The Muth Formation in the Pin Valley (Spiti, N-India)

Im Pin Tal (Spiti) wurden jungproterozoischen und altpaläozoischen Sedimentserien bearbeitet. Lithologische Profile von der Pin Fm., Muth Fm. und Lipak Fm. wurden angefertigt und leicht erkennbare Grenzen zwischen den Formationen definiert. Charakteristische lithologische Variationen ermöglichen eine überregionale Korrelation dieser Serien mit den Tethys Sedimenten von Zanskar bis Kumaon. Die Muth Fm. wird anhand ihrer sedimentären Strukturen als ein Barriereninsel System interpretiert. Basierend auf lithologischen Veränderungen und unterschiedlichen sedimentärer Strukturen, werden 4 Fazies Assoziationen (FA1-FA4) unterschieden. Vom Liegenden ins Hangende finden sich beach, shoreface bis foreshore, Küstendünen, Lagune und abschließend wieder shoreface Ablagerungen. Die Spurenfossilien Vergesellschaftung besteht aus zahlreichen Palmichnium antarcticum und Diplichnites gouldi. Deutlich seltener finden sich Diplopodichnus biformis, Taenidium barretti, Didymaulichnus cf. lyelli, Didymaulyponomos cf. rowei, Metaichnia isp. und verticale Bohrgänge mit unklarer systematischer Zuordnung. Da in der Muth Fm. gut datierbaren Fossilien gefunden wurden, läßt sich lediglich das Mindestalter der Formation anhand der Datierung der überlagernden Lipak Fm. feststellen. Es wurden deshalb aus den ersten Kalkbänken der Lipak Fm. Gut erhaltene Conodonten, etwa 30 m oberhalb der Lipak Basis, zeigen ein mitteldevonisches Alter (Givet) an. SE von Mikkim wurden zahlreiche deformation bands im gesamten Aufschlußbereich gefunden. Die Rekonstruktion dieser Strukturen auf ihre Orientierung vor der Verfaltung durch die Himalaya Orogenese, zeigt Ost-West streichende, subvertical einfallende Störungen, die eine Deformation anzeigen, die älter ist als die Himalaya Orogenese. Da es sich dabei um Strukturen handelt, die aus porösen Sandsteinen beschrieben sind, liegt das Alter dieser Deformation zwischen dem Sedimentationsalter der Muth Fm. und deren vollständiger Zementation.Uppermost Proterozoic to Lower Paleozoic sedimentary sequences in the Pin Valley (Spiti) have been investigated. Lithological sections of the Pin Fm., Muth Fm. and Lipak Fm. have been measured, and useful, clear recognizable boundaries between the Formations have been defined. Typical lithological variations permit the regional correlation with Tethyan sediments from Zanskar to Kumaon. Sedimentary structures indicate that the Muth Fm. was deposited in a barrier-island system. Based on lithological variations and different sedimentary structures, four facies (FA1-FA4) have been distinguished, comprising (beginning at the base) shoreface to foreshore, coastal dune, lagoon and again shoreface depositional environments. The ichnoassemblage consists of abundant Palmichnium antarcticum and Diplichnites gouldi with rarer Diplopodichnus biformis, Taenidium barretti, Didymaulichnus cf. lyelli, Didymaulyponomos cf. rowei, Metaichnia isp. and vertical burrows of unclear affinity. Due to the lack of age-indicative fossils in the Muth Fm. the lower age limit of the Formation is constrained by the age of the overlying Lipak Fm. Conondont samples have been taken at the lowermost occurrence of limestone beds in the Lipak Fm. (c. 30 m above the base of the Formation), that yielded nicely preserved conodonts of Givetian age. Deformation bands are very common in the Muth Fm. SE of Mikkim. Restored to their original orientation, they represent near vertical, E-W striking faults, indicating pre-Himalayan deformation with an older age limit represented by the age of sedimentation and a younger age limit represented by the age of complete cementation of the arenite

Surfaces from the visual past : recovering high-resolution terrain data from historic aerial imagery for multitemporal landscape analysis

Historic aerial images are invaluable sources of aid to archaeological research. Often collected with large-format photogrammetric quality cameras, these images are potential archives of multidimensional data that can be used to recover information about historic landscapes that have been lost to modern development. However, a lack of camera information for many historic images coupled with physical degradation of their media has often made it difficult to compute geometrically rigorous 3D content from such imagery. While advances in photogrammetry and computer vision over the last two decades have made possible the extraction of accurate and detailed 3D topographical data from high-quality digital images emanating from uncalibrated or unknown cameras, the target source material for these algorithms is normally digital content and thus not negatively affected by the passage of time. In this paper, we present refinements to a computer vision-based workflow for the extraction of 3D data from historic aerial imagery, using readily available software, specific image preprocessing techniques and in-field measurement observations to mitigate some shortcomings of archival imagery and improve extraction of historical digital elevation models (hDEMs) for use in landscape archaeological research. We apply the developed method to a series of historic image sets and modern topographic data covering a period of over 70 years in western Sicily (Italy) and evaluate the outcome. The resulting series of hDEMs form a temporal data stack which is compared with modern high-resolution terrain data using a geomorphic change detection approach, providing a quantification of landscape change through time in extent and depth, and the impact of this change on archaeological resources

