North Asian Continent Research Articles

Stable isotopic characteristics of precipitation related to the environmental controlling factors in Ningbo, East China.

Hydrogen and oxygen stable isotopes (δ2H and δ18O) in precipitation were analysed from June 2018 to May 2020 in Ningbo and were influenced by the subtropical monsoon climate in East China. The δ2H and δ18O values of precipitation in Ningbo varied from -90.0 to 6.0‰ and from -13.5 to -1.6‰, respectively. The local meteoric water line (LMWL) in Ningbo was obtained as δ2H = 9.27 δ18O + 35.95 and had a larger slope and intercept compared to the global meteoric water line (GMWL) because its water vapour sources were oceans. The more negative δ18O values and lower deuterium excess (D-excess) of precipitation in summer were due to water vapour sources from the East China Sea, the South Sea and the Western Pacific, which are controlled by the southeasterly monsoon. In contrast, the less negative δ18O and higher D-excess of precipitation in winter were influenced by water vapour sources from the North Asian continent and North China transported by the northwesterly monsoon. The precipitation amount effect was significant in Ningbo, especially in summer. The inverse temperature effect was appeared in Ningbo, except winter. These two effects may be caused mainly by the monsoon climate rather than by the secondary evaporation effect.

PGE mineralization in andesite explosive breccias associated with the poperechny iron-manganese deposit (Lesser Khingan, Far East Russia): Whole-rock geochemical, 190Pt-4He isotopic, and mineralogical evidence

We report in this paper an unusual occurrence of platinum-group minerals in evolved explosive breccia associated with the Poperechny iron-manganese deposit (Lesser Khingan Range, Far East Russia). PGMs in andesite breccia are represented by Fe-Pt solid solutions (85%) and PGM (mostly Os-Ir-Ru) solid solutions, sulfides and sulfarsenides (15%). Textural and compositional variations in PGM assemblages suggest that Pt-Fe and Os-Ir-Ru solid solutions, as well as erlichmanite-laurite series sulfides were formed during high-temperature fractionation of mantle-derived mafic parental melt (similar to Alaskan-type complexes) and were entrained in the evolved andesitic melt during its emplacement in the crust. Pd-Pt plumbostannide and copper-gold solid solutions reflect late magmatic re-crystallization and metasomatism. Early Cretaceous (~125 Ma) age of ferroplatinum in the explosive breccia suggests that PGM-bearing ultramafic material could have been sampled during regional slab-window tectonics related to the Late Mesozoic subduction of Izanagi plate along southern margin of the North Asian continent.

The Study of the Unusual Development of the Super Tropical Storms Surrounding Indonesia Maritime Continent Area In March 2018

The winter season 2017/2018 could be one of the unusual conditions with increasing the winter storm activities over Northern Hemisphere to affect aerodrome closed for certain airports in big cities of the United States of America and Canada in Northern America Continent, it could be over European Countries and North Asian Continent. The freezing water Niagara for the first time during last 50 years could be the additional condition from coolest than normal and it might longer than usual based upon public information and collecting the global climatic chart from National Climate Centers under coordination from the World Meteorological Organization.

Unusual Weather & Climatic System In Indonesia Maritime Continent Area In the Beginning 2018

The winter season 2017/2018 could be one of the unusual conditions with increasing the winter storm activities over Northern Hemisphere to affect aerodrome closed for certain airports in big cities of the United States of America and Canada in Northern America Continent, it could be over European Countries and North Asian Continent. The freezing water Niagara for the first time during last 50 years could be the additional condition from coolest than normal and it might longer than usual based upon public information and collecting the global climatic chart from National Climate Centers under coordination from the World Meteorological Organization.

Long Term Winter Season 2017/2018 Northern Hemisophere and Their Impact over Indonesia Maritime Continent Area

The winter season 2017/2018 could be one of the unusual condition with increasing the winter storm activities over Northern Hemisphere to affect aerodrome closed for certain airports in big city of the United States of America and Canada in Northern America Continent, it could be over European Countries and North Asian Continent. The freezing water Niagara for the first time during last 50 years could be additional condition from coolest than normal and it might longer than usual based upon public information and collecting the global climatic chart from National Climate Centers under coordination from the World Meteorological Organization.

