Geology Reference
In-Depth Information
drilling mud dilution by pore water; sticking and seizure of
drillpipes, pushing out of drill-pipes by the rock entering the
borehole, etc.).
In some regions, the sediment fill comprises thick complexes of alter-
nating competent and incompetent rocks. There, syngenetic AHPP in clay
series with the density inversion in the sedimentary sequence and low shear
strength is a geodynamic factor of dominating importance for a number of
processes and phenomena, which include:
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Formation processes of regional tectonic plan.
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Local structure-formation.
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Faulting.
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“Overturned” and nappe tectonics.
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Isoclinal and disharmonic folding;
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Cleavage.
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Tectonic breccia.
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Crypto-diapirism and complete diapirism.
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Mélange, “twisted” clay lamination “crushed” clays).
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Natural hydraulic fracturing.
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Mud volcanism, etc. (Durmishyan, Muradian and Rachinsky,
1982; Rachinsky and Kerimov, 1989).
In the most contrasting form, a similar connection is recorded in tec-
tonically active basins belonging to the “unbalanced” type. They include
the South Caspian (Kobystan, Baku Archipelago), Indolo-Kuban (Kerch-
Taman zone), Tersk-Caspian (Tersk and Sunzha zones), Carpathian
(Internal zone), Sea of Okhotsk (Sakhalin Isl.), Irrawaddy-Andaman
(Myanmar portion), Sumatra, Orinoco (Trinidad Isl.) basins. In these
basins the thick sedimentary section most often built up in the environ-
ment of the avalanche sedimentation is lithofacially nonuniform, include
mosaic-fault-blocks with strong manifestations of macro- and micro-seis-
micity, mud volcanism, diapirism, neotectonic effects. It is 75-95% clays
with thickness of individual unconsolidated or poorly consolidated clay
series reaching 1-5 km (Bagir-Zadeh, Kerimov and Salayev, 1988; Beka
and Vysotsky, 1976; Dolenko, 1962; Reference Book…, 1976; Tectonic
structure…, 1968, etc.).
In all these basins, tectonic deformations were caused by cumulative
realization of elastoplastic properties of clays in the process of their gravity
and geotectonic unbalanced consolidation. They were also caused by the
effects of “buoyancy” (Archimedes force) as a result of density inversion
