Dh. Watkinson, FLUID-ROCK INTERACTION AT CONTACT OF LINDSLEY-4B NI-CU-PGE OREBODY AND ENCLOSING GRANITIC-ROCKS, SUDBURY, CANADA, Transactions - Institution of Mining and Metallurgy. Section B. Applied earth science, 103, 1994, pp. 20000121-20000128
Part of the contact of the 4b Ni-Cu-platinum-group element (PGE) orebo
dy, Lindsley mine, Sudbury, Canada, with the enclosing Murray granite
is characterized by the presence of recrystallized and biotitic Sudbur
y Breccia; in places the contact is faulted and sheared. In other area
s of contact partly silicified granite contains disseminated chalcopyr
ite and quartz-chalcopyrite veins with other minor minerals. Both ore
and veins contain platinum-group minerals (PGM); predominant PGM are m
ichenerite, kotulskite, merenskyite and sperrylite with gold, galena a
nd Bitellurides. At some silicified-granite contacts Mn-rich garnets,
some containing inclusions of PGM and quartz, are associated with biot
ite + epidote + stilpnomelane + quartz. PGM as well as Au also occur w
ithin Cl-rich biotite and ferropyrosmalite in massive sulphide and in
siliceous ore. Quartz, chalcopyrite and feldspar in the contact rocks
and in veins contain abundant, highly saline fluid inclusions. Standar
d thermometry and analysis by scanning electron microscopy with energy
-dispersive spectroscopy of the daughter minerals (NaCl, CaCl2, BaCl2,
KCl and Fe-Mn hydroxychlorides) reveal that the fluids were trapped a
t intermediate temperatures. The 4b orebody is surrounded by a sheath
of brecciated granite (Sudbury Breccia) but is close to the Contact Su
blayer; during and after emplacement of sulphide magma saline formatio
nal fluid that was resident in the breccia interacted with hot massive
sulphides in and near the Sublayer and remobilized Cu, Au and PGE. Th
is fluid reacted with cooler rocks and ore in footwall fractures, enri
ching the 4b protore and producing the adjacent Cu- and PGE-enriched q
uartz veins. Exploration for Cu and PGE enrichment in footwall rocks o
f the Sudbury South Range is warranted not only in zones of magmatic o
re in the Contact Sublayer but also in fractures and permeable units w
ithin Sudbury Breccia.