Filter Results
2458 results
The Chinese Altai in the Central Asian Orogenic Belt is characterized by the occurrence of kyanite- and andalusite-type metamorphic zones. However, the tectonic setting associated with these metamorphic zones is still debated. Here we present structural observations from the southern Chinese Altai (Aletai area), where a relict kyanite zone occurs within an andalusite-type metamorphic zonal sequence of sillimanite, andalusite-sillimanite, andalusite-staurolite, staurolite-garnet and biotite. We document two major phases of folding in this area. The earlier structures (D1) developed synchronously with kyanite growth and are represented by an axial planar fabric of tight folds. D1 fabric is mostly obliterated by later deformation, but is inferred to be penetrative as indicated by a profound intersection lineation (L21). The second generation of deformation (D2) is associated with superimposed F2 folds and a dominant axial planar foliation (S2) with ~NW–SE orientation. Microstructural observations show that D2 structures are associated with the andalusite-type metamorphic series, which is characterized by an early-D2 occurrence of sillimanite, staurolite-garnet and biotite zonal sequence overprinted by the late-D2 growth of andalusite. Combining with previous metamorphic data, we consider that these two folding events (D1 and D2) correspond with the development of kyanite- and andalusite-type metamorphic zones, respectively, which records the burial and exhumation history of metamorphic rocks possibly in response to Devonian-Carboniferous accretion/collision and Permian transpressional tectonics. The latter was associated with oblique convergence between the Chinese Altai and the intra-oceanic arc system of the East/West Junggar.
Data Types:
  • Geospatial Data
  • Image
  • Document
An assemblage of 500 (385 quartz and 115 chert) experimentally knapped artefacts, underwent human trampling over the course of two weeks by a team of 10–12 excavators wearing soft-soled shoes used while excavating in the rock shelter. Two zones of trampling were used: Zone 1, a high artefact density, low trampling intensity, and lower soil compaction and rockiness; and Zone 2, a low artefact density, high trampling intensity, higher soil compaction and rockiness. The primary questions were to understand the difference in fracture rates and types between the chert and quartz, and the difference between the zones of artefact density, trampling intensity, and soil density. The results have shown that significantly more quartz fractured and were damaged compared to chert, and for both materials there was significantly more breakage in the zone with the higher trampling intensity and higher soil compaction and rockiness. There was no discerned association between the original artefacts' size or weight and the occurrence of breakage of the quartz and chert artefacts, except for a very weak association for narrower and thinner quartz artefacts being more likely to break. Overall, there was relatively little horizontal or vertical movement of the artefacts over the two weeks, with the largest size ranges moving the most, but with no significant difference in the movement of artefacts amongst the smaller size ranges.
Data Types:
  • Geospatial Data
  • Image
  • Tabular Data
The study of wear marks on Palaeolithic quartz tools allows an understanding of how they were used. The present work reports a functional study of a sample of Mousterian quartz industry from Level F of the Navalmaíllo Rock Shelter (Pinilla del Valle, Madrid, Spain). This level, a palimpsest, preserves the remains of a Neanderthal occupation. Traceological inspection revealed the tools made at the site were very versatile.
Data Types:
  • Geospatial Data
  • Image
  • Tabular Data
Myxomycetes are heterotrophic eukaryote organisms that have three life stages, none of which are known to be resistant to fire. The response of myxobiota to different severity of fire is not well known either. We examined myxomycetes in Pinus mugo plantations following a crown fire and in Pinus sylvestris plantations following a surface fire during the first three years after the wildfire event in forested coastal sand dunes in western Lithuania. Additionally, we investigated myxomycetes in corresponding unburned stands. All studied sites (unburned and burned) bore rather different myxomycete assemblages but the disparities of the species compositions between both burn types were more pronounced showing that fire severity had stronger impact on myxomycete species composition than the pre-fire stand type. Analysis of myxomycete assemblages (including the results from field collections, bark and litter cultures) showed that surface fire sites bore the highest number of post-fire species compared to crown fire and unburned sites. Dynamic annual changes in species composition were observed in all studied sites but only crown fire plots showed a clear chronosequence of post-fire myxomycete assemblages. Fire impact promoted establishment and/or sporulation of myxomycete species that are rare in similar unburned stands, or are usually confined to other types of forests and substrata. In addition, individual myxomycete species tended to switch substratum usage during the course of vegetation succession, with a final return to their usual substrata. This possibly signaled the end of early stage of post-fire succession.
