Isotopic Constraints on Earth System Processes. Группа авторов. Читать онлайн. Newlib. NEWLIB.NET

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Mineralogie, WWU Münster* DS‐TIMS 0.91 0.03 Bermingham et al. (2018) IFM‐GEOMAR Leibniz‐Institut fur Meereswissenschaften, Keil, Germany & University of Saskatchewan Isotope Laboratory, Department of Geological Sciences, University of Saskatchewan, Canada DS‐TIMS 0.93 0.17 Amini et al. (2009) Institut de Physique du Globe de Paris MC‐ICP‐MS 0.90 0.08 Valdes et al. (2014) Institut de Physique du Globe de Paris MC‐ICP‐MS 1.00 0.10 Amsellem et al. (2019, 2020) Princeton University** MC‐ICP‐MS 0.99 0.14 Blattler & Higgins (2017) Arizona State University** DS‐MC‐ICP‐MS 0.85 0.16 Ionov et al. (2019) State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Wuhan** MC‐ICP‐MS 1.03 0.14 Chen et al. (2018, 2019a,b)

      Note: ∆44 Ca/40CaBSE‐SRM915a = δ44Ca/40CaBSE ‐ δ44Ca/40CaSRM915a

      MC‐ICP‐MS methods obtain δ44 Ca/40Ca by multiplying δ44Ca/42Ca by a scaling factor. If not stated standard errors are estimated by multiplying those reported by 2.049.

      * Value estimated by comparison of reported δ44Ca/40Ca of BHVO‐2 to that of Huang et al. (2011).

      ** Value estimated by comparison of reported δ44Ca/40Ca of SRM915b to that of Simon et al. (2017).

Schematic illustration of maps of Central America, Eastern Africa, and Europe showing location of the studied samples.

      (Central American map modified from Patino et al., 2000).

      Two fresh carbonatite lavas, collected immediately after eruptions in 2007 and 2008 from Oldoinyo Lengai volcano, Tanzania, were also selected for this study. Oldoinyo Lengai is located on the eastern branch of the East African Rift Valley and is the only modern extrusive carbonatite locality (Fig. 3.1). The sample from 2007 (OL lava 2007) is representative of the large volumes of rare, relatively Na‐rich (natro‐) carbonatite lavas extruded until August 2007. The younger lava (OL lava 4‐7‐08) was extruded at a time when Oldoinyo Lengai was erupting more silicic ashes (Fischer et al., 2009). Both samples were provided to me by T. Fisher.

Schematic illustration of regional variations in trace element ratios along the Central American volcanic arc.

      (data from Patino et al., 1997, 2000).

Schematic illustration of calcium isotopic composition of Central American volcanic arc magmas (this study), extrusive Oldoinyo Lengai carbonatite lavas (this study), and intrusive Laacher See carbonatite clast (this study).