Reconstructing paleoelevation in eroded orogens

Hydrogen isotope and Ar-40/Ar-39 geochronological data are presented from muscovite within a crustal-scale extensional detachment of the Shuswap Metamorphic Complex, North American Cordillera. The hydrogen isotope compositions (deltaD(ms)) of precisely dated muscovite attain values as low as -156parts per thousand in the detachment mylonite, whereas footwall quartzite has a deltaD(ms) value of -81parts per thousand. The very low deltaD(ms) values in the detachment are best explained by infiltration of meteoric water, with maximum deltaD values of -135parts per thousand +/- 3parts per thousand, during extensional unroofing of the orogen at 49.0-47.9 Ma. On the basis of the empirically determined relationship between elevation and isotopic composition of precipitation, the reconstructed early Eocene paleoelevations of the orogen are 4060 +/- 250 m to 4320 +/- 250 m, at least 1000 m higher than the highest present-day peaks. We propose that the isotopic composition of surface-derived waters in extensional detachments represents a newly recognized method to estimate maximum paleoelevations attained immediately preceding extensional orogenic collapse.

Microstructural, chemical and textural records during growth of snowball garnet

The growth history of two populations of snowball garnet from the Lukmanier Pass area (central Swiss Alps) was examined through a detailed analysis of three-dimensional geometry, chemical zoning and crystallographic orientation. The first population, collected in the hinge of a chevron-type fold, shows an apparent rotation of 360 degrees. The first 270 degrees are characterized by spiral-shaped inclusion trails, gradual and concentric Mn zoning and a single crystallographic orientation, whereas in the last 90 degrees, crenulated inclusion trails and secondary Mn maxima centred on distinct crystallographic garnet domains are observed. Microstructural, geochemical and textural data indicate a radical change in growth regime between the two growth sequences. In the first 270 degrees, growth occurred under rotational non-coaxial flow, whereas in the last 90 degrees, garnet grew under a non-rotational shortening regime. The second population, collected in the limb of the same chevron-type fold structure, is characterized by a spiral geometry that does not exceed 270 degrees of apparent rotation. These garnet microstructures do not record any evidence for a modification of the stress field during garnet growth. Concentric Mn zoning as well as a single crystallographic orientation are observed for the entire spiral. Electron backscatter diffraction data indicate that nearly all central domains in the snowball garnet are characterized by one [001] axis oriented (sub-)parallel to the symmetry axis and by another [001] axis oriented (sub-)parallel to the orientation of the internal foliation. These features suggest that the crystallographic orientation across the garnet spiral is not random and that a relation exists among the symmetry axis, the internal foliation and the crystallographic orientation.

Three-dimensional sequence stratigraphy and subtle stratigraphic traps associated with systems tracts: West Cameron region, offshore Louisiana, Gulf of Mexico

Three-dimensional sequence stratigraphy is a potent exploration and development tool for the discovery of subtle stratigraphic traps. Reservoir morphology, heterogeneity and subtle stratigraphic trapping mechanisms can be better understood through systematic horizontal identification of sedimentary facies of systems tracts provided by three-dimensional attribute maps used as an important complement to the sequential analysis on the two-dimensional seismic lines and the well log data. On new prospects as well as on already-producing fields, the additional input of sequential analysis on three-dimensional data enables the identification, location and precise delimitation of new potentially productive zones. The first part of this paper presents four typical horizontal seismic facies assigned to the successive systems tracts of a third- or fourth-order sequence deposited in inner to outer neritic conditions on a elastic shelf. The construction of this synthetic representative sequence is based on the observed reproducibility of the horizontal seismic facies response to cyclic eustatic events on more than 35 sequences registered in the Gulf coast Plio-Pleistocene and Late Miocene, offshore Louisiana in the West Cameron region of the Gulf of Mexico. The second part shows how three-dimensional sequence stratigraphy can contribute in localizing and understanding sedimentary facies associated with productive zones. A case study in the early Middle Miocene Cibicides opima sands shows multiple stacked gas accumulations in the top slope fan, prograding wedge and basal transgressive systems tract of the third-order sequence between SB15.5 and SB 13.8 Ma.

