List of Titles

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The Karoo igneous province: an introduction

- Eales, Hugh V, Marsh, Julian S, Cox, K G

Authors: Eales, Hugh V , Marsh, Julian S , Cox, K G
Date: 1984
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/133945 , vital:37043 , http://pascal-francis.inist.fr/vibad/index.php?action=getRecordDetailamp;idt=6519910
Description: The Karoo rocks are amongst the earliest manifestations of igneous activity accompanying the break-up of Gondwanaland during the early Mesozoic. Remnants of the once extensive lava sequence and the associated dolerite sills are found throughout southern Africa south of latitude 150S, the present outcrop being ca. 140,000 km². The main peak of volcanic activity is dated at about 190 m.y. and is probably coincident with the earliest stages of the opening of the Indian Ocean by the separation of Antarctica from southern Africa.
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Date Issued: 1984

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Petrology and geochemistry of early cretaceous bimodal continental flood volcanism of the NW Etendeka, Namibia Part 2: characteristics and petrogenesis of the high-Ti latite and high-Ti and low-Ti voluminous quartz latite eruptives

- Ewart, A, Marsh, Julian S, Milner, Simon C, Duncan, Andrew R, Kamber, B S, Armstrong, R A

Authors: Ewart, A , Marsh, Julian S , Milner, Simon C , Duncan, Andrew R , Kamber, B S , Armstrong, R A
Date: 2004
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/150593 , vital:38987 , https://doi.org/10.1093/petrology/egg082
Description: As a result of their relative concentration towards the respective Atlantic margins, the silicic eruptives of the Paraná (Brazil)–Etendeka large igneous province are disproportionately abundant in the Etendeka of Namibia. The NW Etendeka silicic units, dated at ∼132 Ma, occupy the upper stratigraphic levels of the volcanic sequences, restricted to the coastal zone, and comprise three latites and five quartz latites (QL).
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Date Issued: 2004

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Petrology and geochemistry of peridotite xenoliths from the Letlhakane kimberlites, Botswana

- Stiefenhofer, J, Viljoen, K S, Marsh, Julian S

Authors: Stiefenhofer, J , Viljoen, K S , Marsh, Julian S
Date: 1997
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/149705 , vital:38876 , https://doi.org/10.1007/s004100050272
Description: The diamondiferous Letlhakane kimberlites are intruded into the Proterozoic Magondi Belt of Botswana. Given the general correlation of diamondiferous kimberlites with Archaean cratons, the apparent tectonic setting of these kimberlites is somewhat anomalous. Xenoliths in kimberlite diatremes provide a window into the underlying crust and upper mantle and, with the aid of detailed petrological and geochemical study, can help unravel problems of tectonic setting.
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Date Issued: 1997

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The geochemistry of potassic lavas from Vulsini, central Italy and implications for mantle enrichment processes beneath the Roman region

- Rogers, N W, Hawkesworth, C J, Parker, R J, Marsh, Julian S

Authors: Rogers, N W , Hawkesworth, C J , Parker, R J , Marsh, Julian S
Date: 1985
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/136034 , vital:37330 , https://doi.org/10.1007/BF00378265
Description: Major and trace element and 143Nd/144Nd (0.51209–0.51216) and 87Sr/86Sr (0.70879–0.71105) isotope analyses are presented on a representative group of lavas from the Vulsini district of the Roman magmatic province. Three distinct series are identified; the high-K and low-K series are similar to those described from other Italian volcanoes, while the third is represented by a group of relatively undifferentiated leucite basanites which are thought to be near-primary mantle melts.
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Date Issued: 1985

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New chemical analyses of the Suurberg volcanic rocks and their significance in relation to Mesozoic volcanism in Southern Africa

