A study was undertaken at the Golden Patricia Mine in Northwestern Ontario to determine the applicability of geochemical sampling in the mine area.  Four different sites were mapped in detail and 50 samples were collected in total.  All diamicton samples were analyzed for whole rock composition by ICP and XRF, and for gold values by fire assay/AAS.  The major sediment cover in the area is flow diamiction with isolated areas of locally derived diamicton.  The depositional environment is thought to be a proglacial setting, dominated by massive debris flows.  The flow material is poorly-sorted and does not indicate any noticeable geochemical trends which would suggest the presence of a glacial dispersal train.  All data supports the conclusion that geochemical sampling in the area would not prove useful as an indicator of possible up-ice source of economic mineralization.

Rocks of the Coldwell alkalic complex have intruded metasedimentary and metavolcanic rocks of the Schreiber-White Lake greenstone terrain.  The complex is believed to be the product of three intrusive magmatic episodes.  The oldest episode is characterized by gabbro and augite syenite and is exposed at the southwest margin of the complex.

The intrusion of the two units has produced a thermal metamorphic aureole that attains pyroxene hornfel facies at the contact with the gabbro.  The gabbro unit shows evidence of deformation resulting in cataclasis and recystallization of the feldspar.  This has produced a protoclastic to porphyroclastic texture.  The syenite is the later unit and has intruded the gabbro.

Within the two units is found a relatively complex suite of dyke rocks showing a complex intrusive history.  The most common dyke rock is lamprophyre.  This can be broken down into three types which represent approximately four periods of intrusion.  The youngest set is characterized by having "phenocrysts" of resorbed quartz.  The quartz may either represent high-pressure phenocrysts or xenocrysts.

The study area is contained entirely within the Quetico Subprovince (of the Superior Province, Canadian Shield) in which a metasedimentary sequence is exposed.  The metasedimentary sequence consist of phyllites, wackes, sandstones, pebbly sandstones and conglomerates.  The metasediments exhibit many of the features characteristic of turbidites.  The Bouma sequence of internal sedimentary structures in the ideal turbidite bed occurs, in whole or part, throughout the area.  Many reasonably diagnostic sedimentary features suggest that the study area may be part of a large submarine fan.

Grade of the syn-tectonic metamorphism increases from north to south.  Compatible mineral assemblages characteristic of the chlorite and biotite zones of the low grade greenschist faces are defined.

Detailed structural mapping has led to the establishment of major anticline-syncline fold structures in the area.  One dominant folding episode, accompanied by a penetrative axial planar cleavage has produced easterly trending, moderately plunging fold structures.

Placer accumulations are formed by the preferential sedimentation of heavy minerals from the general population of detritus being transported by a fluid.  The depth, velocity, and grain size conditions under which placers form on beaches, sand-dominated meandering, and braided fluvial systems is at present only partially understood.  Our knowledge of the controls on alluvial placer formation in gravel-dominated longitudinal bars of braided rivers is even more poorly developed despite their obvious economic importance.

The accumulation of heavy minerals in coarse-grained longitudinal gravel bars was studied by examining and sampling surficial and matrix sediments from modern, naturally occurring bars, and by simulating these bars under a variety of controlled flow conditions in a sediment-water recirculating flume.

Two processes dominated the deposition of sediments in both the natural and artificial systems studied:  1) suspension rain out; and  2)  avalanche face progradation.  Sediments which were deposited as a result of avalanche face progradation were found to contain significantly higher concentrations of heavy minerals in both the naturally occurring and experimental longitudinal gravel bars.  Data also indicate that the difference in heavy mineral content amongst sediments deposited as a result of these two processes will increase substantially with increasing density of the detrital minerals present.  This suggests that denser heavy minerals are more likely to be deposited amongst less dense surficial sediments whereas less dense heavy minerals are more likely to be vertically distributed throughout the bar sequence.

