Vol. LV., No. 4. 
51 
OUTLINE OF THE GEOLOGY OF THE MOROBE 
GOLDFIELDS. 
By N. H. Fisher, D.Sc., Mineral Resources Survey, Canberra. 
(Plates 1 and 2.) 
( Received 15th June, 1943; issued separately, 2 6th June, 1944.) 
KAINDI SERIES. 
The earliest rocks exposed in the Morobe district are the Kaindi 
series of metamorphics, and these, in one form or another, constitute the 
host rocks of most of the mineral occurrences. They consist of schists, 
slates, phyllites, with lenses of limestone and calcareous shales, and are 
mostly of sedimentary origin, though greenish rocks which are probably 
metamorphosed igneous tuffs are also found within the series. In places 
the schists are very micaceous and laminated, but the dominant type 
is a phyllite composed mainly of quartz granules and scales of micaceous 
minerals, chiefly biotite, a few plagioclase crystals and varying amounts 
of chlorite, pyrite, titanite, magnetite, ilmenite and rutile. The effects 
of shearing are nearly always pronounced and in some cases at least the 
induced schistosity crosses the original bedding planes of the rock. The 
limestone lenses are fine-grained and homogeneous, recrystallised to a 
greater or less extent, and despite extensive search, no trace of fossils 
has yet been found. The only evidence therefore that exists for the age 
of the Kaindi series is that it is intruded by pre-Tertiary granite, and 
from general considerations it is at least as old as Palaeozoic, The 
structure of the series throughout the Morobe district comprises a series 
of broad folds trending in a generally northeast-southwest direction. 
Over much of the central goldfield area this structure is obscured locally 
by granitic and porphyry intrusives, and the commonest strike direction 
here is from east -west to southeast-northwest, with a dip generally 
towards the south or southwest. This metamorphic series forms the 
basement right through the Mandated Territory, on New Britain and 
New Ireland as well as the mainland, upon which the later sediments 
have been deposited. It is not intended to infer that it is all one series 
throughout, in fact there are evidences at Edie Creek of disconformity 
between different portions, which, however, are probably closely related 
in time, and in the Waria area at least of a wider unconformity, so that 
the basement rocks which so far it has been possible to map only as a 
metamorphic complex probably were originally deposited in several 
different stages with possibly diastrophic periods intervening. 
MOROBE BATHOLITH. 
Intruding the Kaindi Series is the Morobe granodioritic batholith, 
which occupies extensive areas both to the northeast and southwest of 
the principal goldbearing district, while smaller outcrops are plentiful 
G 
