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The accurate dating of prehistoric eruptions is essential for reconstructing volcanic sequences and for preparing volcanic-hazard assessments. The chronology of the eruptions of the Datong volcanic field (DVF) in eastern China has been debated for several decades, especially the start and end of volcanism. Loess sediments incorporated in explosive volcanic products have been described from the Dongpingshan scoria cone in the DVF. We conducted radiocarbon dating of the loess sediments, which produced an age of ~7300 cal yr BP for the Dongpingshan volcanic eruption. This result confirms the eruption of the DVF during the Holocene, and it provides important evidence for assessing volcanic hazards in this densely populated region. The Holocene age of the eruption indicates that DVF is dormant, contrary to previous studies which concluded that the DVF is extinct and that its volcanic eruptions ended at ~100 ka. In addition, this study documents a new method of dating Late Pleistocene to Holocene volcanic eruptions in and around the DVF, where loess sediments are widespread and may be preserved within volcanic products. • Datong is not an extinct volcanic field. • First radiocarbon dating of Datong volcanic field was present. • The most recent eruption of the Datong volcanic field was not older than ~7300 cal a BP. [ABSTRACT FROM AUTHOR]

Wudalianchi volcanic field (WDLC) is one of the youngest intracontinental monogenetic volcanic fields in China. The 1719–1721 CE Laoheishan-Huoshaoshan eruption, and the 1776 CE Laoheishan eruption are the latest eruptions in WDLC based on the local historical records. However, most of the recent explosive eruptive products around WDLC are attributed to the 1719–1721 CE Laoheishan-Huoshaoshan eruption while less attentions were paid on the 1776 CE Laoheishan eruption. There are two types of scoria fall deposits around Laoheishan volcano, i.e. the upper light grey high vesicular scoria deposit (US) and below dark low vesicular scoria deposit (BS). Most of the glass shards from US exhibit >4% Na 2 O while BS show <4% Na 2 O. In addition, US presents two different glass composition clusters, indicating a complex magma batch feeding the eruption. Broadly, all of these eruptive products from WDLC have extreme high potassium (usually >5%) content with trachyandesitic to tephriphonolitic in composition that can be clearly distinguished from those from other nearby volcanic regions, such as Nuomin (~150 km to Nangelaqiushan lake (NGLQ)), Arxan-Chaihe (~450 km to NGLQ), Longgang (~700 km to NGLQ) and Jingbohu (~550 km to NGLQ). A cryptotephra layer is clearly revealed as a distinct peak in magnetic susceptibility measurements from NGLQ ~ 8 km northwest to Laoheishan volcano. Glass composition of the cryptotephra layer recorded in NGLQ is similar to the proximal US around Laoheishan volcano. On basis of historical records and field observations, we ascribed US to the 1776 CE Laoheishan eruption and BS to the 1719–1721 CE Laoheishan-Huoshaoshan eruption. Consequently, historical records assigned a precise age (1776 CE) for the tephra recorded in NGLQ, and thus can be used to refine the age model of these lacustrine sediments. • Ash from the most recent eruption (1776 CE) in the Wudalianchi volcanic field was identified. • A cryptotephra layer from 1776 CE Laoheishan eruption was detected in the Lake Nangelaqiushan. • The 1776 CE Laoheishan and 1719–1721 CE Laoheishan-Huoshaoshan eruption show different glass composition. [ABSTRACT FROM AUTHOR]

Abstract: Prehistoric Holocene eruptions of Changbaishan volcano in Northeast China are poorly dated, with the exception of the 946 CE Millennium eruption. Poorly refined age estimates for the earlier eruptions present problems for the reconstruction of the eruptive history of the volcano. The Qixiangzhan eruption (QE) is a major controversial event in terms of its eruptive timing (ranging from ~88 to ~4 kyr) and style (effusive or explosive). As a result of the imprecise age estimates for the eruption, a geomagnetic field excursion recorded within the QE comendite has been variably correlated with a number of different excursion events observed elsewhere. In this study, a visible early Holocene tephra was identified in Yuanchi Lake, ~30 km east of the Changbaishan volcanic vent, and was dated to 8831‐8100 cal yr BP using Bayesian age modelling. Glass shard compositions enable the correlation of this tephra with the poorly dated QE, as well as with a tephra (SG14‐1058) recorded in Lake Suigetsu, in central Japan. These correlations confirm that the QE was explosive and that the ash from the QE can serve as an important early Holocene marker bed across East Asia. In addition, we propose an age of ~8100 cal yr BP for the QE based on the precise date of the Suigetsu SG14‐1058 tephra. Our results also confirm that the geomagnetic field excursion recorded in the Qixiangzhan comendite dates to ~8100 cal yr BP. [ABSTRACT FROM AUTHOR]

