• Aucun résultat trouvé

Tectonic evolution of the Rukwa rift basin and interaction with the Rungwe Volcanic Province, Western Tanzania

N/A
N/A
Info
Télécharger
Protected

Academic year: 2021

Partager "Tectonic evolution of the Rukwa rift basin and interaction with the Rungwe Volcanic Province, Western Tanzania"

Copied!
1
0
0

Chargement.... (Voir le texte intégral maintenant)

Texte intégral

(1)

24

rd

Colloquium of African Geology, Addis Ababa, Ethiopia, January 8-14, 2013. Abstract Volume, p. 123.

Tectonic evolution of the Rukwa rift basin and interaction with the Rungwe Volcanic Province, Western Tanzania

Damien Delvaux

1, 2

, Elly Bryan Temu

3

, Alan Deino

4

, Michael Kraml

5

1

Royal museum for Central Africa, B-3080 Tervuren, Belgium, damien.delvaux@africamuseum.be

2

School of Geosciences, University of the Witwatersrand, Johannesburg, 2050 Wits, South Africa

3

Geological Survey of Tanzania, Box 903, Dodoma, Tanzania

4

Berkeley Geochronological Center, CA 94709, USA

5

GeoThermal Engineering GmbH, D - 76133 Karlsruhe

The Rukwa rift basin in Western Tanzania has a long tectonic history which is related to the Cenozoic development

of the western branch of the East African rift system and its interaction with the eastern branch in the Rungwe

volcanic province. A recent synthesis by Roberts et al (Nature geoscience, 25 March 2012) show that rift-related

volcanism started ~ 20 Ma ago, coeval with the initiation of the Eastern rift branch. Using results from field

structural analysis, new Ar-Ar and U-Th dating, fault kinematics and paleostress reconstructions, we precise the

tectonic evolution of the Songwe valley which links the southeastern extremity of the Rukwa depression to the

Rungwe volcanic province. It currently lies in a strike-slip setting which is responsible for Quaternary pull-apart

development, controlling a geothermal hot spring field and related travertine deposits. Older travertine deposits,

dating back to 360 Ka formed along the margin of paleo-lake Rukwa, when its water level was much higher than the

present-day one. These deposits have been uplifted together with a regional doming related to the Late Quaternary

volcanic activity centered on the Rungwe and Ngozi volcanoes. Late Neogene sedimentation in the Songwe valley

has been constrained between 3.7 and 1.8 Ma by Ar-Ar dating of volcanic deposits. Two older tectono-sedimenatary

periods have also been evidenced by apatite fission track and the work of Roberts et al. (2012). In complement to

this, the middle Miocene age for the phonolites of the Usangu basin that links the eastern rift branch to the Rungwe

volcanic province has been confirmed by a new Ar-Ar dating (17.7 Ma). This suggest that the Usangu basin also

started to develop much earlier than the Pleistocene as previously proposed. The tectonic stress field of this area is at

odd to the general stress field associated to the east African rift system. It is related to a local stress perturbation due

to the interaction between different rift segments in this area which forms the triple point between the Nubia,

Victoria and Rovuma tectonic plates.

Références

Télécharger maintenant ( PDF - 1 Page - 32.77 KB )

Documents relatifs

The Cenozoic volcanism in the Kivu rift: Assessment of the tectonic setting, geochemistry, and geochronology of the volcanic activity in the South-Kivu and Virunga regions

The Cenozoic volcanism in the Kivu rift: Assessment of the tectonic setting, geochemistry, and geochronology of the volcanic activity in the South-Kivu and Virunga regions.. As

Tectonic and stratigraphic evolution of the Western Alboran Sea Basin in the last 25 Myrs

Unlike the Early Miocene sequence offshore Spain (Martínez del Olmo and Comas, 2008), the seismic reflections of the SU1 unit are higher in amplitude, and the isopach

Paleogeothermal Gradients across an Inverted Hyperextended Rift System: Example of the Mauléon Fossil Rift (Western Pyrenees)

All the major domains of the Mauléon rift system were sampled in order to (1) obtain RSCM peak temperatures on the precollisional sedimentary in fill, (2) examine the

Geodynamics and synchronous filling of a rift type-basin evolved through compression tectonics (The western margin of the Levant Basin)

Field observations onshore Cyprus reveal that tectonostratigraphic evolution of the Levant region and are of great value for the interpretation of the deep offshore

Active tectonics in the western branch of the East African Rift System Damien Delvaux

Using the rich archives of the Royal Museum for Central Africa, publications and own field observations, we present a compilation of available data relative to the

POSITION DU LAMARCKISME CHIMIQUE DANS LE DÉTERMINISME DE L'ÉVOLUTION

L'esprit primitif d'invention et de détermination se manifeste avec constance par les ins- tincts et persiste dans l'organisation cérébrale la mieux douée : le

Assimilation of HF radar surface currents to optimize forcing in the northwestern Mediterranean Sea

Millot, C.: Circulation in the western Mediterranean Sea, J. Part I: Model-data comparisons, J. M.: Assimilation of surface velocity data into a primitive equation coastal ocean

Peste des Petits Ruminants at the wildlife-livestock interface in the western Albertine rift and nile basin, East Africa

History of PPR in East Africa, characteristics of natural and livestock systems in study areas from Uganda, South Sudan, and Democratic Republic of the Congo, Table S1: