Southern African topography and erosion history: plumes or plate tectonics?

The physiography of southern Africa comprises a narrow coastal plain, separated from an inland plateau by a horseshoe-shaped escarpment. The interior of the inland plateau is a sedimentary basin. The drainage network of southern Africa is characterized by three river divides, broadly parallel to the coastline. These features contrast strongly with the broad dome and radial drainage patterns predicted by models which ascribe the physiography of southern Africa to uplift over a deep mantle plume. The drainage divides are interpreted as axes of epeirogenic uplift. The ages of these axes, which young from the margin to the interior, correlate closely with major reorganizations of spreading regimes in the oceanic ridges surrounding southern Africa, suggesting an origin from stresses related to plate motion. Successive epeirogenic uplifts of southern Africa on the axes, forming the major river divides, initiated cyclic episodes of denudation, which are coeval with erosion surfaces recognized elsewhere across Africa.     

‘Bringing government to the people’: women, local governance and community participation in South Africa

This paper considers the ongoing political transformations in South Africa in the context of debates about good governance and participatory democracy. It first appraises the current transformations of local government in South Africa, focusing specifically on relationships between gender equality and citizenship on the one hand, and local government policy, legislation, and community participation on the other, and then explores meanings of participation and how they inform approaches towards local socio-economic development. The findings of primary research conducted with civil society organisations and black women in communities in the Cape Town metropolitan area are explored through three interrelated themes. First, the model of structured participation that is central to South Africa’s democratic transformation is assessed from the perspective of black women. Second, cultures of alienation, both within local governance structures and amongst black women and the extent to which recent restructuring is combating or contributing to these are explored. Third, how participation policies are dealing with conflict within and between target groups are analysed, whether stakeholder group politics obliterate important differences in interests and whether alternative structures might be more effective in terms of women’s participation and empowerment. Finally, the findings are interpreted in relation to theoretical concepts of good governance and participatory democracy, and the potential and problems of realising South Africa’s transformation process toward developmental local government are assessed.     

Mesozoic exhumation of the southern Cape, South Africa, quantified using apatite fission track thermochronology

Southern Africa's topography is distinctive. An inland plateau of low relief and high average elevation is separated from a coastal plane of high relief and low average elevation by a steeply dipping escarpment. The origin and evolution of this topography is poorly understood because, unlike high plateaus elsewhere, its development cannot be easily linked to present day compressional plate boundary processes. Understanding the development of this regional landscape since the break-up of Gondwana is a first order step towards resolving regional epeirogenesis. We present data that quantifies the timing and extent of exhumation across the southern Cape escarpment and coastal plane, using apatite fission track analysis (AFTA) of 25 outcrop samples and 31 samples from three deep boreholes (KW1/67, SA1/66, CR1/68). Outcrop fission track (AFT) ages are Cretaceous and are significantly younger than the stratigraphic ages of their host rocks, indicating that the samples have experienced elevated paleotemperatures. Mean track lengths vary from 11.86 to 14.23 μm. The lack of Cenozoic apatite ages suggests that major cooling was over by the end Cretaceous. The results for three boreholes, situated seaward (south) of the escarpment, indicate an episode of increased denudation in the mid-late Cretaceous (100–80 Ma). An earlier episode of increased denudation (140–120 Ma) is identified from a borehole north of the escarpment. Thermal modelling indicates a history involving 2.5–3.5 km of denudation in the mid-late Cretaceous (100–80 Ma) at a rate of 175 to 125 m/Ma. The AFT data suggest that less than 1 km of overburden has been eroded regionally since the late Cretaceous (< 80 Ma) at a rate of 10 to 15 m/Ma, but do not discount the possibility of minor (in relative amplitude) episodes of uplift and river incision through the Cenozoic. The reasons for rapid denudation in these early and mid-Cretaceous episodes are less clear, but may be related to epeirogenic uplift associated with an increase in mantle buoyancy as reflected in two punctuated episodes of alkaline intrusions (e.g. kimberlites) across southern Africa and contemporaneous formation of two large mafic igneous provinces (~ 130 and 90 Ma) flanking its continental margins. Because Cenozoic denudation rates are relatively minimal, epeirogenic uplift of southern Africa and its distinct topography cannot be primarily related to Cenozoic mantle processes, consistent with the lack of any significant igneous activity across this region during that time.     

