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The active growth of a fault-and-thrust belt in frontal zones of Himalaya is a prominent topographical feature, extending 2500 km from Assam to Pakistan. In this paper, kinematical analysis of frontal anticlines and spatial mapping of active faults based on geomorphological features such as drainage pattern development, fault scarps and uplifted Quaternary alluvial fans are presented. We analyse the geomorphic and hydrographic expressions of the Chandigarh and the Janauri active anticlines in the NW India Siwaliks. To investigate the morphological scenario during the folding process, we used spatial imagery, geomorphometric parameters extracted from digital elevation models and fieldwork. Folding between the Beas and Sutlej Rivers gives clear geomorphological evidence of recent fold growth, presumably driven by movements of blind thrust faults. Structural style within the Janauri and Chandigarh anticlines is highly variable (fault-propagation folds, pop-up structures and transfer faults). The approach presented here involves analysis of topography and drainage incision of selected landforms to detect growth of active anticlines and transfer faults. Landforms that indicate active folding above a southwest-dipping frontal thrust and a northeastdipping back-thrust are described. Along-strike differences in ridge morphology are measured to describe the interaction of river channel patterns with folds and thrust faults and to define history of anticline growth. The evolution of the apparently continuous Janauri ridge has occurred by the coalescence of independent segments growing towards each other. By contrast, systematic drainage basin asymmetry shows that the Chandigarh anticline ridge has propagated laterally from NW to SE. D

ZusammenfassungDer zentrale Hohe Atlas ist eine intrakontinentale Gebirgskette, die sich im Bereich der zwischen dem Sahara-Plateau und dem marokkanischen Variszikum gelegenen Trias-und Jurabecken herausbildete. Dieses junge Gebirge, dessen h6ch-ste Erhebungen tiber 4000 Meter hoch sind, ist dutch einen relativ geringen Verkttrzungsgrad gekennzeichnet. Axial tritt jedoch eine Schieferung auf im Bereich der N80 ~ E ausgerichteten antiklinalen Hauptfalten sowie fund um die N45 ~ E verlaufenden >>Intrusions-Falten<< und die Gangfelder. Die r~iumlichen Beziehungen dieser Schieferung zu den synsediment~iren Faltungsstrukturen und den G~ingen legen die Vermutung nahe, dab ihre Hausbildung w~ihrend des Doggers mit dem Aufstieg und dem Eindringen der Plutone in das Sedimentgestein zeitlich zusammenfiel. In diesem Zeitraum erfolgte eine Strukturumkehrung, die das allm~ihliche Verschliel3en der Becken und das Zustandekommen der Schieferung bewirkte.Im Laufe des Terti~irs wurde nach und nach das gesamte Atlasgebiet einer etwa N-S gerichteten Einspannung ausgesetzt. Mit der Ablagerung immer grrberer Sedimente in den letzten Randbekken setzte schliel31ich im Oligoz~in die orogene Inversion ein, die das Gebirgsrelief bedingt hat. AbstractThe Central High Atlas is characterized by a relatively mild deformation, with a local development of a more or less penetrative cleavage in the axial part of the belt. Locally, this cleavage and the plutonic bodies which outcrop in the core of most of the north-east trending anticlines (ridges >>with intrusions<<) are overlain by a disconformable sequence that comprises red clastic deposits which are capped by Cenomano-Turonian limestones. The age of these red deposits are bracketted between Bathonian to Mid-Cretaceous. Therefore, the spatial relationship of the cleavage with mafic intrusions, in the axial part of the Central High Atlas, suggests that it developed contemporaneously with the emplacement of magmas, probably during Mid-Jurassic times. During this period, the structural inversion occurred, from a transtensional regime to a transpressive regime.There are few indications that an important shortening persisted within the axial part of the Central High Atlas after the end of the Jurassic. Along the northern and the southern borders of the belt, however, Cretaceous and Cenozoic strata were deposited. Their sedimentary facies bear witness of successive stages of the Atlas evolution. Especially, the rapidly coarsening up of the clastic deposits since the Oligocene in these marginal basins indicates the onset of the rising up of the belt, i. e. the orogenic inversion.

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