- Marsh, Julian S, Lock, B E, Fuchter, W H

Authors: Marsh, Julian S , Lock, B E , Fuchter, W H
Date: 1979
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/133231 , vital:36951
Description: Volcanic rocks are found associated with several of the late Mesozoic basins of southern South Africa. Bentonites are known from Plettenberg Bay and, according to an unconfirmed report, they are also found in the Worcester Basin, while vitric tuffs have been recorded from east of Oudtshoorn. The most extensive occurrences, however, are those of the Suurberg Group, which crops out sporadically around the margins of the Algoa Basin.
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Date Issued: 1979

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The distribution of platinum group elements in the Insizwa lobe, Mount Ayliff Complex, South Africa: implications for Ni-Cu-PGE sulfide exploration in the Karoo igneous province

- Maier, W D, Marsh, Julian S, Barnes, Sarah-Jane, Dodd, D C

Authors: Maier, W D , Marsh, Julian S , Barnes, Sarah-Jane , Dodd, D C
Date: 2002
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/150353 , vital:38969 , https://0-doi.org.wam.seals.ac.za/10.2113/gsecongeo.97.6.1293
Description: The Mount Ayliff Complex of the Eastern Cape province of South Africa is a layered intrusion of some 800 km2 surface area and up to 1,200 m thickness. On the basis of compositional similarities and spatial association, it is generally interpreted to form part of the Karoo igneous province. Similarities between the Mount Ayliff Complex and the staging chambers and feeder conduits to flood basalts that host magmatic sulfide ores elsewhere in the world suggest that the Mount Ayliff Complex may have an enhanced potential for Noril’sk-Talnakh–type massive Ni-Cu sulfide ores, an idea that is supported by the well-known sulfide occurrence at Waterfall Gorge.
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Date Issued: 2002

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Oxygen isotope geochemistry of the Mesozoic volcanics of the Etendeka Formation, Namibia

- Harris, Chris, Smith, H Stuart, Milner, Simon C, Erlank, Anthony J, Duncan, Andrew R, Marsh, Julian S, Ikin, Nicholas P

Authors: Harris, Chris , Smith, H Stuart , Milner, Simon C , Erlank, Anthony J , Duncan, Andrew R , Marsh, Julian S , Ikin, Nicholas P
Date: 1989
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/143272 , vital:38219 , https://doi.org/10.1007/BF00371087
Description: The Etendeka Formation volcanics consist of a bimodal association of basalts and quartz latites. Forty three new whole rock oxygen isotope analyses are reported for all the major magma types. All the rocks except a minor suite of dolerites have higher δ18O values than normal mantle. The basic rocks (average of 29=8.8‰) have significantly different δ18O to the acid rocks (average of 10=14.4‰). These data are apparently consistent with previously published petrogenetic models, which propose that the basalts were affected by crustal contamination and that the quartz latites are crustally derived.
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Date Issued: 1989

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Magma flow inferred from AMS fabrics in a layered mafic sill, Insizwa, South Africa

- Ferré, Eric C, Bordarier, Cecile, Marsh, Julian S

Authors: Ferré, Eric C , Bordarier, Cecile , Marsh, Julian S
Date: 2002
Language: English
Type: Article
Identifier: vital:6733 , http://hdl.handle.net/10962/d1007543
Description: The Insizwa sill, is a 25-km-diameter, >1000-m-thick layered mafic intrusion, part of the Karoo Igneous Province in South Africa. The peridotitic and gabbronoritic rocks are undeformed and mineral fabrics demonstrably result from magma flow. A horizontal, centimeter-scale model layering is visible in numerous outcrops. Plagioclase crystals are both tabular and elongated. Their preferred orientation, parallel to the layering, forms a foliation and a NW–SE lineation, respectively interpreted as the magma flow plane and flow direction. Throughout the 78 stations of this study (699 specimens), magnetic susceptibilities (K[subscript m]) range from 750 to 10,000×10[superscript (−6)] SI. The magnetic anisotropy (P[subscript j]) ranges from 1.03 to 1.08. Magnetic ellipsoids are both prolate and oblate (average T[subscript j]≈0). Anisotropy of magnetic susceptibility (AMS) fabrics are dominated by multidomain to pseudo-single domain magnetite. High-field magnetic experiments indicate that the paramagnetic contribution from the mafic silicates is less than 50 percentage for low susceptibility rock types. The anisotropy results from magnetite grain shape solely as shown by no significant increase in P[subscript j] with increasing K[subscript m]. The magnetic lineation (305°, 05°) is consistent throughout the sill at various scales and coincides with the mineral lineation in average. In contrast, the magnetic foliation (125° NE 10°) is generally perpendicular to the mineral foliation and to the layering. Several explanations for this odd configuration are discussed. The variations of magnetic parameters across the layering and field observations point to a multiple injection. The magnetic lineation is consistent with the presence of a single feeder dike situated to the SE of the sill.
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Date Issued: 2002