Strath terraces of Jinshaan Canyon, Yellow River, and Quaternary tectonic movements of the Ordos Plateau, North China

ABSTRACT Studies of the strath terraces in Jinshaan Canyon − where the Yellow River cuts through the Ordos Plateau in the continental interior of China − provide an opportunity to solve some of the critical problems associated with Quaternary tectonic movement of the plateau. Six strath terraces indicate that five episodes of regional epeirogenic uplift affected the Ordos Plateau during the Quaternary. The local tectonic deformation is superimposed on the regional epeirogenic uplift, expressed either as faulting or as non-uniform uplift induced by local arching. The results have important implications for understanding the relationship between the regional epeirogenic uplift of the Ordos Plateau and the uplift of the Qingzang Plateau, time lines of climate change in the regional epeirogenic uplift landscape, and the genesis of strath terraces associated with the through-flowing plateau drainage in the continental interior.     

黄河晋陕峡谷河流阶地和鄂尔多斯高原第四纪构造运动

本文通过黄河晋陕峡谷河段21个地点的阶地横剖面观察和阶地对比研究,确定出6级宽谷阶地序列,同时,依据17个放射性测年数据对阶地定年。6级宽谷阶地序列揭示了鄂尔多斯高原第四纪区域造陆隆起和局部构造变形,区域造陆隆起的发生时间比之青藏高原隆起要滞后0．113～0．25Ma,而且,平均区域造陆隆起量比之青藏高原的内部和边缘的隆起量小得多。晋陕峡谷河段发生过3期加积作用幕,指示着造陆隆起景观中的气候变化时间线。渭河盆地北缘的韩城断裂悬崖带记录着构造基准面下降,影响的河流长度仅为21～127km。     

Recent vertical crustal movements from precise leveling surveys in the Blue Ridge and Piedmont Provinces, North Carolina and Georgia

Examination of two lines of repeated leveling in North Carolina and Georgia reveals

1. (1) apparent uplift at the Blue Ridge-Piedmont physiographic boundary (the AtlanticGulf drainage divide) relative to the Atlantic Coastal Plain on the east and the Valley and Ridge province to the west; and

2. (2) large tilts over short baselines superimposed upon the regional pattern in the vicinity of the nearby Blue Ridge—Piedmont geologic boundary (the Brevard fault zone). In the North Carolina profile a very pronounced correlation between topography and movement suggests possible systematic leveling error, but the observed movements appear to be larger than those normally attributed to leveling error. Thus, either refraction or rod errors are larger than expected, or the movement is real and strongly correlates with topography along this portion of the leveling line.

Anomalously high stream-gradients over both resistant and nonresistant lithologies are found around the drainage divide in North Carolina, and may be associated with the relative uplift inferred from releveling. The drainage divide in Georgia, also characterized by relative uplift on the movement profile, approximately separates two different types of stream patterns. In both cases evidence presented here suggests that stream morphology may be responding to contemporary deformation as implied by the observed elevation changes. The relative uplift in North Carolina also correlates with a positive Bouguer gravity anomaly of 30–40 mGal in the midst of the regional Blue Ridge gravity low, although the significance of the correlation is unclear.The close spatial correspondence between the zone of maximum uplift and the drainage divide suggests that the vertical movements and geomorphic anomalies may result from the same mechanism, although the nature of such is unclear. One possible mechanism could be displacement at depth along the nearby Brevard zone. However, on the basis of dislocation modeling it appears that the geodetic observations cannot be adequately explained by surface deformation associated with any simple models of slip on the Brevard zone.     

Contemporary movements and tectonics on Canada's west coast: A discussion

Evidence from published tidal records and geodetic relevelling data in British Columbia indicates that there is a consistent pattern of contemporary uplift on the outer coast (2 mm/yr) and subsidence on the inner coast (1–2 mm/yr). The zero uplift contour or “hinge-line” runs through Hecate Strait, Georgia Strait and Victoria. This pattern continues southwards into Washington State but is interrupted to the north by considerable uplift in southeastern Alaska.Although glacio-isostatic recovery has dominated vertical movements in the region over the last 10,000 years, the distribution and trend of the observed contemporary movements are not compatible with the pattern to be expected from this source and are most probably tectonic in origin. There is, however, no clear distinction between the movements seen opposite the Queen Charlotte transform margin and the Vancouver Island convergent margin. Comparison with movements observed at other active plate margins show that the pattern is essentially similar to that seen in association with subduction and convergence.The paradox that the vertical movement rates are much too great to explain observed geology and topography may be soluble by assuming that discontinuous lateral shifts of the movement pattern occur on a scale of hundreds of thousands of years.     