Late Permian to Triassic intraplate orogeny of the southern Tianshan and adjacent regions, NW China

The South Tianshan Orogen and adjacent regions of Central Asia are located in the southwestern part of the Central Asian Orogenic Belt. The formation of South Tianshan Orogen was a diachronous, scissors-like process, which took place during the Palaeozoic, and its western segment was accepted as a site of the final collision between the Tarim Craton and the North Asian continent, which occurred in the late Palaeozoic. However, the post-collisional tectonic evolution of the South Tianshan Orogen and adjacent regions remains debatable.Based on previous studies and recent geochronogical data, we suggest that the final collision between the Tarim Craton and the North Asian continent occurred during the late Carboniferous. Therefore, the Permian was a period of intracontinental environment in the southern Tianshan and adjacent regions. We propose that an earlier, small-scale intraplate orogenic stage occurred in late Permian to Triassic time, which was the first intraplate process in the South Tianshan Orogen and adjacent regions. The later large-scale and well-known Neogene to Quaternary intraplate orogeny was induced by the collision between the India subcontinent and the Eurasian plate. The paper presents a new evolutionary model for the South Tianshan Orogen and adjacent regions, which includes seven stages: (I) late Ordovician–early Silurian opening of the South Tianshan Ocean; (II) middle Silurian–middle Devonian subduction of the South Tianshan Ocean beneath an active margin of the North Asian continent; (III) late Devonian–late Carboniferous closure of the South Tianshan Ocean and collision between the Kazakhstan-Yili and Tarim continental blocks; (IV) early Permian post-collisional magmatism and rifting; (V) late Permian–Triassic the first intraplate orogeny; (VI) Jurassic–Palaeogene tectonic stagnation and (VII) Neocene–Quaternary intraplate orogeny.

Magmatism at the Eurasian–North American modern plate boundary: Constraints from alkaline volcanism in the Chersky Belt (Yakutia)

The Chersky seismic belt (NE-Russia) forms the modern plate boundary of the Eurasian−North American continental plate. The geodynamic evolution of this continent−continent setting is highly complex and remains a matter of debate, as the extent and influence of the Mid-Arctic Ocean spreading center on the North Asian continent since the Eocene remains unclear. The progression from a tensional stress regime to a modern day transpressional one in the Chersky seismic belt, makes the understanding even more complicated. The alkaline volcanism that has erupted along the Chersky range from Eocene through to the Recent can provide constraints on the geodynamic evolution of this continental boundary, however, the source and petrogenetic evolution of these volcanic rocks and their initiating mechanisms are poorly understood.We studied basanites of the central Chersky belt, which are thought to represent the first alkaline volcanic activity in the area, after initial opening of the Arctic Ocean basin. We present mineral and bulk rock geochemical data as well as Sr–Nd–Pb–Hf isotopes of the alkaline suite of rocks combined with new precise K–Ar and 40Ar/39Ar dating, and discuss an integrated tectono-magmatic model for the Chersky belt. Our findings show that the basanites were generated from a homogeneous asthenospheric mantle reservoir with an EM-1 isotopic flavor, under relatively ‘dry’ conditions at segregation depths around 110km and temperatures of ~1500°C. Trace element and isotope systematics combined with mantle potential temperature estimates offer no confirmation of magmatism related to subduction or plume activity. Mineral geochemical and petrographical observations together with bulk geochemical evidence indicate a rapid ascent of melts and high cooling rates after emplacement in the continental crust. Our preferred model is that volcanism was triggered by extension and thinning of the lithosphere combined with adiabatic upwelling of the underlying mantle at 37Ma. This suggests that at that time, rift tectonics in the Mid-Arctic Ocean most likely had also affected the North-Asian continent, causing volcanic activity in the Chersky belt, before the regional geodynamic regime changed from a tensional to compressional. Our conclusions contribute not only to the understanding of volcanism in the Chersky seismic belt (NE-Russia) but also to general aspects of plate dynamics between the Eurasian and North American continent.