In the natural systems studied, heavy mineral content was found to be much higher in poorly sorted, coarse-grained sediments deposited amongst pebble sized clasts.  Flume tank experimentation similarly revealed that detrital lead content was highest amongst pebble sized clasts during the fastest velocity runs.  In addition, an increase in clast size resulted in a decrease in the amount of heavy minerals accumulating in surficial sediments.

This study has also highlighted two processes which result in the formation of alluvial depositional placer accumulations in coarse-grained braided river systems.  The first process occurs as a result of heavy minerals in channel bottom sediments becoming progressively enriched through the winnowing of less dense sediments, resulting in the formation of an erosional placer deposit.  Flume experimentation revealed that when high concentrations of heavy minerals armouring the stream-bed were reached, this often resulted in the initiation of their movement downstream.  This process can also be triggered by catastrophic events such as large floods or regional tectonic uplift.  A sudden increase in energy typically associated with such events results in the flushing of erosional placers and their eventual deposition in areas of higher preservation potential.  Therefore, a catastrophic adjustment helps to flush out erosional placer deposits in to the basin to form a depositional placer accumulation.  The second process of depositional placer formation results from heavy minerals traveling in bed load transport, while less dense sediments are kept mostly in suspension.  With a decrease in velocity, heavy minerals are sedimented with hydraulically equivalent sized, less dense sediments in open framework gravels.  

The Sibley Group is an unmetamorphosed Mesoproterozoic red bed sequence, commonly flat-lying, that formed in an intracratonic basin between 1450 Ma and 1500 Ma.  It covers an area of 15,000 km², and reaches a total thickness of 950 m.  Recent drilling projects in the Nipigon Plate have provided a unique opportunity to study the basin using data obtained from a combination of 25 drill holes and surface outcrops.  This has allowed a re-examination of the lithostratigraphy, as well as providing insight into the basin architecture.  Previously, the Sibley Group consisted of only three formations: the Pass Lake Formation, the Rossport Formation, and the Kama Hill Formation (Cheadle, 1986a).  Two additional formations have been introduced here: the Outan Island Formation and the Nipigon Bay Formation.  The Pass Lake Formation, interpreted as a fluvial-lacustrine system, is divided into the Loon Lake Member and the Fork Bay Member (Cheadle, 1986a).  The Rossport Formation is separated into the Channel Island Member, the Middlebrun Bay Member, and the Fire Hill Member (Cheadle, 1986a).  These consist of cyclic dolomite-siltstone layers, stromatolites and red mudstone, which represent a playa lake, sabkha, and mudflat environments.  The Kama Hill Formation is not subdivided, and is composed of purple shales and siltstones interpreted as subaerial mudflat deposits.  The Outan Island Formation has been divided into the deltaic Lyon Member and the fluvial Hele Member.  The Nipigon Bay Formation consists of cross-stratified sandstone beds, and is thought to denote an aeolian environment.

Geochemistry has been used to examine formation-scale trends in weathering chracteristics and provenance.  Samples were collected from drill holes spanning the entire thickness of the Sibley Group, and the concentrations of various elements were plotted against depth to appraise variations between Formations.

A paleomagnetic study was also conducted on the Sibley Group.  The first part involved comparing paleopoles from samples of the Pass Lake, Kama Hill, and Nipigon Bay Formations.  This revealed a probable depositional paleopole age between 1450 Ma and 1500 Ma, with remagnetization events at approximately 1350 Ma and 1100 Ma.  The second part involved a study of paleo-secular variation in the Rossport Formation, which resulted in the documentation of one of the oldest known examples of paleo-secular variation yet discovered.

This study concentrates on a section through a lateral correlative of the cyclic facies contained in the Rossport Formation present in the Noranda drill core NI-92-5.  The location of this drill hole is north of other cored sections and outcrops of the cyclic facies and represents a more basin center environment.  The cyclic facies to the south consists of alternating layers of dolomite and red shale with individual layers, in the approximately 40 m thick assemblage, varying from mm- to dm-scale.  In drill hole NI-92-5 the layering is at a similar scale, but is composed of alternations between what was first thought to be dolomite-rich and gypsum-rich intervals, reflecting wet and dry seasonality in the central playa environment.