尼日尔三角洲坡脚逆冲带沉积样式及构造控制

研究尼日尔三角洲深水坡脚逆冲带沉积样式、构造对沉积的控制可以揭示深水沉积分布与演化特征.运用生长地层翼旋转机理和地震相分析技术对研究区的沉积类型、构造与沉积关系进行了分析.认为在深水陆坡重力滑动作用所形成的微盆地内, 层序边界表现为微盆地边缘上超不整合面或重力流对下伏地层的侵蚀不整合; 逆冲构造隆升速率与沉积速率共同控制了重力流可容空间和沉积充填样式; 沉积垂向演化以块状搬运复合体-浊积扇-深海披覆泥或浊积扇-深海披覆泥为特征.在充分考虑构造隆升和沉积速率影响因素的基础上, 建立了单一微盆地和多个微盆地的沉积演化模式.      

内蒙古西部银根-额济纳旗盆地重力场与 断裂构造的特征

为了研究银根-额济纳旗盆地的构造特征,为该区油气资源远景调查评价提供依据,系统地收集、研究了已有的重力调查资料,分析了研究区重力场的特征及其成因,推断了研究区的断裂构造体系。研究区区域重力异常主要是由莫霍面起伏变化引起的,剩余重力异常重力高与重力低相间分布的特征,可能一方面反映了研究区凹陷与隆起分布的范围及展布特征,另一方面反映了凹陷与隆起之间发育非对称的断裂。研究区主要发育北东东向(北东向)、北西西向2组断裂,这2组断裂对基底结构、性质、隆坳格架及中生代盆地展布起重要的控制作用。基底断裂将研究区分割成多个块体,使盆地形成凹、凸相间的结构特征。     

关于福建印支运动性质的讨论

福建印支期强烈的抬升和伸展现象的地质事实已为广大地质工作者所公认，从抬升造陆作用，褶皱造山作用两探讨了印支运动的性质，认为鲆支运行的褶皱造山特征不明显，而隆升造陆特征显著。     

Density structure of the cratonic mantle in southern Africa: 1. Implications for dynamic topography

The origin of high topography in southern Africa is enigmatic. By comparing topography in different cratons, we demonstrate that in southern Africa both the Archean and Proterozoic blocks have surface elevation 500–700 m higher than in any other craton worldwide, except for the Tanzanian Craton. An unusually high topography may be caused by a low density (high depletion) of the cratonic lithospheric mantle and/or by the dynamic support of the mantle with origin below the depth of isostatic compensation (assumed here to be at the lithosphere base). We use free-board constraints to examine the relative contributions of the both factors to surface topography in the cratons of southern Africa. Our analysis takes advantage of the SASE seismic experiment which provided high resolution regional models of the crustal thickness.We calculate the model of density structure of the lithospheric mantle in southern Africa and show that it has an overall agreement with xenolith-based data for lithospheric terranes of different ages. Density of lithospheric mantle has significant short-wavelength variations in all tectonic blocks of southern Africa and has typical SPT values of ca. 3.37–3.41 g/cm³ in the Cape Fold and Namaqua–Natal fold belts, ca. 3.34–3.35 g/cm³ in the Proterozoic Okwa block and the Bushveld Intrusion Complex, ca. 3.34–3.37 g/cm³ in the Limpopo Belt, and ca. 3.32–3.33 g/cm³ in the Kaapvaal and southern Zimbabwe cratons.The results indicate that 0.5–1.0 km of surface topography, with the most likely value of ca. 0.5 km, cannot be explained by the lithosphere structure within the petrologically permitted range of mantle densities and requires the dynamic (or static) contribution from the sublithospheric mantle. Given a low amplitude of regional free air gravity anomalies (ca. + 20 mGal on average), we propose that mantle residual (dynamic) topography may be associated with the low-density region below the depth of isostatic compensation. A possible candidate is the low velocity layer between the lithospheric base and the mantle transition zone, where a temperature anomaly of 100–200 °C in a ca. 100–150 km thick layer may explain the observed reduction in Vs velocity and may produce ca. 0.5–1.0 km to the regional topographic uplift.     

