The enigmatic origin and emplacement of the Samosir Island lava domes, Toba Caldera, Sumatra, Indonesia

Chesner, Craig A.; Barbee, Olivia; McIntosh, William C.

doi:10.1007/s00445-020-1359-9

Cited by 12 publications

(12 citation statements)

References 20 publications

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“…This is comparable with the 500,000 years of YTT magmatism 7 . Although evidence for the vents or caldera margin associated with the OTT is scarce because the YTT presumably engulfed them 30 , the similar whole rock and zircon geochemistry of OTT and YTT 3,17,18,31,32 (Fig. 2) and similarly long magmatic duration may indicate that they are similar in size.…”

Section: Discussionmentioning

confidence: 99%

Magmatic history of the Oldest Toba Tuff inferred from zircon U–Pb geochronology

Ito

2020

Sci Rep

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The magmatic history of the Oldest Toba Tuff (OTT), the second largest in volume after the Youngest Toba Tuff (YTT), northern Sumatra, Indonesia, was investigated using U–Pb zircon dating by LA-ICP-MS. Zircon dates obtained from surface and interior sections yielded ages of 0.84 ± 0.03 Ma and 0.97 ± 0.03 Ma, respectively. The youngest OTT zircon ages were in accordance with the 40Ar/39Ar eruption age of ~ 0.8 Ma, whereas the oldest zircon dates were ~ 1.20 Ma. Therefore, the distribution of zircon U–Pb ages is interpreted to reflect protracted zircon crystallization, suggesting that the estimated 800–2,300 km3 of OTT magma accumulated and evolved for at least 400,000 years prior to eruption. This result is comparable to the volume and timescales of YTT magmatism. The similarities of both magmatic duration and geochemistry between OTT and YTT may indicate that they are similar in size and that the caldera collapse that generated OTT might be much larger previously interpreted.

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Section: Discussionmentioning

confidence: 99%

Magmatic history of the Oldest Toba Tuff inferred from zircon U–Pb geochronology

Ito

2020

Sci Rep

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“…Subsequent resurgence formed the Samosir Island in the middle of the caldera (Chesner et al., 2020; Mucek et al., 2017). Post‐YTT magmatic activities produced rhyolitic to basaltic lava domes/stratocones within and around the Toba Caldera, including the Sipisupisu stratocone, which is located on the northwestern tip of the Toba Caldera and comprises of basaltic to rhyolitic rocks (Chesner et al., 2020; Mucek et al., 2017; Wark et al., 2000). Samples investigated in this study include the four silicic Toba tuffs (i.e., the HDT, OTT, MTT, and YTT) and Haranggaol Andesite collected within and around the Toba Caldera (Figure 1b).…”

Section: Geological Settings and Samplesmentioning

confidence: 99%

“…Finally, the ∼74 ka Youngest Toba Tuff (YTT) released ∼5,300 km 3 of dacitic‐rhyolitic magmas and resulted in a magnificent collapsed Toba Caldera (Costa et al., 2014; Mark et al., 2014; Storey et al., 2012). Subsequent resurgence formed the Samosir Island in the middle of the caldera (Chesner et al., 2020; Mucek et al., 2017). Post‐YTT magmatic activities produced rhyolitic to basaltic lava domes/stratocones within and around the Toba Caldera, including the Sipisupisu stratocone, which is located on the northwestern tip of the Toba Caldera and comprises of basaltic to rhyolitic rocks (Chesner et al., 2020; Mucek et al., 2017; Wark et al., 2000).…”

Section: Geological Settings and Samplesmentioning

confidence: 99%

New Insights Into the Petrogenesis of Voluminous Crustal‐Signature Silicic Volcanic Rocks of the Toba Eruptions (Indonesia)

