One Million Years tephra record at IODP Sites U1436 and U1437: Insights into explosive volcanism from the Japan and Izu arcs

Abstract

The 1 Myr tephra records of IODP (International Ocean Discovery Program) Holes U1436A and U1437B in the Izu‐Bonin fore‐ and reararc were investigated in order to assess provenance and eruptive volumes, respectively. In total, 304 tephra samples were examined and 260 primary tephra layers were identified. Tephra provenance was determined by means of major and trace element compositions of glass shards and distinguished between Japan and Izu‐Bonin arc origin of the tephra layers. A total of 33 marine tephra compositions were correlated to the Japan arc and 227 to the Izu arc. Twenty marine tephra layers were correlated between the two drilling sites. Additionally, we defined eleven correlations of marine tephra deposits to major widespread Japanese eruptions; from the 1.05 Ma Shishimuta‐Pink Tephra to the 30 ka Aira‐Tn Tephra, both from Kyushu Island. These eruptions provide independent time markers within the sediment record and six correlations were used to date tephra layers from Japan in Hole U1436A to establish an alternative age model for this hole. Furthermore, the minimum distal tephra volumes of all detected events were calculated, which enabled the comparison of the tephra volumes that derived from the Japan and the Izu‐Bonin arcs. For some of the major Japanese eruptions these are the first volume estimations that also include distal deposits. All of the Japanese tephras derived from events with eruption magnitude Mv ≥ 5.6 and three of the investigated eruptions reach magnitudes Mv ≥ 7. Volcanic events of the Izu‐Bonin arc have mostly eruption magnitudes Mv ≤ 5.

Tephrostratigraphy and Provenance From IODP Expedition 352, Izu‐Bonin Arc: Tracing Tephra Sources and Volumes From the Oligocene to Recent

“…This assumption allows the construction of a tear‐drop‐shaped isopach with aperture angles of 45°, 60°, and 90° (average angles for Pleistocene eruptions; e.g., Kimura et al, ; Machida, ). Then, on the resulting distribution area an exponential thickness decrease with distance from the eruptive vent has been applied (see also Kutterolf et al, ; Schindlbeck et al, ).…”

Depositional setting, provenance, and tectonic-volcanic setting of Eocene–Recent deep-sea sediments of the oceanic Izu–Bonin forearc, northwest Pacific (IODP Expedition 352)

“…This diagram indicates the relative influence of IBM versus Honshu volcanic products because low SiO 2 /CaO ratios at low K 2 O concentrations reflect IBM sources (e.g. Schindlbeck et al 2017; average tephra compositions in Figure 11(a) are represented by stars).…”

Tuffaceous Mud is a Volumetrically Important Volcaniclastic Facies of Submarine Arc Volcanism and Record of Climate Change

“…Haraguchi et al, ; Hochstaedter et al, ; Ishizuka et al, ; Tamura et al, 2009; Taylor & Nesbitt, ). Schindlbeck et al () made a similar distinction and attribution for vitriclasts in <1 Ma discrete ashes (Table ). However, we lack the trace element and isotope data needed to definitively distinguish between volcanic front versus rear arc sources for the medium‐K rhyolites, or between Japanese versus rear arc sources for higher‐K ones.…”