U-Pb monazite ages of the Kabanga mafic-ultramafic intrusions and contact aureoles, central Africa: Geochronological and tectonic implications

AbstractMafic-ultramafic rocks of the Kabanga-Musongati alignment in the East African nickel belt occur as Bushveld-type layered intrusions emplaced in metasedimentary sequences. The age of the mafic-ultramafic intrusions remains poorly constrained, though they are regarded to be part of ca. 1375 Ma bimodal magmatism dominated by voluminous S-type granites. In this study, we investigated igneous monazite and zircon from a differentiated layered intrusion and metamorphic monazite from the contact aureole. The monazite shows contrasting crystal morphology, chemical composition, and U-Pb ages. Monazite that formed by contact metamorphism in response to emplacement of mafic-ultramafic melts is characterized by extremely high Th and U and yielded a weighted mean 207Pb/206Pb age of 1402 ± 9 Ma, which is in agreement with dates from the igneous monazite and zircon. The ages indicate that the intrusion of ultramafic melts was substantially earlier (by ∼25 m.y., 95% confidence) than the prevailing S-type granites, calling for a reappraisal of the previously suggested model of coeval, bimodal magmatism. Monazite in the metapelitic rocks also records two younger growth events at ca. 1375 Ma and ca. 990 Ma, coeval with metamorphism during emplacement of S-type granites and tin-bearing granites, respectively. In conjunction with available geologic evidence, we propose that the Kabanga-Musongati mafic-ultramafic intrusions likely heralded a structurally controlled thermal anomaly related to Nuna breakup, which culminated during the ca. 1375 Ma Kibaran event, manifested as extensive intracrustal melting in the adjoining Karagwe-Ankole belt, producing voluminous S-type granites. The Grenvillian-aged (ca. 990 Ma) tin-bearing granite and related Sn mineralization appear to be the far-field record of tectonothermal events associated with collision along the Irumide belt during Rodinia assembly. Since monazite is a ubiquitous trace phase in pelitic sedimentary rocks, in contact aureoles of mafic-ultramafic intrusions, and in regional metamorphic belts, our study highlights the potential of using metamorphic monazite to determine ages of mafic-ultramafic intrusions, and to reconstruct postemplacement metamorphic history of the host terranes.

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The early history of West African highlife music

Popular Music ◽

10.1017/s0261143000003524 ◽

1989 ◽

Vol 8 (3) ◽

pp. 221-230 ◽

Cited By ~ 11

Author(s):

John Collins

Keyword(s):

South Africa ◽

North Africa ◽

Central Africa ◽

West African ◽

Early History ◽

Dance Music ◽

East African ◽

East African Coast ◽

African Coast ◽

History Of

Highlife is one of the myriad varieties of acculturated popular dance-music styles that have been emerging from Africa this century and which fuse African with Western (i.e. European and American) and islamic influences. Besides highlife, other examples include kwela, township jive and mbaqanga from South Africa, chimurenga from Zimbabwe, the benga beat from Kenya, taraab music from the East African coast, Congo jazz (soukous) from Central Africa, rai music from North Africa, juju and apala music from western Nigeria, makossa from the Cameroons and mbalax from Senegal.

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Metamorphism of the pelitic rocks of the Snyder Group in the contact aureole of the Kiglapait layered intrusion, Labrador: effects of buffering partial pressures of water

Canadian Journal of Earth Sciences ◽

10.1139/e82-168 ◽

1982 ◽

Vol 19 (10) ◽

pp. 1888-1909 ◽

Cited By ~ 18

Author(s):

J. Alexander Speer

Keyword(s):

