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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]

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]

The Changbaishan Millennium eruption (~ AD 940s) produced a widely distributed tephra layer around northeast Asia. This tephra layer serves as a marker bed in Greenland ice cores and in marine, lake, archeological and tsunami sediments in Japan and the surrounding region. However, little attention has been paid to the widespread sediments west of Changbaishan volcano. Here we present new stratigraphic, geochemical, varve chronology, and 14 C geochronological data from the varved sediments in Lake Sihailongwan, Longgang volcanic field, Northeast China, extending the westerly margin of this eruption. The distinctive geochemical characteristic of volcanic glass (ranging from trachyte to rhyolite), similar to those of proximal and distal tephra, confirmed the occurrence of Changbaishan Millennium eruption ash in the lake, illustrating the westward dispersal fan of the ash deposits. The position of the peak concentration of glass shards of this tephra was dated to 953 ± 37 AD by varve chronology, and the radiocarbon samples immediately above this tephra gave a date of 940–1020 AD, overlapping the most recent ages for this eruption. The occurrence of Changbaishan Millennium eruption ash in this lake enables a direct and precise synchronization with other high-resolution archives in Northeast Asia, such as maar lakes and peat and marine sediments, thus providing an isochronous marker for a range of sedimentary contexts. [ABSTRACT FROM AUTHOR]

The sediments of maar lakes often provide paleoenvironmental records which are highly suitable for palaeoclimatic studies. The main advantages of the records from maar lakes compared with other lacustrine records are as follows: First, the presence of varves (annually laminated layers) and tephra layers, as well as other materials (like terrestrial plant macrofossils, charcoals, organic carbon, organic shells) suitable for isotopic dating (like AMS 14C, 210Pb, 137Cs, 238U/230Th, 40Ar/39Ar), provides the possibility of developing several independent chronologies, enabling the development of robust, high-resolution chronologies. Second, maars and maar lakes can provide continuous sedimentary records spanning tens of thousands of years (Tianyang Maar in China is hosted the longest known record spanning at least 400 kyr BP) that are ideal for the investigation of climate change on different timescales, including orbital, millennial-centennial and annual-decadal. Third, recent studies of biomarkers based on long-chain alkenones (LCAs) and glycerol dialkyl glycerol tetraethers (GDGTs) have demonstrated the potential of maar lakes for quantitative paleotemperature reconstruction. In this study, we review some of the more significant achievements of palaeoclimatic research based on maar lake sediment sequences from China, with the focus on chronology, multiple timescales and quantitative paleoclimatic reconstruction. • Varves and tephra layers existed in maar sediment can develop high-resolution chronologies combined with isotopic dating. • Maars and maar lakes provide continuous sedimentary records for the investigation of climate change. • Biomarkers (LCAs or GDGTs) from maar sediment provide the potentials for quantitative paleotemperature reconstruction. [ABSTRACT FROM AUTHOR]