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Promotion of the Etendeka Formation to Group status: a new integrated stratigraphy

- Milner, Simon C, Duncan, Andrew R, Ewart, A, Marsh, Julian S

Authors: Milner, Simon C , Duncan, Andrew R , Ewart, A , Marsh, Julian S
Date: 1994
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/145482 , vital:38442
Description: The Etendeka volcanic rocks of northwestem Namibia are currently defined as the upper part of the Karoo Sequence in Namibia and have thus been represented as stratigraphically equivalent to the volcanic rocks of the Karoo Sequence in South Africa, Botswana, Lesotho, Swaziland and Zimbabwe. However, the Etendeka volcanic rocks (130-135 Ma) are considerably younger than those of the Karoo Sequence (180-190 Ma) in the areas mentioned above. They are compositionally distinct from Karoo volcanic rocks, and constitute an eastern portion of the Parana Igneous Province of Brazil. Stratigraphic studies have shown the Etendeka Formation to be made up of several definable volcanic successions and it is suggested that these successions now be formally recognized as Formations within an Etendeka Group which itself should no longer be part of the Karoo Sequence. Prominent quartz latite units and sequences of basalt flows are defined as Members within the new Formations.
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Date Issued: 1994

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An attempt to constrain the age, duration, and eruptive history of the Karoo flood basalt: Naude's Nek section (South Africa)

- Moulin, Maud, Fluteau, Frédéric, Courtillot, Vincent, Marsh, Julian S, Delpech, Guillaume, Quidelleur, Xavier, Gérard, Martine, Jay, Anne E

Authors: Moulin, Maud , Fluteau, Frédéric , Courtillot, Vincent , Marsh, Julian S , Delpech, Guillaume , Quidelleur, Xavier , Gérard, Martine , Jay, Anne E
Date: 2011
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/145022 , vital:38401 , https://doi.org/10.1029/2011JB008210
Description: We have carried out paleomagnetic sampling of a ∼750 m sequence of the Karoo large igneous province (Naude's Nek Pass, South Africa). K‐Ar dating (Cassignol‐Gillot) has been performed on four samples from the 650 m upper unit (mean age 179.2 ± 1.8 Ma) and a sample from the lower unit (184.8 ± 2.6 Ma). A succession of two phases of volcanism is suggested. The lower 25 flows (115 m thick) have recorded a reversed polarity; the next 23 flows (135 m thick) are transitional and contribute a detailed record of the “Van Zijl” (1962) Jurassic reversal.
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Date Issued: 2011

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Geochemistry and petrogenesis of the Etendeka volcanic rocks from SWA Namibia

- Erlank, Anthony J, Marsh, Julian S, Duncan, Andrew R, Miller, R M, Hawkesworth, C J, Betton, P J, Rex, D C

Authors: Erlank, Anthony J , Marsh, Julian S , Duncan, Andrew R , Miller, R M , Hawkesworth, C J , Betton, P J , Rex, D C
Date: 1984
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/133923 , vital:37041 , https://pascal-francis.inist.fr/vibad/index.php?action=getRecordDetailamp;idt=6519919
Description: The volcanic rocks of the Etendeka Formation from north-west SWA/Namibia have a present-day coverage of 70,000 km² and comprise a series of interbedded basalts, latites and quartz latites, together with four varieties of intrusive dolerite. Apart from one group of dolerites (regional dolerites) which have mineralogical and geochemical similarities to the Lesotho Formation lavas from the Central area, the Etendeka volcanics differ from all other Karoo volcanics by virtue of their Cretaceous age, stratigraphy, mineralogy, geochemistry, and range in mineralogical, elemental and isotopic compositions for the basaltic rocks.
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Date Issued: 1984

