The Yatela gold deposit in Mali, West Africa: The final product of a long-lived history of hydrothermal alteration and weathering

2016 ◽  
Vol 113 ◽  
pp. 73-87 ◽  
Author(s):  
Quentin Masurel ◽  
John Miller ◽  
Kim A.A. Hein ◽  
Eric Hanssen ◽  
Nicolas Thébaud ◽  
...  
1993 ◽  
Vol 20 ◽  
pp. 173-184 ◽  
Author(s):  
Robin Law

This paper draws attention to an ambitious project in the publication of source material for the precolonial history of West Africa, which has recently been approved for inclusion in the Fontes Historiae Africanae series of the British Academy. In addition to self-promotion, however, I wish also to take the opportunity to air some of the problems of editorial strategy and choice which arise with regard to the editing and presentation of this material, in the hope of provoking some helpful feedback on these issues.The material to be published consists of correspondence of the Royal African Company of England relating to the West African coast in the late seventeenth century. The history of the Royal African Company (hereafter RAC) is in general terms well known, especially through the pioneering (and still not superseded) study by K.G. Davies (1957). The Company was chartered in 1672 with a legal monopoly of English trade with Africa. Its headquarters in West Africa was at Cape Coast (or, in the original form of the name, Cabo Corso) Castle on the Gold Coast, and it maintained forts or factories not only on the Gold Coast itself, but also at the Gambia, in Sierra Leone, and at Offra and Whydah on the Slave Coast. It lost its monopoly of the African trade in 1698, and thereafter went into decline, effectively ceasing to operate as a trading concern in the 1720s, although it continued to manage the English possessions on the coast of West Africa until it was replaced by a regulated company (i.e., one open to all traders), the Company of Merchants Trading to Africa, in 1750.


1993 ◽  
Vol 30 (4) ◽  
pp. 764-768 ◽  
Author(s):  
John M. Murphy ◽  
Arne Bakke

Eight apatite and two zircon fission-track ages provide evidence of complex Tertiary thermal overprinting by hydrothermal fluids in the Gilmore Dome area. Five ages on apatite from the Fort Knox gold deposit average 41 Ma, one from the Stepovich prospect is 80 Ma, and two from Pedro Dome average 67 Ma. Elevations of these samples overlap but their ages do not, indicating that each area experienced a different thermal history.Ages of apatite from the Fort Knox gold deposit decrease with elevation from 42 to 36 Ma but have data trends indicative of complex cooling. Two ~51 Ma ages on zircon indicate that maximum temperatures approached or exceeded ~180 °C. An alteration assemblage of chalcedony + zeolite + calcite + clay in the deposit resulted from deposition by a paleo-hydrothermal system. The data suggest that the system followed a complex cooling path from > 180 to < 110 °C between 51 and 36 Ma, and that final cooling to below 60 °C occurred after ~25 Ma.The 80 Ma age from Stepovich prospect either resulted from cooling after intrusion of the underlying pluton (~90 Ma) or records postintrusion thermal overprinting sometime after ~50 Ma. The 67 Ma samples from Pedro Dome may also have experienced partial age reduction during later heating. The differences in the data from the different areas and the presence of a late alteration assemblage at Fort Knox suggest that the fluids responsible for heating were largely confined to the highly fractured and porous Fort Knox pluton.


2021 ◽  
pp. 002190962110549
Author(s):  
Oliver Coates

The National Negro Publishers Association (NNPA) Commission to West Africa in 1944–1945 represents a major episode in the history of World War II Africa, as well as in American–West Africa relations. Three African American reporters toured the Gold Coast, Sierra Leone, Nigeria, Liberia, and the Congo between November 1944 and February 1945, before returning to Washington, DC to report to President Roosevelt. They documented their tour in the pages of the Baltimore Afro-American, the Chicago Defender, and the Norfolk Journal and Guide. Their Americans’ visit had a significant impact in wartime West Africa and was widely documented in the African press. This article examines the NNPA tour geographically, before analyzing American reporters’ interactions with West Africans, and assessing African responses to the tour. Drawing on both African American and West African newspapers, it situates the NNPA tour within the history of World War II West Africa, and in terms of African print culture. It argues that the NNPA tour became the focus of West African hopes for future political, economic, and intellectual relations with African Americans, while revealing how the NNPA reporters engaged African audiences during their tour.


Zootaxa ◽  
2018 ◽  
Vol 4504 (2) ◽  
pp. 151 ◽  
Author(s):  
MATTHEW H. SHIRLEY ◽  
AMANDA N. CARR ◽  
JENNIFER H. NESTLER ◽  
KENT A. VLIET ◽  
CHRISTOPHER A. BROCHU

Molecular and morphological evidence has shown that the African slender-snouted, or sharp-nosed, crocodile Mecistops cataphractus (Cuvier, 1824) is comprised of two superficially cryptic species: one endemic to West Africa and the other endemic to Central Africa. Our ability to characterize the two species is compromised by the complicated taxonomic history of the lineage and overlapping ranges of variation in distinguishing morphological features. The name M. cataphractus was evidently originally based on West African material, but the holotype is now lost. Although types exist for other names based on the West African form, the name M. cataphractus is sufficiently entrenched in the literature, and other names sufficiently obscure, to justify retypification. Here, we designate a neotype for M. cataphractus and restrict it to West Africa. We resurrect M. leptorhynchus as a valid species from Central Africa and identify exemplary referred specimens that, collectively, overcome the obscurity and diagnostic limits of the extant holotype. We additionally indicate suitable neotype material in the event the holotype is lost, destroyed, or otherwise needing replacement, and we rectify the previously erroneous type locality designation. We provide a revised diagnosis for crown Mecistops, and revise and update previous descriptions of the two living species, including providing both more complete descriptions and discussion of diagnostic characters. Finally, we provide considerable discussion of the current state of knowledge of these species’ ecology, natural history, and distribution. 


2015 ◽  
Vol 2 (9) ◽  
pp. 150370 ◽  
Author(s):  
Karen L. Bell ◽  
Haripriya Rangan ◽  
Christian A. Kull ◽  
Daniel J. Murphy

To investigate the pathways of introduction of the African baobab, Adansonia digitata , to the Indian subcontinent, we examined 10 microsatellite loci in individuals from Africa, India, the Mascarenes and Malaysia, and matched this with historical evidence of human interactions between source and destination regions. Genetic analysis showed broad congruence of African clusters with biogeographic regions except along the Zambezi (Mozambique) and Kilwa (Tanzania), where populations included a mixture of individuals assigned to at least two different clusters. Individuals from West Africa, the Mascarenes, southeast India and Malaysia shared a cluster. Baobabs from western and central India clustered separately from Africa. Genetic diversity was lower in populations from the Indian subcontinent than in African populations, but the former contained private alleles. Phylogenetic analysis showed Indian populations were closest to those from the Mombasa-Dar es Salaam coast. The genetic results provide evidence of multiple introductions of African baobabs to the Indian subcontinent over a longer time period than previously assumed. Individuals belonging to different genetic clusters in Zambezi and Kilwa may reflect the history of trafficking captives from inland areas to supply the slave trade between the fifteenth and nineteenth centuries. Baobabs in the Mascarenes, southeast India and Malaysia indicate introduction from West Africa through eighteenth and nineteenth century European colonial networks.


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