Tectonics and geodynamics of the Central Asian Foldbelt: the role of Late Paleozoic large-amplitude strike-slip faults

The following structural elements have been recognized to constitute the tectonic demarcation of Central Asian Foldbelt: (1) The Kazakhstan–Baikal composite continent, its basement formed in Vendian–Cambrian as a result of Paleoasian oceanic crust, along with Precambrian microcontinents and Gondwana-type terranes, subduction beneath the southeastern margin of the Siberian continent (western margin in present-day coordinates). The subduction and subsequent collision of microcontinents and terranes with the Kazakhstan–Tuva–Mongolia island arc led to crustal consolidation and formation of the composite-continent basement. In Late Cambrian and Early Ordovician, this continent was separated from Siberia by the Ob'–Zaisan ocean basin. (2) The Vendian and Paleozoic Siberian continental margin complexes comprising the Vendian–Cambrian Kuznetsk–Altai island arc and the rock complexes of Ordovician–Early Devonian passive margin and Devonian to Early Carboniferous active margin. Fragments of Vendian–Early Cambrian oceanic crust represented by ophiolite and paleo-oceanic mounds dominate in the accretionary wedges of island arc. The Gondwana-type continental blocks are absent in western Siberian continental margin complexes and supposedly formed at the convergent boundary of a different ocean, probably, Paleopacific. (3) The Middle–Late Paleozoic Charysh–Terekta–Ulagan–Sayan suture-shear zone separating the continental margin complexes of Siberia and Kazakhstan–Baikal. It is composed of fragments of Cambrian and Early Ordovician oceanic crust of the Ob'–Zaisan basin, Ordovician blueschists and Cambrian–Ordovician turbidites, and Middle Paleozoic metamorphic rocks of shear zones. In the suture zone, the Kazakhstan–Baikal continental masses moved westward along the southeastern margin of Siberia. In Late Devonian and Early Carboniferous, the continents amalgamated to form the North Asian continent. (4) The Late Paleozoic strike-slip faults forming an orogenic collage of terranes, which resulted from Late Devonian to Early Carboniferous collision between Kazakhstan–Baikal and Siberian continents and Late Carboniferous to Permian and Late Permian to Early Triassic collisions between East European Craton and North Asian continent. As a result, the Vendian to Middle Paleozoic accretion-collisional continental margins of Siberia and the entire Kazakhstan–Baikal composite continent became fragmented by large-amplitude (up to a few thousand kilometers) strike-slip faults and conjugate thrusts into several strike-slip terranes, which mixed with each other and thus disrupted the original geodynamic, tectonic, and paleogeographic demarcation.

Tectonics of Northeast Asia: An overview

The tectonic units of the Verkhoyansk-Chukotka Mesozoides and the Koryak-Kamchatka Fold Region substantially differ from each other in the structure and composition of terranes. The geodynamic settings of terrane formation are defined and the main stages of their tectonic history are reconstructed. The formation of Mesozoides was mainly controlled by collision, largely between the continent and the Kolyma-Omolon and Chukchi microcontinents. The accretionary structure of the Koryak Highland comprises various terranes transported by Pacific plates and docked to the Asian continent, periodically accreting its margin. The following evolutionary stages are established: destruction of the North Asian continent (Ordovician, Late Devonian-Early Carboniferous, Permian-Triassic); amalgamation (Middle Jurassic for Kolyma and Mid-Cretaceous for Koryak terranes); collision (terminal Early Cretaceous); and continental growth (terminal Early Cretaceous, terminal Late Cretaceous, middle Eocene).

South Anyui suture: tectono-stratigraphy, deformations, and principal tectonic events

Abstract. Geochronologic and structural data from the terranes of the South Anyui suture zone record a protracted deformational history before, during and after an Early Cretaceous collision of the passive margin of the Chukotka-Arctic Alaska continental block with the active continental margin of the North Asian continent. Preceding this collision, the island arc complexes of the Yarakvaam terrane on the northern margin of the North Asian craton record Early Carboniferous to Neocomian ages in ophiolite, sedimentary, and volcanic rocks. Triassic to Jurassic amphibolites constrain the timing of subduction and intraoceanic deformation along this margin. The protracted (Neocomian to Aptian) collision of the Chukotka passive margin with the North Asian continent is preserved in a range of structural styles including first north verging folding, then south verging folding, and finally late collisional dextral strike slip motions which likely record a change from orthogonal collision to oblique collision. Due to this collision, the southern passive margin of Chukotka was overthrust by tectonic nappes composed of tectono-stratigraphic complexes of the South Anyui terrane. Greenschists with ages of 115–119 Ma are related to the last stages of this collision. The postcollisional orogenic stage (Albian to Cenomanian) is characterized by sinistral strike slip faults and an extensional environment.