Layered Intrusion ◽

Granulite Facies ◽

Metamorphic Grade ◽

Contact Metamorphism ◽

Contact Aureole ◽

Partial Pressures ◽

Dehydration Reactions ◽

Mineral Assemblages ◽

Temperature Ranges ◽

Pelitic Rocks

The petrography and mineral chemistries of the Aphebian Snyder Group pelitic rocks in the contact aureole of the Kiglapait layered intrusion, Labrador reveal a rapid increase in metamorphic grade over 1.7 km from the greenschist facies to the granulite facies. Three zones of metamorphic grade are defined by the aluminum silicates: I, andalusite; II, andalusite + sillimanite; and III, sillimanite. In addition to the succession in the aluminum silicates, progressive metamorphic mineral assemblages, with quartz, K-feldspar, and plagioclase, evolve from chlorite + biotite + muscovite through cordierite + biotite ± muscovite and garnet + cordierite + biotite to orthopyroxene + garnet + cordierite + biotite and eventually either orthopyroxene + cordierite ± biotite or orthopyroxene + garnet + cordierite. Anatectites, believed to be derived from pelitic rocks, intrude as small stocks in zone III. They comprise biotite + cordierite ± garnet ± orthopyroxene monzogranites or granodiorites with accessory ilmenite, rutile, monazite, and dumortierite.The contact metamorphism is isobaric with pressure just above the intersection of the muscovite + quartz decomposition with the andalusite–sillimanite transition. Most published geobarometers place the estimated pressure of metamorphism at 4 ± 1 kbar (400 ± 100 MPa), but use of the lower Holdaway triple point would put it at 2.25 kbar (225 MPa). The temperature ranges from 450 °C in zone I to 900 °C or more adjacent to the Kiglapait intrusion. The range of values of [Formula: see text] is estimated to be 0.1–0.9Ptotal. Because most reactions are dehydration reactions, conditions of [Formula: see text] less than Ptotal allow the metamorphic reactions to buffer the partial pressure of water. This results in the common occurrence of low-variance assemblages and leads to an apparent overlapping of mineral assemblages and mineral chemistries with increasing metamorphic grade.

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Zircon record of the igneous and metamorphic history of the Fiskenæsset anorthosite complex in southern West Greenland

Geological Survey of Denmark and Greenland Bulletin ◽

10.34194/geusb.v20.4980 ◽

1969 ◽

Vol 20 ◽

pp. 67-70 ◽

Cited By ~ 3

Author(s):

Nynke Keulen ◽

Tomas Næraa ◽

Thomas F. Kokfelt ◽

John C. Schumacher ◽

Anders Scherstén

Keyword(s):

North Atlantic ◽

Layered Intrusion ◽

Mineral Chemistry ◽

Joint Project ◽

West Greenland ◽

Metamorphic History ◽

The North ◽

History Of ◽

The North Atlantic ◽

North Atlantic Craton

The Fiskenæsset complex in southern West Greenland is part of the North Atlantic craton and is a layered intrusion consisting of gabbro, ultramafic and anorthositic rocks that was deformed during multiple episodes of folding and metamorphism (Myers 1985). We collected late-stage magmatic hornblenditic dykes and adjacent anorthosites and studied these samples integratively with several in situ techniques to determine the igneous and metamorphic history of the Fiskenæsset complex. The work presented here is part of an ongoing joint project between the Greenland Bureau of Minerals and Petroleum and the Geological Survey of Denmark and Greenland (GEUS). Here we report on new radiometric ages and mineral chemistry data from anorthosites from the North Atlantic craton in southern West Greenland (Fig. 1).

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A history of botanical collections in the Luangwa Valley, Zambia

Archives of Natural History ◽

10.3366/anh.1998.25.2.283 ◽

1998 ◽

Vol 25 (2) ◽

pp. 283-291

Author(s):

P.S.M. PHIRI ◽

D.M. MOORE

Keyword(s):

Eighteenth Century ◽

Environmental Impact ◽

Impact Assessment ◽

Vascular Plants ◽

Central Africa ◽

Peak Activity ◽

Historical Account ◽

History Of ◽

The 1960S ◽

Made In

Central Africa remained botanically unknown to the outside world up to the end of the eighteenth century. This paper provides a historical account of plant explorations in the Luangwa Valley. The first plant specimens were collected in 1897 and the last serious botanical explorations were made in 1993. During this period there have been 58 plant collectors in the Luangwa Valley with peak activity recorded in the 1960s. In 1989 1,348 species of vascular plants were described in the Luangwa Valley. More botanical collecting is needed with a view to finding new plant taxa, and also to provide a satisfactory basis for applied disciplines such as ecology, phytogeography, conservation and environmental impact assessment.

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The War of Legs

Transfers ◽

10.3167/trans.2015.050207 ◽

2015 ◽

Vol 5 (2) ◽

pp. 102-120

Author(s):

Michael Pesek

Keyword(s):

World War I ◽

Medical Care ◽

East Africa ◽

Transport Infrastructure ◽

World War ◽

East African ◽

Colonial State ◽

History Of ◽

Main Factors ◽

Belgian Congo

This article describes the little-known history of military labor and transport during the East African campaign of World War I. Based on sources from German, Belgian, and British archives and publications, it considers the issue of military transport and supply in the thick of war. Traditional histories of World War I tend to be those of battles, but what follows is a history of roads and footpaths. More than a million Africans served as porters for the troops. Many paid with their lives. The organization of military labor was a huge task for the colonial and military bureaucracies for which they were hardly prepared. However, the need to organize military transport eventually initiated a process of modernization of the colonial state in the Belgian Congo and British East Africa. This process was not without backlash or failure. The Germans lost their well-developed military transport infrastructure during the Allied offensive of 1916. The British and Belgians went to war with the question of transport unresolved. They were unable to recruit enough Africans for military labor, a situation made worse by failures in the supplies by porters of food and medical care. One of the main factors that contributed to the success of German forces was the Allies' failure in the “war of legs.”