S.E.M. and X.R.D. analysis indicate that the sequence was metamorphosed.  The following minerals represent the progression of metamorphic facies, from lower to higher T towards the diabase sill:  talc, tremolite, and pargasite.  Clinochlore and calcite are found throughout the metamorphic series.  The metamorphism masks the primary layering in places.  However, S.E.M. analysis clearly shows the mineralogical layering, reflecting variations in primary geochemical constituents between individual laminae.  ICP-AES analysis also highlights the varying compositions of the sequence.  The pargasite tends to exist in layers with differing K and Na proportions.  The K⁺ and Na⁺ ions may reflect the incorporation of KCl and NaCl.  Both of the minerals are found in S.E.M. sections taken near the middle of the sequence.  Nb and Ba show unusual concentrations and fluctuations, and need to be studied further.

Clastic input is variable between individual layers, but shows an increase at the top of the section.  This increase is related to the appearance of sand sheets, which typically mark the end of the cyclic facies in the Sibley Group sediments.  Clastic material becomes slightly enriched in elements denoting a mafic rock source up-section.

New exposure of the Paleoproterozoic Animikie Group at the Terry Fox Monument northeast of Thunder Bay reveals several thrust faults that cut through the Gunflint Formation, Sudbury Impact layer and the overlying Rove Formation.  This discover has implications for the timing of thrust-fault deformation in the area north of Lake Superior.  Previously, thrust-fault deformation in the Gunflint Formation was interpreted to be associated with the Penokean orogeny.  New evidence collected at the Terry Fox Monument suggests thrust faulting may be related to late Penokean deformation or possibly a younger orogeny.  Thrust faulting at this location is observed cutting the impact layer and overlying Rove Formation meaning that this deformation may be too young to be attributed to the Penokean orogeny.

The thrust faults at the Terry Fox Monument rock cut are mainly expressed as small discrete bedding plane faults with few kinematic indicators or piercing points to quantify the displacement.  The faults are most easily identified where they cut through stratigraphy, once identified faults can be traced laterally along the outcrop.  Similar to other units present, thrust faults within the impact layer are identified by slickenlines or slickenfibres on fault plane surfaces.  The faults can be traced along strike until they are either covered by overburden or cut by a prominent normal fault which displaces all units in the hangingwall down to the south several meters.

The carbonate fraction of recent of recent sediments from the northern Lake Superior basin was analysed as to mineralogy and trace element distributions.

Three carbonate phases; low-magnesium calcite, protodolomite and dolomite are present.  Detrital minerals include quartz, alkali and plagioclase feldspars, illite, vermiculite and chlorite.

The trace elements analysed are strontium, manganese and barium.  The distribution of these elements appears to be controlled by the carbonate mineralogy.  The strontium is concentrated in the calcite while the barium is found preferentially in the dolomite.

The study area includes Hazelwood Lake and vicinity and is situated north of Thunder Bay, Ontario.  Metasedimentary rocks dominate and form part of the Shebandowan-Wawa volcanic-plutonic belt.  They form sequences of interbedded greywackes and mudstones and exhibit many of the features characteristic of turbidites.  The framework minerals, in order of abundance, are quartz, feldspar and rock fragments.  The rock fragments are mainly felsic volcanics with lesser amounts of plutonic rock fragments.

The Bouma sequence of internal sedimentary structures present in the ideal turbidite bed occurs, in whole or part, throughout the area.  It appears, that in the area, the rocks are folded in a series of gently plunging folds with steeply dipping axial surfaces.  To some extent, the evidence suggests multiple episodes of folding to have occurred.

The majority of the turbidites are characteristic of distal deposition.  The presence of proximal beds intermixed with distal beds is probably the result of contribution of detritus from multiple sources.  The rock fragments indicate a mixed felsic-volcanic and granitic provenance.