A geochemical and petrological study of volcanic rocks in the Beardmore-Geraldton Archaean Greenstone Belt, Northwestern Ontario

Three repetitive sequences of northward youngIng, east striking, linear, volcano-sedimentary units are found in the late Archaean BeardmoreGeraldton greenstone belt, situated within the Wabigoon subprovince of the Superior Province of northwestern Ontario. The volcanic components are characterised by basaltic flows that are pillowed at the top and underlain by variably deformed massive flows which may In part be intrusive. Petrographic examination of the volcanic units indicates regional metamorphism up to greenschist facies (T=3250 C - 4500 C, P=2kbars) overprinted by a lower amphibolite facies thermal event (T=5750 C, P=2kbars) confined to the south-eastern portion of the belt. Chemical element results suggest olivine, plagioclase and pyroxene are the main fractionating mineral phases. Mobility studies on the varIOUS chemical elements indicate that K, Ca, Na and Sr are relatively mobile, while P, Zr, Ti, Fet (total iron = Fe203) and Mg are relatively immobile. Discriminant diagrams employing immobile element suggests that the majority of the samples are of oceanic affinity with a minor proportion displaying an island arc affinity. Such a transitional tectonic setting IS also refle.cted in REE data where two groups of volcanic samples are recognised. Oceanic tholeiites are LREE depleted with [La/Sm] N = 0.65 and a relatively flat HREE profile with [Sm/Yb] N = 1.2. Island arc type basalts (calc-alkaline) are LREE enriched, with a [La/Sm] N = 1.6, and a relatively higher fractionated HREE profile with [Sm/Yb] N = 1.9. Petrogenetic modelling performed on oceanIC tholeiites suggests derivation from a depleted spinel lherzolite source which undergoes 20% partial melting. Island arc type basalts can be derived by 10% partial melting of a hypothetical amphibolitised oceanic tholeiite source. The majority of the volcanic rocks in the Beardmore-Geraldton Belt are interpreted to represent fragments of oceanic crust trapped at a consuming plate margin. Subsequent post accretionary intrusion of gabbroic rocks (sensu lato) with calc-alkaline affinity is considered to result in the apparent hybrid tectonic setting recognized for the BGB.

Geochemistry and petrogenesis of the McElroy and Larder Lake assemblages, Abitibi Greenstone Belt, Northeastern Ontario

The McElroy and Larder Lake assemblages, located in the southern Abitibi Greenstone Belt are two late Archean metavolcanic sequences having markedly contrasting physical characteristics arid are separated from one another by a regional fault. An assemblage is an informal term which describes stratified volcanic and/or sedimentary rock units built during a specific time period in a similar depositional or volcanic setting and are commonly bounded by faults, unconformities or intrusions. The petrology and petrogenesis of these assemblages have been investigated to determine if a genetic link exists between the two adjacent assemblages. The McElroy assemblage is homoclinal sequence of evolved massive and pillowed fl.ows, which except for the basal unit represents a progressively fractionated volcanic pile. From the base to the top of the assemblage the lithologies include Fe-tholeiitic, dendritic flows; komatiite basaltic, ultramafic flows; Mg-tholeiitic, leucogabbro; Mg-tholeiitic, massive flows and Fe-tholeiitic, pillowed flows. Massive flows range from coarse grained to aphanitic and are commonly plagioclase glomerophyric. The Larder Lake assemblage consists of komatiitic, Mg-rich and Fe-rich tholeiitic basalts, structurally disrupted by folds and faults. Tholeiitic rocks in the Larder Lake assemblage range from aphanitic to coarse grained massive and pillowed flows. Komatiitic flows contain both spinifex and massive textures. Geochemical variability within both assemblages is attributed to different petrogenetic histories. The lithologies of the McElroy assemblage were derived by partial melting of a primitive mantle source followed by various degrees of crystal fractionation. Partial melting of a primitive mantle source generated the ultramafic flows and possibly other flows in the assemblage. Fractionation of ultramafic flows may have also produced the more evolved McElroy lithologies. The highly evolved, basal, dendritic flow may represent the upper unit 3 of a missing volcanic pile in which continued magmatism generated the remaining McElroy lithologies. Alternatively, the dendritic flows may represent a primary lava derived from a low degree (10-15%) partial melt of a primitive mantle source which was followed by continued partial melting to generate the ultramafic flows. The Larder Lake lithologies were derived by partial melting of a komatiitic source followed by gabbroic fractionation. The tectonic environment for both assemblages is interpreted to be an oceanic arc setting. The McElroy assemblage lavas were generated in a mature back arc setting whereas the Larder Lake lithologies were produced during the early stages of komatiitc crust subduction. This setting is consistent with previous models involving plate tectonic processes for the generation of other metavolcanic assemblages in the Abitibi Greenstone Belt.

