scholarly journals Effect of variable CO2on eclogite-derived andesite and lherzolite reaction at 3 GPa-Implications for mantle source characteristics of alkalic ocean island basalts

2014 ◽  
Vol 15 (4) ◽  
pp. 1533-1557 ◽  
Author(s):  
Ananya Mallik ◽  
Rajdeep Dasgupta
Keyword(s):  
Mantle Source ◽  
Ocean Island ◽  
Ocean Island Basalts ◽  
Source Characteristics

Triple oxygen isotope constraints on the origin of ocean island basalts

2020 ◽  
Author(s):  
Xiaobin Cao ◽  
Huiming Bao ◽  
Yongbo Peng
Keyword(s):  
Theoretical Calculation ◽  
Oxygen Isotope ◽  
Mantle Source ◽  
Plate Tectonics ◽  
Unique Feature ◽  
Published Data ◽  
Ocean Island ◽  
Ocean Island Basalts ◽  
Geochemical Proxies ◽  
Subducted Oceanic Crust

<p> </p><p><span>Understanding the origin of ocean island basalts (OIB) has important bearings on Earth’s deep mantle. Although it is widely accepted that subducted oceanic crust, as a consequence of plate tectonics, contributes material to OIB’s formation, its exact fraction in OIB’s mantle source remains ambiguous largely due to uncertainties associated with existing geochemical proxies. We have shown, through theoretical calculation and examining published data, that unlike many known proxies, triple oxygen isotope compositions (i.e. Δ<sup>17</sup>O) in olivine samples are not affected by crystallization and partial melting. This unique feature allows olivine Δ<sup>17</sup>O values to identify and quantify the fractions of subducted ocean sediments and hydrothermally altered oceanic crusts in OIB’s mantle source. In this work, new Δ<sup>17</sup>O measurements for OIB will be presented, and the implications will be discussed.<span>  </span></span></p><p> </p>

Subducted and recycled lithosphere as the mantle source of ocean island basalts from southern Polynesia, central Pacific

1989 ◽  
Vol 77 (1) ◽  
pp. 1-18 ◽  
Author(s):  
C. Dupuy ◽  
H.G. Barsczus ◽  
J. Dostal ◽  
P. Vidal ◽  
J.-M. Liotard
Keyword(s):  
Mantle Source ◽  
Central Pacific ◽  
Ocean Island ◽  
Ocean Island Basalts

scholarly journals Remnants of early Earth differentiation in the deepest mantle-derived lavas

2020 ◽  
Vol 118 (1) ◽  
pp. e2015211118
Author(s):  
Andrea Giuliani ◽  
Matthew G. Jackson ◽  
Angus Fitzpayne ◽  
Hayden Dalton
Keyword(s):  
Mantle Source ◽  
Isotope Composition ◽  
Volcanic Rocks ◽  
Primitive Mantle ◽  
Early Earth ◽  
Apparent Contradiction ◽  
Ocean Island ◽  
Melt Extraction ◽  
Ocean Island Basalts ◽  
Isotopic Compositions

The noble gas isotope systematics of ocean island basalts suggest the existence of primordial mantle signatures in the deep mantle. Yet, the isotopic compositions of lithophile elements (Sr, Nd, Hf) in these lavas require derivation from a mantle source that is geochemically depleted by melt extraction rather than primitive. Here, this apparent contradiction is resolved by employing a compilation of the Sr, Nd, and Hf isotope composition of kimberlites—volcanic rocks that originate at great depth beneath continents. This compilation includes kimberlites as old as 2.06 billion years and shows that kimberlites do not derive from a primitive mantle source but sample the same geochemically depleted component (where geochemical depletion refers to ancient melt extraction) common to most oceanic island basalts, previously called PREMA (prevalent mantle) or FOZO (focal zone). Extrapolation of the Nd and Hf isotopic compositions of the kimberlite source to the age of Earth formation yields a143Nd/144Nd-176Hf/177Hf composition within error of chondrite meteorites, which include the likely parent bodies of Earth. This supports a hypothesis where the source of kimberlites and ocean island basalts contains a long-lived component that formed by melt extraction from a domain with chondritic143Nd/144Nd and176Hf/177Hf shortly after Earth accretion. The geographic distribution of kimberlites containing the PREMA component suggests that these remnants of early Earth differentiation are located in large seismically anomalous regions corresponding to thermochemical piles above the core–mantle boundary. PREMA could have been stored in these structures for most of Earth’s history, partially shielded from convective homogenization.

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