Cenozoic landscape evolution of the Kruger National Park as derived from cosmogenic nuclide analyses

In contrast to active tectonic settings, little is known about the potential feedback between surface processes and climate change in tectonically inactive cratonic regions. Here, we studied the driving forces of erosion and landscape evolution in the Kruger National Park in South Africa using cosmogenic nuclide dating. ¹⁰Be‐derived catchment‐wide erosion rates (~2 and ~10 mm ka^?1) are similar in magnitude to erosion and rock uplift elsewhere in South Africa, suggesting that (1) rock uplift is solely the isostatic response to erosion and (2) the first‐order topography is likely of Cretaceous age. The topographic maturity is promoted by widespread exposure of rocks resistant to erosion. Our data, however, suggest that local variations in rock resistance lead to transient landscape changes, with local increases in relief and erosion rates.     

Modelling the geoid and sea-surface topography in coastal areas

This paper looks at the relation between the time-averaged level of the sea surface and a gravimertic geoid, as determined in coastal areas. Measurements in local regions can now be accurate enough to demonstrate that the geoid and mean sea level are not even parallel to each other, let alone identical. The accuracy and pattern structure of surface gravity data in some shelf seas is comparable with those on land, so that a marine geoid can be derived from surface data without using satellite altimetry. The geodetic objective is then to combine the two to determine sea surface topography. In principle, gravimetric studies provide the absolute datum so that local oceanographic models on the shelf can be combined with sea surface topography models related to the global ocean circulation. In contrast, sea surface topography information near deep ocean coasts must come from external sources and satellite altimetry used to give the gravity data needed to offset the less good coverage by ship-borne gravimetry.Marine Bouguer anomalies enable two specific problems of gravity anomaly patterns near the continent ocean transition to be overcome. The necessary extension of Stokes' condensation reduction is developed and illustrated along a north-south profile from the Mediterranean across the Cote d'Azur. The effect on gravity of deep ocean water introduces a geoid correction in the form of a dipolar ridge whose amplitude at the shore is about 11 cm. In addition to geostrophic currents, a semi-quantitative model for the thermohaline effects on sea surface topography is discussed in relation to sea level differences between the Atlantic and Mediterranean.In considering appropriate algorithms for local geoid computation, Kirby's Iterative Fourier Combination routine for combining altimetry and surface gravity is extended to account for global sea surface topography. The impact of very fast spherical harmonic analysis algorithms is discussed and a simple physical model is given which explains the short coherence lengths found for the global gravity field. This necessary assumption for any local geoid computation was hitherto purely empirical.Finally, the use of land data such as tide gauges, ellipsoidal heights from GPS, and orthometric heights from first order levelling are reviewed as ways of corroborating geodetic estimates of sea surface topography and its relation to levelling datums. Successful examples are given from southern England.     

南薇西盆地重磁场特征及油气资源远景

结合南薇西盆地及邻区的重、磁力异常特征分析与综合反演,文章对该区油气有利远景区进行了预测。南薇西盆地北部坳陷和北部隆起以高重高磁特征为主,火山活动强烈。中部坳陷、南部隆起及南部坳陷的北部表现为整体低重、低磁背景上的局部团块状高重、高磁异常,为火山岩与碳酸盐台地的综合反映。南薇西盆地新生界厚度呈北东向条带状薄厚相间的特征,南部坳陷新生界厚度最大,中部坳陷次之。盆地北部处于莫霍面隆起区,而南部莫霍面相对较深,为减薄型陆壳的特征。北部坳陷和北部隆起居里面整体较浅,可能与南海扩张引起岩石圈的强烈伸展减薄、地幔物质上侵有关。中部坳陷和南部隆起的居里面明显浅于南部坳陷,表明中部坳陷和南部隆起的热活动强于南部坳陷。重磁场特征及其反演结果与石油地质特征表明,南薇西盆地的中部坳陷、南部隆起及其西南盆地外围的区域应为盆地最好的油气远景区,其次为南部坳陷,北部坳陷和北部隆起油气潜力不大。在油气远景区内,局部团块状、等轴状的重力高异常区部分可能为碳酸盐台地,生物礁较为发育,应为未来的勘探目标。      

Flexural and gravity modelling of the Mérida Andes and Barinas–Apure Basin, Western Venezuela