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Some geochemical constraints upon models for the crystallization of the upper critical zone-main zone interval, northwestern Bushveld complex

- Eales, Hugh V, Marsh, Julian S, Mitchell, Andrew A, de Klerk, William J, Kruger, Floris J, Field, Matthew

Authors: Eales, Hugh V , Marsh, Julian S , Mitchell, Andrew A , de Klerk, William J , Kruger, Floris J , Field, Matthew
Date: 1986
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/136044 , vital:37331 , https://doi.org/10.1180/minmag.1986.050.358.03
Description: Ratios between elements Mg, Fe, Co, Cr, Ni, V, and Sc are consistently different in mafic rocks of the upper critical zone, and those above the Bastard unit. Within the 300 m section above the Merensky Reef, 87Sr/86Sr ratios increase from c.0.7063 to c.0.7087, irrespective of rock type. Decoupling of Mg/(Mg + Fe2+) ratios and the Ca contents of plagioclase, and wide variations in the proportions of anorthosite within the Bastard, Merensky, and Merensky Footwall units, are inconsistent with anorthosite formation by simple fractional crystallization of magma batches of limited volume.
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Date Issued: 1986

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MORB-related dolerites associated with the final phases of Karoo flood basalt volcanism in southern Africa.

- Duncan, Andrew R, Armstrong, R A, Erlank, Anthony J, Marsh, Julian S, Watkins, R T

Authors: Duncan, Andrew R , Armstrong, R A , Erlank, Anthony J , Marsh, Julian S , Watkins, R T
Date: 1990
Language: English
Type: text , conference paper
Identifier: http://hdl.handle.net/10962/143299 , vital:38222 , https://pascal-francis.inist.fr/vibad/index.php?action=getRecordDetailampidt=6938249
Description: The Rooi Rand dyke swarm is approximately 200km long and up to 20km wide. It crops out in the southern portion of the Lebombo monocline where the dykes intrude basalts of the Sabie River Basalt Formation which is the major basaltic unit in the eastern portion of the Karoo volcanic succession. The Horingbaai dolerites form thin dykes and sills which intrude the base of the Etendeka lava pile (considered part of the Karoo Volcanics, but correlated with the Serra Geral Formation of Brazil) along the coast of Namibia. Both the Rooi Rand and Horingbaai magma types are similar in composition to enriched MORB and are compositionally distinct from most of the Karoo-basalts they intrude.
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Date Issued: 1990

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Preliminary geochemical data for dolerite dykes and sills of the southern part of the Etendeka Igneous Province

- Marsh, Julian S, Erlank, Anthony J, Duncan, Andrew R

Authors: Marsh, Julian S , Erlank, Anthony J , Duncan, Andrew R
Date: 1991
Language: English
Type: text , report
Identifier: http://hdl.handle.net/10962/132133 , vital:36803
Description: Over the last 15 years systematic geochemical and petrological investigation of the igneous rocks of the Early Cretaceous - Late Jurassic Etendeka Igneous Province of northwestern Namibia have focused on the tholeiitic basaltic lavas and interbedded silicic volcanic rocks and the large central subvolcanic complexes of Brandberg, Erongo, Okenyenya, Messum, Doros and Cape Cross. Previously these rocks were grouped into the Karoo Volcanic Province of South Africa, but in view of the distinct age difference between the igneous rocks of the Etendeka region and Karoo rocks occurring elsewhere in southern Africa , we propose to regard them as constituting a separate Etendeka Igneous Province which exhibits a close lithological, geochemical and temporal correlation with the Parana Flood Basalt Province of South America.
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Date Issued: 1991

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