 |
| Titel |
Thermal conditions during deformation of partially molten crust from TitaniQ geothermometry: rheological implications for the anatectic domain of the Araçuaí belt, eastern Brazil |
| VerfasserIn |
G. C. G. Cavalcante, A. Vauchez, C. Merlet, M. Egydio-Silva, M. H. Bezerra de Holanda, B. Boyer |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1869-9510
|
| Digitales Dokument |
URL |
| Erschienen |
In: Solid Earth ; 5, no. 2 ; Nr. 5, no. 2 (2014-12-03), S.1223-1242 |
| Datensatznummer |
250115354
|
| Publikation (Nr.) |
 copernicus.org/se-5-1223-2014.pdf |
|
|
|
|
|
| Zusammenfassung |
| During the Neoproterozoic orogeny, the middle crust of the Araçuaí
belt underwent widespread partial melting. At the regional scale, this
anatectic domain is characterized by a progressive rotation of the flow
direction from south to north, suggesting a 3-D deformation of the anatectic
middle crust. To better determine whether melt volumes present in the
anatectic middle crust of the Araçuaí orogen were large enough to
allow a combination of gravity-driven and convergence-driven deformation, we
used the titanium-in-quartz (TitaniQ) geothermometer to estimate the
crystallization temperatures of quartz grains in the anatectic rocks. When
possible, we compared these estimates with thermobarometric estimates from
traditional exchange geothermobarometers applied to neighboring migmatitic
kinzigites. TitaniQ temperatures range from 750 to 900 °C, suggesting
that quartz starts crystallizing at minimum temperatures of
≥ 800 °C. These results, combined with the bulk-rock chemical
composition of diatexites, allows the estimation of a minimum of
~ 30% melt and a corresponding viscosity of
~ 109–1010 Pa s. Such a minimum melt content and low
viscosity are in agreement with interconnected melt networks observed in the
field. Considering that these characteristics are homogeneous over a wide
area, this supports the finding that the strength of the middle crust was
severely weakened by extensive partial melting, making it prone to
gravity-driven flow and lateral extrusion. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|