Bitumens in the late Variscan hydrothermal vein-type uranium deposit of Pribram, Czech Republic: Sources, radiation-induced alteration, and relation to mineralization

The late Variscan (275-278 Ma) Pribram uranium deposit is one of the largest known accumulations of uraniferous bitumens in hydrothermal veins. The deposit extends along the northwestern boundary of the Central Bohemian pluton (345-335 Ma) with low-grade metamorphosed Late Proterozoic and unmetamorphosed Cambrian rocks. From a net uranium production of 41,742 metric tons (t), more than 6,000 t were extracted from bitumen-uraninite ores during 43 years of exploration and mining. Three morphological varieties of solid bitumen are recognized: globular, asphaltlike, and cokelike. While the globular bitumen is uranium free, the other two types are uraniferous. The amount of bitumen in ore veins gradually decreases toward the contact with the plutonic body and increases with depth. Two types of bitumen microtextures are recognized using high-resolution transmission electron microscopy: amorphous and microporous, the former being less common in uraniferous samples. A lower Raman peak area ratio (1,360/1,575 cm(-1)) in mineralized bitumens (0.9) compared with uranium-free samples (2.0) indicates a lower degree of microtextural organization in the latter The H/C and O/C atomic ratios in uranium-free bitumens (0.9-1.1 and 0.09, respectively) are higher than those in mineralized samples (H/C = 0.3-0.8, O/C = 0.03-0.09). The chloroform extractable matter yield is Very low in uranium-free bitumens (0.30-0.35% of the total organic carbon,TOC) and decreases with uranium content increase. The extracted solid uraniferous bitumen infrared spectra show depletion in aliphatic CH2 and CH3 groups compared to uranium-free samples. The concentration of oxygen-bearing functional groups relative to aromatic bonds in the IR spectra of uranium-free and mineralized bitumen, however, do not differ significantly. C-13 NMR confirmed than the aromaticity of a uraniferous sample is higher (F-ar = 0.61) than in the uranium-free bitumen (F-ar = 0.51). Pyrolysates from uraniferous and nonuraniferous bitumens do not differ significantly, being predominantly cresol, alkylphenols, alkylbenzenes, and alkylnaphthalenes. The liquid pyrolysate yield decreases significantly with increasing uranium content. The delta(13)C Values of bulk uranium-free bitumens and low-grade uraniferous, asphaltlike bitumens range from -43.6 to 52.3 per mil. High-grade, cokelike, uraniferous bitumens are more C-13 depleted (54.5 to -58.4 parts per thousand). In contrast to the very light isotopic ratios of the high-grade uraniferous cokelike bitumen bulk carbon, the individual n-alkanes and isoprenoids (pristane and phytane) extracted from the same sample are significantly C-13 enriched. The isotopic composition of the C13-24 n-alkanes extracted from the high-grade uraniferous sample (delta(13)C = -28.0 to 32.6 parts per thousand) are heavier compared with the same compounds in a uranium-free sample (delta(13)C = 31.9 to 33.8 parts per thousand). It is proposed that the bitumen source was the isotopically light (delta(13)C = 35.8 to 30.2 parts per thousand) organic matter of the Upper Proterozoic host rocks that were pyrolyzed during intrusion of the Central Bohemian pluton. The C-13- depleted pyrolysates were mobilized from the innermost part of the contact-metamorphic aureole, accumulated in structural traps in less thermally influenced parts of the sedimentary complex and were later extracted by hydrothermal fluids. Bitumens at the Pribram deposit are younger than the main part of the uranium mineralization and were formed through water-washing and radiation-induced polymerization of both the gaseous and liquid pyrolysates. Direct evidence for pyrolysate reduction of uranium in the hydrothermal system is difficult to obtain as the chemical composition of the original organic fluid phase was modified during water-washing and radiolytic alteration. However, indirect evidence-e.g., higher O/C atomic ratios in uranium-free bitumens (0.1) relative to the Upper Proterozoic source rocks (0.02-0.05), isotopically very light carbon in associated whewellite (delta(13)C = 31.7 to -28.4 parts per thousand), and the striking absence of bitumens in the pre-uranium, hematite stage of the mineralization-indicates that oxidation of organic fluids may have contributed to lowering of aO(2) and uraninite precipitation.