A detailed tephrostratigraphy of an active volcano is essential for evaluating its eruptive history, forecasting future eruptions and correlation with distal tephra records. Changbaishan volcano is known for its Millennium eruption (ME, AD 940s; VEI 7) and the ME tephra has been detected in Greenland ice cores ∼9000 km from the vent. However, the pre-Millennium (pre-ME) and post-Millennium (post-ME) eruptions are still poorly characterized. In this study, we present a detailed late Holocene eruptive sequence of Changbaishan volcano based on single glass shard compositions from tephra samples collected from around the caldera rim and flanks. Tephra ages are constrained by optically stimulated luminescence (OSL) and AMS 14 C dates. Tephra from the mid-Holocene pre-ME eruption can be divided into two pyroclastic fall subunits, and it cannot be correlated with any known Changbaishan-sourced tephra recorded in the Japan Sea based on major element composition of glass shards, such as the B-J (Baegdusan-Japan Basin) and B-V (Baegdusan-Vladivostok-oki) tephras. ME pyroclastic fall deposits from the caldera rims and volcanic flanks can be correlated to the juvenile pumice lapilli or blocks within the pyroclastic density current (PDC) deposits deposited in the valleys around the volcano based on glass shard compositions. Our results indicate that the glass shard compositions of proximal ME tephra are more varied than previously thought and can be correlated with distal ME tephra. In addition, widely-dispersed mafic scoria was ejected by the ME Plinian column and deposited on the western and southern summits and the eastern flank of the volcano. Data for glass from post-ME eruptions, such as the historically-documented AD 1403, AD 1668 and AD 1702 eruptions, are reported here for the first time. Except for the ME, other Holocene eruptions, including pre-ME and post-ME eruptions, had the potential to form widely-distributed tephra layers around northeast Asia, and our dataset provides a proximal reference for tephra and cryptotephra studies in surrounding areas. [ABSTRACT FROM AUTHOR]

A 5 mm thick tephra layer has been identified in the lacustrine sediments of Moon Lake in the Arxan-Chaihe volcanic field (ACVF) in Greater Khingan Mountains (NE China). The visible tephra layer is clearly revealed as a distinct peak in magnetic susceptibility measurements. The tephra layer consists mainly of brown vesicular glass shards and minor amounts of plagioclase, olivine and clinopyroxene. Major and minor element analysis has been carried out on the glass shards and plagioclase minerals. Glass shards show low concentrations of K 2 O, similar to the eruptive products derived from post-Miocene volcanoes of the ACVF. The plagioclase phenocrysts in both lava and tephra from ACVF, and in the tephra recorded in Moon Lake are labradorites. During the Late Pleistocene to Holocene, there were also extensive explosive eruptions in the nearby Nuominhe volcanic field (NVF). Volcanic rocks from the ACVF are easily distinguished from those derived from the NVF, having distinctly different K 2 O concentrations. This compositional variation is likely the result of different magmatic processes operating in the ACVF and NVF. Radiocarbon dating on organic materials from the lacustrine sediments dates the tephra layer to ca. 14,200 cal yrs BP, which implies that it was generated by a previously unknown Late Pleistocene explosive eruption in the ACVF. These results, for the first time, give a direct tephra record in this area, and suggest that identification of further tephra and/or cryptotephra in local sedimentary basins such as crater lakes of scoria cones and maars will be significant for dating the Late Pleistocene to Holocene volcanic eruptions and will help to establish a detailed record of the volcanic activity in the ACVF. The newly discovered tephra layer also provides a dated tephrochronological marker layer, which will in future studies provide a means to synchronise local sedimentary records of the climatically variable Late Glacial. [ABSTRACT FROM AUTHOR]

Volcanic glass compositions and tephra layer age are critical for anchoring their sources and correlating among different sites; however, such work may be imprecise when the tephra has varied compositions. The ash from Changbaishan Millennium eruption (940s AD), a widely distributed tephra layer, has been detected in the far-east areas of Russia, the Korean Peninsula, Japan, and in Greenland ice cores. There are some debates on the presence of this tephra from sedimentary archives to the west of Changbaishan volcano, such as lake and peat sediments in the Longgang volcanic field. In this paper, major element compositions for clinopyroxene and Fe-Ti oxides were performed on proximal tephra from Changbaishan and the Millennium eruption ash record in Lake Sihailongwan. Clinopyroxene and Fe-Ti oxides microlites from Sihailongwan show augite- ferroaugite and titanmagnetite compositions, similar to those from dark pumice in Changbaishan proximal tephra, but different from the light grey pumice, which has ferrohedenbergite and ilmenite microlite compositions. This result implies that the tephra recorded in Sihailongwan was mainly from the trachytic eruptive phase of the Millennium eruption, and the rhyolitic eruptive phase made a relatively small contribution to this area. Analyzing clinopyroxene and Fe-Ti oxides microlites is a new method for correlating tephra layers from Changbaishan Millennium eruption. [ABSTRACT FROM AUTHOR]

"Maars and Environment" highlights maar research in China and sheds light on the wealth of information a maar volcano can store from the pure volcanology to understanding magma fragmentation to the sedimentology of deep lacustrine basins which record changing environmental conditions. Furthermore, maar volcanoes are the type of small-volume, monogenetic volcanoes where the rising magma can strongly influence the environment. This Special Issue will provide a snapshot of maar research especially from the maars and their environmental aspects. [Extracted from the article]