Cabinet Card of African Canadian by Photographer W. J. Rea, of Windsor [n.d.]

An unidentified African Canadian man is featured in this cabinet card by W. J. Rea, photographer, of Windsor, Ontario. The man appears to be in official dress, possibly of a religious or legal nature. This cabinet card bears the stamp of the photographer, W. J. Rea, in black ink along the bottom of the card and on the reverse. While it is undated, it is likely from the 1870s or 1880s. This cabinet card was in the possession of Iris Sloman Bell, of St. Catharines, Ontario. The Sloman - Bell family descendants include African American slaves from the United States who settled in Canada."Cabinet card photographs were first introduced in 1866. They were initially employed for landscapes rather than portraitures. Cabinet cards replaced Carte de visite photographs as the popular mode of photography. Cabinet cards became the standard for photographic portraits in 1870. Cabinet cards experienced their peak in popularity in the 1880's. Cabinet cards were still being produced in the United States until the early 1900's and continued to be produced in Europe even longer. The best way to describe a cabinet card is that it is a thin photograph that is mounted on a card that measures 4 1/4″ by 6 1/2″. Cabinet cards frequently have artistic logos and information on the bottom or the reverse of the card which advertised the photographer or the photography studio's services." Source: http://cabinetcardgallery.wordpress.com/category/cabinet-card-history/

Small Cabinet Card of African American Man by John S. Thom, of Lucan, Ontario [n.d.]

A very small cabinet card type photograph of an unidentified man, possibly a relative of the Bell - Sloman family. A handwritten entry on the reverse of the photograph indicates it was taken by John S. Thom, of Lucan. No date is provided, however, John S. Thom is known to have been a photographer in Lucan from 1877-1882. This cabinet card was in the possession of Iris Sloman Bell, of St. Catharines. Relatives of the Sloman - Bell family include former African American slaves who settled in Canada.John S. Thom is listed as a photographer in Lucan, Ontario from 1877-1882. Aside from photography, he also operated a general store and sold notions. It appears he then moved to Sarnia, Ont. and is listed as a photographer there from 1882-1900. He is also recorded as being a Sarnia bicycle dealer. Source: Phillips, Glen C. The Ontario photographers list (1851-1900). Sarnia: Iron Gate Publishing Co., 1990.

Cabinet Card of Young African Canadian by The Dominion Photo Studio, Toronto [n.d.]

This unidentified African Canadian man is photographed at the Dominion Photo Studio, located at 388 Queen St. West in Toronto. The photographer's name is not known. No date is provided, however, the Dominion Studio is listed as operating from 1893-1894. The reverse of the card displays the Dominion Photo Studio stamp in gold lettering (image also attached). The gentleman in this cabinet card is possibly a relative of the Sloman - Bell family, who settled in the London and St. Catharines areas of Ontario. This cabinet card was among the family memorabilia in the possession of Iris Sloman Bell, of St. Catharines. Relatives of the Sloman - Bell family include former African American slaves who came to Canada.The Dominion Portait Co. is listed as operating from 1893-1894 in Toronto. There is an additional listing for the Dominion Portrait Co. (Gourlay and Clark props.) for 1894. Source: Phillips, Glen C. The Ontario photographers list (1851-1900). Sarnia: Iron Gate Publishing Co., 1990. "Cabinet card photographs were first introduced in 1866. They were initially employed for landscapes rather than portraitures. Cabinet cards replaced Carte de visite photographs as the popular mode of photography. Cabinet cards became the standard for photographic portraits in 1870. Cabinet cards experienced their peak in popularity in the 1880's. Cabinet cards were still being produced in the United States until the early 1900's and continued to be produced in Europe even longer. The best way to describe a cabinet card is that it is a thin photograph that is mounted on a card that measures 4 1/4″ by 6 1/2″. Cabinet cards frequently have artistic logos and information on the bottom or the reverse of the card which advertised the photographer or the photography studio's services." Source: http://cabinetcardgallery.wordpress.com/category/cabinet-card-history/

Tintype of Unidentified African American Woman Leaning on Chair [n.d.]

