40 research outputs found
A Maastrichtian palaeomagnetic pole for the Pacific plate from a skewness analysis of marine magnetic anomaly 32
Assessing the age of relief growth in the Andes of northern Chile: Magneto-polarity chronologies from Neogene continental sections
The significance of Messinian occurrences of Globorotalia margaritae and Globorotalia puncticulata in Sicily
Pliocene extensional tectonics in the Eastern Central Patagonian Cordillera: geochronological constraints and new field evidence
Paleomagnetic polarity of the pyroclastic flow deposits from the Hakkoda Caldera, Northeast Japan
Radiolarian biostratigraphy from the Neogene Kuromatsunai Formation in the Imakane area, south-western Hokkaido, Japan
Notes on the systematics and biogeographical relationships of Antarctic and sub-Antarctic Rhodophyta with descriptions of four new genera and five new species
Faunal changes in Cenozoic deep-sea ostracod assemblages from the South Atlantic and the Southern Ocean and their palaeoceanographical implications
Tectonic Processes Along the Chile Convergent Margin
The Chile subduction zone, spanning more than 3500 km, provides a unique setting for studying, along a single plate boundary, the factors that govern tectonic processes at convergent margins. At large scale, the Chile trench is segmented by the subduction of the Chile Rise, an active spreading center, and by the Juan Fernández hot spot ridge. In addition, the extreme climatic change from the Atacama Desert in the north to the glacially influenced southern latitudes produces a dramatic variability in the volume of sediment supplied to the trench. The distribution of sediment along the trench is further influenced by the high relief gradients of the segmented oceanic lithosphere.
We interpret new and reprocessed multichannel seismic reflection profiles, and multibeam bathymetric data, to study the variability in tectonic processes along the entire convergent margin. In central and south Chile, where the trench contains thick turbidite infill, accretionary prisms, some 50–60 km wide, have developed. These prisms, however, are ephemeral and can be rapidly removed by high-relief, morphological features on the incoming oceanic plate. Where topographic barriers inhibit the transport of turbidites along the trench, sediment infill abruptly decreases to less than 1 km thick and is confined to a narrow zone at the trench axis. There, all sediment is subducted; the margin is extending by normal faulting and collapsing due to basal tectonic erosion. The transition from accretion to tectonic erosion occurs over short distances (a few tens of km) along the trench.
In the turbidite-starved northern Chile trench, ~1 km of slope debris reaches the trench and is subsequently subducted. There, tectonic erosion is causing pronounced steepening of the margin, associated pervasive extension across the slope and into the emerged coastal area, and consequent collapse of the overriding plate. The volume of subducting material varies little along much of the margin. However, the composition of the material varies from slope debris of upper-plate fragments and material removed from the upper plate by basal erosion, to turbidites derived from the Andes