Abstract In March 1833 Charles Darwin discovered Devonian fossils in the Falkland Islands. He was excited by his find but could have had little premonition of the long-running geological controversy that he was initiating. Darwin's fossils matched a coeval South African fauna and, as further collections were made, the association was apparently strengthened. A particularly important contribution arose around 1910 through collaborations between a local collector, Constance Allardyce, and professional palaeontologists: Ernest Schwarz in South Africa and John Clarke in the USA. The accumulating evidence was seized upon by the early proponents of ‘displacement theory’ – continental drift – notably Alexander Du Toit, who relocated the Falkland Islands northward for his 1927 South Atlantic reconstruction. A more radical, but geologically sounder proposal arose in 1952 when Ray Adie suggested that the Falkland Islands, rotated through 180°, had originated as the eastward culmination of the Cape Fold Belt and Karoo Basin. In effect, Adie had presciently described a rotated microplate, perhaps the first on record. An opposing view saw the Falkland Islands as part of a fixed, South American promontory, and argument around these two contrasting interpretations of South Atlantic geology continues to the present day.

Abstract Orientated carbonate (calcite twinning strains; n = 78 with 2414 twin measurements) and quartzites (finite strains; n = 15) were collected around Gondwana to study the deformational history associated with the amalgamation of the supercontinent. The Buzios orogen (545–500 Ma), within interior Gondwana, records the high-grade collisional orogen between the São Francisco Craton (Brazil) and the Congo–Angola Craton (Angola and Namibia), and twinning strains in calc-silicates record a SE–NW shortening fabric parallel to the thrust transport. Along Gondwana's southern margin, the Saldanian–Ross–Delamerian orogen (590–480 Ma) is marked by a regional unconformity that cuts into deformed Neoproterozoic–Ordovician sedimentary rocks and associated intrusions. Cambrian carbonate is preserved in the central part of the southern Gondwana margin, namely in the Kango Inlier of the Cape Fold Belt and the Ellsworth, Pensacola and Transantarctic mountains. Paleozoic carbonate is not preserved in the Ventana Mountains in Argentina, in the Falkland Islands/Islas Malvinas or in Tasmania. Twinning strains in these Cambrian carbonate strata and synorogenic veins record a complex, overprinted deformation history with no stable foreland strain reference. The Kurgiakh orogen (490 Ma) along Gondwana's northern margin is also defined by a regional Ordovician unconformity throughout the Himalaya; these rocks record a mix of layer-parallel and layer-normal twinning strains with a likely Himalayan (40 Ma) strain overprint and no autochthonous foreland strain site. Conversely, the Gondwanide orogen (250 Ma) along Gondwana's southern margin has three foreland (autochthonous) sites for comparison with 59 allochthonous thrust-belt strain analyses. From west to east, these include: finite strains from Devonian quartzite preserve a layer-parallel shortening (LPS) strain rotated clockwise in the Ventana Mountains of Argentina; frontal (calcite twins) and internal (quartzite strains) samples in the Cape Fold Belt preserve a LPS fabric that is rotated clockwise from the autochthonous north–south horizontal shortening in the foreland strain site; Falkland Devonian quartzite shows the same clockwise rotation of the LPS fabric; and Permian limestone and veins in Tasmania record a thrust transport-parallel LPS fabric. Early amalgamation of Gondwana (Ordovician) is preserved by local layer-parallel and layer-normal strain without evidence of far-field deformation, whereas the Gondwanide orogen (Permian) is dominated by layer-parallel shortening, locally rotated by dextral shear along the margin, that propagated across the supercontinent.

