Tectonic events, continental intraplate volcanism, and mantle plume activity in northern Arabia: Constraints from geochemistry and Ar‐Ar dating of Syrian lavas

Abstract

New 40Ar/39Ar ages combined with chemical and Sr, Nd, and Pb isotope data for volcanic rocks from Syria along with published data of Syrian and Arabian lavas constrain the spatiotemporal evolution of volcanism, melting regime, and magmatic sources contributing to the volcanic activity in northern Arabia. Several volcanic phases occurred in different parts of Syria in the last 20 Ma that partly correlate with different tectonic events like displacements along the Dead Sea Fault system or slab break‐off beneath the Bitlis suture zone, although the large volume of magmas and their composition suggest that hot mantle material caused volcanism. Low Ce/Pb (<20), Nb/Th (<10), and Sr, Nd, and Pb isotope variations of Syrian lavas indicate the role of crustal contamination in magma genesis, and contamination of magmas with up to 30% of continental crustal material can explain their 87Sr/86Sr. Fractionation‐corrected major element compositions and REE ratios of uncontaminated lavas suggest a pressure‐controlled melting regime in western Arabia that varies from shallow and high‐degree melt formation in the south to increasingly deeper regions and lower extents of the beginning melting process northward. Temperature estimates of calculated primary, crustally uncontaminated Arabian lavas indicate their formation at elevated mantle temperatures (Texcess ∼ 100–200°C) being characteristic for their generation in a plume mantle region. The Sr, Nd, and Pb isotope systematic of crustally uncontaminated Syrian lavas reveal a sublithospheric and a mantle plume source involvement in their formation, whereas a (hydrous) lithospheric origin of lavas can be excluded on the basis of negative correlations between Ba/La and K/La. The characteristically high 206Pb/204Pb (∼19.5) of the mantle plume source can be explained by material entrainment associated with the Afar mantle plume. The Syrian volcanic rocks are generally younger than lavas from the southern Afro‐Arabian region, indicating a northward progression of the commencing volcanism since the arrival of the Afar mantle plume beneath Ethiopia/Djibouti some 30 Ma ago. The distribution of crustally uncontaminated high 206Pb/204Pb lavas in Arabia indicates a spatial influence of the Afar plume of ∼2600 km in northward direction with an estimated flow velocity of plume material on the order of 22 cm/a.

Magmatic evolution of the South Shetland Islands, Antarctica, and implications for continental crust formation

“…The 40 Ar-39 Ar ages of the samples ( Table 1 in supplementary material) were determined at IFM-GEOMAR, Leibniz-Institut für Meereswissenschaften, Kiel, following the methods outlined previously in Krienitz et al (2009). The samples were selected based on thin section observations and K 2 O concentrations.…”

Heterogeneous mantle sources feeding the volcanic activity of Mt. Karacadağ (SE Turkey)

“…These data are compared with those of the early-stage (Siverek Stage, divided into Early-and Plateau-phases in the diagrams; Ercan et al, 1991;Lustrino et al, 2010) and the nearly coeval 'anorogenic' magmas emplaced in Anatolian and north-western Arabian plates (Turkey and Mushrek fields, respectively, in the diagrams; Arger et al, 2000;Yurtmen et al, 2000;Alpaslan, 2007;Demir et al, 2007;Ekici et al, 2007;Krienitz et al, 2007Krienitz et al, , 2009Lustrino and Wilson, 2007;Lease and Abdel-Rahman, 2008;Temel et al, 2010, and references therein). Throughout the text, we refer to the Siverek Stage volcanics ($11-2.7 Ma) by the term 'old' samples.…”

“…Literature data for Karacadag rocks (crosses) from Pearce et al (1990), Ercan et al (1991) andAlici Sen et al (2004). Also shown are other Neogene alkaline rocks of neighbouring volcanic districts from the Arabian plate (Mashrek) and throughout the Anatolian plate (Turkey) Literature data are in Lustrino and Wilson (2007) and more recent papers (Alpaslan, 2007;Demir et al, 2007;Ekici et al, 2007;Krienitz et al, 2007Krienitz et al, , 2009Lease and Abdel-Rahman, 2008;Temel et al, 2010). The complete dataset (678 whole rock analyses for Mashrek, 421 data for Turkey, 180 data for Karacadag) can be requested to the first author.…”

Caldera-forming eruptions of the Quaternary Kone Volcanic Complex, Ethiopia

“…Volcanic plateaux bounding the rift (e.g. Di Paola, 1972) are thought to have developed above one or more mantle plumes (Schilling et al, 1992;Marty et al, 1996;Ebinger and Sleep, 1998;George et al, 1998;Rogers et al, 2000;Ebinger and Casey, 2001;George and Rogers, 2002;Nyblade, 2002;Krienitz et al, 2009). According to Rooney et al (2007), the location of the KVC coincides with the part of the MER that has a lithosphere transitional between continental and oceanic settings.…”