Oxygen isotope compositions of iron oxides from high-grade BIF-hosted iron ore deposits of the Central Hamersley Province, Western Australia: Constraints on the evolution of hydrothermal fluids

The Hamersley province of northwest Australia is one of the world's premier iron ore regions with high-grade martite-microplaty hematite iron ore deposits mostly hosted within banded iron formation (BIF) sequences of the Brockman Iron Formations of the Hamersley Group. These high-grade iron ores contain between 60 and 68 wt percent Fe, and formed by the multistage interaction of hydrothermal fluids with the host BIF formation. The oxygen isotope compositions of magnetite and hematite from BIF, hydrothermal alteration assemblages, and high-grade iron Ore were analyzed from the Mount Tom Price, Paraburdoo, and Charmar iron ore deposits. The delta(18)O values of magnetite and hematite from hydrothermal alteration assemblages and high-grade iron ore range from -9.0 to -2.9 per mil, a depletion of 5 to 15 per mil relative to the host BIF. The delta(18)O values are spatially controlled by faults within the deposits, a response to higher fluid flux and larger influence the isotopic compositions by the hydrothermal fluids. The oxygen isotope composition of hydrothermal fluids (delta(18)O(fluid)) indicates that the decrease in the (18)O content of iron oxides was due to the interaction of both basinal brines and meteoric fluids with the original BIF. Late-stage talc-bearing ore at the Mount Tom Price deposit formed in the presence of a pulse of delta(18)O-enriched basinal brine, indicating that hydrothermal fluids may have repeatedly interacted with the BIFs during the Paleoproterozoic.

Anachronistic facies from a drowned Lower Triassic carbonate platform: Lower member of the Alwa Formation (Ba'id Exotic), Oman Mountains

- The lower member of the Alwa Formation (Lower Olenekian), found within the Ba'id Exotic in the Oman Mountains (Sultanate of Oman), consists of ammonoid-bearing, pelagic limestones that were deposited on an isolated, drowned carbonate platform on the Neotethyan Gondwana margin. The strata contain a variety of unusual carbonate textures and features, including thrombolites, Frutexites-bearing microbialites that contain synsedimentary cements, matrix-free breccias surrounded by isopachous calcite cement, and fissures and cavities filled with large botryoidal cements. Thrombolites are found throughout the study interval, and occur as 0.5-1.0 m thick lenses or beds that contain laterally laterally-linked stromatactis cavities. The Frutexites-bearing microbialites occur less frequently, and also form lenses or beds, up to 30 cm thick; the microbialites may be laminated, and often developed on hardgrounds. In addition, the Frutexites-bearing microbialites also contain synsedimentary calcite cement crusts and botryoids (typically <1 cm thick) that harbour layers or pockets of what appear to be bacterial sheaths and coccoids, and are indicative of biologically mediated precipitation of the cement bodies. Slumping following lithification led to fracturing of the limestone and the precipitation of large, botryoidal aragonite cements in fissures that cut across the primary fabric. Environmental conditions, specifically palaeoxygenation and the degree of calcium carbonate supersaturation, likely controlled whether the thrombolites (high level of calcium carbonate supersaturation associated with vertical mixing of water masses and dysoxic conditions) or Frutexites-bearing microbialites (low level of calcium carbonate supersaturation associated with anoxic conditions and deposition below a stable chemocline) formed. The results of this study point to continued environmental stress in the region during the Early Triassic that likely contributed to the uneven recovery from the Permian-Triassic mass extinction.

Preservation of an extreme transient geotherm in the Raft River detachment shear zone

Extensional detachment systems separate hot footwalls from cool hanging walls, but the degree to which this thermal gradient is the product of ductile or brittle deformation or a preserved original transient geotherm is unclear. Oxygen isotope thermometry using recrystallized quartz-muscovite pairs indicates a smooth thermal gradient (140 degrees C/100 m) across the gently dipping, quartzite-dominated detachment zone that bounds the Raft River core complex in northwest Utah (United States). Hydrogen isotope values of muscovite (delta D-Ms similar to-100 parts per thousand) and fluid inclusions in quartz (delta D-Fluid similar to-85 parts per thousand) indicate the presence of meteoric fluids during detachment dynamics. Recrystallized grain-shape fabrics and quartz c-axis fabric patterns reveal a large component of coaxial strain (pure shear), consistent with thinning of the detachment section. Therefore, the high thermal gradient preserved in the Raft River detachment reflects the transient geotherm that developed owing to shearing, thinning, and the potentially prominent role of convective flow of surface fluids.

