An overview of chemically zoned hotspots on Earth
Geochemical studies have demonstrated that the lavas from individual hotspots are usually chemically heterogeneous. Systematic spatial variations have been recognized in some hotspot tracks such as the Hawaii (e.g. Abouchami et al., 2005, Nature) and the Galapagos (e.g. Hoernle et al., 2000, Geology). It is however still a matter of debate what causes these spatial chemical heterogeneities. Earlier models favored mixing between plume material and depleted asthenosphere and/or lithospheric mantle (e.g. Tatsumoto, 1978, EPSL), whereas newer studies have argued that geochemical zonation of hotspot tracks reflect lateral zonation within the plume that ultimately reflect tapping of different geochemical reservoirs in the plume source (e.g. Hoernle et al., 2000, Geology; Lohmann et al., 2009, EPSL; Farnetani and Hofmann, 2009, 2010, EPSL). Since the sources of most zoned hotspots are located at the margins of the Large Lower-mantle Low-Shear-Wave Velocity Provinces (LLSVPs), the prevalent model is that zoned plumes sample the interface between the LLSVPs and the ambient surrounding mantle (Weiss et al., 2011, Nature Geoscience; Huang et al., 2011, Nature Geoscience; Farnetani et al., 2012; Rohde et al., 2013, Geology; Schwindrofska et al., 2016, EPSL). Studies of the entire evolution of individual hotspots, such as Tristan-Gough and Hawaii, show that these hotspots only became zoned during their later history (Hoernle et al., 2015, Nature Comm.). A model will be presented to explain the evolution of end member zoned hotspot systems.
https://www.munich-geocenter.org/events/seminars/frontiers-in-earth-sciences-20/an-overview-of-chemically-zoned-hotspots-on-earth
https://www.munich-geocenter.org/logo.png
An overview of chemically zoned hotspots on Earth
Abstract
Geochemical studies have demonstrated that the lavas from individual hotspots are usually chemically heterogeneous. Systematic spatial variations have been recognized in some hotspot tracks such as the Hawaii (e.g. Abouchami et al., 2005, Nature) and the Galapagos (e.g. Hoernle et al., 2000, Geology). It is however still a matter of debate what causes these spatial chemical heterogeneities. Earlier models favored mixing between plume material and depleted asthenosphere and/or lithospheric mantle (e.g. Tatsumoto, 1978, EPSL), whereas newer studies have argued that geochemical zonation of hotspot tracks reflect lateral zonation within the plume that ultimately reflect tapping of different geochemical reservoirs in the plume source (e.g. Hoernle et al., 2000, Geology; Lohmann et al., 2009, EPSL; Farnetani and Hofmann, 2009, 2010, EPSL). Since the sources of most zoned hotspots are located at the margins of the Large Lower-mantle Low-Shear-Wave Velocity Provinces (LLSVPs), the prevalent model is that zoned plumes sample the interface between the LLSVPs and the ambient surrounding mantle (Weiss et al., 2011, Nature Geoscience; Huang et al., 2011, Nature Geoscience; Farnetani et al., 2012; Rohde et al., 2013, Geology; Schwindrofska et al., 2016, EPSL). Studies of the entire evolution of individual hotspots, such as Tristan-Gough and Hawaii, show that these hotspots only became zoned during their later history (Hoernle et al., 2015, Nature Comm.). A model will be presented to explain the evolution of end member zoned hotspot systems.
