3/31/2021 0 Comments Miracle Box 2.49 Surumu Indir
T he Tonila fa ilure ap pears t o represe nt an anom alous ev ent rela ted to the p articu lar clim atic cond itions at the tim e of the colla pse.Sulpizio Universit degli Studi di Bari Aldo Moro Gianluca Norini Italian National Research Council Download full-text PDF Read full-text Download full-text PDF Read full-text Download citation Copy link Link copied Read full-text Download citation Copy link Link copied Citations (64) References (54) Figures (14) Abstract and Figures Throughout its history, Colima Volcano has experienced numerous partial edifice collapses with associated emplacement of debris avalanche deposits of contrasting volume, morphology and texture.A detailed stratigraphic study in the south-eastern sector of the volcano allowed the recognition of two debris avalanche deposits, named San Marcos ( 28,000 cal yr BP, V 1.3 km3) and Tonila (15,00016,000 cal yr BP, V 1 km3 ).
This work sheds light on the pre-failure conditions of the volcano based primarily on a detailed textural study of debris avalanche deposits and their associated pyroclastic and volcaniclastic successions. ![]() The 28,000 cal yr BP San Marcos collapse was promoted by edifice steep flanks and ongoing tectonic and volcanotectonic deformation, and was followed by a magmatic eruption that emplaced pyroclastic flow deposits. In contrast, the Tonila failure occurred just after the Last Glacial Maximum (22,00018,000 cal BP) and, in addition to the typical debris avalanche textural characteristics (angular to sub-angular clasts, coarse matrix, jigsaw fit) it shows a hybrid facies characterized by debris avalanche blocks embedded in a finer, homogenous and partially cemented matrix, a texture more characteristic of debris flow deposits. The Tonila debris avalanche is directly overlain by a 7-m thick hydromagmatic pyroclastic succession. Massive debris flow deposits, often more than 10 m thick and containing large amounts of tree trunk logs, represent the top unit in the succession. Fluvial deposits also occur throughout all successions; these represent periods of highly localized stream reworking. All these lines of evidence point to the presence of water in the edifice prior to the Tonila failure, suggesting it may have been a weakening factor. The Tonila failure appears to represent an anomalous event related to the particular climatic conditions at the time of the collapse. The presence of extensive water at the onset of deglaciation modified the mobility of the debris avalanche, and led to the formation of a thick sequence of debris flows. Aster image showing the location of the Jalisco and Michoacan blocks and the Colima Volcanic Complex in the Colima Graben. Shadow relief image showing the distribution of the San Marcos (SM-DAD, blue broken-line) and Tonila (T-DAD, red broken-line) debris avalanche deposits as well as main study sites. White dots indicate the outcrops location, numbers indicate the outcrops mentioned in the text. Photograph and schematic column of section Pcr53 where San Marcos debris avalanche (SM-DAD a) is overlaid by pyroclatic sequences (c, d, f, g) and reworked material (b, e). SM-DAD presents in clast-rich matrix facies (crMF) with fragments ranging in size from a few centimeters to meters and with a small matrix fraction. In contrast, the T-DAD presents in Matrix facies (MF) with clasts smaller that 0.25 m. Figures - uploaded by Matteo Roverato Author content All figure content in this area was uploaded by Matteo Roverato Content may be subject to copyright. Miracle Box 2.49 Surumu Indir Free Public FullDiscover the worlds research 20 million members 135 million publications 700k research projects Join for free Public Full-text 1 Content uploaded by Matteo Roverato Author content All content in this area was uploaded by Matteo Roverato on Jul 11, 2018 Content may be subject to copyright. Furthermore, we show how the climate at the time of the Tonila collapse in uenced t he failu re mecha nisms. Th e N 28,000 cal yr BP San Marcos collapse was promoted by edi ce steep anks and ongoing tectonic and volcanotectonic deformation, and was followed by a magmat ic erupti on that empl aced pyro clastic ow deposits. In contrast, the Tonila failure occurred just after the Last Glac ial Maximu m (22,000 18,000 cal BP) and, in add ition to the typ ical debris av alanch e textural characteristics (angular to sub-angular clasts, coarse matrix, jigsaw t) it shows a hybrid facies characteriz ed by debris av alanch e blocks embe dded in a ner, homoge nous an d partia lly cemen ted matr ix, a text ure mor e character istic of debris ow deposits. Th e Tonila debri s avalanche is dir ectly overl ain by a 7-m thick hydromagmatic pyroclastic succession. ![]() Fluvial deposits also occur throughout all successions; these represent periods of highly localized st ream reworking. All these lines of evidence point to the presence of water in the edi ce prio r to the To nila fai lure, su ggestin g it may hav e been a wea kening f actor.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |