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| Titel |
Geochemical evidence of past earthquakes in sediments of the Reloncavi fjord (Chilean Patagonia) during the last ∼1000 years |
| VerfasserIn |
Lorena Rebolledo, Carina Lange, Práxedes Muñoz, Marco Salamanca |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250099759
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| Publikation (Nr.) |
 EGU/EGU2014-15574.pdf |
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| Zusammenfassung |
| The Chilean fjords are excellent archives of paleoearthquakes, tsunamis and landslides
(St-Onge et al., 2012 in Sedimentary Geology 243-244: 89–107). Here we report on new
sedimentological and geochemical evidence of past earthquakes in sediments of the
Reloncavi fjord, Northern Patagonia (41°S, 72°W), during the last ~1000 years. We
recovered four sediment cores from the Reloncaví fjord (RH-5B, RH-5C, RH-6B, RH7B,
water depth range = 90–260 m; core length range = 45–75 cm). Age models were based on
210Pb, AMS-14C and the first appearance of the diatom Rhizosolenia setigera cf. pungens
in the fossil record as statigraphic marker. The cores span the last ~122 to 800
years of sedimentation with sedimentation rates ranging between 0.1 and 0.24 cm
yr-1.
The cores revealed evidence of turbidites associated with the historical earthquakes of
1960, 1837, 1737 and 1575 AD, and an earlier period for which there is no historical
information, 1200–1400 AD. The turbidites exhibit a grading-up pattern with sand layers, and
are characterized by a decrease in organic carbon and biogenic opal, an increase in the C/N
molar ratio, negative values of δ13Corg(average -27),and an increase in the relative
abundance of Paralia sulcata, a diatom associated with sandy environments, being the turbite
layers mainly freshwater in origen.
We suggest that these turbidite layers were triggered by past earthquakes that produced
movement of land from the cliff areas that surround the Reloncaví fjord.
Funding: Project FONDECYT # 11110103 and COPAS Sur-Austral project PFB-31. |
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