The hottest lavas of the Phanerozoic
نویسنده
چکیده
The mantle plume hypothesis is widely accepted for the formation of large igneous provinces and many modern day hotspot volcanoes. Petrologic models suggest that plume-derived melts originate at high mantle temperatures (>1500 °C) relative to those generated at ambient midocean ridge conditions (~1350 °C). Earth’s mantle has also appreciably cooled during its history due to heat loss and decrease in radioactive heat production, thus the temperatures of modern day basalts are substantially lower than those produced during the Archean (>2.5 Ga), as recorded by komatiites (>1700 °C). Here, we provide evidence that the ~90 Ma Galapagos-related Tortugal Suite accreted in Costa Rica not only record mantle potential temperatures as high as ancient Archean komatiites (~1800 °C), but we also collected the highest olivine-spinel crystallization temperatures ever reported in the literature (1600 °C). Therefore, to the best of our knowledge, this suite represents the record of the hottest lavas of the Phanerozoic. These type of magmas occurred more frequently during the Archean due to overall higher ambient mantle temperatures, yet our data suggest that anomalously hot, isolated domains still exist in the deep portions of the planet that have survived billions of years of mantle convection and cooling. This finding is in line with the recent results that showed that early-formed 182W/184W mantle heterogeneities, produced during the first 50 million years of planetary accretion, survived to present time and has been sampled by mantle plumes. Our finding supports the existence of primitive Archean reservoirs, although in most plumes recycling and cooler ambient mantle entrainment probably dilutes its signature. EARTH SCIENCE
منابع مشابه
" Aerosol Impacts on Marine Ecosystems "
The initial melting of mantle plumes produced unparalleled volumes of lava that formed large igneous provinces (LIPs). These events were sometimes so large that they triggered catastrophic mass extinctions and oceanic anoxic events. Global tomography and numerical models suggest that mantle plume occurrences are closely linked to the margins of the large low shear velocity provinces (LLSVPs) lo...
متن کاملPetrogenetic Evolution of Plio-Quaternary Mafic Lavas in Nehbandan (East Iran)
Both the Sistan Suture Zone of eastern Iran and the Nehbandan Fault contain Plio-Quaternary Nehbandan mafic lavas. Positive anomalies in the large ion lithophile elements (LILE) and negative anomalies in Nb (niobium) exist in these mafic lavas. This indicates the occurrence of subduction magmatism and post-collision volcanism. Petrologic and geochemical analyses distinguished two groups of lava...
متن کاملOsmium isotopic evidence for mesozoic removal of lithospheric mantle beneath the sierra nevada, california
Thermobarometric and Os isotopic data for peridotite xenoliths from late Miocene and younger lavas in the Sierra Nevada reveal that the lithospheric mantle is vertically stratified: the shallowest portions (<45 to 60 kilometers) are cold (670 degrees to 740 degrees C) and show evidence for heating and yield Proterozoic Os model ages, whereas the deeper portions (45 to 100 kilometers) yield Phan...
متن کاملLate Palaeozoic Ultramafic Lavas in Yunnan, SW China, and their Geodynamic Significance
marine sequences within several orogenic belts in YunWe report petrological and geochemical data on ultramafic pillow nan, SW China (Figs 1 and 2; Fang et al., 1996). These lavas from Late Palaeozoic marine sequences in Yunnan, SW lavas have been interpreted to be oceanic plateaux or China. These lavas have >26 wt % MgO, euhedral to subhedral seamount eruptive rocks associated with mantle plume...
متن کاملMorphology and Petrogenesis of Pillow Lavas from the Ganj Ophiolitic Complex, Southeastern Kerman, Iran
The Upper Cretaceous Ganj complex, a part of the Jazmurian ophiolitic belt, is located on the western boundary of Jazmurian depression and separated from Kahnuj ophiolitic complex by north-south trending Jiroft fault. The complex consists of lava flows, pillow lavas, acidic plutonic and sedimentary rocks which are intruded by northwest-southeast trending dykes. It does not resemble a classical ...
متن کامل