| dc.description.abstract | The Ham diatreme and dyke are post-late
Silurian intrusions located in north-central Somerset
Island and are the most northerly known kimberlites in
the Somerset Island kimberlite province. The Ham
diatreme, which consists of three petrographically
distinct varieties of kimberlite, formed as a series
of fluidized intrusions at the intersection of
several regional fracture sets. Type lA kimberlite
is petrographically similar to the Ham dyke (a single
intrusion located 1.5 km to the east) and forms the
flanks of the Ham diatreme. This dark, massive rock
contains phenocrysts and xenocrysts of garnet, olivine,
chrome-diopside, phlogopite, spinel and carbonate in
a serpentine-carbonate groundmass containing carbonate
and serpentine emulsion textures. Type IB kimberlite,
which occupies the central portion of the Ham diatreme,
is a highly altered, light green, serpentine-carbonate-rich
rock formed by the prograde serpentinization and
carbonatization of Type lA kimberlite. This
alteration occurred during the degassing of structurally
lower portions of the Ham diatreme. Type 2 kimberlite
is a carbonate-rich mineralogical equivalent of Type
lA kimberlite and formed as a late stage dyke within
the Ham. diatreme. | |
