The Namaqua sector of the Namaqua-Natal Province consists of large tectonostratigraphic terranes, some of which includes Paleoproterozoic fragments inherited from the supercontinent Columbia. Most of the terranes became part of Rodinia during the Mesoproterozoic Namaqua Orogeny (1.3-1.0 Ga, Grenvillian). The terranes in the western foreland of the Kaapvaal Craton (Kheis Subprovince) form a thin-skin fold and thrust belt (5-15 km depth to sole thrust). Westerly directed thrusting towards the hinterland is reminiscent of thick-skin tectonics, associated with the exhumation of high grade facies terranes, such as the granulitic and migmatitic Griinau Terrane. Upper amphibolite Upington Terrane was thrusted from the west onto thrust sheets contiguous to Kaapvaal Craton, in turn over-ridden near Prieska by the Griinau Terrane. Severity of the ductile deformation is illustrated by regional shear zones, ubiquitous recumbent isoclinal folds and allochthonous mega sheath folds in the Griinau Terrane. Vergence reversal of fold and thrust structures along a narrow (10-20 km) northwesterly trending zone (Vergence Inversion Zone, VIZ), represents a crustal scale pop-up structure coincident with the Namaqua Front, a paired low-high gravity anomaly linked to a mega-scale anticline-syncline pair caused by deep-seated thrusting of the Columbian Moho.Late Columbian extension (1.6-1.3 Ga, diachronous with early Rodinian events) produced parautochthonous basins with volcano-sedimentary sequences, deformed during the Namaqua Orogeny. Early to mid-Columbian (2.3-1.9 Ga) rocks form basement to the mobile belt, with Steinkopf Terrane as type outcrop area (probably time-equivalent with the Grunau and Pofadder Terranes, Sperrgebiet Domain, Rehoboth structural Province and part of the Congo Craton). The western boundary of the Kaapvaal Craton (and composite Kalahari Craton) exhibits structural wedge edges of Archaean Kaapvaal basement and Ventersdorp-Vaalian basins. Columbia-Kaapvaal Detachment (COLKAD), a decollement between Kaapvaal and Columbia cratons (footwall) and Olifantshoek and other Namaqua terranes (hanging wall) extends for > 600 km westwards.Namaqua crust was thickened (20-25 km) by both structural stacking and sheeted intrusions (Namaqua tectogenesis) with clockwise PTt-paths in the west-central Namaqua sector (Olifantshoek, Griinau, Pofadder, Bladgrond Terranes). In the western part (Okiep/Garies Terrane), crust was dominantly thickened by massive sheetlike granitoid intrusions resulting in granulite grade and anti-clockwise PTt-paths. COLKAD-rooted inter/intra-terrane thrusts are subhorizontal except where rotated by subvertical (discrete) shear zones (e.g. Tantalite Valley and Brakbos-Doringberg-Dabep). Crustal thickening and granulite-uplift stimulated temperature rise with anatexis-palingenesis of early Columbian/supracrustal rocks. Kilometer-scale granitoid bodies, derived from predominantly Columbian crust (according to isotopic source rock models) that are emplaced along shear zones, caused a rise in the brittle to ductile transition zone (i.e. mid-crustal conditions) and low-pressure granulite facies.

