Long-term evolution of subduction zones and the development of wide magmatic arcs
Late Mesozoic-Cenozoic igneous rocks cover a large area in southwestern United States and northern Mexico, which extends over several provinces with contrasting structural and petrotectonic characteristics and lithospheric structure. Chemical and petrographic data show magmatic arc affinities, parti...
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| Format: | Article |
| Language: | English |
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Universidad Nacional Autónoma de México, Instituto de Geofísica
1997-02-01
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| Series: | Geofísica Internacional |
| Subjects: | |
| Online Access: | http://www.geofisica.unam.mx/unid_apoyo/editorial/publicaciones/investigacion/geofisica_internacional/anteriores/1997/02/urrutia.html |
| _version_ | 1827882632128495616 |
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| author | Ofelia Morton-Bermea Jaime Urrutia-Fucugauchi |
| author_facet | Ofelia Morton-Bermea Jaime Urrutia-Fucugauchi |
| author_sort | Ofelia Morton-Bermea |
| collection | DOAJ |
| description | Late Mesozoic-Cenozoic igneous rocks cover a large area in southwestern United States and northern Mexico, which extends over several provinces with contrasting structural and petrotectonic characteristics and lithospheric structure. Chemical and petrographic data show magmatic arc affinities, particularly for the calc-alkaline suites, supporting a genetic link with the plate convergence process between the North American and the Farallon and Kula plates. However, the width of the magmatic arc (in excess of 1100 km) and the trench-arc gap (estimated from paleogeographic reconstructions) are in marked contrast when compared to the ranges observed in contemporary subduction zone-magmatic arc systems. Geochronological and stratigraphic studies have documented apparent east-west migration patterns of activity, which sup¬port that the magmatic province is the result of a long-term evolution of the convergent continental margin. The wide magmatic province defined by the space-time pattern of geochronological data is referred to as a spatial magmatic arc. Several models with changing geometrical, kinematic and dynamic relationships are discussed: (1) variable subduction dip-constant depth and range of melting (magma generation zone); (2) variable dip-variable depth and range of melting; (3) low-angle subduction and variable trench-arc gap (lateral migration of trench due to variable dip in the shallow zone and sediment accretion); (4) extensional tectonism; and (5) intra-arc and back-arc extension. The space-time pat¬terns show that the spatial magmatic arc was displaced away from the trench up to 450 km between 120 Myr to 55 Myr, and then back towards the trench between 30 Myr to 20-15 Myr. The width of the spatial magmatic arc increased up to 550 km from 120 Myr to 70 Myr and then remained fairly constant up to 20 Myr. Igneous rocks at the easternmost end of the magmatic arc occur in the Gulf alkaline province, whose geochemical and petrographic characteristics show a transition from subduction related to intraplate extension, in agreement with a model of low-angle subduction and lateral migration of activity during the Tertiary. |
| first_indexed | 2024-03-12T19:00:32Z |
| format | Article |
| id | doaj.art-9b74d8677e7e4c658cb7374f9751b18d |
| institution | Directory Open Access Journal |
| issn | 0016-7169 |
| language | English |
| last_indexed | 2024-03-12T19:00:32Z |
| publishDate | 1997-02-01 |
| publisher | Universidad Nacional Autónoma de México, Instituto de Geofísica |
| record_format | Article |
| series | Geofísica Internacional |
| spelling | doaj.art-9b74d8677e7e4c658cb7374f9751b18d2023-08-02T06:41:45ZengUniversidad Nacional Autónoma de México, Instituto de GeofísicaGeofísica Internacional0016-71691997-02-0136287110Long-term evolution of subduction zones and the development of wide magmatic arcsOfelia Morton-BermeaJaime Urrutia-FucugauchiLate Mesozoic-Cenozoic igneous rocks cover a large area in southwestern United States and northern Mexico, which extends over several provinces with contrasting structural and petrotectonic characteristics and lithospheric structure. Chemical and petrographic data show magmatic arc affinities, particularly for the calc-alkaline suites, supporting a genetic link with the plate convergence process between the North American and the Farallon and Kula plates. However, the width of the magmatic arc (in excess of 1100 km) and the trench-arc gap (estimated from paleogeographic reconstructions) are in marked contrast when compared to the ranges observed in contemporary subduction zone-magmatic arc systems. Geochronological and stratigraphic studies have documented apparent east-west migration patterns of activity, which sup¬port that the magmatic province is the result of a long-term evolution of the convergent continental margin. The wide magmatic province defined by the space-time pattern of geochronological data is referred to as a spatial magmatic arc. Several models with changing geometrical, kinematic and dynamic relationships are discussed: (1) variable subduction dip-constant depth and range of melting (magma generation zone); (2) variable dip-variable depth and range of melting; (3) low-angle subduction and variable trench-arc gap (lateral migration of trench due to variable dip in the shallow zone and sediment accretion); (4) extensional tectonism; and (5) intra-arc and back-arc extension. The space-time pat¬terns show that the spatial magmatic arc was displaced away from the trench up to 450 km between 120 Myr to 55 Myr, and then back towards the trench between 30 Myr to 20-15 Myr. The width of the spatial magmatic arc increased up to 550 km from 120 Myr to 70 Myr and then remained fairly constant up to 20 Myr. Igneous rocks at the easternmost end of the magmatic arc occur in the Gulf alkaline province, whose geochemical and petrographic characteristics show a transition from subduction related to intraplate extension, in agreement with a model of low-angle subduction and lateral migration of activity during the Tertiary.http://www.geofisica.unam.mx/unid_apoyo/editorial/publicaciones/investigacion/geofisica_internacional/anteriores/1997/02/urrutia.htmlAncient magmatic arcssubductiongeochronologynorthern Mexicosouthwestern United States |
| spellingShingle | Ofelia Morton-Bermea Jaime Urrutia-Fucugauchi Long-term evolution of subduction zones and the development of wide magmatic arcs Geofísica Internacional Ancient magmatic arcs subduction geochronology northern Mexico southwestern United States |
| title | Long-term evolution of subduction zones and the development of wide magmatic arcs |
| title_full | Long-term evolution of subduction zones and the development of wide magmatic arcs |
| title_fullStr | Long-term evolution of subduction zones and the development of wide magmatic arcs |
| title_full_unstemmed | Long-term evolution of subduction zones and the development of wide magmatic arcs |
| title_short | Long-term evolution of subduction zones and the development of wide magmatic arcs |
| title_sort | long term evolution of subduction zones and the development of wide magmatic arcs |
| topic | Ancient magmatic arcs subduction geochronology northern Mexico southwestern United States |
| url | http://www.geofisica.unam.mx/unid_apoyo/editorial/publicaciones/investigacion/geofisica_internacional/anteriores/1997/02/urrutia.html |
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