICT SULFIDE FORMATIONS OF TAG HYDROTHE RMAL FIELD, MID-ATLANTIC (26-DEGREES-N, 45-DEGREES-W), Okeanologia, 34(4), 1994, pp. 590-599
During the 23-th Cruise of the R/V ''Akademik Mstislav Keldysh'' an th
e TAG hydrothermal field a huge cone-shaped hydrothermal MIR Mound was
descovered. Its dimensions are: diameter near basement is more than 7
00 m, height 50 - 70 m. The total weight of hydrothermal material is a
bout 10 million tons. The MIR Mound is divided into two zones: the you
ng internal and the old outer. The internal zone diameter is about 400
m. There is a dense ''forest'' of high temperature sulfide chimneys i
nside the internal zone. The outer zone width is 150 - 200 m. Low temp
erature hydrothermal minerals (hydroxides of Fe and Mn, opal, sometime
s - sulfides) are mainly inside the outer zone. The outer zone is part
ly covered by sediments. The radiocarbon dating of sediments accumulat
ed near the MIR Mound showed that it began to form yearlier that 25 k.
y. B. P. The periods of hydrothermal activization were 23 - 25, 12 -
16 and 4 - 8 k. y. B. P. Deep tow photographing, side scan survey and
sediment studies have indicated that 2.5 km to the North from MIR Moun
d another inactive hydrothermal mound of similar dimensions exists.