Research Article| June 01, 2017 The Saldanha Bay Volcanic Complex: Clarifying the Cambrian geology of the Postberg-Saldanha area, West Coast, South Africa: Comment A.E. Schoch; A.E. Schoch Department of Geology, University of the Free State, Bloemfontein, South Africa e-mail: aesc@iafrica.com; reyno.scheepers@gmail.com Search for other works by this author on: GSW Google Scholar R. Scheepers R. Scheepers Department of Geology, University of the Free State, Bloemfontein, South Africa e-mail: aesc@iafrica.com; reyno.scheepers@gmail.com Search for other works by this author on: GSW Google Scholar South African Journal of Geology (2017) 120 (2): 271–272. https://doi.org/10.25131/gssajg.120.2.271 Article history first online: 17 Nov 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation A.E. Schoch, R. Scheepers; The Saldanha Bay Volcanic Complex: Clarifying the Cambrian geology of the Postberg-Saldanha area, West Coast, South Africa: Comment. South African Journal of Geology 2017;; 120 (2): 271–272. doi: https://doi.org/10.25131/gssajg.120.2.271 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietySouth African Journal of Geology Search Advanced Search Clemens and Stevens (2016) are to be congratulated on an excellent summary of the truly amazing volcanic phase of the Cape Granite Suite; the distinction between two large eruptive centres in the Postberg nature reserve as described by Scheepers and Nortjé (2000) and the Saldanha region west of the town is well founded. In view of the extent of the Saldanha+Postberg occurrence, yet undescribed Cape volcanic phenomena, dated at ~515 Ma (Scheepers and Poujol 2002), could well occur elsewhere, particularly in the Tygerberg terrane. The tempo of crustal uplift history will need to be addressed, because we are... You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Bavenite, (Ca-4[(Al,Be)(4)(Si-9(O,OH)(26-n))](OH)(2+n)), is present in a pegmatite of the Paarl Pluton, a metaluminous I-type granite of Late Precambrian age. We are not aware of any other previous description of a beryllium mineral occurrence in the Cape Granite Suite. The pegmatite consists essentially of quartz and microcline microperthite together with albite, calcite and fluorite. A hydrothermal alteration assemblage of epidote, chlorite and bavenite occurs in vugs and veins within the pegmatite. Stilbite, which is stable below 170 degrees C, is also present, but not texturally related to the alteration assemblage. Microthermometric analyses and mineral chemistry of associated minerals elucidate the conditions of formation for the bavenite. According to primary fluid inclusions in the cores of euhedral quartz, the minimum temperature of crystallization of the pegmatite is 450 degrees C. Homogenization temperatures of later fluids indicate a minimum temperature of 210 degrees C for the main hydrothermal event. Chlorite geotherrnometry yields crystallization temperatures around 320 degrees C. The bavenite formed between 210 degrees C and 320 degrees C, at a pressure of less than 2 kbar.

The region around Augrabies in the Namaqua sector provides insights into the processes that formed the Namaqua-Natal tectonic Province. Progressive ductile shear deformation during the long lasting Namaqua Orogeny was coeval with the global Grenvillian Orogeny. The Mesoproterozoic Namaqua-Natal Province is composed of severely deformed and metamorphosed rocks in terranes bounded by major thrust and shear zones. The interpreted research results deal with events around the Hartbees River Thrust, a suture zone where the granulite grade Grunau (Kakamas) terrane was overthrust onto the amphibolite grade Bladgrond (Bushmanland) terrane. The series of distinct deformation stages D-1-D-6 that have been identified during previous research in the western regions of the Namaqua sector, is also discernible in the study region around Augrabies. Microbeam geochronological techniques were used to date zircons from four samples of a granitic rock (the Karama'am Augen Gneiss) intrusive into the Hartbees River Thrust zone, and of a sample of granite (the Augrabies Granite) from the core of a large allochthonous sheath fold nappe in the Grunau terrane. The mean crystallisation age of the Karama'am intrusive is 1108 +/- 4 Ma and of the Augrabies Granite 1168 +/- 6 Ma. The sheath fold core of the latter granite is enclosed in the sheetlike Rooipad Granite (Riemvasmaak Granite) previously determined to be 1155 +/- 7 Ma. Crustal residence times deduced from Lu-Hf isotopic compositions of zircon cores and xenocrysts, cluster around 1710 Ma for the Augrabies Granite and about 200 Ma older for the Karama'am Granite Gneiss (with the oldest date at 2069 Ma). Collectively the available data enable reconstruction of the sequence of Namaqua Orogeny deformation stages: terrane assembly (D-1) at similar to 1195 Ma with metamorphism at 1191 +/- 12 Ma, pervasive folding and thrusting (D-2) at 1168 +/- 6 Ma, formation of major sheath and coaxial folds (D-3) at 1155 +/- 7 Ma, late open folds (D-4) at 1090 +/- 16 and a late metamorphism (coeval with major shear zones D-5-D-6?) at 1018 +/- 11 to 1024 +/- 14 Ma. (C) 2015 Elsevier B.V. All rights reserved.