Data Types:
  • Geospatial Data
  • Image
  • Tabular Data
  • Document
This study compares the adult survivorship profiles of people interred in the Saint-Thomas d’Aizier leprosarium, estimated by cementochronology, to eight archaeological series in northern France dated from Late Antiquity to the Late Middle Ages, periods of significant visibility for Hansen's disease (leprosy). The goals are to understand the impact of leprosy on various social groups and to explore the cause of leprosy's decline by analyzing male and female fertility. Survival rates differed between medieval leprosy-free sites and the Saint-Thomas d’Aizier leprosarium, although this difference was statistically significant only for the female leprosarium sample. The selective female frailty, a consequence of social exclusion and the collapse of the quality of life, combined with the infertility of lepromatous couples, offer a multi-causal explanation to the end of the expansion and then decline of leprosy in southern and western European countries.
Data Types:
  • Geospatial Data
  • Image
  • Tabular Data
The objective of the present study is to test our general knowledge of sex-specific survival differences in past northern France societies by implementing the tooth cementum annulations method of age estimation (i.e., cementochronology) to bio-archaeological series. 1255 individual estimated ages at death covering a millennium from the 3rd c. AD to the 15th c. AD matched different patterns of sex mortality from the late Antiquity to the Late Middle Age. Female survival curves are consistently inferior to those of their male counterparts. Maternal mortality is clearly visible in survival curves between 20 and 50 years of age in individual sites and pooled samples. Variations of sex mortalities also affected sites with peculiar recruitment, such as religious communities, pathological samples, leprosaria, and migrants. Whisker plots of median ages at death variations confirmed in both sex that populations within the Early Middle Ages were better off compared to Late Antiquity and Late Medieval Ages when group inequalities prevailed. Due to its sensitivity and applicability to small samples, cementochronology should be extended to other series.
Data Types:
  • Geospatial Data
  • Image
  • Tabular Data
Although the impact of ash on the hydrological and erosive response of burned soils has been studied in the last years, the effect of ash wettability on particle detachment by splash erosion has been rarely studied. In this research, we have studied the effect of wettable and water-repellent ash on the intensity of splash erosion after a prescribed burn in a Mediterranean shrubland. Runoff rates from wettable and water-repellent ash layers were also studied by rainfall simulation experiments (6mmmin−1 during 10min) at plot scale. Splash erosion experiments showed that the intensity of ash water repellency strongly conditioned the detachment and mobilization of ash and soil particles due to raindrop impacts in the post-fire. Although the intensity of water repellency and the amount of ash decreased through the experimental period, it was observed that splash erosion in originally water-repellent ash areas was about three times higher than in wettable ash areas. Plot-scale rainfall simulation experiments showed that runoff rates were much higher in water-repellent ash areas, where runoff rates increase with decreasing depth of the ash layer. In water-repellent ash areas, thick ash layers store a significant proportion of water that does not infiltrate soil, but contributes to relatively low runoff rates. In contrast, thin water-repellent ash layers are rapidly redistributed by rainfall, and the burned mineral soil surface is exposed. Pore clogging with fine water-repellent ash particles enhances runoff rates. During low or moderate intensity storms, patches of wettable/water-repellent ash arrange in a pattern that produces water infiltration/runoff generation areas, reducing the connectivity of water and sediments through the slope.
