A critical examination of evidence used to re-interpret the Hornitos mega-breccia as a mass-flow deposit caused by cliff failure

The mega-breccia at Homitos, northern Chile, was recently re-interpreted as a mass flow deposit caused by cliff failure, without any link to a tsunami backwash or the Eltanin meteorite impact at 2.5 Ma. While agreeing with the latter in the light of new microbiological data, it is here argued that m...

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Autor principal:	Le Roux,Jacobus P
Lenguaje:	English
Publicado:	Servicio Nacional de Geología y Minería (SERNAGEOMIN) 2015
Materias:	Eltanin Tsunami Mass flow Sedimentary dykes Rip-up mega-clasts Foraminifer index fossils
Acceso en línea:	http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-71062015000100008
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spelling	oai:scielo:S0718-710620150001000082015-03-12A critical examination of evidence used to re-interpret the Hornitos mega-breccia as a mass-flow deposit caused by cliff failureLe Roux,Jacobus P Eltanin Tsunami Mass flow Sedimentary dykes Rip-up mega-clasts Foraminifer index fossils The mega-breccia at Homitos, northern Chile, was recently re-interpreted as a mass flow deposit caused by cliff failure, without any link to a tsunami backwash or the Eltanin meteorite impact at 2.5 Ma. While agreeing with the latter in the light of new microbiological data, it is here argued that mass flow can also be caused by tsunami backwash events and would be difficult to distinguish from those caused by gravity alone, especially as the Hornitos outcrop is of limited extent. However, a mechanism for downward dyke injection can be postulated for tsunami-related mass flows, but would not be applicable to normal debris flows generated by cliff collapse. The new age range of the Portada Formation coincides with similar deposits at Carrizalillo, Ranquil, Caldera and possibly Caleta Verde, suggesting that one or more mega-tsunamis might have struck the Chilean coastline during the Messinian.info:eu-repo/semantics/openAccessServicio Nacional de Geología y Minería (SERNAGEOMIN)Andean geology v.42 n.1 20152015-01-01text/htmlhttp://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-71062015000100008en10.5027/andgeoV42n1-a08
institution	Scielo Chile
collection	Scielo Chile
language	English
topic	Eltanin Tsunami Mass flow Sedimentary dykes Rip-up mega-clasts Foraminifer index fossils
spellingShingle	Eltanin Tsunami Mass flow Sedimentary dykes Rip-up mega-clasts Foraminifer index fossils Le Roux,Jacobus P A critical examination of evidence used to re-interpret the Hornitos mega-breccia as a mass-flow deposit caused by cliff failure
description	The mega-breccia at Homitos, northern Chile, was recently re-interpreted as a mass flow deposit caused by cliff failure, without any link to a tsunami backwash or the Eltanin meteorite impact at 2.5 Ma. While agreeing with the latter in the light of new microbiological data, it is here argued that mass flow can also be caused by tsunami backwash events and would be difficult to distinguish from those caused by gravity alone, especially as the Hornitos outcrop is of limited extent. However, a mechanism for downward dyke injection can be postulated for tsunami-related mass flows, but would not be applicable to normal debris flows generated by cliff collapse. The new age range of the Portada Formation coincides with similar deposits at Carrizalillo, Ranquil, Caldera and possibly Caleta Verde, suggesting that one or more mega-tsunamis might have struck the Chilean coastline during the Messinian.
author	Le Roux,Jacobus P
author_facet	Le Roux,Jacobus P
author_sort	Le Roux,Jacobus P
title	A critical examination of evidence used to re-interpret the Hornitos mega-breccia as a mass-flow deposit caused by cliff failure
title_short	A critical examination of evidence used to re-interpret the Hornitos mega-breccia as a mass-flow deposit caused by cliff failure
title_full	A critical examination of evidence used to re-interpret the Hornitos mega-breccia as a mass-flow deposit caused by cliff failure
title_fullStr	A critical examination of evidence used to re-interpret the Hornitos mega-breccia as a mass-flow deposit caused by cliff failure
title_full_unstemmed	A critical examination of evidence used to re-interpret the Hornitos mega-breccia as a mass-flow deposit caused by cliff failure
title_sort	critical examination of evidence used to re-interpret the hornitos mega-breccia as a mass-flow deposit caused by cliff failure
publisher	Servicio Nacional de Geología y Minería (SERNAGEOMIN)
publishDate	2015
url	http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-71062015000100008
work_keys_str_mv	AT lerouxjacobusp acriticalexaminationofevidenceusedtoreinterpretthehornitosmegabrecciaasamassflowdepositcausedbyclifffailure AT lerouxjacobusp criticalexaminationofevidenceusedtoreinterpretthehornitosmegabrecciaasamassflowdepositcausedbyclifffailure
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A critical examination of evidence used to re-interpret the Hornitos mega-breccia as a mass-flow deposit caused by cliff failure

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