Sixteen tectonic terranes of the Namaqua-Natal metamorphic complex are distinguished (the Aggeneys, Agulhas, Bladgrond, Gamka, Grootdrink, Grunau, Fraserburg, Upington, Margate, Mossel, Mzumbe, Okiep, Olifantshoek, Steinkopf, Pofadder, and Tugela terranes). Evidence obtained from field investigations in the outcrop regions of Namaqualand and Natal are correlated with the geophysical data, enabling recognition of terrane suboutcrops in the regions covered by Phanerozoic deposits in the south. This is illustrated by nine selected profiles over the western and southern parts of the metamorphic complex. Four terranes that have not been observed in outcrop are postulated (Agulhas, Fraserburg, Gamka and Mossel terranes) and may represent extensions of some of the Natal terranes (Mzumbe and Margate terranes). The depth to Moho is generally about 40 km, diminishing dramatically at the present continental edge to as little as 15 km. Listric thrust ramps may originate on rises of the gently undulating topography of the Moho zone. Zones of thrusting and later shearing often exploit older structures and fabrics. The terranes that participated in the Grenvillian Namaqua-Natal Orogeny exhibit a dichotomy of vergences regionally. Those that moved to the northeast and north accreted onto the Archaean Kaapvaal Craton before becoming part of the Kalahari Craton. Terranes with vergences to the south and southwest were amalgamated onto other Archaean cratons. All of the composite cratons took part in the assembly of Rodinia. (C) 2014 Elsevier Ltd. All rights reserved.

The Namaqua Orogeny is interpreted in terms of Rodinia assembly during Grenvillian times at 1.3-1.0 Ga. The exposed terranes of the Namaqua Metamorphic Complex provide evidence of crustal thickening owing to horizontal shortening and massive silicic magmatism during amalgamation of the Kalahari Craton. This accretion stage of the Namaqua Orogeny produced coplanar and colinear LS-tectonite fabrics of sillimanite and higher metamorphic grades (the D-1-D-3 deformation phases, 1220-1065 Ma), that are sub-parallel to the SW-directed tectonic overthrust transport direction of the terranes.The structures formed during the accretion stage are typical of major ductile shear zones in the mid-crust that are formed during continent-continent collisions. After a pause of 150 Ma all of the terranes were comprehensively folded and sheared during the post-accretion stage (the D-4-D-6 deformation events). The D-4 event produced macroscopic upright to inclined asymmetric Z-folds with fold hinges sub-parallel to the SW-directed tectonic transport direction (in terms of contemporary Gondwana coordinates). This post-accretion stage involved continued but oblique NW-directed movement of the Kalahari Craton, coupled with N-S compression.Attributes of the F-4 structures are interpreted in terms of five models: the thrust-ramp-, constrictive, strike-slip-, transtensional- and differential (wrench-shear) transport models. It is concluded that the last-mentioned is the only model that explains all of the observed characteristics. Sub-horizontal wrench-shear that caused reorientation of the incremental strain ellipsoid is superimposed on all earlier structures, resulting in the production of oblique folds in the thrusted terranes. This wrench-shear model explains the end-phase of a protracted orogenic cycle involving an indentational continent collision at 1.030 Ga, possibly between the Kalahari and Laurentia Cratons. The deformation affected the entire crust and even the upper part of the underlying mantle. (C) 2013 Elsevier B.V. All rights reserved.

The stratigraphy of the Aggeneys Terrane is discussed, one of at least eleven tectono-stratigraphic terranes of the Namaqua mobile belt. The severe deformation of the region caused isoclinal folding, structural duplications and excisions everywhere, presenting a formidable obstacle to regional correlation of the stratigraphic sequences. Geological mapping of lithological types proves unable to characterize the supracrustal rocks. For compilation of the various metasedimentary sequences, detailed sequence mapping is required. The lateral continuity of characteristic sequence packages on dekametre scale and the systematic recording of defined polarity, enables unequivocal correlation and classification of the metasediments.The deformation of the Aggeneys Terrane resulted in different east-west trending strain domains: a northern zone of lower strain (zone I) with nearly uninterrupted stratigraphy, and a southern zone of higher strain (zone II) with fragmented stratigraphy wherein the supracrustal successions are preserved in mega sheath folds and fold nappes only. Because of the economic interest in Cu-Pb-Zn deposits of one formation (the Gams Formation), most detailed studies have in the past been restricted to the disrupted zone. The complete stratigraphic column can however be compiled in the zone of lower strain, where it is apparent that the metasediments may be divided into six units. The units of the Aggeneys Subgroup (mentioned in descending order) are the Koeris, Gams, Hotson, Thammaberg, Skelmpoort and Wortel Formations.In the zone of disrupted stratigraphy (zone II), the portions of the various formations preserved in specific fold nappe structures can be recognized easily in spite of facies variations, excisions and structural juxtapositions. Facies variations include differences in thickness and non-deposition. To illustrate all distributional aspects, maps and interpretations are presented for the regions around Swartberg (Black Mountain) and the Soutkloof fold nappe in the Aggeneys Hills (Aggeneysberge). It is concluded that the interpretational system employed for the Aggeneys Terrane, has powerful predictive properties. The system provides convincing modeling of the mechanisms controlling the stratigraphic development of the entire western Namaqua-Natal mobile belt.

Other| December 01, 2008 Comments on the paper by D.H. Cornell and Å. Pettersson (SAJG, 110, 575–584 (2007) W.P. Colliston; W.P. Colliston University of the Free State, Bloemfontein, South Africa e-mail: colliswp.sci@ufs.ac.za; aesc@iafrica.com; praekehe.sci@ufs.ac.za Search for other works by this author on: GSW Google Scholar A.E. Schoch; A.E. Schoch University of the Free State, Bloemfontein, South Africa e-mail: colliswp.sci@ufs.ac.za; aesc@iafrica.com; praekehe.sci@ufs.ac.za Search for other works by this author on: GSW Google Scholar H.E Praekelt H.E Praekelt University of the Free State, Bloemfontein, South Africa e-mail: colliswp.sci@ufs.ac.za; aesc@iafrica.com; praekehe.sci@ufs.ac.za Search for other works by this author on: GSW Google Scholar Author and Article Information W.P. Colliston University of the Free State, Bloemfontein, South Africa e-mail: colliswp.sci@ufs.ac.za; aesc@iafrica.com; praekehe.sci@ufs.ac.za A.E. Schoch University of the Free State, Bloemfontein, South Africa e-mail: colliswp.sci@ufs.ac.za; aesc@iafrica.com; praekehe.sci@ufs.ac.za H.E Praekelt University of the Free State, Bloemfontein, South Africa e-mail: colliswp.sci@ufs.ac.za; aesc@iafrica.com; praekehe.sci@ufs.ac.za Publisher: Geological Society of South Africa First Online: 09 Mar 2017 Online ISSN: 1996-8590 Print ISSN: 1012-0750 © 2008 Geological Society of South Africa South African Journal of Geology (2008) 111 (4): 465–466. https://doi.org/10.2113/gssajg.111.4.465 Article history First Online: 09 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation W.P. Colliston, A.E. Schoch, H.E Praekelt; Comments on the paper by D.H. Cornell and Å. Pettersson (SAJG, 110, 575–584 (2007). South African Journal of Geology 2008;; 111 (4): 465–466. doi: https://doi.org/10.2113/gssajg.111.4.465 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietySouth African Journal of Geology Search Advanced Search The authors are to be congratulated on excellent new zircon dates that contribute to terrane demarcation in the eastern part of the Namaqua mobile belt. Because we were involved in terrane definition of the mobile belt for some