Fabric Code: tpr191a

Manus andesitic placer

Quartz-free andesitic tempers occur as moderately sorted, fine to medium-grained, subangular to subrounded volcanic sand. Plagioclase feldspar, clinopyroxene, and hornblende are the principal mineral grains, with varied volcanic rock fragments and opaque iron oxides the only other grain types present. The volcanic rock fragments are nearly all microlitic (pilotaxitic to hyalopilitic) or vitric, with internal textures suggestive of the groundmasses of andesitic rocks.

Sites:

Mineral and Rock Abundances

None (0) Minor (1) Few (2) Common (3) Frequent (4) Major (5) Very Dominant (6)
0% 0-5% 5-15% 15-30 % 30-50% 50-70% 70-100%

Name Cal. QuartzFeldspar Pyroxene Amphibole Opaques OlivineBiotite Muscovite Epidote Garnet/ SpinelIg./Met. Rocks Sed. Rocks Grog Lithics/ Region
Max 1 0 2 4 2 4 0 0 0 0 0 1 0 0 microlitic, vitric
Min 0 0 2 4 2 4 0 0 0 0 0 1 0 0 Bismarck

Representative slides:

Slide Site Possible OriginCal. QuartzFeldspar Pyroxene Amphibole Opaques OlivineBiotite Muscovite Epidote Garnet/ Spinel Ig./Met. Rocks Sed. Rocks Grog Lithics
WD_41_6 Manus (Manus) 0 0 2 4 2 4 0 0 0 0 0 1 0 0 vitric, microlitic

WD_41_6

GDB59_3 GDB59_3
Sherd GDB59-3 from Manus (Manus). Slide WD_41_6 from Dickinson Collection, Bishop Museum. x4 Magnification PPL (left) XPL (right). Scale bar: 0.5mm. High resolution image in VIMIPO (user: Guest pwd: Guest). Imaged by K. Hardy and M. Leclerc, ANU.

Quartz-free andesitic temper sand. Coastal placer sand present. Pyroxene > Hornblende.


References:

145 Manus, Admiralty, PNG, 1997 (Dickinson, W.)

150 Mussau, Manus, New Hanover, New Ireland, PNG, 1997 (Dickinson, W.)