Situated between the Altai Mountains and the Chinese Loess Plateau, the current territory of Mongolia played a pivotal role in Pleistocene human population dynamics in Northeast Asia with ...archaeological evidence suggesting the existence of cultural links with southern Siberia beginning in the Late Pleistocene. Here, we present preliminary results from the newly discovered site of Kharganyn Gol 5 in northern Mongolia. The results obtained from the Kharganyn Gol 5 site allow new reconstructions of chrono-cultural sequences and human behavior in eastern Central Asia. The site has yielded evidence of human occupation corresponding to several phases of the regional Upper Paleolithic. In addition, we present the first evidence of human occupation of the region prior to Greenland Interstadial 12 (GI12; 40,000–43,000 BP) and discuss the implications of such data. The Kharganyn Gol River basin contains sedimentary rock formations including numerous raw material outcrops, containing various types of chert. Prehistoric people used all these chert varieties for tool production, but the modes of raw material exploitation changed through time. This paper reports the presence, unique in Central and North Asia, of a non-utilitarian object made of muscovite mica in an Initial Upper Paleolithic assemblage in Archaeological Horizon 5 of the Kharganyn Gol 5 site.
The paper presents new original data on the Devonian felsic volcanism of the NW Rudny Altai (Russia) in the west of Central Asian Orogenic Belt (CAOB) – the front part of the Altai convergent margin ...of the Siberian continent. Two geochemical types of subvolcanic rhyolites were emplaced synchronously with the bimodal rhyolite-basalt association, which began to form in the end-Emsian, and clearly manifested on the border of the Givetian and the Frasnian. The rhyolites yield zircon U-Pb ages of ca. 390 Ma (R1-type) and 380 Ma (R2- and R3-types), reflecting two peaks of the volcanic activity. Most of these rocks have extreme petrochemical characteristics of high SiO2 contents and have contrast Na/K ratios. Their compositions are transition between calc-alkaline and tholeiite series: (La/Yb)n ~ 2–7, Zr/Y ~ 4 (Zr < 350 ppm) and La/Sm ~ 0.55–1. Rhyolites bear the distinctive geochemical signature of A-type felsic magma, such as enrichments in Zr, Nb, Y and Ce (>350 ppm), Zr (>250 ppm), and high Ga/Al (>2.6) values. The island-arc-like R1-rhyolite formed immediately after the beginning of rifting due to widespread crustal melting under reduced conditions. The generation of rift-like R2- and R3-rhyolites took place under non-equilibrium conditions, synchronously with the rise in the upper crust of Givetian-Frasnian basic magmas, as a result of the active lithospheric extension and high thermal input from the underlying hot mantle. We propose an extension regime in the transition area between the island-arc and back-arc basin for the origin of rhyolites. The study of the Devonian volcanism of the Rudny Altai gives important information about the processes that occurred at the initial stage of the formation of the Altai convergent margin.
In the front of the Altai convergent margin (NW Rudny Altai) of the Siberian continent two different geochemical types of subvolcanic rhyolites were emplaced consistently between ~390 and 380 Ma. Progressive rifting is assumed, as indicated by consistent generation, first island-arc-like rhyolites (R1), and then rift-like rhyolites (R2 and R3). The arc-like R1-rhyolite formed immediately after the beginning of rifting due to widespread crustal melting under reduced conditions. The R2- and R3-rhyolite was generated under non-equilibrium conditions, synchronously with the rise of basalts in the upper crust, as a reflection of the prolonged lithospheric extension and high thermal input from underlying hot mantle. Display omitted
•Early Devonian tectono-thermal evolution in the Central Asian Orogenic Belt•The rift-related bimodal-type rhyolites volcanism in a rear-arc/back-arc basin setting•Two different geochemical types of rhyolites were emplaced between ~390 and 380 Ma.