time (e.g.Colliston et al., 1992), we are very interested in all new isotopic data that can place time constraints on the details of the tectonic history of the region. Hopefully these results will lead to more investigations of a similar nature. We agree in broad context with the synthesis of the authors according to which crustal blocks were... You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Research Article| March 01, 2008 Response to the papers by Bailie et al. concerning the age and deposition of the Bushmanland Group (South African Journal of Geology, 110, 59–86) and single zircon ages of the Aggeneys Granite Suite (South African Journal of Geology, 110, 87–110) Russell Bailie; Russell Bailie Department of Geological Sciences, University of Cape Town, Private Bag, Rondebosch, 7700, South Africa, Present address: Paleoproterozoic Mineralisation Research Group, Dept. of Geology, University of Johannesburg, P.O. Box 524, Auckland Park, Johannesburg, 2006, South Africa, e-mail: russellb@postgrad.uj.ac.za Search for other works by this author on: GSW Google Scholar Richard Armstrong; Richard Armstrong Research School of Earth Sciences, The Australian National University, Canberra, 0200, A.C.T., Australia, e-mail: richard.armstrong@anu.edu.au Search for other works by this author on: GSW Google Scholar David Reid David Reid Department of Geological Sciences, University of Cape Town, Private Bag, Rondebosch, 7700, South Africa, e-mail: dlr@geology.uct.ac.za Search for other works by this author on: GSW Google Scholar Author and Article Information Russell Bailie Department of Geological Sciences, University of Cape Town, Private Bag, Rondebosch, 7700, South Africa, Present address: Paleoproterozoic Mineralisation Research Group, Dept. of Geology, University of Johannesburg, P.O. Box 524, Auckland Park, Johannesburg, 2006, South Africa, e-mail: russellb@postgrad.uj.ac.za Richard Armstrong Research School of Earth Sciences, The Australian National University, Canberra, 0200, A.C.T., Australia, e-mail: richard.armstrong@anu.edu.au David Reid Department of Geological Sciences, University of Cape Town, Private Bag, Rondebosch, 7700, South Africa, e-mail: dlr@geology.uct.ac.za Publisher: Geological Society of South Africa First Online: 09 Mar 2017 Online ISSN: 1996-8590 Print ISSN: 1012-0750 © 2008, The Clay Minerals Society South African Journal of Geology (2008) 111 (1): 112–113. https://doi.org/10.2113/gssajg.111.1.112 Article history First Online: 09 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation Russell Bailie, Richard Armstrong, David Reid; Response to the papers by Bailie et al. concerning the age and deposition of the Bushmanland Group (South African Journal of Geology, 110, 59–86) and single zircon ages of the Aggeneys Granite Suite (South African Journal of Geology, 110, 87–110). South African Journal of Geology 2008;; 111 (1): 112–113. doi: https://doi.org/10.2113/gssajg.111.1.112 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietySouth African Journal of Geology Search Advanced Search We appreciate the comments by Colliston et al. (2008) on our recent publications concerning the age and deposition of the Bushmanland Group and the age of the Aggeneys Granite Suite (Bailie et al., 2007a; b). We welcome the debate around the geological significance of the analytical results but note that this can vary according to the stratigraphic/structural models that themselves evolve. We agree with Colliston et al. (2008) that the Namaqua mobile belt is highly structurally complex, being divided into a number of terranes bounded by major thrust faults and with complex stratigraphic relationships... You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Two periods of deformation have been documented by detailed mapping in a strip of 3000 km(2) along the Orange (Gariep) River. The it-tapping has enabled field discrimination and regional correlation of well-exposed plutonic tectonites that volumetrically dominate the western part of the Namaqua mobile belt. The associated metasedimentary and metavolcanic successions that supplied tectonostratigraphic keys for correlation of rock units, were described in previous publications. Deformation took place during an orogenesis that may he termed the Orange River Event (ORO, similar to 2.0 to similar to 1.6 Ga, with associated calcalkaline magmatism) and the later Namaqua Event (NMO, similar to 1.2 to similar to 1.1 Ga, with associated