cataclasite


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cataclasite

[‚kad·ə′klā‚sīt]
(petrology)
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The tectonic contacts demonstrate abundant evidence for brittle deformation, with the development of cataclasite, fault breccia, and chatter marks.
These clasts are distributed continuously within sheets of cohesive cataclasite over a 2 x 4 km area in proximity to the Lucky Strike Orebody, and appear to be the remnants of an orebody that was dismembered and scattered by thrusting.
The Paredones Amarillos deposit is a silicified shear zone locally known as cataclasite.
The mineralization is confined to a zone of cataclasite and mylonite basement rock.
The angular relations between the cataclastic rocks and the conglomerate units, combined with the presence of cataclasite clasts in the conglomerate units and evidence of dip-slip faults within the basin, suggest an extensional setting, where listric normal faults outline detachment allochthons.
Basement rocks are mainly early Aphebian to Archean granites and gneisses including numerous mylonite or cataclasite zones.
Slickensides in the basalt cataclasite are developed in quartz and celadonite.
Basaltic cataclasite contains only rare zeolites, as at Wasson Bluff.
Several lines of evidence indicate that this Waite composite fault zone is the locus of brittle fault reactivation for the entire NFS: (1) the post-Acadian redbeds crop out solely within the Waite zone; (2) although brittle structures are also present locally in the Kellyland and Codyville fault zones and in the intervening areas, they are most abundant in the Waite zone; (3) Waite zone brittle faults contain the greatest amount of both fine- and coarse-grained cataclasite; (4) map-scale brittle fault offset is restricted to the Waite zone; (5) in contrast, the Kellyland and Codyville zones exhibit only very small-scale brittle structures, typically expressed as narrow (<5 cm) cataclasite veins within second-order faults.
Mineralization is typified by quartz veins within a strongly sericite-carbonate altered shear zone, with disseminated visible gold, tellurides and minor sulfides occurring within multiple phases of quartz veining and cataclasites.
These shears are comprised of silicified cataclasites and altered granite, as well as quartz veins with strong visible gold and telluride mineralization with minor amounts of sulphides.
All drill holes intersected the Lucky Shot Shear, which is typified by strong chlorite-serecite-carbonate alteration, brecciation and silicified cataclasites.