The present study focuses on the field description of a bimodal volcanic rock centre and fault types present in Taiz area located in the southern part of Yemen. Taiz area serves as one of the key areas to understand the Afro-Arabian bimodal volcanism and the emplacement of Afar plume and the relationship between extension tectonics and magmatism. Taiz area comprises bimodal volcanic rocks encompassing mafic and silicic lava flows and pyroclastic rocks. The lava flows were erupted in five phases – three major basic and two acid phases. Lower basalt sequence (Tb1) is the oldest and main phase of flood basalt volcanism, formed as part of a wide spread volcanism within the Afro-Arabian region. This is followed by lower silicic sequence phase (Tr1) consisting of varied assortment of lithologies such as rhyolite flows with subordinate ignimbrites, welded ash, pyroclastic breccia, and random pumice and obsidian. The middle basalt sequence phase (Tb2) has been formed from the flows fed by fissure-dyke systems and separated from Tr1 by red colored weathering band of saprolitic bole (paleosol). The latest silicic sequence phase (Tr2) with limited exposures in the region, comprises rhyolitic plug domes, rhyolitic lava flows and locally welded and unwelded volcaniclastic deposits. In places, the silicic volcanic rocks have been diagenetically altered to bentonitic clay minerals and zeolites. The youngest phase of volcanic rocks represented by the basaltic rocks in the region (Tb3) is exposed in few outcrops along the southeastern slope of the mapped area and conformably capping the Tr2. It includes the basaltic flows intercalated with mafic conglomerate and tuff layers. The study area has been subjected to tensional tectonic regime throughout much of the Tertiary and extensions led to volcanism, granitic rock intrusions and formation of structural elements such as normal faults and deep joints. NW, NE, and E-W are the three major trends of faults recognized and these are related to the progressive rifting of Red Sea and Gulf of Aden.
Mysore Ramachandraiah Janardhana,
Abdul-Aleam Ahmed Al-Qadhi,
Cenozoic Eruptive Stratigraphy and Structure in Taiz area of Yemen, Earth Sciences.
Vol. 3, No. 3,
2014, pp. 85-96.
Wanming, D., Cenozoic volcanism and intraplate subduction at the northern margin of the Tibetan plateau Chinese J. of Geo. Ch. Research, vol. 10. (2), pp140-152, 1991.
Xia, L., Li, X., Ma, Z., Xu, X., and Xia, Z., Cenozoic volcanism and tectonic evolution of the Tibetan plateau Gondwana Research, vol. 19. (4), pp850-866, 2011.
Wang, X.K., Qiu, S.w., Song, C.c., Kulakov, A., Tashchi, S., and Myasnikov, E., Cenozoic volcanism and geothermal resources in Northeast China. Geo. Sc. Chinese., vol. 11. (2), 2001, pp150-154.
Dickinson, W., Tectonic implications of Cenozoic volcanism in coastal California. Overview, Geo. Soc. Bull. America. , vol. 109. (8), August 1997, pp936-954.
Cioni, R., Salaro, L., and Pioli, L., The Cenozoic volcanism of San Pietro Island (Sardinia, Italy). Rendiconti Seminario Facoltà Scienze Univ. Cagliari Supplemento, vol. 71. Fasc. 2, 2001.
Beydoun, Z. R. Southern Arabia and northern Somalia: comparative geology: Phil. Trans. Roy. Soc. London, 267: 267-292, 1970.
Bertrand, H., Chazot, G., Blichert-Toft, J., and Thoral, S. Implications of widespread high-µ volcanism on the Arabian Plate for Afar mantle plume and lithosphere composition. Chemical Geology. 198: 47– 61, 2003.
Al-Kadasi, M. Temporal and spatial evaluation of the basal flow of the Yemen Volcanic Group. Unpublished Ph. D. Thesis, Royal Holloway Collage, Landon university, UK. 301pp, 1994.
Davidson, A., and Rex D.C. Age of volcanism and rifting in southwestern Ethiopia. Nature. 283: 657– 658, 1980.