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The Permian to Triassic tectonic evolution of the Song Hien structure in NE Vietnam is poorly understood and if the Emeishan plume or the Indosinian orogeny contributed to Song Hien ...magmatism is controversial. Reliable estimates of the timing of magmatic activity in the region could help in clarifying this disputed history. However, very few U-Pb zircon ages are available, particularly for mafic–ultramafic intrusions. This study aimed to provide additional information on the timing of magmatism in this region. Sensitive-high-resolution-ion-microprobe (SHRIMP) and laser-ablation-inductively-coupled-mass-spectrometry (LA-ICP-MS) were used to obtain U-Pb ages for zircons from ultramafic to mafic, mafic to intermediate, and felsic intrusions and felsic volcanic suites within the Song Hien structure. Ultramafic to mafic intrusions consist of plagioclase-bearing lherzolite and olivine gabbro. Mafic to intermediate intrusions are composed of monzogabbro and quartz monzonite. There are granodioritic and granitic intrusions and rhyolite suites. Ultramafic to mafic rocks have ages of 252.2 ± 2.5 Ma to 246.5 ± 1.0 Ma, whereas mafic to intermediate rocks have ages of 250.1 ± 1.9 Ma to 246.7 ± 1.6 Ma. Felsic rocks have ages of 248.4 ± 2.6 Ma to 247.6 ± 1.5 Ma.. Our new zircon U-Pb ages indicate a peak of magmatic activity at 247–248 Ma, that generated both mafic and felsic units. Additionally, U-Pb ages of single zircon grains from both mafic and felsic suites show two similar peaks at 250 Ma and 241–243 Ma. These peaks coupled with data from the internal structure of age-patterned grains may reflect the continuous growth of zircons in magma chambers. The results further confirm that igneous activities in the Song Hien structure were 12 Myr younger than the Emeishan mantle plume. Therefore, this magmatism in the Song Hien structure is not temporally correlated with the Emeishan plume. We suggest that the studied magmatism in the Song Hien structure traced the Triassic subduction/collision inversion related to the Indochina–South China amalgamation (the Indosinian orogeny). The 247–252 Ma interval could correspond to its pre-collision stage. Based on previously published and newly received regional age data, we suggest that the timing of events linked to the Indosinian orogeny in northern Vietnam may be described as: pre-collision (245–255 Ma), syn‐collision (230–245 Ma, with the main peak at 230–240 Ma), and post-collision (200–230 Ma).
•The first evidence of ornament-making at the territory of modern Mongolia dated to Initial Upper Paleolithic.•Drilling was the most common technique of ornament-making in Initial Upper ...Paleolithic.•The first evidence of mica usage is dated to 38,000 years ago.•People could transport “exotic” raw material in 500 km at least.
Little is known about the acquisition and transport of rare or “exotic” raw materials in the Initial Upper Paleolithic (IUP). A recently discovered perforated muscovite (mica) flakelet at the Kharganyn Gol 5 site in the middle Selenga Basin of Mongolia raises the question of how far ancient humans ranged to access this material. Here, we present the initial results of an ongoing study, including dating by 40Ar/39Ar and identification of the muscovite source. The age of the Mongolian muscovite correlates with the Oktyabr’skaya outcrop in the Russian Transbaikal region, >500 km from the site. The Buteeliin Nuruu Mountains, near the Kharganyn Gol 5 site, are geologically similar and potentially contain as-yet unknown muscovite outcrops. This evidence suggests that Initial Upper Paleolithic populations had developed social networks or moved over long distances, using the Upper Paleolithic Selenga Corridor in both cases. Alternatively, the area’s Pleistocene occupants may have known the geological resources of their home range better than we do now.
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•Small-intrusion-hosted Ni-Cu-PGE sulfide occurrences within the Song Hien domain.•Two types of magmatic sulfide mineralization within mafic-ultramafic bodies of the Cao Bang ...Complex.•Growth perspectives for Ni-Cu-PGE sulfide deposits in northeastern Vietnam.
This paper discusses new data on the abundance and distribution of chalcophile elements (Ni, Cu, and PGE) in several small Permian–Triassic-aged sulfide-bearing mafic-ultramafic intrusions, namely the Dong Sang, Bo Ninh, Na Hoan and Ha Tri, belonging to the Cao Bang Complex in the Song Hien domain, Northeastern Vietnam. Mineral potential for Ni-Cu (-PGE) deposits in this domain is poorly understood in contrast to the Song Da domain in northwestern Vietnam, in which the well-known Ban Phuc Cu-Ni-PGE deposit is located. The disseminated sulfides from the Dong Sang, Bo Ninh and Na Hoan intrusions have very similar moderately fractionated chalcophile element abundance patterns, with positive Pd and negative Ru anomalies, and similar ratios of Pd/Ir (1–30) and (Pt+Pd)/(Ir+Ru+Os) (1–23), indicating a genetic link between these sulfides and the previously studied Suoi Cun intrusion, which also belongs to the Cao Bang complex and hosts Ni-Cu-PGE sulfides. The similar Cu/Pd ratios (3100–17100) of the sulfides from these intrusions are close to generally accepted ratios for the mantle range, and this indicates that sulfides were separated from a primary relatively PGE-undepleted magma as a result of a single sulfide segregation event. The sulfur isotopic data (δ34S) are in the range of −2.0 to −3.4‰ and indicate that the mantle is the dominant source of the sulfur, although the native values presumably allow for a small contribution from crustal S. In contrast, the disseminated and massive sulfides from the Ha Tri intrusion have high Pd/Ir (>100) and (Pt+Pd)/Ir (>140) ratios, indicating very high degrees of fractionation of a sulfide liquid, and it also has a wider range of δ34S values between +1.5 and −1.5‰ that overlap with that of the mantle. Mantle-like Cu/Pd ratios (3400–10600) indicate that no interaction has occurred between the sulfide liquid and a large volume of fresh magma in an open system. The results suggest two types of magmatic sulfide mineralization within mafic-ultramafic bodies of the Cao Bang Complex: (I) mineralization related to sulfide-bearing olivine-rich crystal mush and formed by multiple injections of magma into (and through?) the intrusion from the same source (as recorded in the Suoi Cun, Dong Sang, Bo Ninh, Na Hoan intrusions), and (II) mineralization hosted within closed system terminal chambers (as recorded in the Ha Tri intrusion).
