Using precious metal probes to quantify mid-ocean ridge magmatic processes
نویسندگان
چکیده
Basalts from the East Pacific Rise (EPR), Siqueiros transform zone and Mid-Atlantic Ridge (MAR) area have been analyzed for platinum-group elements (PGE) a wide range of incompatible elements. The low PGE content most primitive mid-ocean ridge basalts (MORB) suggests that they leave mantle sulfide-saturated but become sulfide under-saturated, as consequence decompression, during their ascent to MOR magma chamber. Because pressure drop is small, ascending enters chamber slightly under-saturated requires only small amount fractional crystallization return it sulfide-saturation. Sulfide-saturation marked by Pd melt falling over an order magnitude at ca. 9.5 wt.% MgO. However, once has sulfide-saturated, shows no evidence further decline in with decreasing MgO system evolves. This must result regular replenishment underlying axial fresh batches magma. Most replenishments occur when resident between ∼9 6.5 We combine tight constraints imposed highly compatible abundances, those strongly elements, produce first model successfully accounts variations both classes open ridges chambers normal-type MORB (N-MORB). show lack basalts, MgO, frequent (between 1% 4%) similar magnitude, rather than large initial inputs systematically near 100% zero life individual system. Assuming spreading rate ∼110 mm/yr EPR 9°N, 14 yr 1991–1992 2005–2006 eruptions, calculated volume erupted intruded 2.3 × 103 m3/m length. If expelled represents 0.5% accessible chamber, suggested modeling, tapping 4.6 105
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ژورنال
عنوان ژورنال: Earth and Planetary Science Letters
سال: 2021
ISSN: ['1385-013X', '0012-821X']
DOI: https://doi.org/10.1016/j.epsl.2020.116603