granitic magmatism). The ORO magmatism includes the Vioolsdrif Suite, represented by outcrops of deformed leucogranite, adamellite, granodiorite and mafic rocks that were later intruded by small mafic complexes. The products of the NMO magmatism include various members correlated with the Little Namaqualand Suite (the Kabis, Pipeline, Swartmodder, Koeipoort, Mission, Coboop and Eendoorn gneisses).Textural properties of the metaplutonic rocks vary front very coarsely porphyroblastic (eg. Eendoorn gneiss, megacrysts >10 cm) to fine even-grained (e.g. some Kabis gneiss). The megacrysts, invariably composite on microscopic scale, are deformed relicts of phenocrysts. Variation in strain is well illustrated by megacrysts that grade front nearly equidimensional to flattened, visible as pencil-shaped streaks on exposed Surfaces. Several gneisses that appear to be unrelated because of different textural properties, merely record variation in strain intensity (e.g. the little deformed granodioritic occurrences at Vioolsdrif are coeval with severely deformed rocks at Pella, 150 km furthur to the east). Detailed structural-stratigraphic mapping and petrographic study helped to prevent unnecessary proliferation of names.Compressional tectonics were responsible for the general style of both orogeneses reflecting the effects of progressive ductile shearing rather than consecutive discrete deformational events. ORO intrusives belong to specific tectonic terranes and tend to be batholithic (in the Pofadder terrane). The grade of metamorphism was greenschist to amphibolite. The rapid tectonism of the subsequent NMO cycle led to terrane accretion and to granulite/upper amphibolite grade metamorphism. Associated granitic intrusives are not terrane-specific. The predominant sheet-like to phacolithic habits reflect emplacement during horizontal tectonism.

The volcaniclastic sediments and nephelinite lavas of the Mashikiri Formation, Lebombo Group, have been well documented in the Pafuri region and in the Sabi region, Zimbabwe. The well-exposed section along the Olifants River in the Kruger National Park provides cogent additional information. The Shishwayini Beds at the base of the succession represents volcaniclastic deposits on the Tshipise Sandstone Member of the Clarens Formation. The rest of the Mashikiri Formation in the Olifants River section is nephelinite in which nepheline is accompanied by olivine, clinopyroxene, devitrified glass, katophorite and opaque oxides. Chemical modelling shows that the nephelinites were derived by partial melting of mantle peridotite enriched in incompatible trace elements and by subsequent fractionation of pyroxene and olivine. Crustal contamination did not play a significant role in derived magma composition. The Olifants River section defines a third source of undersaturated parent magma distinct from the two sources previously identified from outcrops to the north by other authors.

Hydrothermally altered and mineralised lavas of the -2.7 Ga Ventersdorp Supergroup were sampled at two localities near Douglas (Kalkdam and Katlani). Propylitic alteration has affected some of the lavas (the dark coloured amygdaloidal type), while others (the light coloured amygdaloidal type), show signs of potassium metasomatism as well, representing at least two mineralisation events. A Rb/Sr age of 2014 +/- 38 Ma was obtained on clinochlore from the amygdales and whole rock samples. This is interpreted to be the age of the first hydrothermal alteration and main mineralisation of the lavas, Variable isotopic values for Sr and Pb suggest a complex provenance for the hydrothermal fluids, whilst a narrow range of delta(34)S in galena (-3.4 to -6.3 parts per thousand) indicates a specific Source region. Four fluid inclusion populations are dominated by a brine population (Tm = -12.9 degrees C) with a model density of 1.07g/cm(3) (Th = 117 degrees C). The temperature of the fluid must have been similar to 270 degrees C according to the chlorite geothermometer of Cathelineau. The temperature of entrapment implies a pressure of roughly 2 kb when the slope of the relevant isochore (1.07g/cm(3)) is taken into account. Fluids seem to have migrated along channelways that were provided during extensive fracturing such as along the Griquatown fault zone. This migration probably propagated from rocks of the Transvaal Supergroup (Griquatown and Kuruman Formations) into the underlying Ventersdorp lavas.

