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Diatom records in tropical settings have been used to appraise paleomonsoons throughout the Quaternary period due to their ubiquitous presence, rapid response, and preservation in sediments. Despite this, diatoms have been rarely used to assess the Asian monsoonal climate. As the Asian monsoon comprises the Indian and East Asian subsystems, it plays a significant role in global hydrological and energy cycles. Keeping global climate in mind, we reviewed the dynamics and causes of Asian monsoon variability (covering major records exclusive from the tropics) on different spatial and temporal scales using diatoms as a proxy record. The data have been compiled from 50 papers spanning fresh and marine sediment archives, covering entire monsoon regimes, predominantly from Southeast Asia. This study classified the data based on various geological periods ranging from the Pleistocene Epoch to the Holocene Meghalayan age (600 ka −300 a BP). Diatom proxies indicate fluctuating hydrological conditions and varying monsoon intensity throughout the Quaternary period and show regional scale coherence for specific climatic events. Diatom records from both inland and marine sediment archives indicate a wet and warm period during the mid–Pleistocene (590–300 kyr) and a cold climate and weakened East Asian monsoon during 300–140 kyr. Through the late Pleistocene period (75 to 15 kyr), monsoonal conditions were intense, wet and warm during the interglacial stages and weaker and dry during glacial stages across South and East Asia. During the Last Glacial Maximum (24.5–18 kyr), the monsoon significantly weakened with cold climatic conditions in southern Asia, and increased precipitation across East Asia. A majority of the published records witnessed an enhanced Asian monsoon and a warm and humid period towards the early to mid–Holocene, with a decline in the monsoon after the mid–Holocene accompanying intermittent intense wetter conditions. Diatom records from the sediment archives at many geographic locations hold signatures of extreme events such as the Younger Dryas cold event around 13.3–11.3 kyr BP, the Medieval Warm Period around 1.3 to 0.8 kyr, and the Little Ice Age in between 0.6 and 0.3 kyr. Further, we indicate that several sites from different monsoon-dominated geographic-climatic zones should be re-investigated with high resolution across spatial and temporal palaeoclimatic periods (including existing databases) with careful diatom taxonomy to strengthen a climatic reconstruction of this monsoon-dominated region of Asia. [ABSTRACT FROM AUTHOR]

The study of large-scale and long-term sedimentary hiatus and exhumation in vast intraplate basins is of great significance for unravelling their tectonic development, morphodynamics and relationships with petroleum occurrence. The Ordos Basin is an intra-cratonic depression in the western part of the North China Craton that gradually subsides from the Proterozoic to the Mesozoic and contains several post-1.8 Ga unconformities, some of which are related to a series of Cenozoic tectonic events contributing to current plateau setting. While previously published thermochronological data have identified Mesozoic–Cenozoic multiphase cooling events, we report in this paper new apatite fission-track, zircon (U Th)/He, and zircon U Pb geochronology on Paleoproterozoic borehole samples from the oldest sedimentary rocks in the Ordos Basin. Taken together, our data reveal cooling events at ca. 2.44 Ga, 1.97 Ga, 1.84 Ga, 630–570 Ma, 570–277 Ma, 75–15 Ma and ~ 15 Ma. Seismic reflection profiles and associated well cross-section interpretations are used to identify the basin's major unconformities and decipher the stratigraphic pattern. The six recognized unconformities exist between (1) the Precambrian and Cambrian, (2) the Cambrian and Ordovician, (3) the Lower Paleozoic and Upper Paleozoic, (4) the Middle-Upper Triassic and Jurassic, (5) the Jurassic and Lower Cretaceous and (6) the Cretaceous and Cenozoic. The new data allow a re-assessment of the Ordos Basin's amount and timing of erosion and burial. Integrating the existing evidence of exhumation, we interpret the Neoproterozoic cooling and exhumation events as a response to the Neoproterozoic Glaciations during the breakup of Rodina, while Phanerozoic wide subsidence of the Ordos Basin is interrupted by several differential exhumation and cooling events under the multiplate interactions in East Asia. Particularly, late Miocene (ca. 15–8 Ma) exhumation, synchronous topography inversion and deposition of Red Clay involve feedback relationships between tectonics and strengthening of Asian winter monsoon. Our results provide novel insights into of long-term exhumation and related unconformities concerning East Asia orogeny and climate events and impose important constraints on petroleum exploration. • The Ordos Basin experiences long term and multiple stage differential exhumation. • New thermochronological data reveal the cooling event of the Ordos Basin during the Neoproterozoic Snowball Earth. • The tiered cratonic scale unconformities of the Ordos Basin are recognized. • Unconformities and exhumation events across the western NCC originate from long term plate tectonic and climate change. [ABSTRACT FROM AUTHOR]