A small tintype of a young Black woman dressed in white. The date, location and name of the photographer are unknown. This tintype was among the family memorabilia belonging to Iris Sloman Bell, of St. Catharines, Ontario. Relatives of the Sloman - Bell family are descended from former American slaves."Tintypes were the invention of Prof. Hamilton Smith of Ohio. They begin as thin sheets of iron, covered with a layer of black paint. This serves as the base for the same iodized collodion coating and silver nitrate bath used in the ambrotype process. First made in 1856, millions were produced well into the twentieth century. When tintypes were finished in the same sorts of mats and cases used for ambrotypes, it can be almost impossible to distinguish which process was used without removing the image to examine the substrate." Source: American Museum of Photography http://www.photographymuseum.com/primer.html

Tintype of African American Gentleman Seated on Stool [n.d.]

An unidentified man poses for his portrait seated on a stool in this undated black and white tintype photograph. This tintype was in the possession of Iris Sloman Bell, of St. Catharines, Ontario. Relatives of the Bell - Sloman family include former Black slaves from the United States who settled in Canada."Tintypes were the invention of Prof. Hamilton Smith of Ohio. They begin as thin sheets of iron, covered with a layer of black paint. This serves as the base for the same iodized collodion coating and silver nitrate bath used in the ambrotype process. First made in 1856, millions were produced well into the twentieth century. When tintypes were finished in the same sorts of mats and cases used for ambrotypes, it can be almost impossible to distinguish which process was used without removing the image to examine the substrate." Source: American Museum of Photography http://www.photographymuseum.com/primer.html

Tintype of Young African American Woman Seated at Table [n.d.]

Black and white tintype of an unidentified woman seated with hand-colored red detail on her scarf and the tablecloth. The date, location and photographer are unknown. This tintype was in the possession of Iris Sloman Bell, of St. Catharines, Ontario. Relatives of the Bell - Sloman families include former slaves from the United States who escaped to Canada. They later settled in the London and St. Catharines areas of southern Ontario."Tintypes were the invention of Prof. Hamilton Smith of Ohio. They begin as thin sheets of iron, covered with a layer of black paint. This serves as the base for the same iodized collodion coating and silver nitrate bath used in the ambrotype process. First made in 1856, millions were produced well into the twentieth century. When tintypes were finished in the same sorts of mats and cases used for ambrotypes, it can be almost impossible to distinguish which process was used without removing the image to examine the substrate." Source: American Museum of Photography http://www.photographymuseum.com/primer.html

Tintype Portrait of African American Couple [n.d.]

An unidentified couple is pictured in this early black and white tintype photograph. The date, location and name of the photographer are unknown. This tintype was in the possession of Iris Sloman Bell, of St. Catharines, Ontario. The Bell - Sloman families have relatives who are descended from African American slaves who settled in Canada."Tintypes were the invention of Prof. Hamilton Smith of Ohio. They begin as thin sheets of iron, covered with a layer of black paint. This serves as the base for the same iodized collodion coating and silver nitrate bath used in the ambrotype process. First made in 1856, millions were produced well into the twentieth century. When tintypes were finished in the same sorts of mats and cases used for ambrotypes, it can be almost impossible to distinguish which process was used without removing the image to examine the substrate." Source: American Museum of Photography http://www.photographymuseum.com/primer.html

Tintype of African American Man Standing at Wooden Fence [n.d.]

An unidentified African American man poses beside a wooden fence in the studio of an unknown photographer in this small black and white tintype photograph. A painted landscape serves as the backdrop. This tintype was in the possession of Iris Sloman Bell, of St. Catharines, Ontario. The Sloman - Bell families are descended from former American slaves who settled in Canada."Tintypes were the invention of Prof. Hamilton Smith of Ohio. They begin as thin sheets of iron, covered with a layer of black paint. This serves as the base for the same iodized collodion coating and silver nitrate bath used in the ambrotype process. First made in 1856, millions were produced well into the twentieth century. When tintypes were finished in the same sorts of mats and cases used for ambrotypes, it can be almost impossible to distinguish which process was used without removing the image to examine the substrate." Source: American Museum of Photography http://www.photographymuseum.com/primer.html

Tintype of African American Woman Standing with Book [n.d.]

A woman standing with a book beside a table covered with a decorative cloth is featured in this small black and white tintype photograph. The tintype has been mounted in a paper slip frame with gold edging. There is a small area of red, hand-colored highlighting on the tablecloth. The backdrop appears to be a painted landscape scene. The tintype is undated and there is no indication of the identity of the woman in the photo or the photographer. This tintype was in the possession of Iris Sloman Bell, of St. Catharines, Ontario. The Sloman - Bell families have relatives who are former slaves from the United States who later settled in southern Ontario."Tintypes were the invention of Prof. Hamilton Smith of Ohio. They begin as thin sheets of iron, covered with a layer of black paint. This serves as the base for the same iodized collodion coating and silver nitrate bath used in the ambrotype process. First made in 1856, millions were produced well into the twentieth century. When tintypes were finished in the same sorts of mats and cases used for ambrotypes, it can be almost impossible to distinguish which process was used without removing the image to examine the substrate." Source: American Museum of Photography http://www.photographymuseum.com/primer.html

Tintype of Three African American Women [n.d.]

Three unidentified Black women, two seated and one standing, pose against a painted backdrop in the studio of an unknown photographer. This small black and white tintype has been cut on the upper and lower left-hand corners. The back of the tintype is a copper color. This photograph was among the family memorabilia in the possession of Iris Sloman Bell, of St. Catharines, Ontario. Relatives of the Sloman - Bell families include former American slaves who settled in Canada."Tintypes were the invention of Prof. Hamilton Smith of Ohio. They begin as thin sheets of iron, covered with a layer of black paint. This serves as the base for the same iodized collodion coating and silver nitrate bath used in the ambrotype process. First made in 1856, millions were produced well into the twentieth century. When tintypes were finished in the same sorts of mats and cases used for ambrotypes, it can be almost impossible to distinguish which process was used without removing the image to examine the substrate." Source: American Museum of Photography http://www.photographymuseum.com/primer.html

Tintype of Seated African American Gentleman [n.d.]

An unidentified young African American gentleman sits cross-legged on a decorative wooden stool in this small black and white tintype photograph. The date and name of the photographer are unknown. Hand-colored red detailing is visible on the curtain cord and the tablecloth. This tintype was in the possession of Iris Sloman Bell, of St. Catharines, Ontario. Relatives of the Sloman - Bell families were former American slaves who settled in Canada."Tintypes were the invention of Prof. Hamilton Smith of Ohio. They begin as thin sheets of iron, covered with a layer of black paint. This serves as the base for the same iodized collodion coating and silver nitrate bath used in the ambrotype process. First made in 1856, millions were produced well into the twentieth century. When tintypes were finished in the same sorts of mats and cases used for ambrotypes, it can be almost impossible to distinguish which process was used without removing the image to examine the substrate." Source: American Museum of Photography http://www.photographymuseum.com/primer.html

Tintype of Young African American Woman Standing with Purse [n.d.]

An unidentified young African American woman stands beside a chair in this small black and white tintype, undated. The name of the photographer is unknown. This tintype was in the possession of the Iris Sloman Bell, of St. Catharines. The Sloman - Bell families have relatives who are descended from former American slaves who settled in Canada."Tintypes were the invention of Prof. Hamilton Smith of Ohio. They begin as thin sheets of iron, covered with a layer of black paint. This serves as the base for the same iodized collodion coating and silver nitrate bath used in the ambrotype process. First made in 1856, millions were produced well into the twentieth century. When tintypes were finished in the same sorts of mats and cases used for ambrotypes, it can be almost impossible to distinguish which process was used without removing the image to examine the substrate." Source: American Museum of Photography http://www.photographymuseum.com/primer.html