Paleoseismic Observations of an Onshore Transform Boundary: the Magallanes-fagnano Fault, Tierra Del Fuego, Argentina
نویسنده
چکیده
We present preliminary information on the geomorphologic features and paleoseismic record associated with the ruptures of two Ms 7.8 earthquakes that struck Tierra del Fuego and the southernmost continental margin of South America on December 17, 1949. The fault scarp was surveyed in several places east of Lago Fagnano and a trench across a secondary fault trace of the Magallanes-Fagnano fault `was excavated at the Río San Pablo. The observed deformation in a 9 kyr-old peat bog sequence suggests evidence for two, and possibly three pre1949 paleoearthquakes is preserved in the stratigraphy. The scarp reaches heights up to 11 m in late Pleistocene-Holocene(?) deposits, but the vertical component of the 1949 events was always less than ~1 m. This observation also argues for the occurrence of previous events during the Quaternary. Along the part of the fault we investigated east of Lago Fagnano, the horizontal component of the 1949 rupture does not exceed 4 m and is likely lower than 0.4 m, which is consistent with the kinematics of a local releasing bend, or at the end of a strike-slip rupture zone.
منابع مشابه
Description of the Earliest Fossil Penguin from South America and First Paleogene Vertebrate Locality of Tierra Del Fuego, Argentina
We report the discovery of the first vertebrate from the Paleogene of Tierra del Fuego (Isla Grande), Argentina, in southernmost South America. The specimen consists of parts of an associated pelvic girdle and limb that are identified as belonging to the penguin stem clade (Aves: Pansphenisciformes). The specimen, from an exposure of the Leticia Formation (late middle Eocene), is the earliest k...
متن کاملVariations of Mesozooplankton Composition in a Eutrophicated Semi-enclosed System (encerrada Bay, Tierra Del Fuego, Argentina)
متن کامل
Teeth and Bones as Sources of DNA for Genetic Diversity and Sex Identification of Commerson’s Dolphins (Cephalorhynchus commersonii) from Tierra del Fuego, Argentina
Museum specimens are often the only source of genetic material for many species of cetaceans. Most of the protocols that have been developed to extract DNA from teeth and bone samples involve mechanical or chemical disintegration of the material. An alternative method to the mechanical reduction process is presented here for 212 Commerson’s dolphin (Cephalorhynchus commersonii) samples collecte...
متن کاملMicrobial planktonic communities of freshwater environments from Tierra del Fuego: dominant trophic strategies in lakes with contrasting features
JUAN F. SAAD1, M. ROMINA SCHIAFFINO1, ALICIAVINOCUR1,2, INÉS O’FARRELL1, GUILLERMO TELL1 AND IRINA IZAGUIRRE1* 1 DEPARTAMENTO DE ECOLOGÍA, GENÉTICA Y EVOLUCIÓN, FACULTAD DE CIENCIAS EXACTAS Y NATURALES, UNIVERSIDAD DE BUENOS AIRES, IEGEBA (CONICET-UBA), BUENOS AIRES C1428EHA, ARGENTINA AND DEPARTAMENTO DE BIODIVERSIDAD Y BIOLOGÍA EXPERIMENTAL, FACULTAD DE CIENCIAS EXACTAS Y NATURALES, UNIVERSID...
متن کاملNutrient cycling in Nothofagus pumilio forests along an altitudinal gradient in Tierra del Fuego, Argentina
Nothofagus pumilio (lenga) forests form monocultures from sea level to timberline in Tierra de Fuego, Argentina. Past studies suggested that the life form change from erect forest to krummholz had advantages to forest function. Aboveground net primary productivity (NPP) and organic matter production per unit leaf area and growing season day were higher in krummholz than in adjacent short erect ...
متن کامل