Search results for "IMU"
showing 10 items of 16028 documents
Evaluación de los procesos superficiales de escorrentía en cárcavas originadas en olivares convencionales. Un apartado a tener en cuenta en la planif…
2019
RESUMEN Se analiza la respuesta hidrológica de una cárcava efímera frente a un evento de lluvia equivalente de frecuencia "ordinaria" (=1 año) a partir de una simulación de escorrentía en una cuenca experimental con olivar en Puente Genil, Córdoba (España). Mil litros de agua fueron bombeados durante 10 minutos y la descarga total, la velocidad superficial de avance de frente de flujo, la concentración de sedimentos y los cambios morfológicos en el perfil transversal fueron calculados. Los resultados mostraron elevadas diferencias entre las tasas de escorrentía de hasta un 17% entre las condiciones "secas" y "húmedas". La concentración de sedimentos instantánea llegó a alcanzar valores de h…
Productivity modes in the Mediterranean Sea during Dansgaard–Oeschger (20,000–70,000 yr ago) oscillations
2013
The study of planktonic organisms during abrupt climatic variations of the last glacial period (Dansgaard-Oeschger oscillations, D-O) may reveal important insights on climatic, oceanographic and biological interactions. Here we present planktic foraminifera and coccolithophore data collected at the Ocean Drilling Program Site 963 (Sicily Channel), with a mean sampling resolution of respectively 43.5 and 98.9. yr, over the interval between 70,000 and 20,000. yr ago. The paleoenvironmental reconstruction suggests that three different scenarios can be seen across each D-O cycle: 1. oligotrophic surface water and a deep thermocline for the early Interstadials; 2. a Deep Chlorophyll Maximum and …
Age and sedimentary record of inland eolian sediments in Lithuania, NE European Sand Belt
2015
We present a study based on four inland eolian locations in Eastern, Central and Southeastern Lithuania belonging to the northeastern part of the ‘European Sand Belt’ (ESB). Although there have been several previous studies of the ESB, this north-eastern extension has not been investigated before in any detail. The sedimentary structural–textural features are investigated and a chronology was derived using optically stimulated luminescence on both quartz and feldspar. The sedimentary structures and the rounding and surface characteristics of the quartz grains argue for a predominance of eolian transport. Additionally, some structural alternations and a significant contribution of non-eolian…
Globorotalia truncatulinoides in Central - Western Mediterranean Sea during the Little Ice Age
2020
Abstract Globorotalia truncatulinoides oscillations have been recorded from different marine sediment cores collected in the central and western Mediterranean Sea. The abundances of this species over the last 500 yrs. demonstrates its potential value as bio-indicator of particular oceanographic condition during the Maunder Minimum (MM) event of the Little Ice Age (LIA). The comparison between the G. truncatulinoides abundance patterns of the Balearic Basin, central and south Tyrrhenian Sea and central and eastern Sicily Channel allows to highlight a similar response of this species during the MM event in the central-western Mediterranean Sea. The ecological meanings of this species and its …
Large-scale, millennial-length temperature reconstructions from tree-rings
2018
Supported by the German Science Foundation, grants # Inst 247/665-1 FUGG and ES 161/9-1. SSG acknowledges support by the Alexander von Humboldt Foundation, KJA by US National Science Foundation grants AGS-1501856 and NSF AGS-1501834, and JL and LS by the Belmont Forum and JPI-Climate, Collaborative Research Action INTEGRATE. Over the past two decades, the dendroclimate community has produced various annually resolved, warm season temperature reconstructions for the extratropical Northern Hemisphere. Here we compare these tree-ring based reconstructions back to 831 CE and present a set of basic metrics to provide guidance for non-specialists on their interpretation and use. We specifically d…
The north-eastern aeolian ‘European Sand Belt’ as potential record of environmental changes: A case study from Eastern Latvia and Southern Estonia
2016
Abstract The Latvian and Estonian inland dunes belong to the north-eastern part of the ‘European Sand Belt’ (ESB). These dunes are widely distributed over broad glaciolacustrine plains and Late Glacial alluvial deltas, considered to be potential sources for the aeolian material. Little is known about these aeolian sediments and their substratum; here we present a detailed sedimentary structural and textural characterisation together with a luminescence-based chronology. Through a comparison between grain-size, rounding of quartz grains and surface characteristics in medium/coarse (0.5–0.8 mm) sand, and the light mineral content, we found an alternation of aeolian and periglacial components.…
Summer air temperature, reconstructions from the last glacial stage based on rodents from the site Taillis-des-Coteaux (Vienne), Western France.
2014
AbstractThe oxygen isotope composition of phosphate from tooth enamel of rodents (δ18Op) constitutes a valuable proxy to reconstruct past air temperatures in continental environments. This method has been applied to rodent dental remains from three genera, Arvicola sp., Microtus sp. and Dicrostonyx sp., coming from Taillis-des-Coteaux, Vienne, France. This archaeological site contains an exceptionally preserved sedimentary sequence spanning almost the whole Upper Palaeolithic, including seven stratigraphic layers dated from 35 to 17 cal ka BP. The abundant presence of rodent remains offers the opportunity to quantify the climatic fluctuations coeval of the various stages of human occupation…
New tree-ring evidence for the Late Glacial period from the northern pre-Alps in eastern Switzerland
2018
Abstract The rate and magnitude of temperature variability at the transition from the Last Glacial Maximum into the early Holocene represents a natural analog to current and predicted climate change. A limited number of high-resolution proxy archives, however, challenges our understanding of environmental conditions during this period. Here, we present combined dendrochronological and radiocarbon evidence from 253 newly discovered subfossil pine stumps from Zurich, Switzerland. The individual trees reveal ages of 41–506 years and were growing between the Allerod and Preboreal (∼13′900–11′300 cal BP). Together with previously collected pines from this region, this world's best preserved Late…
Caribbean hydroclimate and vegetation history across the last glacial period
2019
Abstract We present a new speleothem trace element and stable isotope record, which extends previous paleoclimate evidence from Cuban speleothems to the last 96 ka. Multiple proxies were used to reconstruct Caribbean hydroclimate and vegetation variability on orbital to millennial timescales. In particular, our proxies indicate a shift to more abundant C4 (compared to C3) vegetation and/or reduced soil activity during the Last Glacial Maximum. Our results confirm the close link of Caribbean precipitation to North Atlantic climate variability, insolation and the strength of the AMOC. The associated variations in Caribbean SSTs and the shift of the ITCZ led to substantial changes of the hydro…
Human occupation and environmental change in the western Maghreb during the Last Glacial Maximum (LGM) and the Late Glacial. New evidence from the Ib…
2019
With the onset of the Last Glacial Maximum (LGM), hunter-gatherers of the so-called Iberomaurusian techno-complex appeared in what is now the Mediterranean Maghreb. During a period of about seven thousand years, these groups left sandy occupation layers in a limited number of archaeological sites, while at the beginning of Greenland Interstadial (GI) 1, the sudden shift towards the deposition of shell-rich sediments and the increase in number of sites document clear changes in subsistence strategies as well as occupation density. It is highly likely that these shifts in human behaviour are related to paleoenvironmental changes in the area, which, so far, are poorly documented in geological …