The Thauthe meteorite that fell in July 2002 contains small grains ( < 3 μm) of berthierite and stibnite. These antimony-bearing phases were identified by aid of energy dispersive and wavelength dispersive X-ray spectrometry. This is the first reported occurrence of antimony sulphides in a meteorite.

The Thuathe meteorite fell on 21 July 2002 between 15:45 SAST (first sightings) and 15:49 (local sightings). The meteorite is classified as an H4 / 5 type ordinary chondrite, confirmed by whole rock and mineralogical analyses. The minerals found in the meteorite were kamacite, troilite, albitic plagioclase, forsteritic olivine, diopside, enstatite, and chromitic spinel. Temperatures were obtained from the orthopyroxene-clinopyroxene, orthopyroxene-olivine and clinopyroxene-olivine systems, that yielded values of 1200-1600°C. With respect to average chondrites, the Thuathe meteorite samples are depleted in Zr, and enriched in Rb, Th, Ta, Ba, La, Sr, Sc, Co and Ni.

The western part of the Mid-Proterozoic Namaqua mobile belt consists of a series of tectonostratigraphic terranes, including the Aggeneys terrane. In the centre of the Aggeneys terrane occurs a duplex of five fold nappes, represented by the Aggeneys Hills. One of these, the Quarry fold nappe, contains sections through a distinctive volcano-sedimentary sequence correlated with the Koeris Formation that elsewhere overlies the Hotson Formation with ore-bearing assemblages. A description of the stratigraphic and petrological characteristics of the volcano-sedimentary sequence can supply guides to Underlying Broken Hill type deposits in other parts of the Aggeneys terrane.The exposed portion of the Koeris Formation that was mapped in detail in the Quarry fold nappe, is 220m thick and is interpreted to be stratigraphically inverted because of large-scale thrusting and folding. The sequence starts with Mg-rich mafic lavas (now amphibolite with hornblende and cummingtonite), followed by a sedimentary sequence (now quartz-muscovite schist). The succeeding metarhyolite and felsic breccia are overlain by mafic metalava and breccia with intercalated clastic products (now quartz-muscovite schist With mafic lenses), A subsequent major clastic incursion represented by conglomerate (called the main conglomerate), is terminated by massive amygdaloidal lava flows (termed the main amphibolite). The main amphibolite is followed by sedimentary rocks (now schist and quartzite) that are in turn overlain by lava (now homogeneous amphibolite). The sequence ends with volcanoclastic conglomerate/agglomerate succeeded by fine-grained clastic deposits (now quartz-mica schist).Regional metamorphism at amphibolite grade yielded peak temperatures in the range of 400 to 700degreesC at greater than or equal to4 kbar. However epidote-rich parageneses (such as epidote-garnet-quartz) that locally transect the regional fabric, indicates the introduction of Ca, Si and Fe subsequent to the metamorphic peak. Vestiges of earlier alteration are represented by crystallographically zoned cordierite and anthophyllite in rocks of appropriate composition. In most of the exposed sequence, primary features such as vesicles and pillow structures have been retained in spite of the metamorphism, except in zones of high strain. The same can be said of the chemical composition of samples representing typical amphibolite and metarhyolite, matching average tholeiite and rhyolite/rhyodacite.The lavas were generated from an upper mantle source near to 1 600 Ma ago, during extensional crustal conditions subsequent to the infilling of cratonic sedimentary basins in an alluvial-fan/fluvial environment. The volcanism was followed by the Namaqua Orogeny, a long-lived compressional period that included terrane amalgamation and felsic magmatism at similar to1 200 Ma ago. The orogeny was terminated during renewed extensional conditions, when easterly orientated shear zones of regional extent were formed near to 1 100 Ma ago.

The Thuathe meteorite fell on 21 July 2002 between 15:45 SAST (first sightings) and 15:49 (local sightings). The meteorite is classified as an H4/5 type ordinary chondrite, confirmed by whole rock and mineralogical analyses. The minerals found in the meteorite were kamacite, troilite, albitic plagioclase, forsteritic olivine, diopside, enstatite, and chromitic spinel. Temperatures were obtained from the orthopyroxene-clinopyroxene, orthopyroxene-olivine and clinopyroxene-olivine systems, that yielded values of 1200-1600degreesC. With respect to average chondrites, the Thuathe meteorite samples are depleted in Zr, and enriched in Rb, Th, Ta, Ba, La, Sr, Sc, Co and Ni.

