In the summer of 1980, during reconnaissance mapping with the Geological Survey of Canada a succession of mafic flows and volcaniclastic sediments, subsequently named the Ingrid group, was discovered about 2500 metres west of the Nain-Churchill Province's boundary.

The group consists of basalt, porphyritic basalt, conglomerates, greywackes and siltstone metamorphosed from upper greenschist to epidote-amphibolite facies.  These units observed have been deposited upon Churchill Province gneisses in Aphebian to Paleohelikian time and have been folded, faulted in a very complex manner.

The geology of Elbo Lake consists of granulite metasedimentary rocks, a megacrystic granite unit and a medium grained granite gneiss unit.  Mylonite zones are common in the area and show up as strong topographic lineaments.  The thin section mineralogy suggests granulite Facies metamorphism with later retrogression to amphibolite Facies.  Owing to the lack of good structural data a precise determination of the deformation sequence was difficult to determine.  However stereograms of the foliation measurements indicate a dome or half dome structure in the north-eastern portion of the thesis area.

Sheared, steeply dipping volcanic rocks of the Triassic Nicola Group are found on the west side of the Thompson River.  Mapping of the 11 square kilometer Silica claim group located southwest of the town of Ashcroft, B.C., has revealed a sequence of intermediate and porphyritic felsic rocks.  This assemblage has been intruded by quartz diorite stocks, thought to be associated with the Guichon Creek batholith.  Petrographic and limited geochemical work has been done in order to better describe the observed rock units.  These studies imply that most of the siliceous, pyritic, quartz-feldspar porphyritic rocks have the magmatic characteristics of rhyolite flows, and may not be "silicified greenstones" or crystal tuffs as previously described.  Associated minor copper mineralization is seen both as co-precipitated chalcopyrite in pyrite hosted in small podiform masses of chlorite schist, and as malchite in quartz veins.  Despite the presence of the Guichon Creek batholith, the sulfide occurrences do not appear to be of porphyry-type mineralization; these may be indicative of volcanogenic sulfide concentrations located down dip or along strike of the sheared strata.

The area is underlain by Archean volcanic and sedimentary rocks of the Superior structural province and forms part of the Shebandowan-Wawa volcanic-plutonic belt.

In the study area, a volcanic succession with intercalated sedimentary rocks is exposed.  Volcanism is of the bimodal, basalt-rhyolite type.  Pyroclastic rocks from part of the volcanic pile and occur together with rudaceous sedimentary strata.  One complete and two incomplete cycles of mafic to felsic volcanism, followed by sedimentation, are observed in the area.  A sulfide (pyrite-chert) and an oxide (banded magnetite-jasper) facies iron formation outcrops within the area.

At least one deformational event is recorded by the steeply dipping bedding planes of sedimentary units.  A variably developed cleavage is present in most rocks.  Cleavage-bedding relationship and local younging data suggest a synclincal axis to the north of the area.  The rocks have been metamorphosed to greenschist and lower epidote-amphibilite facies conditions.

A small hornblende gabbro intrusive is situated near the centre of the area.

The Coldwell Complex, a group of Neohelikian alkaline rocks cutting the Archean Schreiber-White River Greenstone Belt, is the result of three westward migrating centres of intrusion.  The Little Pic River Breccia Zone is located two to three kilometers from the western margin.  Centre III syenites, xenolith compositions and dike structures are the major topics of discussion in this thesis.

Field mapping and detailed petrographic studies allowed an intrusional history to be derived for the local area.

The Little Pick River Breccia Zone is determined to be an intrusive breccia with post-intrusive block faulting altering the structure to the west.  Different structural levels are interpreted to be present in the Coldwell Complex (Mitchell and Platt, 1982).  Considering the high volume of country-roick metavolcanic xenoliths, it is surmised that the Little Pic River Breccia Zone is a "near to roof" assemblage which was downfaulted.

Textural variants of the early Centre III syenites described as coarse-grained, contaminated-porphyroblastic and fine-grained, are present.  Several colour variations of later Centre III quartz syenites also show widely variable textural relationships, grading from medium-grained to pegmatitic. 