Data Types:
  • Geospatial Data
  • Image
  • Tabular Data
The Archaean Yilgarn Craton (Western Australia) is a world-class metallogenic province, hosting considerable resources of Au, Ag, Ni, Cu, Zn and Fe. Here we present trace element compositions of pyrite from >30 orogenic Au and 5 volcanic hosted massive sulphide (VHMS) deposits across the Yilgarn. Pyrites from VHMS deposits tend to have higher Sn, Se, Cu, Pb, Bi and lower Ni relative to orogenic deposits. VHMS deposit pyrites commonly have Co>Ni, As>100Au, Te>Au, Se>Te. Orogenic gold deposits could be subdivided based on association of Au with As or Te. Pyrites from AuAs ores generally have Pb/Bi>5, Se/Te>5, Pb/Sb100 and the majority of Au is refractory (in pyrite structure). At the same time AuTe association pyrites are characterised by lower values of Pb/Bi, Se/Te and Tl/Te, higher values of Ag/Au, Pb/Sb and Au generally resides in inclusions of different compositions. Our data can be used at the exploration stage to distinguish between VHMS vs Orogenic Au signatures. For all studied deposits inclusion populations are summarised with implications for Au and Ag deportment. Orogenic Au deposits from the Yilgarn mostly have multistage formation histories reflected in the presence of multiple generations of pyrites. However, only some deposits record multiple high Au mineralisation events.
Data Types:
  • Geospatial Data
  • Image
  • Tabular Data
  • Document
Wildfire is a recurrent phenomenon in Mediterranean ecosystems and contributes to soil degradation and desertification, which are partially caused by alterations to soil organic matter (SOM). The SOM composition from a Cambisol under a Mediterranean forest affected by a wildfire is studied in detail in order to assess soil health status and better understand of soil recovery after the fire event. The soil was sampled one month and twenty-five months after the wildfire. A nearby unburnt site was taken as control soil. Soil rehabilitation actions involving heavy machinery to remove burnt vegetation were conducted sixteen months after the wildfire. Immediately after fire the SOM increased in topsoil due to inputs from charred vegetation, whereas a decrease was observed in the underlying soil layer. Twenty-five months after fire soil-pH increased in fire-affected topsoil due to the presence of ashes, a decrease in SOM content was recorded for the burnt topsoil and similar trend was observed for the water holding capacity. The pyro-chromatograms of burned soils revealed the formation of additional aromatic compounds. The thermal cracking of long-chain n-alkanes was also detected. Solid-state 13C NMR spectroscopy supported the increase of aromatic compounds in the fire-affected topsoil due to the accumulation of charcoal, whereas the deeper soil sections were not affected by the fire. Two years later, soil parameters for the unburnt and burnt sites showed comparable values. The reduction of the relative intensity in the aromatic C region of the NMR spectra indicated a decrease in the charcoal content of the topsoil. Due to the negligible slope in the sampling site, the loss of charcoal was explained by the post-fire restoration activity, degradation, leaching of pyrogenic SOM into deeper soil horizons or wind erosion. Our results support that in the Mediterranean region, fire-induced alteration of the SOM is not lasting in the long-term.
Data Types:
  • Geospatial Data
  • Image
  • Tabular Data
In recent decades the intensification of agricultural production in many European countries has been one of the key components of land-use change. The impact of agricultural intensification varies according to national and local contexts and a greater understanding of the drivers of intensification will help to mitigate against its negative impacts and harness potential benefits. This paper analyses changes in land use intensity in six case studies in Europe. A total of 437 landowners were interviewed and their responses were analysed in relation to changes in land use intensity and agricultural production between 2001 and 2011. In the case studies in Western and Eastern Europe we observed stabilisation during the last decade, and no clear tendency of increase or decrease of land use intensity. The use of fertilizers and pesticides seems to have decreased in our cases in Western Europe, which is contrary to trends in Eastern Europe. Agricultural production remained stable in almost all cases, except for an increase in Austria and Romania which may indicate that the farming efficiency has increased. A statistical analysis showed a division between study areas in Romania and Austria (increasing land use intensity) versus those in the Netherlands, Denmark and Greece (decreasing). In the Mediterranean cases we observe a process where agriculture is becoming increasingly marginalised, at the same time as changes in function with regard to urbanisation and recreational land uses have taken place. Logistic regression highlighted the importance of farm size and farmer type in understanding changes in land use intensity. The dominant pattern of stabilisation which has occurred over the past 10 years may also partly be a result of effective EU and national environmental and agricultural policies, which are increasingly concerned with improving environmental conditions in rural areas.
Data Types:
  • Geospatial Data
  • Image
  • Tabular Data
3