| Titre | A new geological map of the Lau Basin (southwestern Pacific Ocean) reveals crustal growth processes in arc-backarc systems |
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| Auteur | Stewart, M S; Hannington, M D; Emberley, J; Baxter, A T; Krätschell, A; Petersen, S; Brandl, P A; Anderson, M O; Mercier-Langevin, P; Mensing, R; Breker, K; Fassbender, M L |
| Source | Geosphere vol. 18, no. 2, 2022 p. 910-943, https://doi.org/10.1130/GES02340.1  Accès ouvert |
| Image |  |
| Année | 2022 |
| Séries alt. | Ressources naturelles Canada, Contribution externe 20220098 |
| Éditeur | The Geological Society of America |
| Document | publication en série |
| Lang. | anglais |
| DOI | https://doi.org/10.1130/GES02340.1 |
| Media | papier; numérique; en ligne |
| Formats | pdf |
| Lat/Long OENS | -180.0000 -172.0000 -14.0000 -22.0000 |
| Sujets | techniques de cartographie; lithostratigraphie; bathymétrie; levés géophysiques; stratigraphie |
| Illustrations | cartes géologiques généralisées; cartes de localisation |
| Diffusé | 2022 02 11 |
| Résumé | (disponible en anglais seulement)
A 1:1,000,000-scale lithostratigraphic assemblage map of the Lau Basin (southwestern Pacific Ocean) has been created using remote predictive mapping (RPM)
techniques developed by geological surveys on land. Formation-level geological units were identified in training sets at scales of 1:100,000-1:200,000 in different parts of the basin and then extrapolated to the areas where geological data are
sparse. The final compilation is presented together with a quantitative analysis of assemblage-level crustal growth based on area-age relationships of the assigned units. The data sets used to develop mapping criteria and an internally consistent
legend for the compilation included high-resolution ship-based multibeam, satellite- and ship-based gravity, magnetics, seafloor imaging, and sampling data. The correlation of units was informed by published geochronological information and kinematic
models of basin opening. The map covers >1,000,000 km2 of the Lau-Tonga arc-backarc system, subdivided into nine assemblage types: forearc crust (9% by area), crust of the active volcanic arc (7%), backarc rifts and spreading centers (20%),
transitional arc-backarc crust (13%), relict arc crust (38%), relict backarc crust (8%), and undivided arc-backarc assemblages (<5%), plus oceanic assemblages, intraplate volcanoes, and carbonate platforms. Major differences in the proportions of
assemblage types compared to other intraoceanic subduction systems (e.g., Mariana backarc, North Fiji Basin) underscore the complex geological makeup of the Lau Basin. Backarc crust formed and is forming simultaneously at 12 different locations in
the basin in response to widely distributed extension, and this is considered to be a dominant pattern of crustal accretion in large arc-backarc systems. Accelerated basin opening and a microplate breakout north of the Peggy Ridge has been
accommodated by seven different spreading centers. The result is an intricate mosaic of small intact assemblages in the north of the basin, compared to fewer and larger assemblages in the south. Although the oldest rocks are Eocene (~40 m.y. old
basement of the Lau and Tonga Ridges), half of the backarc crust in the map area formed within the last 3 m.y. and therefore represents some of the fastest growing crust on Earth, associated with prolific magmatic and hydrothermal activity. These
observations provide important clues to the geological evolution and makeup of ancient backarc basins and to processes of crustal growth that ultimately lead to the emergence of continents. |
| Sommaire | (Résumé en langage clair et simple, non publié)
Cette publication présente une carte géologique détaillée du Bassin de Lau (Pacifique Sud-Ouest, Tonga) et décrit également les méthodes
utilisées pour la cartographie à un niveau de détail sans précédent de la géologie du fond océanique. Une analyse quantitative des principales unités géologiques et du taux de croissance crustale est aussi présentée. |
| GEOSCAN ID | 330169 |
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