to platformal assemblages in the pre-2.7 Ga North Caribou terrane of the Superior Province, Canada. Crown copyright © 2000 Published by Elsevier Science B.V. All rights reserved.
Keywords
:
Archean; Sediments; Volcanism; Quartz arenite; Andesite; Baltic; Superior
1. Introduction
Quartz-rich metasedimentary rocks and spa- tially associated sedimentary carbonates, typical
of stable platforms, are generally scarce in Archean greenstone belts Ojakangas, 1985. Re-
cent work in the Superior Province has revealed Archean
greenstone assemblages
containing quartz-rich sedimentary units in at least three
geodynamic settings: stable shallow water plat- forms Wood et al., 1986; De Kemp, 1987;
Thurston and Chivers, 1990, submarine fans with evidence for cannibalization of platformal rocks
Cortis, 1991, and quartz-rich conglomerates and arenites
in pull-apart
basins Born,
1995. Kozhevnikov 1992 identified a spatial associa-
tion of andesites and quartz arenites within Archean
greenstones of
the Parandovo-Tik-
shozero greenstone belt near the Karelian Belo- morian collision zone boundary Glebovitsky,
1973; Volodichev,
1990; Glebovitsky,
1993; Lobach-Zhuchenko et al., 1995; Glebovitsky et
al., 1996 which caused us to investigate two quartz-rich sedimentary assemblages in this region
to assess their similarity with possible Superior Province analogues. The andesite-quartz arenite
association has not been seen in the Superior Province quartz-rich sedimentary units Thurston,
1990.
In the classification of assemblages for Archean greenstone belts, quartz-rich sedimentary units
including quartz arenites are typical of platform assemblages
Thurston and
Chivers, 1990;
Thurston, 1994. The high mineralogical and tex- tural maturity of these rocks, the presence of
trough and hummocky bedding in them, associa- tion with stromatolitic carbonates, and, finally,
their occurrence over thousands of km
2
in the Sachigo and central Wabigoon subprovinces,
provide a basis for regarding many as members of platform successions formed under shallow-water
conditions along a passive continental margin Thurston and Chivers, 1990.
The literature on Archean greenstone belts shows that similar quartz arenites have been re-
ported from platform assemblages in the many cratons Thurston and Chivers, 1990. They are
known in the Dharwar craton, India Srinivasan and Ojakangas, 1986, in the Bulawayo green-
stone belt on the Zimbabwian Shield Bickle et al., 1975, in the Moodies Group in the Barberton
belt of the Kaapvaal craton Eriksson, 1980, within the Tanzanian craton in the Dodoman
system Kimambo, 1984, in the West African craton Rollinson, 1978 and in the Yilgarn Gee,
1982 and Murchison Watkins and Hickman, 1988 blocks, Australia.
In the Baltic Shield, quartz arenite-bearing as- semblages have been described in some greenstone
belts Fig. 1. In the Koitelainen area, Central Lapland, the sequence which consists of quartz
arenites, mica schists, phyllites, volcanic conglom- erates and mafic to ultramafic volcanics has an
age of less than 2.7 Ga and rests on ca. 3.1 Ga granitoids Kroner et al., 1981. It represents a
Lapponian
sequence of
presumably Lower
Proterozoic age Gaa´l and Gorvatschev, 1987. In North Karelia, Russia, a possible age analogue of
the above strata is represented by Sumian rocks that lie with a regolithic lower contact on Archean
granitoids. In these successions, cross-bedded quartz arenites form a basal horizon overlain by
andesite-basaltic lava Korosov, 1991. In the Kostomuksha greenstone belt Fig. 1, cross-bed-
ded staurolite-sillimanite quartz arenites are asso- ciated with pillow basalt Kozhevnikov, 1982. In
the Tipasjarvi belt Fig. 1, kyanite-staurolite quartz arenites associated with BIF and black
shales are present in the upper part of the felsic volcanic unit in the lower Koivomaki Formation
Taipale, 1983. Discussing the origin of these quartz arenites weathering, fumarolic activity be-
tween volcanic eruptions and metasomatic alter- ations, Taipale 1983 concluded that the quartz
arenites could be produced during alteration of
felsic volcanics in the course of ore formation. In the Kuhmo belt Fig. 1, quartz arenites with
2.8 – 3.0 Ga detrital zircons Hyppo¨nen, 1983 were described from the Hietapera-Kivivaara area
Piirainnen, 1988, where they form part of a felsic volcanic-sedimentary unit in the Juurikkaniemi
Formation
which consists
of metarhyolites,
metadacites, volcanic breccia, lapilli tuffs, tuffites and tuffaceous turbidites. The age of this unit is
estimated at 2798 9 15 Ma Hyppo¨nen, 1983. Northwards, in the Moisiovaara area Fig. 1,
immature sericitic quartz arenites associated with polymictic conglomerates lie between tholeiites
and komatiites. An old tonalite – trondhjemite – granodiorite complex and felsic rocks from the
Kuhmo belt are regarded as sources of 2996 9 60 and 2803 9 238 Ma detrital zircons Hyppo¨nen,
1983 as well as clasts in congomerates Lu- ukkonen, 1988. In the Hisovaara greenstone belt
Fig. 2, quartz arenites are described in associa- tion with underlying andesites as well as overlying
felsic
volcanics and
sedimentary rocks
Kozhevnikov, 1992; Kozhevnikov et al., 1992. According to Thurston 1990, so far no andesites
have been found in platform assemblages. When distinguishing the types of assemblages most re-
cently proposed for Archean greenstone belts, the andesite-quartz arenite association revealed in the
Hisovaara greenstone belt is considered a fairly rare type of assemblage with a ‘continental’ style
of volcanism whose depositional environment is ‘open to speculation’ Thurston, 1994. However,
knowledge of such an assemblage type may be useful in discussing models for the tectonic evolu-
tion of greenstone belts and in comparative analy- sis and correlation of Archean cratons.
2. Geological setting