Metavolcanics and Centre II xenoliths show varying degrees of metasomatism, resulting in porphyroblast growth and/or complete alteration to secondary mineral assemblages.

Microsyenite dikes are an important structural feature, locally defining a regional stress pattern.  Compositons vary widely in this group, hence no particular dike phase can be correlated to a specific joint set.

The Island Belt Silver Region lies within a northeast-trending fracture zone in Proterozoic sedimentary and igneous rocks of the Southern Province of the Canadian Shield.  It comprises a number of vein occurrences on offshore islands in northwestern Lake Superior and along its shoreline south and east of the City of Thunder Bay, Ontario.  The belt-like spatial association of these occurrences and their similar vein attitudes is due to structural localization in linear fracture zones related to regional rifting and subsidence of the Lake Superior Basin in the late Proterozoic time.  Not all of these veins are argentiferous, and some contain only trace amounts of silver.  Ore and gangue mineralogies vary widely between sites from simple quartz-calcite ± barite veins with galena, pyrite and sphalerite to complex "five-element" (Ag-Bi-Ni-Co-As) assemblages such as that at Silver Islet; the latter is unique in its complexity.  Vein systems may be simple, composite or fill brecciated shear zones.  The predominant primary textures are those related to open-space filling.  These include rhythmic crustification, euhedral and multi-stage crystal growth, zonation and hydrothermal brecciation.  Secondary textures, resulting from weathering, oxidation-reduction and supergene processes, are related to near surface alteration while deformation textures are probably due to ongoing fault movement and post-crystallization tectonism.  The more complexly mineralized veins crosscut igneous intrusive bodies at high angles approaching 90° and are usually associated with gabbroic rocks, while veins associated with diabase are relatively mineralogically simple.

The Mainland Belt Silver Region is found in a fracture zone that parallels that of the Island Belt and was formed during the same tectonic event.  The respective mineralogies of the veins of the two Belts are superficially similar.  The major differences are related to the homogeneity of the Mainland Belt deposits and the relative heterogeneity of those in the Island Belt, whose occurrences are associated with later diabasic and gabbroic intrusives.  The mafic rocks of both Belts are petrogenetically related.

The Island Belt occurrences may be related, but variances arising from an episodic vein-filling history imply a complex regional metallogeny.  The source of the vein metals is perhaps a combination of the distillation of metals from Rove sedimentary rocks and input of metals such as Ni, Co and Ag from an associated mafic intrusion, which is the heat source for both metal mobilization and hydrothermal circulation.

The Archean mafic metavolcanics of the map area represent the northwestern extremity of the southern sedimentary-dominated belt of the Beardmore-Geraldton Region.  As such these rocks occupy a part of the Wabigoon Volcanic-Plutonic Supracrustal Belt of the Superior Province, Canadian Shield.  The rocks display many interesting primary megascopic features including: pillows; amygdules; and brecciation.  Such features were used to define map units.  The highly fractionated basalts of the map area are significant for both structural and petrologic studies.

These rocks have been weakly deformed.  This was determined by measurements of:  pillow, amygdule, and phenocryst shape; and pillow selvage thickness.  The individual contributions of synvolcanic and regional tectonic deformation processes cannot be evaluated.  However, it is evident that both have played a part in producing the strain now observed in these rocks.

Petrology, including petrography and geochemistry, of study area samples can be used to ascertain the tectonic regime of the Beardmore-Geraldton Region.  Several factors tend to disguise this effort.  Spilitization, low grade regional metamorphism, and subsequent hydrothermal alteration must be considered.  However, these effects can be stripped off by the use of relatively immobile elements for classification discriminations.  With these facts in mind, the rocks appear to be ocean floor basalts extruded in an inter-arc basin.  This determination is proof that Archean volcanic rocks can be studied fully with only a few minor diagnostic restrictions.  To this end thoughts on modern and classical plate tectonic theory as applied to greenstone belt genesis are presented; this despite the fact that neither have been conclusively confirmed nor disproved for the Archean.

