Contribución al estudio de la diagénesis de los carbonatos sedimentarios

[ES] En la formación de los carbonatos marinos magnesita y dolomita, nacidos al borde del mar en lagunas, limanes o albuferas, intervienen factores ciimáticos cuya importancia era hasta ahora apenas conocida El proceso genético es, sin embargo, largo y aun desconocido en su mayor parte. El término "diagénesis" abarca todo este proceso.[EN] In the formation of the marine magnesita and dolomita carbonates come forth at the border of the sea in lagoons limans and lagunes climatic factors interevene, the tatice of which was hardly know up to now. The genetic process is, however, long and still unknow in its greater part. The word "diagenesis" comprises this whole process.Peer reviewe

Holocene and ‘Little Ice Age’ glacial activity in the Marboré Cirque, Monte Perdido Massif, Central Spanish Pyrenees

The Marboré Cirque, which is located in the southern Central Pyrenees on the north face of the Monte Perdido Peak (42°40′0″N; 0.5°0″W; 3355 m), contains a wide variety of Holocene glacial and periglacial deposits, and those from the ‘Little Ice Age’ (‘LIA’) are particularly well developed. Based on geomorphological mapping, cosmogenic exposure dating and previous studies of lacustrine sediment cores, the different deposits were dated and a sequence of geomorphological and paleoenvironmental events was established as follows: (1) The Marboré Cirque was at least partially deglaciated before 12.7 kyr BP. (2) Some ice masses are likely to have persisted in the Early Holocene, although their moraines were destroyed by the advance of glaciers during the Mid Holocene and ‘LIA’. (3) A glacial expansion occurred during the Mid Holocene (5.1 ± 0.1 kyr), represented by a large push moraine that enclosed a unique ice mass at the foot of the Monte Perdido Massif. (4) A melting phase occurred at approximately 3.4 ± 0.2 and 2.5 ± 0.1 kyr (Bronze/Iron Ages) after one of the most important glacial advances of the Neoglacial period. (5) Another glacial expansion occurred during the Dark Age Cold Period (1.4–1.2 kyr), followed by a melting period during the Medieval Climate Anomaly. (6) The ‘LIA’ represented a clear stage of glacial expansion within the Marboré Cirque. Two different pulses of glaciation were detected, separated by a short retraction. The first pulse occurred most likely during the late 17th century or early 18th century (Maunder Minimum), whereas the second occurred between 1790 and ad 1830 (Dalton Minimum). A strong deglaciation process has affected the Marboré Cirque glaciers since the middle of the 19th century. (7) A large rock avalanche occurred during the Mid Holocene, leaving a chaotic deposit that was previously considered to be a Late Glacial moraine. © The Author(s) 2014.This work was supported by HORDA (ref: 83/2009), funded by the Organismo Autónomo de Parques Nacionales, and by INDICA (CGL2011-27753-C02-01 and -02) and CGL2012-35858, funded by the Spanish Ministry of Economy and Competitiveness. Financial support for the Research Group on Geomorphology and Global Change was provided by the Aragón Government and the European Social Fund (ESF-FSE).Peer Reviewe