The Allanridge Formation of the Ventersdorp Supergroup in the Northern Cape Province consists of andesite to basaltic andesite. The properties of these rocks are described by aid of detail from two localities near Douglas (Kalkdam and Katlani), where seven lava flows can be discerned. Greenschist metamorphism. has affected all of the lava flows and sporadic sulphide mineralization has also occurred. The intensity of sulphide mineralization is controlled by porosity so that the amygdaloidal bases and tops of flows are more, affected than the massive parts, hence producing A conspicuous bleaching. Thus light amygdaloidal lavas (LA) that are sporadically mineralised by sphalerite, galena and chalcopyrite can be distinguished from less altered dark amygdaloidal (DA) lavas.Sulphides are present in altered amygdales of the LA together with quartz, chlorite and calcite. These minerals were introduced by means of hydraulic fracturing and brecciation features are common. Sphalerite tends to dominate over galena in the amygdaloidal lava flows, while the opposite is true in the breccia zones. Mass transfer calculations reveal that the net mass loss for LA and DA was 7 to 20 % and 3 to 5% respectively. Enrichment/depletion diagrams illustrate that LA is relatively enriched in SiO2, Al2O3, K2O, P2O5, Rb, Ba, Cr and Zn, while the DA is relatively enriched in MnO, Fe2O3, Nb, Cr, V, Co and Zn with respect to unmineralized lava flows.The alteration of DA may be regarded as propylitic, while changes in LA involved potassium metasomatism. also. Two generations of mineralization can be discerned. The source of the saline fluids capable of transporting metals is probably in the banded iron formations of the Griquatown and Kuruman Formations. Channelways for fluid migration were provided during extensive deformation.

The Aggeneys terrane is composed of gneisses, supracrustal sequences and Broken Hill type base metal sulphide deposits that have been intensely deformed and metamorphosed to upper amphibolite grade. This terrane forms part of the Namaqua metamorphic complex that was amalgamated during the 1.1 to 1.2 Ma Namaqua Orogeny. Preserved stratigraphic sequences can be followed on strike (hundred km scale) in domains of relatively low strain. In high strain (more than 12 gamma) zones, the sequences are discontinuous. Inversion and duplication owing to thrusting and folding are more prevalent in the latter than in the former.The Aggeneys Hills is situated in a regional high strain zone and comprises a late synformal macro-structure, superimposed on five older structural domains. The exposed dimensions of the macro-structure is 20km by 5km and the strike length of the five recumbent folds is 6 to 17km. Zones of high strain that are localised in relatively ductile quartzite-schist sequences separate the recumbent folds. The geometry and stratigraphic relationships of the macrofolds indicate that the stratigraphic packages in the Aggeneys Hills were tectonically emplaced as fold nappes. Collectively these nappes represent a duplex structure.The five fold nappes have been named Soutkloof, Quarry, Klipbok, Dassie and Dabbiepoort. The Quarry fold nappe was chosen as an example to illustrate the details of the structural development of the Aggeneys Hills. Although the deformation is interpreted to have been a progressive ductile shear process, five successive structural events can be locally recognised (D1-5).The Quarry fold nappe is interpreted to be a large kilometre scale sheath fold. The sheath fold provides information about the nature and orientation of the regional strain ellipsoid; the XY-plane trends easterly and is subhorizontal with the X-direction subparallel to the southwesterly trending tectonic transport direction. The mega sheath fold has an allochtonous structure in its northern limb containing correlates of mineralised stratabound units (the Gams member of the Hotson Formation). Structural duplication of ore bearing units may well be present in the unexposed core of the Quarry structure. Similar structural duplication is to be expected in the rest of the high strain zone of the Aggeneys terrane.