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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]

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]

Tephra layers from explosive eruptions can provide valuable isochronous marker horizons for paleoenvironmental studies across large regions. East Asia and Southeast Asia are host to more than half of the Earth's subaerial volcanoes, and tephras from these volcanoes offer significant numbers of widely distributed marker layers. However, the integrated tephrostratigraphic framework of this region is less refined because only limited (crypto-) tephra sequences have been established. In this study, we present a cryptotephra sequence covering the period ∼60–50 ka in East Asia from a lacustrine sediment from Huguangyan Maar Lake, southern China. Four cryptotephra layers were identified, one of which can be correlated with the ∼53.8 ka Unnan eruption (SUn) of Sambe volcano, Japan. This tephra provides a critical isochronous marker horizon for linking paleoenvironmental records from central Japan to southern China, illustrating a consistent environmental shift during early MIS 3 across this region. The three other tephras cannot be correlated with known eruptions, but glass geochemical compositions suggest that they may be from Japan or surrounding areas, implying that they too may be widely distributed around East Asia. Importantly, two of them feature at the start of MIS 3, and thus can be potentially be used to establish the synchroneity of the onset of MIS 3 around East Asia, overcoming challenges that presently hinder the dating of early MIS 3 in this region. • ∼60–50 ka tephrostratigraphic sequence of Huguangyan Maar Lake was established. • Four East Asian widespread tephra layers during early MIS 3 were identified in southern China. • Ash from the ∼53.8 ka Unnan eruption of Sambe, Japan, is a confirmed early MIS 3 marker horizon from Japan to southern China. [ABSTRACT FROM AUTHOR]

• The chloroplast genome of Nymphaea had gene loss. • The ycf2 gene was positively selected. • Nymphaea can be divided into five subgenera. Although there has been a long history of cultivation and research on Nymphaea , the taxonomic relationships and evolutionary relationships among Nymphaea species remain controversial. The chloroplast (cp) genome can provide a new method to determine species origin, evolution, and phylogenetic relationships of Nymphaea. The complete cp genomes of seven Nymphaea species were sequenced by high-throughput sequencing technology, and the structural characteristics and phylogenetic relationships of cp genomes were analyzed. The cp genomes of seven species of Nymphaea had rich variation in large single-copy (LSC) and small single-copy (SSC) regions. A comparative cp genomic analysis of seven Nymphaea species showed that the cp gene sequence of Nymphaea was consistent, with no signs of reverse rearrangement. Using N. colorata as the reference sequence, a total of 8328 single nucleotide polymorphisms (SNPs) and 1579 insertions/deletions were obtained. The degree of variation of the cp genome of the seven Nymphaea species in rpoA – rpl20 , rbcL – ndhC , ndhD – ndhF , and trnN-GUU – ndhA regions was relatively high. The ycf2 gene was positively selected. The phylogenetic analysis showed that the genus Nymphaea can be further divided into five subgenera. [ABSTRACT FROM AUTHOR]

Abstract The thick late Cenozoic deposits of Huaibei Plain provide a record of paleoenvironmental changes in the northern and southern transitional zone of eastern China, and of the evolution of the Asian monsoon system. A detailed magnetostratigraphic study of the Huainan (HN, 481.45-m deep) drill core from the center of Huaibei Plain reveals a magnetic polarity sequence from chron C4n.2n to chron C1n, spanning the interval from ∼8 Ma to the present; it is the first reliable magnetostratigraphic chronology for the late Miocene to present for Huaibei Plain. The stratigraphic sequence contains three intervals characterized by major peaks in magnetic susceptibility (at depths of 58.8 m, 108.0 m and 312.4 m), which can be used as isochronous marker beds for regional stratigraphic correlations in Huaibei Plain. Major changes in sediment grain-size occur at 7.0 and 1.7 Ma, corresponding to pronounced environmental shifts, which we consider reflect the respective strengthening of the South Asian summer monsoon and East Asian winter monsoon at these times. Highlights • Magnetostratigraphy of a drill core from Cenozoic sediments in East China reveals a continuous 8 Myr sequence. • Grain-size data indicate pronounced environmental changes at ∼7.0 and ∼1.7 Ma. • Late Cenozoic sediments of Huaibei Plain can be correlated by three peaks in magnetic susceptibility. • Paleoenvironmental changes at ∼7.0 and ∼1.7 Ma were directly linked to changes in the Asian monsoon system. [ABSTRACT FROM AUTHOR]