LITHOSTRATIGRAPHY, CONODONT BIOSTRATIGRAPHY AND DEPOSITIONAL ENVIRONMENT OF THE MIDDLE DEVONIAN (GIVETIAN) TO EARLY CARBONIFEROUS (TOURNAISIAN) LIPAK FORMATION IN THE PIN VALLEY OF SPITI (NW INDIA)

Bed-by-bed lithostratigraphic sections combined with sequence stratigraphy and conodont biostratigraphy provide new information on the depositional environment and age of the Lipak Formation in the Pin Valley (Spiti). The formation comprises mixed siliciclastic and calcareous sediments at lower levels, richly fossiliferous limestones with two distinct sandstone incursions at higher levels, and dark mudstones followed by a thin siltstone interval. The upper limit of the Lipak Formation is defined by the angular unconformity below the sandstones of the Permian Gechang Formation. Lithologic correlation with sections in upper Lahaul indicates that, in the Pin Valley, the formation has been truncated just below its characteristic gypsum horizon. The lower boundary of the Lipak Formation is gradational from coastal arenites of the Muth Formation; the mappable boundary is drawn at the first appearance of dark carbonaceous, argillaceous siltstone and shale.Sedimentary structures, microfacies and conodont faunas indicate a general shallow marine depositional environment of the Lipak Formation in the Pin Valley; five sequence stratigraphic units have been distinguished. Conodont data demonstrate that the lowest 33 m of the Lipak Formation of the Pin Valley is mid to late Early varcus Subzone with characteristic species of Icriodus and Bipennatus. A previously unrecognised hiatus at c. 33 m above the base, at the boundary of sequence stratigraphic units S1 and S2, represents the interval Middle varcus Subzone to at least the end of the late Famennian Early expansa Zone. Because this hiatus does not correspond to a mappable boundary, no division of the Lipak Formation into named stratigraphic units is suggested, but we refer informally to the sediments represented by cycle S1 as Lipak A, and the sediments represented by cycles S2-S5 as Lipak B. Determination of S1 as Early varcus Subzone provides a maximum age for the gradationally underlying Muth Formation. At 75 m above the base of the composite Lipak Formation section, a 58 cm black to dark grey shale interval within late Famennian fossiliferous limestones conceivably correlates with the Hangenberg Event (end-Middle praesulcata Zone). Younger conodont faunas of the Lipak Formation -dominated by species of Clydagnathus with species of Bispathodus and Pseudopolygnathus also represented- is shown to extend to the mid-Tournaisian Early crenulata Zone.&nbsp

Extensional crustal-scale shear zones in the Western Cyclades (Kea, Greece)

Intense seismicity and intensely developed active and ancient fault systems are common to the Aegean Region. Extending/ thinning crust involves a complex interplay of (1) Gulf of Corinth riftexpansion, (2) west- and south-ward retreat of the Hellenic Trench, (3) westward impingement of the Anatolian Platen, and/or (4) propagation of the Anatolian Fault system into the Aegean. New geological/structural investigations on Kea (also known as Tzia), in the Western Cyclades reveal a low angle crustal-scale, detachment-type ductile shear zone probably formed during Miocene extension and thinning of the continental crust...conferenc

Kinematics and deformation structures in a crustal-scale shear zone on Kea (W. Cyclades, Greece)

It is generally agreed upon that the exhumation of metamorphic rocks in the Aegean is caused by post orogenic extension in the late Oligocene to early Miocene. This extension is in principle largely accommodated by low-angle crustal detachment faulting possibly resulting in the formation of metamorphic core complexes (MCC). Here, we present data from recent structural investigations on the island of Kea in the W. Cyclades, Greece. Our work focussed in the north of the island. Of the ca. 270m total structural thickness that was mapped, the entire section of rocks are highly strained. Exhumation during progressive deformation is recorded by the transition from ductile to brittle/ductile to brittle conditions. The regional characteristics and types of deformation structures vary depending on the protolith and the intensity of strain...conferenc

Late stage evolution of the Serifos Metamorphic Core Complex (Cyclades, Greece)

The island of Serifos is located in the Western Cyclades within the Attic- Cycladic metamorphic belt. It represents the westward continuation of an arcuate belt of Metamorphic Core Complexes with intrusions of late syn-post tectonic intrusions younging from East (e.g. Naxos main activity ca. 12Ma) to West (e.g. Serifos with 9–8Ma). In scientific discussions the dominance of probably continuous extension since ca. 30Ma (e.g. Jolivet & Faccenna, 2000) and the presence of Metamorphic Core Complexes (Lister et al. 1984) is accepted. The speculated roll-back of the subducting plate possibly started due to the slowing down of absolute plate convergence rate between Africa and Eurasia. This model is attractive, because it would also explain the shift from a compressional Andean-type regime to an extensional Mariana-type regime (Jolivet & Faccenna 2000). Contrary to the kinematic directions reported from the Central and Eastern Cyclades, the movement of the hanging wall of the Serifos Metamorphic Core Complex is south directed. The island’s main part is occupied by an undeformed granodiorite. Early granitic intrusions intruded into low-grade M2-crystalline rocks that have been overprinted to as high as amphibolite facies conditions due to contact metamorphism. Parts of these rocks (gneisses and amphibolites) as well as the early intrusions are deformed to mylonites (Grasemann et al. 2004).conferenc