The tectono-magmatic evolution of the North China Craton (NCC) plays a crucial role in understanding the Jurassic–Early Cretaceous (Yanshanian) intracontinental orogeny in East Asia. A holistic understanding of multi-phased deformation and magmatism in the NCC is greatly complicated by the sporadically distributed Mesozoic strata with significantly different stratigraphic associations in various zones. In this paper, we review the Jurassic–Early Cretaceous litho-stratigraphy with emphasis on unconformities to define a coherent chronostratigraphic framework of the entire NCC. Integrating available data concerning tectonic deformation, and geochemistry and fabric of igneous rocks into the well-established coherent chronostratigraphic framework, a four-stage tectonic evolutionary model of the NCC is proposed, providing new insights into the dynamics of the Yanshanian intracontinental orogeny in East Asia. The first stage concerns a N–S extension in the NCC during the Early–early Middle Jurassic (∼200–170 Ma), expressed by the E–W striking brittle normal faults developed in the Lower–lower Middle Jurassic strata, and magmatism along the southern and northern margins of the NCC. It could be related to the post-orogenic extension after the deep continental subduction of the South China Block beneath the NCC. The second one is characterized by a N–S compression (i.e., Event A of the Yanshanian orogeny) in the late Middle Jurassic (∼170–160 Ma), evidenced by the unconformity above the Lower–lower Middle Jurassic strata and the upper Middle Jurassic syn-tectonic deposition. The associated N–S directed thrusts and fault-related folds were mainly localized in the northern part of the NCC, possibly responding to the far-field compression related to the closure of the Mongol–Okhotsk Ocean. The third stage corresponds to a NW–SE compression (i.e., Event B of the Yanshanian orogeny) during the Late Jurassic–earliest Cretaceous (∼160–135 Ma), illustrated by the NW–SE directed thrusts and the overprint of pre-existing N–S directed thrusts by the latter NW–SE directed thrusts. It was well recorded by the Upper Jurassic–lowermost Cretaceous syn-tectonic deposition and the unconformity above. This NW–SE compression in response to the flat slab subduction of the Paleo-Pacific Plate had influenced the entire NCC. However, the latest Middle–early Late Jurassic (∼165–150 Ma) local NE–SW extension, recorded by ductile and brittle normal faults, magnetic lineation in granitic plutons, and magmatism that extended to Northeast China and its adjacent areas, also occurred in the northeastern part of the NCC. This could be related to tectonic transition from the N–S closure of the Mongol–Okhotsk Ocean to the NNW-directed subduction of the Paleo-Pacific Plate. In the latest stage during the Early Cretaceous (∼135–115 Ma), the large-scale crustal extension, characterized by metamorphic core complexes, magmatism, graben or half-graben basins, occurred in a vast area extending more than 4000 km, from Transbaikalia, through the NCC, to the South China Block. It could be the consequence of the lithospheric thinning and the formation of the wide rift due to the southeastward stress relaxation of the NW–SE convergent East Asian continent as the slab rollback of the Paleo-Pacific Plate. These results provide a notable example of polyphase intra-plate deformation and magmatism paradigm in response to intracontinental orogeny with variable plate-boundary geodynamics. [ABSTRACT FROM AUTHOR]

Known as the "third pole" and "water tower of Asia", the Tibetan Plateau (TP) is the home to the largest number of glaciers in the mid-latitudes and one of the most sensitive areas to global climate change due to its special geographical location and powerful thermodynamic effects. In recent years, the TP has been affected by exogenous pollutants and the concentrations of some pollutants have shown an increasing trend, especially light-absorbing aerosols (LAAs), when ice core records, ground- and aircraft-based field campaigns and satellite technology enabled synthesized monitoring. The enhanced warming of the vast majority of regions in TP, together with Arctic warming, and snow/ice decline, represents credible evidence of anthropogenic climate change. This paper provides a comprehensive review of studies on the sources, characteristics and climate impacts of LAAs over the TP. Adjacent to the two major emission sources of LAAs in East Asia and South Asia, the unique geographical location and climatic characteristics of the TP make it possible for TP LAAs to cause atmospheric warming and accelerated glacier melting, affecting the hydrological cycle in South Asia, East Asia and even the Northern Hemisphere, thus causing a series of serious environmental and social problems. LAAs, such as black carbon and dust, can strongly absorb solar radiation and and have significantly influence on climate change. Moreover, light-absorbing impurities (LAIs) on snow/ice can reduce the snow/ice albedo and further accelerate the snow/ice melting. Both LAAs and LAIs over the TP can induce thermodynamic feedback processes, cause significant warming of the TP and then lead to a strengthening of the early monsoon and affect the subsequent evolution of the monsoon. Many mechanisms have been proposed forth regarding how TP LAAs modulate the phase, intensity, and amplitude of the Asian climate system. A wide range of theoretical, observational, and modeling findings on TP LAAs and their climate impacts are synthesized, in which dust aerosols from drylands and black carbon from biomass burning are considered leading components. By coupling an integrated approach with state-of-the-art modeling, high temporal and fine spatial resolution remote sensing observations with increasing sampling over the TP will provide further insights into TP aerosols. • Light-absorbing aerosols warm the Tibetan Plateau, further influence climate system • The external input of light-absorbing aerosols over the Tibetan Plateau is dominant • Climate effects of light-absorbing aerosols or impurities in snow is divergent [ABSTRACT FROM AUTHOR]