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Thermal metamorphic history of Antarctic CV3 and CO3 chondrites inferred from the first and second order Raman peaks of polyaromatic organic carbon

American Mineralogist ◽

10.2138/am-2021-7507 ◽

2020 ◽

Keyword(s):

Organic Carbon ◽

Second Order ◽

Metamorphic History ◽

History Of

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From Stonehenge to Samarkand

10.1093/oso/9780195160918.001.0001 ◽

2006 ◽

Author(s):

Brian Fagan

Keyword(s):

Gustave Flaubert ◽

Central Africa ◽

British Museum ◽

Holy Land ◽

Cruise Ship ◽

Modern Times ◽

Ancient Civilization ◽

Machu Picchu ◽

History Of ◽

The Silk Road

Ever since Roman tourists scratched graffiti on the pyramids and temples of Egypt over two thousand years ago, people have traveled far and wide seeking the great wonders of antiquity. In From Stonehenge to Samarkand, noted archaeologist and popular writer Brian Fagan offers an engaging historical account of our enduring love of ancient architecture--the irresistible impulse to visit strange lands in search of lost cities and forgotten monuments. Here is a marvelous history of archaeological tourism, with generous excerpts from the writings of the tourists themselves. Readers will find Herodotus describing the construction of Babylon; Edward Gibbon receiving inspiration for his seminal work while wandering through the ruins of the Forum in Rome; Gustave Flaubert watching the sunrise from atop the Pyramid of Cheops. We visit Easter Island with Pierre Loti, Machu Picchu with Hiram Bingham, Central Africa with David Livingstone. Fagan describes the early antiquarians, consumed with a passionate and omnivorous curiosity, pondering the mysteries of Stonehenge, but he also considers some of the less reputable figures, such as the Earl of Elgin, who sold large parts of the Parthenon to the British Museum. Finally, he discusses the changing nature of archaeological tourism, from the early romantic wanderings of the solitary figure, communing with the departed spirits of Druids or Mayans, to the cruise-ship excursions of modern times, where masses of tourists are hustled through ruins, barely aware of their surroundings. From the Holy Land to the Silk Road, the Yucatán to Angkor Wat, Fagan follows in the footsteps of the great archaeological travelers to retrieve their first written impressions in a book that will delight anyone fascinated with the landmarks of ancient civilization.

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The geological history of the Lake Rudolf Basin, Kenya colony

Philosophical Transactions of the Royal Society of London Series B Biological Sciences ◽

10.1098/rstb.1939.0001 ◽

1939 ◽

Vol 229 (560) ◽

pp. 219-274 ◽

Cited By ~ 34

Keyword(s):

Rift Valley ◽

Public Works ◽

General Description ◽

Geological History ◽

East African ◽

The Public ◽

Geographical Society ◽

History Of ◽

African Rift ◽

At Home

The Lake Rudolf Rift Valley Expedition was designed to carry out many different lines of investigation in the Lake Rudolf Basin. One of the chief of these was a study of the geological history of that part of the East African Rift Valley. The expedition was assisted financially by The Royal Society, The Geological Society of London, The Royal Geographical Society, The Percy Sladen Trustees and the Geographical and Geological Sections of the British Association. A general description of the activities of the Expedition was given in a paper read before the Royal Geographical Society (Fuchs 1935). Owing to the tragic loss of two members of the expedition, Dr W. S. Dyson and Mr W. R. H. Martin, two fruitless months were spent searching for them. Consequently a great amount of the work planned for the east side of the lake had to be abandoned. Nevertheless, the considerable distance travelled within the 50,000 sq. miles of the Rudolf Basin has enabled me to make out the chief events of its geological history. I am very much indebted to all those who assisted us in the field and at home, in particular to the Kenya Government, the Officers of the King’s African Rifles, and Mr H. L. Sikes of the Public Works Department; I would also like to thank Mr A. M. Champion, Provincial Commissioner of Turkana, who wholeheartedly assisted us in every way possible both in the field and at home, for he has placed at my disposal his own excellent topographical maps and his extensive observations on the geology of the area. I am also deeply indebted to Professor O. T. Jones, Mr Henry Woods and Mr W. Campbell Smith for their criticisms. Mr Campbell Smith has also given me provisional identifications of the rocks.

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