Baker, J.A., Snee, L., and Menzies, M. A brief Oligocene period of flood volcanism: implications for the duration and rate of continental flood volcanism at the Afro-Arabian triple junction. Earth Planet Sci. Lett. 138: 39–55, 1996a.
Hofmann, C., Courtillot, V., Feraud, G., Yirgu, E., Ketefo, E., and Pik, R. Timing of the Ethiopian flood basalt event and implications for plume birth and global change. Nature. 389: 838–841, 1997.
Rochette, P., Tamrat, E., Feraud, G., Pik, R., Courtillot, V., Ketefo, E., Coulon, C., Hofmann, C., Vandamme, D., Yirgu, G. Magnetostratigraphy and timing of the Oligocene Ethiopian traps. Earth Planet Sci. Lett. 164: 497–510, 1998.
Ukstins, I. A., Renne, P. R., Wolfenden, E., Baker, J. A., Ayalew, D., and Menzies, M. Matching conjugate rifted margins:40Ar/39Ar chrono-stratigraphy of pre- and syn-rift bimodal flood volcanism in Ethiopia and Yemen. Earth Planet Sci. Lett., 198: 289–306, 2002.
Ukstins Peate, I. A., Baker, J. A., Al-Kadasi, M., Al-Subbary, A., Knight K. B., Thirlwall, M. F., Peate, D. W., Renne, P. R., and Menzies, M. A. Volcanic stratigraphy of large-volume silicic pyroclastic eruptions during Oligocene Afro-Arabian flood volcanism in Yemen. Bull Volcanol. 68: 135–156, 2005.
Al-Kadasi, M. Geology of Gabal Saber granitic mass. Unpublished M. Sc. Thesis, Sana, a University, Yemen. 232pp, 1988.
Kruck, W., and Schaffer, U. Geological map of the Republic of Yemen, Sheet Taiz. Fed. Inst. Geosci. Nat. Res., Hanover, scale 1:250,000, 1991.
Windley, B. F., Whitehouse, M. J., and Ba-battat, M. A. Early Precambrian gneiss terranes and Pan-African island arcs in Yemen, crustal accretion of the eastern Arabian Shield. Geology. 24: 131-134, 1996.
Beydoun, Z. R., As-Saruri, M. A. L, El-Nakhal, H., Al-Ganad, I. N., Baraba, R. S., Nani, A. O., and Al-Awah, M. H. International lexicon of, Rebublic of Yemen (Second Edition). IUGS, Republic of Yemen Publication. 34: 245p, 1998.
Garzanti,E.,Vezzoli,Ando,S.,and Castiglioni,G. Petrology of Rifted-Margin Sand (Red Sea and Gulf of Aden, Yemen):Journal of Geology,v.109,p.277-297, 2001.
Davison, I., Al-Kadasi, M. Al-Khirbash, S. Al-Subbary A.K., Baker, J.A. Blakey, S. Bosence, D., Dart, C., Heaton, R., McClay, K., Menzies, M., Nicols, G., Owen, L., and Yelland, A. Geological evolution of the southeastern Red Sea Rift margin, Republic of Yemen. Bull. Geol. Soc. Am. 106: 1474-1493, 1994.
Civetta, L., LaVolpe, L., and Lirer, L. K-Ar ages of the Yemen Plateau. Journal of Volcanology and Geothermal Research. 4: 307-314, 1978.
Mohr, P. Ethiopian flood basalt province. Nature. v. 303, p. 577–584, 1983.
Chiesa, S., La Volpe, L., Lirer, L., and Orsi, G. Geological and structural outline of the Yemen Plateau, Yemen Arab Republic. Neues Jahr Geol. 11: 641–656, 1983.
Ayalew, D., Barbery,. P., Marty, B., Reisberg, L., Yirgu, G., Pik, R. Source, genesis, and timing of giant ignimbrite deposits associated with Ethiopian continental flood basalts. Geochim Cosmochim Acta. 66: 1429-1448, 2002.