East Asia is exceptionally rich in diverse geological phenomena related to processes of major global significance in Earth history. Its tectonic evolution is closely related to the subduction of the Izanagi and Pacific plates and the India-Eurasia collision. Thus, this domain presents a vast natural laboratory within which some of the most topical and fundamental problems in Pacific-Asian Tectonics can be addressed. Recent breakthroughs in understanding the tectonic evolution of East Asia have been achieved, involving intraplate deformation, plate fragmentation, plate boundary processes, orogenic collapse, and craton destruction. These advances have been achieved via multidisciplinary work including structural geology, basin research, land and marine geophysics, thermochronology, numerical modeling, geochemistry and classical field geology. In the current context of research in East Asia the time is ripe for a thematic volume of review papers. This special issue is focused on the theme "Pacific-Asian Tectonics". It describes interdisciplinary methods adopted to study Meso-Cenozoic basin-forming mechanisms and evolutionary processes, unravels the timing and characteristics of major intraplate deformation, depicts the spatial-temporal distribution of Meso-Cenozoic igneous rocks, discusses the deep lithospheric structures overlying the subducting oceanic plates, and probes the natures and fates of subduction or collision processes. [ABSTRACT FROM AUTHOR]

From the latest Cretaceous (late Campanian to Maastrichtian, ~75–66 Ma) to the earliest Paleogene, fluctuations in greenhouse climate, inferred primarily from marine sediments, have been linked to volcanism, the Chicxulub asteroid impact, and the Cretaceous-Paleogene (K-Pg) mass extinction. In this paper, we summarize terrestrial climate records in mid-latitude East Asia during the latest Cretaceous and across the K-Pg boundary, based on a multi-proxy approach from the geochronologically well-constrained Sifangtai and Mingshui formations (SMF), accessed by scientific drilling of the Songliao Basin in northeastern China. Evolution of sedimentary environments is characterized by five depositional units of fluvial-deltaic-lacustrine facies. Development of four types of paleosols, including Inceptisols, Aridisols, Vertisols and Alfisols, is interpreted to primarily reflect climatic changes. Correlations among sedimentary facies, paleosol features, illite chemistry index, chemical index of alteration, as well as stable and clumped isotopes of pedogenic carbonates and clay minerals of the SMF validate their reliability for paleoclimate reconstruction, and indicate significant fluctuations in terrestrial climate and sedimentary environment. During global warming intervals possibly triggered by volcanism (e.g. ~69.5–68.5 Ma), the Songliao Basin experienced a warmer and wetter climate with stronger terrestrial chemical weathering and more monsoon-derived moisture sourced from the Pacific. In contrast, during global cooling intervals (e.g. ~70.5–69.5 Ma and ~ 68.5–66.5 Ma), the SMF record a cooler and drier climate with less intensive chemical weathering and more westerlies-derived moisture. Across the K-Pg boundary, dramatic changes in land temperatures and hydroclimate correspond to the latest Maastrichtian warming episode (~66.4–66.1 Ma), the transient cooling preceding the K-Pg boundary (~66.1–66.0 Ma), and the earliest Paleogene warming interval (~66.0–65.7 Ma). Temporal correlation of weathering index changes with the Deccan Traps volcanism suggests that volcanism and subsequent intensified weathering played a major role for climatic changes across the K-Pg boundary. The integrated records of sedimentological and geochemical datasets from the Songliao Basin robustly demonstrate that the terrestrial climate of mid-latitude East Asia responded strongly to greenhouse climate changes and to the catastrophic geological events from the latest Cretaceous to the earliest Paleogene. [ABSTRACT FROM AUTHOR]