Russia has tentatively decided not to try to drill the world's deepest hole to its original 15,000 m (49,212 ft) target depth.
Moscow's Trud newspaper reported that drilling in the SG-3 superdeep hole probably will be halted at the 13,000 m (42,650 ft) mark. Site is on the Kola Peninsula near the Norwegian border west of Murmansk.
Present depth was said to be about 12,261 m (40,226 ft), indicating no progress has been made in more than 1 year.
A Russian report last summer claimed that SG-3 had gone below 13,000 m.
Trud said, "Drilling is continuing, although each additional meter is more difficult. Approximate speed in deepening the hole has been 1,000 m (3,281 ft) in 6 years."
WHAT'S BEEN FOUND
Russian geologists said "traces" of oil, gas, copper, nickel, and gold were found in the 7,000-8,000 m (22,966-26,246 ft) interval. They added that more than 20 kinds of microorganisms were found at great depths, "confirming the hypothesis that life existed on earth in the Precambrian epoch.
"Study of core samples showed that in all respects they resembled lunar soil. This provides strong evidence that the moon was once part of the earth."
SG-3 was spudded in May 1970. The hole reached 39,586 ft in 1984.
Drilling was then suspended "to carry out extensive scientific studies, to change some of the equipment, and to prepare for the next stage of deeper drilling."
Plans called for taking the hole to 14,000 m (45,931 ft) by the end of 1990. But the U.S.S.R.'s Ministry of Geology conceded it would have 11 great difficulty" reaching that mark. A Uralmash-15000 rig has been employed at the hole. Bore diameter is 245 mm.
Meanwhile, under Germany's deep continental drilling project, a hole is being drilled to a target depth of 10,000 m (32,808 ft), possibly 12,000 m (39,370 ft) if conditions permit. The KTB Hauptbohrung hole was spudded in autumn 1990 and reached 22,147 ft last July 30.
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