The kinematic evolution of the Barinas–Apure Basin and the southern Mérida Andes from Lower Miocene to the Present is numerically modelled using flexural isostatic theory and geophysical and geological data. Two published regional transects are used to build up a reference section, which is then used to constrain important parameters (e.g. shortenings and sedimentary thicknesses) for the flexural modelling. To control the location of the main fault system in the flexural model earthquake information is also used. The estimated flexural elastic thickness of the South American lithosphere beneath the Barinas–Apure Basin and the Mérida Andes Range is 25 km. The value for the final total shortening is 60 km. The flexural isostatic model shows that the Andean uplift has caused the South American lithosphere subsidence and the development of the Barinas–Apure Basin.In addition, gravity modelling was used to understand deep crustal features that could not be predicted by flexural theory. Consequently, the best-fit flexural model is used to build a gravity model across the Mérida Andes and the Barinas–Apure Basin preserving the best-controlled structural features from the flexural modelling (e.g. basin wavelength and depth) and slightly changing the main bodies density values and deep crustal structures. The final gravity model is intended to be representative of the major features affecting the gravity field in the study area. The predicted morphology in the lower crustal level of the final gravity model favours the hypothesis of a present delamination or megathrust of the Maracaibo crust over the South American Shield. This process would use the Conrad discontinuity as a main detachment surface within an incipient NW dipping continental subduction.     

Geological evolution of the Afro-Arabian dome

The Afro-Arabian dome includes the elevated continental regions enclosing the Red Sea, Gulf of Aden, and the Ethiopian rift system, and extends northwards as far as Jordan. It is more than an order of magnitude larger than other African uplifts. Both the structures and the igneous rocks of the dome appear to be products of the superimposition of two, perhaps three, semi-independent generating systems, initiated at different times but all still active. A strain pattern dominated by NW-trending basins and rifts first became established early in the Cretaceous. By the end of the Oligocene, much of the extensional strain had been taken up along the Red Sea and Gulf of Aden axes, which subsequently developed into an ocean. Palaeogene “trap” volcanism of mildly alkaline to transitional character was related to this horizontal extension rather than to doming. Further west, the East Sahara swell has a history of intermittent alkaline volcanicity which began in the Mesozoic and was independent of magmatism in the Afro-Arabian dome. Volcanicity specifically related to doming began in the Miocene along a N-S zone of uplift extending from Ethiopia to Syria. This elongated swell forms the northern termination of the East African system of domes and rifts, characterized by episodic vertical uplift but very little extension. Superimposition of epeirogenic uplift upon structures formed by horizontal extension took place in the Neogene. Volcanicity related to vertical tectonics is mildly alkaline in character, whereas transitional and tholeiitic magmas are found along the spreading axes.     

Are the Norwegian mountains compensated by a mantle thermal anomaly at depth?

The Norwegian mountains or Scandes represent a long mountain range stretching from southern Norway to the Arctic and is characterised by a rugged topography and peaks up to 2.5 km high. The origin of this mountain chain far away from any plate boundary remains a matter of passionate debates inside the geoscientific community. Hot mantle “fingers” originating from the Iceland Plume, impacting the base of the Scandinavian lithosphere and creating asthenospheric diapirs is one of the most accepted hypotheses for explaining Cenozoic uplift in Norway. In order to test this hypothesis we conducted integrated gravity and thermal modelling. We used the dense NGU gravity grid (i.e. one measurement every ~ 3 km) and modelled the depth extent and the mass deficit associated to the compensating loads located below the southern Scandes. Assuming that the density deficit below the Scandes is purely thermal in origin, thermal modelling allowed for testing the magnitude of the potentially associated temperature anomaly and its impact on surface heat flow. Recently acquired heat flow data were used in order to constrain the results from the thermal modelling. The results of our integrated geophysical modelling rule out the possibility that the present-day topography of the southern Scandes is compensated by a deep-seated asthenospheric diapir. However, our modelling does not exclude that thermal processes in the deep mantle could have initiated or assisted recent uplift of the southern Scandes.     