The Fry method applied to an augen orthogneiss: Problems and results

The application of the Fry method to measure strain in deformed porphyritic granites is discussed. This method requires that the distribution of markers has to satisfy at least two conditions. It has to be homogeneous and isotropic. Statistics on point distribution with the help of a Morishita diagram can easily test homogeneity. Isotropy can be checked with a cumulative histogram of angles between points. Application of these tests to undeformed (Mte Capanne granite, Elba) and to deformed (Randa orthogneiss, Alps of Switzerland) porphyritic granite reveals that their K-feldspars phenocrysts both satisfy these conditions and can be used as strain markers with the Fry method. Other problems are also examined. One is the possible distribution of deformation on discrete shear-bands. Providing several tests are met, we conclude that the Fry method can be used to estimate strain in deformed porphyritic granites. (c) 2006 Elsevier Ltd. All rights reserved.

Strontium ranelate and alendronate have differing effects on distal tibia bone microstructure in women with osteoporosis.

The structural basis of the antifracture efficacy of strontium ranelate and alendronate is incompletely understood. We compared the effects of strontium ranelate and alendronate on distal tibia microstructure over 2 years using HR-pQCT. In this pre-planned, interim, intention-to-treat analysis at 12 months, 88 osteoporotic postmenopausal women (mean age 63.7 +/- 7.4) were randomized to strontium ranelate 2 g/day or alendronate 70 mg/week in a double-placebo design. Primary endpoints were changes in microstructure. Secondary endpoints included lumbar and hip areal bone mineral density (aBMD), and bone turnover markers. This trial is registered with http://www.controlled-trials.com, number ISRCTN82719233. Baseline characteristics of the two groups were similar. Treatment with strontium ranelate was associated with increases in mean cortical thickness (CTh, 5.3%), cortical area (4.9%) and trabecular density (2.1%) (all P < 0.001, except cortical area P = 0.013). No significant changes were observed with alendronate. Between-group differences in favor of strontium ranelate were observed for CTh, cortical area, BV/TV and trabecular density (P = 0.045, 0.041, 0.048 and 0.035, respectively). aBMD increased to a similar extent with strontium ranelate and alendronate at the spine (5.7% versus 5.1%, respectively) and total hip (3.3% versus 2.2%, respectively). No significant changes were observed in remodeling markers with strontium ranelate, while suppression was observed with alendronate. Within the methodological constraints of HR-pQCT through its possible sensitivity to X-ray attenuation of different minerals, strontium ranelate had greater effects than alendronate on distal tibia cortical thickness and trabecular volumetric density.

High-resolution seismic images of potentially seismogenic structures beneath the northwest Canterbury Plains, New Zealand

The transpressional boundary between the Australian and Pacific plates in the central South Island of New Zealand comprises the Alpine Fault and a broad region of distributed strain concentrated in the Southern Alps but encompassing regions further to the east, including the northwest Canterbury Plains. Low to moderate levels of seismicity (e. g., 2 > M 5 events since 1974 and 2 > M 4.0 in 2009) and Holocene sediments offset or disrupted along rare exposed active fault segments are evidence for ongoing tectonism in the northwest plains, the surface topography of which is remarkably flat and even. Because the geology underlying the late Quaternary alluvial fan deposits that carpet most of the plains is not established, the detailed tectonic evolution of this region and the potential for larger earthquakes is only poorly understood. To address these issues, we have processed and interpreted high-resolution (2.5 m subsurface sampling interval) seismic data acquired along lines strategically located relative to extensive rock exposures to the north, west, and southwest and rare exposures to the east. Geological information provided by these rock exposures offer important constraints on the interpretation of the seismic data. The processed seismic reflection sections image a variably thick layer of generally undisturbed younger (i.e., < 24 ka) Quaternary alluvial sediments unconformably overlying an older (> 59 ka) Quaternary sedimentary sequence that shows evidence of moderate faulting and folding during and subsequent to deposition. These Quaternary units are in unconformable contact with Late Cretaceous-Tertiary interbedded sedimentary and volcanic rocks that are highly faulted, folded, and tilted. The lowest imaged unit is largely reflection-free Permian Triassic basement rocks. Quaternary-age deformation has affected all the rocks underlying the younger alluvial sediments, and there is evidence for ongoing deformation. Eight primary and numerous secondary faults as well as a major anticlinal fold are revealed on the seismic sections. Folded sedimentary and volcanic units are observed in the hanging walls and footwalls of most faults. Five of the primary faults represent plausible extensions of mapped faults, three of which are active. The major anticlinal fold is the probable continuation of known active structure. A magnitude 7.1 earthquake occurred on 4 September 2010 near the southeastern edge of our study area. This predominantly right-lateral strike-slip event and numerous aftershocks (ten with magnitudes >= 5 within one week of the main event) highlight the primary message of our paper: that the generally flat and topographically featureless Canterbury Plains is underlain by a network of active faults that have the potential to generate significant earthquakes.

