On the evening of 11th June 1979, the 35 ton motor cutter
"K. J. V. Steenstrup", belonging to the Geological Survey of
Greenland, anchored in a small bay at Tovqussap nuna, West
Greenland. On board were nine members of the JUGS Commission on
Tectonics and Subcommission on Precambrian Structural Type
Regions. For the next 24 hours a strong gale and snow forced the
members to stay below deck, and while being rocked by the swell
reflected from the nearby cliffs of two-pyroxene diorite at Verdens
Begyndelse ("Beginning of the World" - see Medd. am Gr0nland 123,
plate 1), this small group of tectonic "officials" decided to initiate
the production of a book to be entitled "Precambrian Tectonics
Illustrated". Needless to say, a copy of the magnificent book "
Geology of Greenland", published three years earlier by the Geological
Survey of Greenland, was lying in front of us on the oak table in the
small crowded cabin.
Five years have now elapsed since that windy day, but thanks to the
never-failing enthusiasm of Alfred Kroner, who took on the heavy
editorial task, and to the able assistance of his co-editor Reinhard
Greiling, the ambitious project, conceived while "Steenstrup's" anchor
dragged with the manocuvering gear at "full speed ahead", has now
become a reality.
In the days of modern geoscience, when tectonic theories tend to
become increasingly short-lived, a period of five years may seem
long. However, in this special case I am convinced that the time gone
has not out-dated the project, but rather increased the need for this
sort of book.
"Precambrian Tectonics Illustrated" was originally intended to serve
as a good example which students and younger tectonicians would be
drawn to emulate, thereby increasing interest and activity in the then
somewhat neglected branch of geology - Precambrian structural geology
and tectonics. Our plan was not to produce conceptual papers, but to
show how much can be revealed and solved by accurate mapping and
painstaking structural analysis and, by omission, to indicate how much
still needs to be done. Admittedly, geoscience cannot flourish without
the vitamins and drugs of tectonofanciful models, but the science
receives its basic nourishment from the bread-and-butter observations
of open-eyed field geologists, the foot-slogging infantry who spare no
effort in describing and illustrating the capriciousness of Nature.
As now published, "Precambrian Tectonics Illustrated" has become more
than plain bread-and-butter. Its Table of Contents is a more
variegated menu, but even if not all the dishes offered will appeal to
every taste, I am sure that the reader can put together a good meal
that will provide strength and inspiration to go back to Nature and
collect the ingredients for new dishes.
H. H. Read once said: "Map it my boy and it will all come out". But
don't forget what James Gilluly added: "Most exposures provide answers
only to questions that are put to them". With this in mind - "bon
appetit".
Introduction VII
I. Structural styles in Archaean greenstone and gneiss terranes
Jackson, M. P. A.: Archaean structural styles in the Ancient Gneiss
Complex of Swaziland, southern Africa 1
Lamb, S. H.: Structures on the eastern margin of the Archaean
Barberton greenstone belt, northwest Swaziland 19
Stowe, C. W.: The early Archaean Selukwe nappe, Zimbabwe 41
Anhaeusser, C. R.: Structural elements of Archaean granite-greens/one
terranes as exemplified by the Barberton Mountain Land, southern
Africa 57
Nutman, A. P.: Early Archaean crustal evolution of the Isukasia area,
southern West Greenland 79
Myers, J. S.: Archaean tectonics in the Fiskenaesset region of
southwest Greenland 95
II. Granite tectonics and basement/cover deformation
Hickman, A. H.: Archaean diapirism in the Pilbara Block, Western Australia 113
Schwerdtner, W. M.: Archaean gneiss domes in the Wabigoon Subprovince
of the Canadian Shield northwestern Ontario 129
Snowden, P. A.: Non-diapiric batholiths in the north of the Zimbabwe
Shield 135
Bowes, D. R., N. M. Halden, T. J. Koistinen & A. F. Park: Structural
features of basement and cover rocks in the eastern Svecokarelides,
Finland 147
Ehlers, C. & L. Bergman: Structure and mechanism of intrusion of two
postorogenic granite massifs, southwestern Finland 173
Kroner, A.: Dome structures and basement reactivation in the
Pan-African Damara belt of Namibia 191
III. Shear zones and shear belts
Coward, M. P.: Major shear zones in the Precambrian crust; examples
from NW Scotland and southern Africa and their significance 207
Myers, J. S.: The Nagssugtoqidian mobile belt of Greenland 237
Henderson, J. R.: Description of a virgation in the Foxe Fold Belt,
Melville Peninsula, Canada 251
Davidson, A.: Identification of ductile shear zones in the
southwestern Grenville Province of the Canadian Shield 263
IV. Polyphase deformation and interference patterns
Fyson, W. K.: Fold and cleavage patterns in Archaean metasediments of
the Yellowknife supracrustal domain, Slave Province, Canada 281
Korstgard, J. A. & I. Ermanovics: Archaean and early Proterozoic
tectonics of the Hopedale Block, Labrador, Canada 295
Ez, V. V., D. E. Gaft, T. M. Geptner, L. N. Kukley, B. I. Kuznetsov &
Yu. A. Morozov: Geological structures of some Precambrian complexes in
the USSR 319
Bai Yiliang, Sou Shutain, Liu Ruqi, TangJiaTu & Ma Xingyuan: Fold
interference patterns in Precambrian rocks from three key areas of
eastern China 335
Hobbs, B. E., N. J. Archibald, M. A. Etheridge & V. J. Wall: Tectonic
history of the Broken Hill Block, Australia 353
Stalhos, G.: Svecokarelian folding and interfering macrostructures in
eastern Central Sweden 369
Jackson, M. P. A. & G. A. D. Zelt: Proterozoic crustal reworking and
superposed deformation of metabasite dykes, layered intrusions, and
lavas in Namaqualand, South Africa 381
Greiling, R., A. Kroner & M. F. El Ramly: Structural interference
patterns and their origin in the Pan-African basement of the
southeastern Desert of Egypt 401
List of contributors 413
Subject Index 415