Mattash, M. A. Study of the Cenozoic volcanic rocks and their associated intrusive rock in Yemen in relation to rift development. Unpublished Ph.D thesis, Hungarian Academy of Sciences and Eotvos L. University., Budapest. 112pp, 1994.
Mattash, M. A., and Balogh, K. K-Ar radiometric age data on Cenozoic volcanics and their associated Tertiary intrusions from Yemen. Acta Mineralogica-Petrographica, Szeged-Hungary. 83-92, 1994.
Baker, J. A., Menzies, M., and Snee, L. Stratigraphy, 40Ar/39Ar geochronology and geochemistry of flood volcanism in Yemen. Mineralogical. Magazine. 58A: 42-43 (abstr.), 1995.
Minissale, A., Mattash, M., Vaselli, O., Tassi, F., Al-Ganad, I., Selmo, E., Shawki N., Tedesco, D., Poreda, R., Ad-Dukhain, M. and Hazzae, M. A Geochemical Approach for the Evaluation of the Geothermal Potential in Yemen. Yemen Geoscience Bulletin. 1 (1/2): 1-19, 2009.
Menzies, M. A., Baker, J., Bosence, D., Dart, C., Davison, I., Hurford, A., Al-Kadasi, M., McClay, K., Nicholas, G., Al- Subbary, A. and Yelland, A. The timing of crustal magmatism, uplift and crustal extension-preliminary observations from Yemen. In Magmatism and the causes of continental break-up (ed. B. Storey et al.). Geol. Soc. Lond. Spec. Publ. 68: 293-304, 1992.
Manetti, P., Capaldi, G., Chiesa, S., Civetta, L., Conticelli, S., Gasparon, M., LaVolpe, L., and Orsi, G. Magmatism of the eastern Red Sea margin in the northern part of Yemen from Oligocene to present. Tectonophysics. 198: 181–202, 1991.
Baker, J. A., Thirlwall, M. F., Menzies, M. A. Sr-Nd-Pb isotopic and trace element evidence for crustal contamination of plume-derived flood basalts: Oligocene flood volcanism in western Yemen. Geochim Cosmochim Acta. 60: 2559–2581, 1996b.
Youssef, M. H. Tectonic setting of some Miocene granite intrusions, in relations to the Aden and Red Sea rifts, southwestern border of the Yemen Plateau. Geol. Soc. Egypt., Spec. Publ. 1: 445-459, 1993.
Khanbari, K. Study of Structures and Tectonic Evolution of Yemen Tertiary Granites, by Using Remote Sensing Technique. Journal of Remote Sensing issued by GORS. 21: 63-72, 2008.
Capaldi, G., Chiesa, S., Manetti, P., Orsi, G., Poli, G. Tertiary anorogenic granites of the western border of the Yemen Plateau. Lithos. 20: 433-444, 1987.
Huchon, P., Jestin, F., Cantagrel, J. M., Gaulier, J. M., Al Khirbash, S., Gafaneh, A. Extensional deformations in Yemen since Oli-gocene and the Afar triple junction. Annales Tectonicae. 5 (2): 141-163, 1991.
Zumbo, V., Féraud G., Bertrand, H., and Chazot, G. 40Ar/39Ar chronology of Tertiary magmatic activity in Southern Yemen during the early Red Sea-Aden Rifting. Journal of Volcanology and Geothermal Research. 65: 265-279, 1995.
Chazot, G., Bertrand, H. Genesis of silicic magmas during Tertiary continental rifting in Yemen. Lithos. 36: 69-84, 1995.
El-Gharbawy, R. I. Petrogenesis of granitic rocks of the Jabal Saber area, South Taiz City, Yemen Republic. Chin. J. Geochem. 30: 193–203, 2011.
Youssef, M., El-Shatoury, H. and Al-Kadasi, M." Geology of Gabal Saber Granitic Mass, Taizz, Yemen Republic" in Geology of The Arab World Conf., 1: 433-447, 1992, Cairo University, Egypt.
Khanbari, K., and Huchon, P. Paleostress analysis of the volcanic margins of Yemen. Arab. J. Geosciences. 3: 529-538, 2010.