Basement topography of the Mexicali Valley from spectral and ideal body analysis of gravity data

Source-depth estimations based on analysis of gravity data enabled us to establish the basement topography in the area of the Mexicali Valley (Mexico). Analysis of the radial power spectrum from all the Bouguer gravity anomaly data indicates that the intermediate wave number interval ranging between 0.025 km⁻¹ and 0.112 km⁻¹ with a mean source depth of 3.5 km corresponds to the sedimentary basin. The gravity spectrum was analyzed to estimate the depth to the basement in different square sectors (windows) of the study area. Linear regression analysis was used to calculate the slopes of the respective power spectrums, to subsequently estimate the depths to the basement in each sector. The basement topography obtained in this way ranged from 2.1 to 4.5 km. Our basement topography is consistent with the depths to the basement reported from wells drilled in the study area. The basement is formed by granites to the northeast, dikes to the southwest, and shaped by structural lows and highs, with graben-horst structures at the center of the studied area.An independent estimation of the mean depth to the basement was obtained based on the ideal body theory. In particular trade-off curves relating the lower bound of the density contrast to the depth to the top of the geological interface were computed. If we assume that the sediments outcrop (as is actually the case), the minimum lower bound on the density contrast is 0.0700 g/cm³. This result would imply a maximum thickness of 13.5 km for the sedimentary infill.Seismic velocities of 5.83 and 4.9 km/s for the basement and the sedimentary infill, respectively, indicates densities of 2.86 and 2.56 g/cm³ according to the Nafe and Drake’s relationship between seismic velocities and densities. The corresponding density contrast of 0.3 g/cm³ helped us to constrain the analysis of the trade-off curves accordingly; the sedimentary thickness is of approximately 3.5 km. This result is in agreement with that obtained from our spectral analysis.     

内蒙古西部银根一额济纳旗盆地重力场与断裂构造的特征

为了研究银根一额济纳旗盆地的构造特征,为该区油气资源远景调查评价提供依据,系统地收集、研究了已有的重力调查资料,分析了研究区重力场的特征及其成因,推断了研究区的断裂构造体系。研究区区域重力异常主要是由莫霍面起伏变化引起的,剩余重力异常重力高与重力低相间分布的特征,可能一方面反映了研究区凹陷与隆起分布的范围及展布特征,另一方面反映了凹陷与隆起之间发育非对称的断裂。研究区主要发育北东东向（北东向）、北西西向2组断裂,这2组断裂对基底结构、性质、隆坳格架及中生代盆地展布起重要的控制作用。基底断裂将研究区分割成多个块体,使盆地形成凹、凸相间的结构特征。     

Large-scale distributed deformation controlled topography along the western Africa–Eurasia limit: Tectonic constraints

In the interior of the Iberian Peninsula, the main geomorphic features, mountain ranges and basins, seems to be arranged in several directions whose origin can be related to the N–S plate convergence which occurred along the Cantabro–Pyrenean border during the Eocene–Lower Miocene time span. The Iberian Variscan basement accommodated part of this plate convergence in three E–W trending crustal folds as well as in the reactivation of two left-lateral NNE–SSW strike-slip belts. The rest of the convergence was assumed through the inversion of the Iberian Mesozoic Rift to form the Iberian Chain. This inversion gave rise to a process of oblique crustal shortening involving the development of two right lateral NW–SE shear zones. Crustal folds, strike-slip corridors and one inverted rift compose a tectonic mechanism of pure shear in which the shortening is solved vertically by the development of mountain ranges and related sedimentary basins. This model can be expanded to NW Africa, up to the Atlasic System, where N–S plate convergence seems also to be accommodated in several basement uplifts, Anti-Atlas and Meseta, and through the inversion of two Mesozoic rifts, High and Middle Atlas. In this tectonic situation, the microcontinent Iberia used to be firmly attached to Africa during most part of the Tertiary, in such a way that N–S compressive stresses could be transmitted from the collision of the Pyrenean boundary. This tectonic scenario implies that most part of the Tertiary Eurasia–Africa convergence was not accommodated along the Iberia–Africa interface, but in the Pyrenean plateboundary. A broad zone of distributed deformation resulted from the transmission of compressive stresses from the collision at the Pyrenean border. This distributed, intraplate deformation, can be easily related to the topographic pattern of the Africa–Eurasia interface at the longitude of the Iberian Peninsula.Shortening in the Rif–Betics external zones – and their related topographic features – must be conversely related to more “local” driven mechanisms, the westward displacement of the “exotic” Alboran domain, other than N–S convergence. The remaining NNW–SSE to NW–SE, latest Miocene up to Present convergence is also being accommodated in this zone straddling Iberia and Morocco, at the same time as a new ill-defined plate boundary that is being developed between Europe and Africa.