Geochemical and geothermal study of springs in the Ossola-Simplon Region

Geological, hydrogeological and geochemical surveys were carried out in the Piedilago area (Ossola-Simplon region) in order to investigate the geothermal resources present in this area. Following these surface exploration efforts an exploratory geothermal well of 248 m was drilled in 1991. It discharges a thermal water with temperatures up to 43 degrees C and calcium (sodium) sulphate composition with a TDS close to 1350 mg/l. Chemical geothermometers suggest a reservoir temperature close to 45 degrees C indicating that the well virtually produces the pure uncooled thermal water. The Piedilago ex-ample is here considered as the departure point to establish both general criteria for further geothermal investigations in young mountains chains and taking into consideration all the available data on geology and fluid geochemistry of thermal systems in the Ossola-Simplon region, to constrain a geothermal model for the Lower Pennine Zone.

Origin of mineralizing fluids of the sediment-hosted Navachab gold mine, Namibia: Constraints from stable (O, H, C, S) isotopes

The Navachab gold mine in the Damara belt of central Namibia is characterized by a polymetallic Au-Bi-As-Cu-Ag ore assemblage, including pyrrhotite, chalcopyrite, sphalerite, arsenopyrite, bismuth, gold, bismuthinite, and bismuth tellurides. Gold is hosted by quartz sulfide veins and semimassive sulfide lenses that are developed in a near-vertical sequence of shelf-type metasedimentary rocks, including marble, calcsilicate rock, and biotite schist. The sequence has been intruded by abundant syntectonic lamprophyre, aplite, and pegmatite dikes, documenting widespread igneous activity coeval with mineralization. The majority of quartz from the veins has delta(18)O values of 14 to 15 per mil (V-SMOW). The total variations in delta(18)O values of the biotite schist and calcsilicate rock are relatively small (12-14 parts per thousand), whereas the marble records steep gradients in delta(18)O values (17-21 parts per thousand), the lowest values being recorded at the vein margins. Despite this, there is no correlation between delta(18)O and delta(13)C values and the carbonate content of the rocks, indicating that fluid-rock interaction alone cannot explain the isotopic gradients. In addition, the marble records increased delta(13)C values at the contact to the veins, possibly related to a change in the physicochemical conditions during fluid-rock interaction. Gold is interpreted to have precipitated in equilibrium with metamorphic find (delta(18)O 12-14 parts per thousand; delta D = -40 to -60 parts per thousand) at peak metamorphic conditions of ca. 550 degrees C and 2 kbars, consistent with isotopic fractionations between coexisting calcite, garnet, and clinopyroxene in the alteration halos. The most likely source of the mineralizing fluid was a midcrustal fluid in equilibrium with the Damaran metapelites that underwent prograde metamorphism at amphibolite- to granulite-facies grades. Although there is no isotopic evidence for the contribution of magmatic fluids, they may have been important in contributing to the overall hydraulic regime and high apparent geothermal gradients (ca. 80 degrees C/km(-1)) in the mine area.

