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Paper Number: 149
Saul, J.M.1
1ORYX, Paris,
john.saul@wanadoo.fr
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Large structures with circular 2-D map-outlines have been trapped
during continent-to-continent collisions: –– a “plug” of resistant rock,
255 km in diameter trapped between E. and W. Gondwana in the
Kenya/Tanzania border region east of the Rift Valley [1]; –– a 180 km
diameter feature in south central Turkey at the contact of the
Eurasian-Anatolian plate with the semicircular NW extremity of the
Arabian plate [2]; and a pair of tangent circles, –– the >400 km
diameter “Middle-Ural Ring Struc-ture (MURS)” of Burba [3, 4] partly
within the Urals, –– and a 210 km circle tangent to it to its SW.
All four of these features, each in its own distinctive manner, is
associated with major economic deposits: –– with transparent gems (ruby,
sapphire, tanzanite, kornerupine, garnets, tourmalines…) in the case of
the faint East African circle; –– with oil & gas in faults and
joints opened on the Arabian plate while it pivoted against the 180 km
Turkish circle; –– with the supergiant Romashkino oilfield, which is
situated within the 210 km Uralian structure (visible on the infolded
map in [5]); –– and with the Arlan supergiant oilfield, transparent
gems, and deposits of Fe, Mn, Cr, Ni, Cu, Ti, Pb, Au and Pt on or near
the perimeter of the MURS [4]. At least 3 of these circles are
associated with ophiolites.
Formation of gem-quality crystals requires locally low pressure, as
does accumulation of oil & gas. The depths at which metamorphic gems
crystallize indicates that these 2-D circles are surface expressions of
deeply-eroded deeply-penetrating 3-D plugs. As such, they are
interpreted as orogenically rejuvenated vestiges of the Late Heavy
Bombardment or, alternatively, of the tail end of our planet’s
accretionary period, in either case older than 3800 Ma [1, 6]. The
proximity of ophiolites, plus deep vertical feeders at Romashkino [5],
suggest a deep abiogenic origin for the oil & gas.
Figure 1a, 1b, 1c: Maps emphasizing selected faults, megajoints, primary
occurrences of transparent gems,
and oil & gas fields. Many gem deposits in the Urals lack
good locality data and are not mapped. Circle diameters,
left to right, are 255, 210, >420 and 180 km.
Red trend lines in Fig. 1c indicate possible megajoints.
Oil/gas fields as mapped by Dr. Michael Izady,
www.Gulf2000.Columbia.edu/maps.shtml
[1] Saul, JM (2014) A Geologist Speculates, Les 3 Colonnes,
Paris, 159 pp., ISBN 978-2-37081-004-5
[2] MTA, Ankara (2002) Geological Map of Turkey, 1:500,000, Hatay and
Sivas sheets
[3] Burba, GA (1991) LPI XXII: 153–154
[4] Burba, GA (2003) Vernadsky Institute / Brown University, Moscow,
Microsymposium 38, abstract MS011
[5] Trofimov, VA (2014) Deep CMP Seismic Survey of Oil and Gas
Bearing Areas (in Russian), GEOS, Moscow,
202 pp., with 1:2,000,000 infolded map, ISBN 978-5-89118-644-6
[6] Saul, JM (1978) Nature 271 (no. 5643) 345-349