A baritic horizon occurring within the Arechean supracrustal rocks of the Hemlo area, northern Ontario, exhibits characteristics that suggest a syngenetic origin is likely.  The baritic unit outcrops in five locations situated five to thirteen kilometers east of the town of Marathon, and appears to parallel the regional stratigraphy.  It occurs between pyroclastic plus pillowed mafic metavolcanics to the south and siliceous metasediments plus intermediate to felsic pyroclastic metavolcanics to the north.  The barite is massive, thinly laminated to wispy laminated and is generally interlaminated with recrystallized quartz, albite, pyrite and carbonaceous material, forming a unit one to three meters thick.  The contacts with adjacent rock layers appear conformable.  Rock lithologies associated with the baritic unit include pyritiferous graphitic schists and DE turbiditic argillaceous siltstones (starved basin-type sediments), argillaceous siltstones with green mica (rip-up?) clasts, green mica schists, biotite-hornblende schists, sericite-carbonate schists, mafic metavolcanic fragmentals and flows, a very thin tuffaceous unit and quartz-feldspar porphyry sills.  Although these rock units have likely been structurally transposed relative to one another, their presence at all the barite occurrences suggest that they were formed in special association with the barite.

In comparing the characteristics of the Hemlo baritic horizon with those of other documented modern to Archean syngenetic and epigenetic barite occurrences throughout the world, it becomes evident that the Hemlo occurrences more closely resemble syngenetic than epigenetic deposits.  Characteristics in common with other syngenetic occurrences include: regional and local conformity of the baritic unit with associated lithologies; lateral continuity of the barite horizon (possibly eight kilometers); associated deep water/starved basin-type sedimentary units; the thinly laminated to wispy laminated character of the barite.

Skarn deposits in southern Yukon, southwestern Mackenzie and northern British Columbia are host to a variety of ore elements including tungsten, copper, zinc, lead, silver, molybdenum, and tin.  A study of five of these skarn occurrences in light of recently proposed descriptive classification schemes based on the major ore element assemblages defines each skarn occurrence as a distinct skarn type.

Studies by Dawson and Dick (1978) and Dick (1979) have shown that skarns in this area may be divided into four main groups based on the major ore element assemblages that they contain.  These are:  1) W-Cu,  2) W-Mo,  3) Zn-Pb, and 4) W-Cu-Sn.  Minor ore elements associated within these groups vary from deposit to deposit.

A more recent study by Einaudi et al, (1981) suggests that skarn deposits are best classified on the basis of the dominant economic metal and suggest six major subclasses, consisting of Fe, W, Cu, Zn-Pb, Mo and Sn.

Three scheelite-bearing skarn occurrences on the McDame Prospect in northern British Columbia are defined as tungsten skarns and reflect major ore element assemblages of W-Cu and W-Mo.

Two zinc-lead skarn occurrences on the Norquest Prospect in southern Yukon Territory are defined as zinc-lead/zinc skarns and reflect a dominantly Zn-Pb-(Ag) ore element assemblage.

The Schreiber-Marathon archean greenstone belt forms a part of the Shebandowan-Wawa Subprovince of the Superior structural Province of the Canadian shield.  This thesis focuses on the eastern portion of the Schreiber-Marathon greenstone belt.

Bedrock in this area can be broadly divided into rocks of the Playter Harbour and Heron Bay supracrustal Groups.  The Playter Harbour Group is composed predominantly of high-iron tholeiitic basalts and metasedimentary rocks primarily of volcanogenic origin.  The Heron Bay Group includes calc-alkalic pyroclastic rocks of variable composition, high-iron tholeiitic basalts, and metasedimentary rocks of diverse origin.

The supracrustal rocks of both groups form east-west trending sequences which are intruded by a number of archean plutons and proterozoic sills and dykes.  Regionally, the supracrustal rocks appear to conform closely to the contacts of extensive gneissic complexes of archean age.

Metamorphic grade is typically greenschist facies, however, amphibolite facies assemblages occur locally.

The regional structure of the rocks is complex and with the data available at present, open to a variety of interpretations.  Evidence of widespread, large scale brittle and ductile deformation can be seen throughout the belt.  In outcrop, the structures are highly diverse, often complex, and in many cases deformation is of such a magnitude as to obscure the original nature of the rocks.