Die Töpferin und der Schmied : Basel-Gasfabrik, Grabung 1989/5

RésuméDie Grabung 1989/5 der Archäologischen Bodenforschung Basel-Stadt im Zentrum der Siedlung Basel-Gasfabrik umfasste eine Fläche von etwa 900 m2. Auf etwa 370 m2 konnten intakte latènezeitliche Strukturen festgestellt werden. Der ehemalige Gehhorizont und die darunter liegende Siedlungsschicht waren jedoch nirgends erhalten geblieben.Die in den gewachsenen Boden eingetieften Pfostengrub en erlaubten die Rekonstrulction von zwei rechteckigen Häusern mit je vier Eckpfosten, die als Wohngebäude gedeutet werden.Über das ganze Areal verteilt wurden 14 Gruben unterschiedlicher Form und Grösse ganz oder teilweise ausgegraben. Bei der flachen Grube 261 handelt es sich wohl um den eingetieften Bereich eines kleinen Grubenhauses, das für nicht näher bestimmbare handwerkliche Aktivitäten genutzt wurde. Die beiden mit einem Pfostenbau überdeckten Gruben 258 und 259 können hingegen mit grosser Wahrscheinlichkeit als Schmiedegruben gedeutet werden. In Grube 258 waren gar die Reste von zwei Feuerstellen und der Unterbau eines kaminartigen Abzugs in situ erhalten. Die Gruben 253, 254A, 254B, 255,256 und 257 mit Resten von Lehmausideidungen dienten vermutlich als Getreidesilos. Sie liegen alle im Zentrum des Grabungsareals im Bereich einer anstehenden Lehmschicht. Bei einigen weiteren Gruben könnte es sich um Keller handeln.Im Westen der Grabungsfläche kamen die Heizkanäle von zwei Töpferöfen zum Vorschein. Es handelt sich um einfache Kuppelöfen mit gegenständiger Feuerung. In geringer Entfernung lagen drei kleine Gruben, die vielleicht zur Aufbereitung des Töpferlehms dienten. Aufgrund der klimatischen Verhältnisse ist mit einem saisonalen Betrieb der Töpferöfen während der Sommermonate zu rechnen. Die notwendigen Arbeiten wurden mit grosser Wahrscheinlichkeit von Frauen ausgeführt, da die Männer während dieser Jahreszeit in der Landwirtschaft beschäftigt waren. Der Töpfereibetrieb produzierte grössere Serien scheibengedrehter, reduzierend gebrannter Feinkeramik, von der im Bereich der Öfen zahlreiche Scherben gefunden wurden.Die räumliche Organisation der Bebauung zeugt von einer einheitlichen und wohl kontinuierlichen Nutzung der Grabungsfläche. ImWesten gruppieren sich Haus 1 und die Einrichtungen des Töpfereibetriebs um eine unbebaute Hofzone. Nach Osten zu folgt dann die Zone mit den Getreidesilos. Das östliche Bauensemble besteht aus Haus 2, den Schmiedegruben, dem Grubenhaus sowie einer mutmasslichen Kellergrube. Stratigra-phische Überschneidungen von Befunden sind nur im Bereich der Töpferöfen vorhanden.Die Grubenfüllungen erwiesen sich als sehr fundreich. Die gegen 20000 Keramikscherben repräsentieren das gesamte Spektrum der aus Basel-Gasfabrik bekannten einheimischen Grobund Feinkeramik. Bei den seltenen Scherben von Graphittonkeramik handelt es sich um Importe aus dem ostkeltischen Bereich.Die zahlreichen Amphorenscherben stammen von mindestens 35 verschiedenen Gefässindividuen des Typs Dressel 1A, von denen aber immer nur ein kleiner Prozentsatz vorhanden war. Die Typologie und die Datierung der Befunde zeigen, dass der Amphorenimport erst im Laufe von LT D1 einsetzte.Unter den Kleinfunden verdienen die zahlreichen Silber- und Potinmünzen sowie die Glasfunde besondere Erwähnung. Das Fragment eines möglicherweise latènezeitlichen Glasgefässes stammt leider aus einem unsicheren Fundzusammenhang.Die über 70 Fibeln und Fibelteile sind zu 70% aus Bronze gefertigt. Das Fibelspektrum wird von den Nauheimer Fibeln dominiert. Besonders bei den Eisenfibeln konnten aber auch typologisch ältere Typen identifiziert werden, welche in die Stufen LT C2 und LT D1a gehören. Bei den Glasarmringen machen mittellatènezeitliche Typen gegen 20 % der Fundmenge aus.Von besonderer Bedeutung sind die 23 Menschenknochen von 19 verschiedenen Individuen. Es handelt sich dabei um einen fast vollständigen Schädel, Schädelteile und Fragmente von Langknochen sowie wenige weitere Skelettteile. Die Zusammensetzung des Ensembles und der Zustand der Einzelknochen lässt sich sehr gut mit den Menschenknochen aus den Altgrabungen von Basel-Gasfabrik und aus Manching vergleichen. Eine