Giant submarine landslide grooves in the Neoproterozoic/Lower Cambrian Phe Formation, northwest Himalaya: Mechanisms of formation and palaeogeographic implications

Giant groove casts have been found in the upper Proterozoic to Lower Cambrian Phe Formation (Haimanta Group), a siliciclastic sandstone/shale succession in the Tethyan Zone of the Higher Himalaya tectonic unit. The grooves are among the largest linear erosion structures related to submarine mass-movements observed in the geologic record. They are up to 4 m wide, about 0.2 m deep and can be traced for more than 35 m without changing their character. The grooves are straight, subparallel to cross-cutting striations with shallow semi-circular cross-sections and well-defined superimposed minor ridges and grooves. Groove casts exist on the soles of several sandstone beds within a 73 m thick logged section, commonly associated with flute casts. Their characteristics were compared with several other types of ancient and modern submarine linear erosion structures. A sand-rich, non-channelized basin floor depositional environment is inferred from the lithofacies, the combination of sedimentary structures, the lack of coarse-grained pebbly facies, the lateral continuity of beds, and the lack of channel structures. The grooves probably formed by laminar debris flows/concentrated density flows dragging blocks of already lithified sediment across the basin floor. When the bedding is structurally rotated back to horizontal, the groove casts show consistent North–South oriented palaeocurrent trends, with South-directed palaeocurrent directions indicated by flute casts. These palaeocurrent orientations contrast with previous palaeogeographic reconstructions of this area, which propose sediment delivery from the South. We therefore suggest a new “double provenance” model for the spatial relationship of late Proterozoic to Early Cambrian strata of the Himalaya, in which Lesser and Tethyan Himalayan age-equivalent sediment was deposited in a connected basin, where the former received detritus from the South, and the latter from a hitherto unknown source in the North. One possible candidate for this northern source is the South China Block and an associated Neoproterozoic volcanic arc

Stone Monuments from Carnuntum and Surrounding Areas (Austria) – Petrological Characterization and Quarry Location in a Historical Context

The currently ongoing project on Stone Monuments and Stone Quarrying in the Carnuntum – Vindobona Area (FWF 26368-G21) focuses on petrological and litho-stratigraphic investigations of well-dated Roman stone objects. The majority of the examined monuments are made from local Neogene limestone varieties, sedimentary breccias and sandstones – lithologies widespread in the surroundings of Carnuntum, the edge of the Vienna Basin and the western margin of the Pannonian Basin. Analyses of historical maps and high resolution airborne laser scans (ALS) are used to detect potential ancient quarry areas, which are ground-checked by geological methods. So far, ancient quarrying areas in the immediate surroundings of Carnuntum and in the Leitha Mountains have been localized, providing deposits of different algal limestones and calcareous arenites. This interdisciplinary approach promises to provide insight, not only into the provenance of stone material but also into matters of transportation, workshops and economic interaction between Carnuntum, Vindobona and the hinterland

Geoarchaeology as an essential supplement for largescale, high-resolution archaeological geophysical prospection: case study of Gokstad in Norway

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The Archaic sanctuary on Despotiko Island (Cyclades): Geological outline and lithological characterization of the building stones, with their possible provenance

Lithological comparisons between building stones of an archaic sanctuary on Despotiko (Cyclades) and geological units mapped on this island enabled a distinction to be made between locally derived and possibly imported material. The most common lithologies used in the main sanctuary building (Building A) were medium-grained white calcite marble with thin, rose-coloured dolomite marble layers (Marble 1), coarse grained, white calcite marble (Marble 2), white mylonitic gneiss and grey granitic gneiss; dark grey banded calcite marble and yellowish calcarenite were rarely used. Excepting Marble 2, all building stones in Building A occur on Despotiko and could originate from the island. The occurrence of nine quarries (presently undated) in the surroundings of the sanctuary, seven in white mylonitic gneiss, one in dark grey calcite marble and one in a white calcite marble resembling Marble 1, support a local provenance. Submerged archaeological structures within Despotiko Bay, a classical marble inscription from the sanctuary and partly submerged agriculture trenches at the east coast of Despotiko all suggest that the relative sea-level there was > 3 m lower in the Early Bronze Age and > 1 m lower during Hellenistic times. If vertical tectonic movements are neglected, the present sea-floor bathymetry indicates that an isthmus linked Despotiko, Kimitiri and Antiparos until at least Hellenistic times