Ophiolites in accretionary complexes along the Early Cretaceous margin of NE Asia: age, composition, and geodynamic diversity

Abstract The existing published data, combined with our own new field, petrographic, and geochemical observations and data show that ophiolites of the West Koryak fold system originated in a variety of tectonic environments. This fold system stretches along the boundary shared by two of NE Asia’s largest tectonic units, the Verkhoyansk-Chukotka and Koryak-Kamchatka foldbelts. The fold system abounds in Palaeozoic and Mesozoic ophiolites and sedimentary and volcanic island-arc assemblages. The ophiolites are Palaeozoic and Mesozoic in age. The variety of geological and geochemical signatures implies ophiolite origin in diverse tectonic settings. The Early Palaeozoic ophiolites of the Ganychalan accreted terrane and Devonian(?) ophiolites of the Ust-Belaya accreted terrane are fragments of the Panthalassan oceanic lithosphere. Serpentinite mélange in the Ust-Belaya terrane contains some blocks of island-arc provenance. They are probably Late Palaeozoic-Early Mesozoic in age as determined by K-Ar measurements, which require validation by other techniques. Mesozoic, chiefly Late Jurassic-Early Cretaceous ophiolites of the Beregovoi and Kuyul accreted terranes, originated in a suprasubduction-zone (SSZ) setting (ensimatic island arc and back-arc basin). Among the Mesozoic ophiolites, one finds blocks of oceanic assemblages in serpentinite mélanges as well. Basalt and chert blocks of clearly oceanic derivation are viewed as detached fragments of the upper part of the oceanic lithosphere. The ophiolites have experienced a variety of accretionary scenarios. Palaeozoic ophiolites docked onto the Koni-Taigonos island arc (of Late Palaeozoic-Early Mesozoic age), probably in the Late Palaeozoic or Early Mesozoic, whereas Mesozoic ophiolites accreted onto the Uda-Murgal island arc (of Late Jurassic-Early Cretaceous age) in the terminal Early Cretaceous. Sedimentary deposits, whose base is late Albian in age, make a post-accretionary sequence. These island arcs portray the overall history of the convergent boundary between the North Asian continent and NW Pacific. Ophiolites of the Ganychalan and Ust-Belaya terranes consist of thrust sheets and, jointly with Yelistratov Peninsula ophiolites, make up the basement to the forearc of the Uda-Murgal island arc, ophiolites of Cape Povorotny and Kuyul terrane being incorporated in accretionary prisms of the same arc. Ophiolites and associated metamorphic, volcanic, and sedimentary rocks of Palaeozoic-Early Cretaceous age underwent three deformation phases, each reflecting a different stage in the evolution of the NE Asian continental margin and readily correlative with principal tectonic events in the northern Circum-Pacific region.

福井県中池見盆地と兵庫県黒井盆地にみられる過去１１００００年間の古環境変動

We studied two drilling cores from the Naka-ikemi basin which was deposited during the past 110, 000 years in Fukui Prefecture and the Kuroi basin, which was deposited during the last glacial period in Hyogo Prefecture in central Japan, to reconstruct paleoenvironmental changes from eolian dust deposition. We suggest that two the cores show records of the East Asian monsoon variability correlated to the cool Younger Dryas and Heinrich events H1-H6, and to interglacial/interstadial periods, such as the Dansgaard-Oescheger IS1-IS24 climate intervals, respectively, as seen in the Greenland temperature record. Eolian dust in the two areas was transported from the North Asian continent by the NW winter monsoon judging from the high electron spin resonance (ESR) signal intensity. Periods of strong NW winter monsoon, indicated by eolian dust spikes, were associated with atmospheric cooling and the development of the Siberian high pressure systems. Following every eolian dust spike, the mean diameter of inorganic material increased abruptly. It seems that the increases of grain size reflect fluvial activity induced by the summer monsoon, which correlated with interstadial and interglacial climatic events.