Abstract Brittle structures are crucial for enabling several key natural processes in the Earth's upper crust. In addition, understanding the 3D characteristics and geological evolution of these features is equally important to support various developmental objectives, such as those, inter alia , linked to natural gas, groundwater, hydrothermal minerals and seismicity. In this study, we map various fractures of Gondwana based on the available geological information, satellite imagery and digital elevation data. The lengths and orientations of more than 10 000 fractures in their present-day position reveal four clearly defined patterns, with those striking NW being predominant. Archean–Paleoproterozoic domains are defined by fractures oriented north and NE, whereas the Mesoproterozoic has dominant NNW-striking fractures. In contrast, the Neoproterozoic has mostly NE-striking fractures and the Phanerozoic sequences are defined by a predominant NW and a subordinate west fracture pattern. The style and geometry of these structures can be linked to major geodynamic events that led to the formation of Gondwana building blocks during the Eburnean ( c. 2.2–1.8 Ga), Kibaran ( c. 1.4–1.0 Ga) and Pan African–Brasiliano ( c. 800–550 Ma) orogens, and amalgamation of Pangaea ( c. 350–250 Ma). Many structures were reactivated and new faults formed during opening of the Atlantic and Indian oceans ( c. 180–120 Ma), the India–Asia collision and rifting across East Africa since about 40 Ma. Although the changes in palaeogeography remain difficult to model with accuracy, major structural orientations are corroborated by the occurrence of major mineral deposits and seismicity. The spatial distribution of mapped patterns across the different continents also correlates well with large shale gas prospects and increased groundwater yields. Thus, Gondwana fractures need to be considered in more detail for informing future development related to water and energy use, especially across regions of Africa.

Abstract Outcrops of the Ordovician System in South Africa are extensive; they cover significant portions of the Northern, Western and Eastern Cape provinces as part of the Cape Fold Belt as well as the KwaZulu-Natal Province as supracrustal cover overlying the Natal sector of the Paleoproterozoic Namaqua-Natal metamorphic province. Within the Cape Fold Belt, Ordovician rocks of the Table Mountain Group (Piekenierskloof, Graafwater, Peninsula, Pakhuis and Cedarberg formations as well as the enigmatic Sardinia Bay Formation) outcrop extensively whilst pre-Cape rocks of the Kansa Group (Vaartwell, Uitvlug, Gezwinds Kraal and Schoongezigt formations) and Schoemanspoort Formation are present within the Kango Inlier encapsulated by the fold belt. The Natal Group (Durban and Mariannhill formations) is entirely located within KwaZulu-Natal. For the most part, these metasiliciclastic rocks are markedly unfossiliferous except for the world class fossil deposits of the Cedarberg Formation and important trace fossil sites in the Graafwater, Peninsula and Pakhuis formations. The lack of palaeontological material and other accurate geochronological proxies in these successions (as well as those of the Kansa and Natal groups and Schoemanspoort Formation) makes estimations of relative age constraints tenuous at best and difficult to correlate with global Ordovician chronostratigraphic frameworks. Regardless of the challenges faced in correlating these rocks within global frameworks, these rocks provide a unique low latitude glimpse into Earth surface processes and the feedback loops that ensued within the biological realm along the southern margin of Gondwana.

ABSTRACT We investigated the relationship between tectonism and sedimentation in the Karoo Basin by integrating U-Pb single-grain detrital zircon analyses from seven sandstones with U-Pb zircon analyses from 30 volcanic tuffs. U-Pb detrital zircon data from the Karoo Supergroup strata indicate that the source of the turbiditic, deltaic, and fluvial sediments included an active volcanic province, with increasing contribution from the nearby Cape fold belt through time. The depositional ages obtained from the turbiditic strata of the Karoo Basin, based on U-Pb zircon tuff ages, and the published ages for Cape fold belt deformation suggest that the influx of coarse clastic sediment was synchronous with active deformation of the fold belt during the Gondwanan orogeny. Our tuff ages indicate that peak magmatism began prior to a major deformation event and predated turbidite deposition; initial sedimentation in Karoo turbidite systems coincided with a major deformational phase in the Cape fold belt. U-Pb detrital zircon ages reveal that mid-Permian Karoo turbidites are largely composed of Permian volcaniclastic sediment, whereas the Late Permian and Early Triassic sediment was increasingly sourced from the Cape Supergroup, now exposed in the Cape fold belt. While structural development of the Cape fold belt likely controlled the entry points of sediment into the basin, orogenic uplift may have partitioned the sediment routing systems, severing the connectivity between the active magmatic arc and the basin. We present a model in which a combination of volcanic ejecta, transported via atmospheric suspension, and the formation of entrenched drainages in the catchment areas allowed partial bypassing of continental drainage divides and deposition onto the leeward side of the Cape fold belt.