detaillierte Untersuchung zeigt, dass die Knochen am Ende eines langwierigen Totenrituals, das aufgrund ethno - logischer Vergleiche als mehrstufige Bestattung bezeichnet werden kann, in der Siedlung vergraben wurden. In der Umgebung der Menschenknochen wurden in einigen Fällen auffallend viele Amphorenscherben gefunden, die bezeugen, dass der importierte Wein bei diesen Riten eine bedeutende Rolle spielte. Wahrscheinlich wurden diese Knochen auch als Ahnenrelikte verehrt.Neben den mehrstufigen Bestattungen konnten auch zwei Säuglingsbestattungen identifiziert werden.Die Analyse von Fundmenge und Fundverteilung in den Gruben zeigt, dass die Funde nicht direkt, sondern auf dem Umweg über primäre Deponien in die Gruben gelangten. In den pri-mären Deponien wurden Funde über längere Zeit akkumuliert und mit verschiedenen Erdmaterialien intensiv vermischt.Für den Grossteil der Funde wird eine profane Deutung als Abfälle vorgeschlagen. Daneben können aber auch einige Funde als gezielte Deponierungen angesprochen werden. Ver-schiedene Fibelpaare und wahrscheinlich auch Münzen wurden wohl als Opfergaben in die Gruben gegeben. Ein Zusammenhang dieser Opfergaben mit den Bestattungen von Men-schenknochen ist nicht erkennbar.Die Datierung der Funde zeigt einen Siedlungsbeginn in LT C2 und ein Ende noch vor dem Beginn der Stufe LT D2. Die Kombination dieser Datierungen mit den stratigraphischen Überschneidungen einiger Befunde erlaubt eine Rekonstruktion der Besiedlungsentwicklung auf dem Grabungsareal. Die Gruben 259 und 260 wurden bereits in LT C2 verfüllt, die Schmiedegrube 259 anschliessend durch Grube 258 ersetzt. Die beiden Töpferöfen waren nacheinander in LT D1 in Betrieb. Die beiden Häuser können leider nicht genauer datiert werden.Die Besiedlung des Area's setzte noch vor 150 V. Chr. ein und dauerte maximal 80 Jahre.Die Synthese aller Untersuchungen zeigt, dass auf dem Grabungsareal eine Gruppe von etwa 15 Personen ansässig war, die sich v. a. der Landwirtschaft widmete. Die handwerkliche Tätigkeit (Töpferei, Metallverarbeitung) erreichte keinen vollberuflichen Standard.Die dörfliche Siedlungsgemeinschaft bestand aus bäuerlichen Selbstversorgern, mit anderen Gemeinschaften wurden jedoch Keramik, Handwerksprodukte und Schlachtvieh ausge-tauscht. Von besonderer Bedeutung war offenbar das Getreide, das in grossen Mengen in der Siedlung gelagert wurde und mit grosser Wahrscheinlichkeit für den Export bestimmt war. Die Herkunft dieses Getreides und die sozialen Strukturen hinter diesem Austausch sind nicht ldar, aber mit hoher Wahrscheinlichkeit wurden durch den Getreideexport die Importe wie Salz, Rohstoffe (Metall) und Wein ermöglicht.

Morphostructural analysis of an alpine debris flows catchment: implication for debris supply

Rock slope instabilities are implicitly linked to the supply of sediment and debris recharging channels prone to debris flow. Hence, the incorporation of bedrock structure and terrain morphology can be relevant in the analysis of sediment budget and debris flow hazard assessment. Here, the mode of debris production of the Manival catchment (northern French Alps) is documented by the study of its morphostructural aspects extracted from high resolution DEM. Terrain implication in the process of debris supply is evaluated by: a) A systematic classification of the major morphological units based on the slope gradient that enables a spatial analysis of zones of debris production and deposition. b) A detailed structural analysis performed on DEM in order to identify potential unstable slopes. c) An analysis of the gullies orientation that informs in term of structural control of the sources zones. d) Localisation of high density joints sets that document about whether sources of continuous debris production are controlled by the structural setting of the catchment. These DEM-based indicators can be used as proxies for assessing the influences of the current topography and enable to quantify a degree of susceptibility to mass wasting and hillslope erosion activity. This present contribution suggests some directions for characterizing sediment flux dynamic in small alpine catchment.