The sediments of the Huaibei Plain in semi-humid mid-eastern China represent valuable geological records with respect to eolian–fluvial interactions, depositional environments, and climate change in this region. Provenance and weathering conditions are often reconstructed using sedimentary geochemistry methods. In this study, an 8-m core from Huainan and a set of loess samples from northern and southern China were analyzed for major, trace, and rare earth elements (REEs). Results were compared to determine the samples’ provenance. The major, trace, rare earth elements contents, and grain size distribution were found to fluctuate widely in the 2–8 m section of the Huainan core and more narrowly closer to the surface (0–2 m). This suggests a provenance shift at a depth of 2 m. The TiO 2 /Al 2 O 3 , SiO 2 /Al 2 O 3 , Th/Nb, La/Nb values and REE patterns in the upper core (0–2 m) are similar to those found in samples from the Chinese Loess Plateau (CLP). These results suggest that the CLP in northern China is likely to be the primary origin of the upper part (0–2 m) of the Huainan core. Compared with CLP samples, the upper part of the Huainan core exhibits lower K 2 O/Al 2 O 3 values and higher chemical alteration indices. This is indicative of the material’s substantial weathering during transportation and re-deposition and implies that these sediments could reasonably be classified as typical recycled loess. The sediments may have been transported from the CLP to Huainan as Yellow River flood events, probably during the last deglaciation (∼13.2 ka) as a result of increased precipitation, along with glacier and snow melt in the upper reaches of the Yellow River catchment during this period. This suggests that the Yellow River may have migrated into the Huaihe River catchment much earlier than the earliest historical records (361 BCE) suggest. The implications of this would be profound with respect to Chinese history. [ABSTRACT FROM AUTHOR]

• The lithospheric mantle of the eastern Qiangtang block was metasomatized by subduction related fluids/melts. • Partial melting at different depths and degrees produced various parental magmas. • Magmatic recharge contributed to the wide range of ratios between highly incompatible elements. • Continental subduction of the Songpan-Ganzi block triggered crustal thickening and surface uplift. • The surface of the eastern Qiangtang block reached a moderate elevation (<~3 km) in the late Eocene. Post-collisional magmatism offers significant clues to reveal the deep dynamic process and surface uplift of plateaus. New zircon U-Pb ages, biotite Ar-Ar ages, zircon trace elements, and whole-rock geochemistry, integrated with published data of igneous rocks from the eastern Qiangtang block (eastern Tibetan Plateau) were determined to unravel the geodynamics and constrain the uplift history. These igneous rocks consist of few mafic and many intermediate-felsic series. Geochronological studies reveal that the magmatism mainly occurred in ~43–33 Ma. The late Eocene igneous rocks are characterized by high potassium, enrichment in large ion lithophile elements (LILE, e.g., Rb, Ba, Th, U), depleted in high field strength elements (HFSE, e.g., Nb, Ta, Ti), negligible Eu anomalies, with a wide range of highly incompatible element ratios. The parental magmas of these rocks were most probably generated by different degrees of partial melting of the lithospheric mantle, which were heterogeneously metasomatized by subduction related multiphase fluids/melts. Whole-rock geochemistry, zircon trace elements, and thermodynamic modeling results suggest that the parental magmas experienced complicated and different differentiation processes. Mantle metasomatism, fractional crystallization, and magmatic recharge made contributions to the enrichment of incompatible elements and the wide range ratios between highly incompatible elements. In combination with the estimated Eocene crustal thickness, we suggest that the southward continental subduction of the Songpan-Ganzi block triggered the magmatism, thickened the crust, and induced the surface uplift to no more than ~3 km in the late Eocene. [ABSTRACT FROM AUTHOR]