Generation of Silicic Melts in the Early Izu‐Bonin Arc Recorded by Detrital Zircons in Proximal Arc Volcaniclastic Rocks From the Philippine Sea

Abstract

A 1.2 km thick Paleogene volcaniclastic section at International Ocean Discovery Program Site 351‐U1438 preserves the deep‐marine, proximal record of Izu‐Bonin oceanic arc initiation, and volcano evolution along the Kyushu‐Palau Ridge (KPR). Pb/U ages and trace element compositions of zircons recovered from volcaniclastic sandstones preserve a remarkable temporal record of juvenile island arc evolution. Pb/U ages ranging from 43 to 27 Ma are compatible with provenance in one or more active arc edifices of the northern KPR. The abundances of selected trace elements with high concentrations provide insight into the genesis of U1438 detrital zircon host melts, and represent useful indicators of both short and long‐term variations in melt compositions in arc settings. The Site U1438 zircons span the compositional range between zircons from mid‐ocean ridge gabbros and zircons from relatively enriched continental arcs, as predicted for melts in a primitive oceanic arc setting derived from a highly depleted mantle source. Melt zircon saturation temperatures and Ti‐in‐zircon thermometry suggest a provenance in relatively cool and silicic melts that evolved toward more Th and U‐rich compositions with time. Th, U, and light rare earth element enrichments beginning about 35 Ma are consistent with detrital zircons recording development of regional arc asymmetry and selective trace element‐enriched rear arc silicic melts as the juvenile Izu‐Bonin arc evolved.

Marine Volcaniclastic Record of Early Arc Evolution in the Eastern Ritter Range Pendant, Central Sierra Nevada, California

“… Scandium and Uranium enrichment in oceanic arc and Sierran zircons compared to modern mid‐ocean ridge, back‐arc basin, and intraplate magmatic zircons. Data sources: mid‐ocean ridge zircons from Grimes et al (); intraplate zircons from Carley et al (); back‐arc basin and oceanic arc zircons from Barth et al ().…”

Postmagmatic Tectonic Evolution of the Outer Izu‐Bonin Forearc Revealed by Sediment Basin Structure and Vein Microstructure Analysis: Implications for a 15 Ma Hiatus Between Pacific Plate Subduction Initiation and Forearc Extension

“…It resulted from ~52 Ma of subduction of the Pacific Plate beneath the eastern margin of the Philippine Sea plate (Reagan et al, ). IODP expedition results were published recently, notably concerning the magmatic evolution (Brandl et al, ; Yogodzinski et al, ; Hickey‐Vargas et al, ; Shervais et al, ), and the age of IBM volcanic rocks (Barth et al, ; Ishizuka et al, ; Reagan et al, ). In addition, the drilled cores provided (hemi)pelagic sedimentary‐volcaniclastic successions and tectonic structures that bear information on the tectonic evolution of the outer IBM forearc.…”

Trace Element Characterisation of MAD‐559 Zircon Reference Material for Ion Microprobe Analysis

“…, Barth et al . ). We also measured mass fractions of Li, B, F, Na, Mg, Al, P, K, Ca and Fe that are typically used to monitor incorporation of mineral or melt inclusions, and to evaluate alteration or open‐system processes (e.g., Wang et al .…”

“…It is important to note that the values for 91500 in Table 3 are generally within 1s for measurements or compilations reported by Whitehouse (2004), Wiedenbeck et al (2004), Jochum and Stoll (2008) and Reid et al (2011). Our compilation for 91500 provides a more extensive summary of zircon trace element mass fractions, including Sc, Ti and Nb, which have become important for petrogenetic interpretations (e.g., Ferry and Watson 2007, Grimes et al 2015, Barth et al 2017. We also measured mass fractions of Li, B, F, Na, Mg, Al, P, K, Ca and Fe that are typically used to monitor incorporation of mineral or melt inclusions, and to evaluate alteration or open-system processes (e.g., Wang et al 2014).…”