et al. 2022

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The formation of large‐volume silicic magmas in arc settings is fundamental for understanding trans‐crustal magmatic systems related to subduction zones. Here, we present an integrated study of the four Quaternary Toba eruptions and pre‐caldera Haranggaol Andesite on Sumatra, Indonesia. This rock suite has significantly enriched Sr‐Nd isotopes (87Sr/86Sr = 0.71220–0.71517, εNd = −8.9 to −10.6) compared with other volcanic rocks on Sunda‐Banda arc, but is similar to the post‐caldera (<74 ka) Sipisupisu basalts near the Toba Caldera. Thermodynamic modeling using Magma Chamber Simulator has revealed that the Toba silicic rocks can be produced by a two‐stage assimilation and fractional crystallization of mantle‐derived basaltic melts with compositions similar to the Sipisupisu basalts in the lower and upper crustal magma reservoirs. Binary modeling of Sr‐Nd isotopes suggests that the rocks near the Toba Caldera can be produced by mixing of 5%–10% of the subducting Nicobar Fan sediments (87Sr/86Sr = 0.73493, εNd = −14 on average) with depleted MORB mantle (DMM). Indeed, decompressional partial melting modeling of bulk mixtures of DMM with 7% subducting sediments using pMELTS indicates that the melts generated can have geochemical compositions similar to the Sipisupisu basalts. We therefore argue that hybridization of the subducting sediments with the mantle wedge could be an alternative scenario responsible for the enriched isotopic characteristics of the rocks near Toba. Prolonged fractionation of mantle‐derived enriched/depleted basaltic melts, accompanied by crustal assimilation and crystal‐melt segregation, could be common processes in generating large‐volume silicic magmas on continental arcs.

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“…In Long Valley caldera, USA, voluminous postcaldera rhyolite lavas erupted after the 760-ka eruption of the Bishop Tuff, and exhibit compositions within the range of the zoned Bishop Tuff for most elements (Hildreth, 2004). In Toba caldera, Indonesia, rhyolite lava of the resurgent dome geochemically and mineralogically represents remnant magma that erupted shortly after the climactic 74-ka Youngest Toba Tuff eruption (Chesner et al, 2020;de Silva et al, 2015). At Campi Flegrei, Italy, the post-caldera products show interactions between mafic magmas of deeper origin and more evolved crystal-rich magmas recycling portions of the residual crystal mush (Forni et al, 2018).…”

Section: Comparison To Other Caldera Systemsmentioning

confidence: 99%

Geochemistry of caldera‐forming and resurgent magmas in the Pliocene Hiwada caldera, northeast Japan: An example of a monotonous intermediate system

Yamamoto

2021

Island Arc

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The 2.9-Ma Hotokezawa Ignimbrite, which was ejected from the Aizu caldera cluster in the northeast Japan arc, is a typical monotonous intermediate ignimbrite, with 40-50 vol% crystals and an eruptive volume of >140 km 3 dense-rock equivalent. This ignimbrite filled Hiwada caldera and was deformed by post-caldera plutonic intrusions that formed a resurgent dome. The Hotokezawa Ignimbrite is a calc-alkaline, medium-K dacite to rhyolite with SiO 2 contents of 67.9-71.3 wt%, and has homogeneous trace-element abundances and Sr-Nd isotopic ratios. These geochemical features suggest that the Hotokezawa magma was formed by partial melting of amphibolitic crustal rocks. This crystal-rich magma did not appear during the post-caldera stage. Therefore, it is plausible that the chamber of eruptible magma was emptied by the caldera-forming eruption. In contrast, post-caldera plutonic rocks exhibit a variety of compositions and have a clear SiO 2 gap corresponding to the caldera-forming magma: the early pluton (tonalite) and later ones (quartz porphyry, granite porphyries, and granite) contain 62.0-66.6 and 71.2-76.5 wt% SiO 2 , respectively. The tonalite and the Hotokezawa Ignimbrite form a continuous trend in their major-element variations. The Sr-Nd isotopic ratios of the ignimbrite and tonalite overlap, but those of the porphyries and granite are more enriched. The early tonalite represents the more basic part of the Hiwada caldera system that was held in small pockets separate from the main magma chamber, because its trace-element abundances are varied and distinct from those of the Hotokezawa Ignimbrite. The distinct compositional change from the Hotokezawa Ignimbrite to the late porphyries and granite indicates that the partial melting crust generating felsic magma was renewed by the subsequent intrusion of the mantle melts. The new felsic magma ascended through subsidencerelated faults into the shallow caldera system and emplaced as laccoliths forming the resurgent dome.

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The enigmatic origin and emplacement of the Samosir Island lava domes, Toba Caldera, Sumatra, Indonesia

Cited by 12 publications

References 20 publications

Magmatic history of the Oldest Toba Tuff inferred from zircon U–Pb geochronology

Magmatic history of the Oldest Toba Tuff inferred from zircon U–Pb geochronology

New Insights Into the Petrogenesis of Voluminous Crustal‐Signature Silicic Volcanic Rocks of the Toba Eruptions (Indonesia)

Geochemistry of caldera‐forming and resurgent magmas in the Pliocene Hiwada caldera, northeast Japan: An example of a monotonous intermediate system

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