Eruption history, petrogeochemistry, and geodynamic background of Tengchong volcanoes in Yunnan Province, SW China

The Tengchong Volcanic Field (TVF) is one of the youngest volcanic areas in China, and located in the southwestern part of Yunnan Province, China, adjacent to the collision zone between the Indian Plate and Eurasian Plate. This paper summarizes the results of previous research on the eruption history, petrochemistry, and geodynamic background of the TVF and presents a detailed analysis of the available data. Eruptions took place from the Pliocene to the Holocene and were divided into five stages. The composition of the magma went through two cycles: the N2-Q1 P-Q2 P volcanic rocks went through the evolutionary process from basalt to dacite and the Q3 P-Qh magma evolved from trachybasalt to trachyte. The evolution of magma is mainly related to the crystallisation and separation of pyroxene and ilmenite. The mantle source area of the TVF volcanic rocks was caused by the mixing between the MORB-source mantle and the eastern Indian continental margin sediments (EIS) to different degree. Geophysical data also showed that the Indian Plate has been subducted under the TVF area. There are also magma chambers in the crust within a depth of 25 km in the TVF that are replenished by mantle magma.Supplementary material at https://doi.org/10.6084/m9.figshare.c.5227663

Volcanism in the Longgang Volcanic Field of Northeast China: Insights from eruption history, volcano types, and geochemical characteristics

The Longgang volcanic field (LVF) is a monogenetic volcanic field in China that erupted in the Quaternary, forming more than 100 scoria cones and maars in an area of over 1500 km2. The most recent eruption occurred approximately 1500-1700 years ago. By summarising the results of previous and recent research, this paper reviews the geological background, volcano distribution, eruption history, typical volcanoes, and geochemical characteristics of the LVF. The volcanic activities in the LVF were structurally controlled by near-EW, NW-, and NE-trending faults. An analysis of typical volcanic edifices reveals that at least two eruptive episodes occurred in the Holocene, and most of the maars in the LVF have characteristics of multiple eruptive styles. It is concluded that the eruption types included effusive eruptions, magma explosive eruptions, and phreatomagmatic eruptions. The results of geochemical studies of LVF eruptive products show that most of the rock is trachybasalt and that the magma rarely interacts with crustal rocks. Compared with the previous results for the neighbouring Changbaishan polygenetic volcanic field, the probable origins of their differences in volcanism are discussed.

Correction to: Recent eruption history inferred from eruption ages of the two latest lava fows using multi-dating at Yokodake Volcano, Japan

An amendment to this paper has been published and can be accessed via the original article.

Recent eruption history inferred from eruption ages of the two latest lava flows using multi-dating at Yokodake Volcano, Japan

Reconstruction of the eruption history of an active volcano is necessary to elucidate its volcanic activity and to assess the probability of its volcanic eruption. Yokodake volcano in central Japan is the only active volcano among the Yatsugatake volcano group. It has effused nine lava flows, most of which have not been dated. For this study, we ascertained the eruption ages of the latest lava (Y9) and second most recent lava (Y8) using radiocarbon (14C), thermoluminescence (TL), and paleomagnetic dating methods. Results revealed the eruption ages of the two lava flows and the recent eruption history of Yokodake volcano. Yokodake volcano effused its Y8 lava flow at ca. 3.4 ka, ejected NYk-2 tephra with explosive eruption at ca. 2.4–2.2 ka, and effused the Y9 lava flow associated with Y9-T tephra at ca. 0.6 ka. Magma eruption rates of Yokodake at 34 ky and 3.4 ky were estimated as about 9 × 10−3 km3/ky and 1 × 10−2 km3/ky, indicating a stable eruption rate maintained during the past 34 ky. This result suggests that Yokodake volcano retains some potential for eruption, although the volcanic activity of the Yatsugatake volcanoes (10−1–10−2 km3/ky) has weakened over time.

Constraining the Eruption History of the Rangitoto Volcano using Palaeomagnetic Data

<p>Rangitoto is an island volcano situated outside the city of Auckland, New Zealand. The volcano is the youngest and largest volcano in the monogenetic Auckland Volcanic Field (AVF), with the last eruption occurring about 550-500 calibrated years BP, a date determined from studying historical records. The eruption history of Rangitoto is unknown, however all other volcanoes in the AVF have a brief eruption history. In February 2014 a core spanning 127 metres in length was recovered, consisting of 53 lava flows varying in thickness from 1 to 15 metres. Radiocarbon dates taken from marine sediments found at the bottom of the core, underneath the Rangitoto’s lava flows, suggest that there was early activity as far back as 6000BP, after which Rangitoto may have been dormant until the main shield building phase at around 600BP. Magnetic mineralogy analysis has also shown that much of the core is a reliable recorder of the past geomagnetic field. 156 samples have been analysed for palaeodirectional data and 21 acceptable palaeointensity estimates have been accrued from a range of depths throughout the core length. The collected palaeomagnetic data are used to reconstruct variations in the geomagnetic field, which in turn are used to constrain the eruption rate. Preliminary results suggest that the palaeomagnetic data are incompatible with a short eruption duration of the shield building phase implied by the radiocarbon data (under 100 years) and more compatible with a longer duration of shield building for Rangitoto Island. We discuss alternative explanations for this discrepancy and potential implications of our results in regard to improving hazard planning in Auckland.</p>