Publication Date:
2024-01-09
Description:
Major and trace element profiles of clinopyroxene grains in oceanic gabbros from ODP Hole 735B have been investigated by a combined in situ analytical study with ion probe, and electron microprobe. In contrast to the homogeneous major element compositions, trace elements (REE, Y, Cr, Sr, and Zr) show continuous core to rim zoning profiles. The observed trace element systematics in clinopyroxene cannot be explained by a simple diffusive exchange between melts and gabbros along grain boundaries. A simultaneous modification of the melt composition is required to generate the zoning, although Rayleigh fractional crystallization modelling could mimic the general shape of the profiles. Simultaneous metasomatism between the cumulate crystal and the porous melt during crystal accumulation is the most likely process to explain the zoning. Deformation during solidification of the crystal mush could have caused squeezing out of the incompatible element enriched residual melts (interstitial liquid). Migration of the melt along grain boundaries might carry these melt out of the system. This process named as synkinematic differentiation or differentiation by deformation (Natland and Dick, 2001, doi:10.1016/S0377-0273(01)00211-6) may act as an important magma evolution mechanism in the oceanic crust, at least at slow-spreading ridges.
Keywords:
176-735B; Aluminium (IV); Aluminium (VI); Aluminium oxide; Calcium; Calcium oxide; Cerium; Chromium; Chromium(III) oxide; DEPTH, sediment/rock; DRILL; Drilling/drill rig; DSDP/ODP/IODP sample designation; Dysprosium; Electron microprobe (EMP); Erbium; Europium; Gadolinium; Grain size, mean radius; Indian Ocean; Ion probe analysis; Iron 2+; Iron oxide, FeO; Joides Resolution; Lanthanum; Leg176; Length; Magnesium; Magnesium number; Magnesium oxide; Manganese; Manganese oxide; Neodymium; Nickel oxide; Ocean Drilling Program; ODP; Potassium; Potassium oxide; Samarium; Sample code/label; Silicon; Silicon dioxide; Sodium; Sodium oxide; Strontium; Titanium; Titanium dioxide; Ytterbium; Yttrium; Zirconium
Type:
Dataset
Format:
text/tab-separated-values, 582 data points
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