Dykes composed of basic rocks and granite are formed due to interactions between melts in a wide range of conditions, from contrasting compositions and fluid saturation rates to various tectonic ...settings and processes at different depths. Textures and petrochemical characteristics of the dykes are thus widely variable. This paper is focused on composite dykes observed in the West Sangilen region in South-East Tuva, Russia.The Sangilen wedge is a fragment of the Early Caledonian orogenic structure of the Tuva-Mongolia Massif which evolved in a succession of geodynamic settings, from collision (transpression, 570–480 Ma) to transform faulting (transtension, 480–430 Ma). Intensive tectonic deformation facilitated massive basic-rock and granite magmatism at various layers of the crust and associated heating and metamorphism of the rocks (510–460 Ma). Basic-rock–granite composite dykes were formed in the above-mentioned period in various tectonic settings that controlled conditions of dyke intrusions and their compositions.We distinguish two groups of composite dykes observed on two sites, in the area between the Erzin and Naryn rivers and on the right bank of the Erzin river (Strelka and Erzin Sites, respectively) (Fig. 1). The dykes in both groups originated from one and the same basic-rock melt source. However, mingling of the contrasting melts was carried out by different mechanisms as suggested by the proposed intrusion models.In the area between the Erzin and Naryn rivers (Strelka Site), the host rock of the composite dykes is granite of the Nizhneerzin massif. The mingling dykes are composed of amphibole gabbro and monzogabbro, granosyenite and twofeldspar granite. Contacts between basic and felsic rocks vary from smooth contrasting to complex ‘lacerated’ flameshaped, and gradual transition zones are present (Fig. 6).The dykes were formed at mesoabyssal or abyssal depths, and the subliquidus heat regime was thus maintained for a long time, and even the smallest portions of the basic-rock melt were consolidated through quite a long period of time. As a consequence, indicators of deformation are lacking in the composite dykes, while transition zones and hybridization are present.On the right bank of the Erzin river (Ersin Site), the dykes cut through migmatite-granite of the Erzin formation in the same-name tectonic zone. Contacts with host rocks are transverse. Melanocratic rocks are represented by smallgrained diorite and quartz diorite, and the felsic composite dykes are composed of medium- and small-grained twofeldspar granite and leukogranite. Transition zones, hornfelsing and contact alterations are absent at contacts of all the types (Fig. 8).The composite dykes of this type intruded and emplaced when the shear zone was subject to extension and fragmentation, which predetermined active intrusion of basic and, possibly, felsic melts through conjugated faults. Crystallization of the melts was rapid, and their potential heat impact on the adjoining rocks was thus excluded, as evidenced by the presence of oxygonal chips of igneous and host metamorphic rocks, vein pegmatoid intrusions, and composite dykes of the reticulate-cuspate texture with the dominant basic-rock component.The mingling dykes classified in the first group intruded when the Erzin and Kokmolgarga shear zones were formed at the early stage of the tectonic-magmatic evolution of the Sangilen orogen (510–490 Ma). Intrusions of the basic-rock melts were accompanied by the formation of relatively large massifs of the basic composition, i.e. the Erzin and Bayankol gabbro-monzodiorite massifs, as well as by the occurrence of composite dykes that are abundant in the area between the Erzin and Naryn rivers. In the second stage (460–430 Ma), the composite dykes occurred when the orogen was subject to extension along the system of tectonic zones, the Bashkymugur gabbro-monzodiorite massif was emplaced, and fracture-vein structures, including the dykes, were formed.
Figurative depictions in art first occur ca. 50,000 years ago in Europe, Africa, and Southeast Asia. Considered by most as an advanced form of symbolic behavior, they are restricted to our species. ...Here, we report a piece of ornament interpreted as a phallus-like representation. It was found in a 42,000 ca.-year-old Upper Paleolithic archaeological layer at the open-air archaeological site of Tolbor-21, in Mongolia. Mineralogical, microscopic, and rugosimetric analyses points toward the allochthonous origin of the pendant and a complex functional history. Three-dimensional phallic pendants are unknown in the Paleolithic record, and this discovery predates the earliest known sexed anthropomorphic representation. It attests that hunter-gatherer communities used sex anatomical attributes as symbols at a very early stage of their dispersal in the region. The pendant was produced during a period that overlaps with age estimates for early introgression events between Homo sapiens and Denisovans, and in a region where such encounters are plausible.
The mafic-ultramafic massifs with the PGE-Cu-Ni mineralization located in North-Central Mongolia: Oortsog, Dulaan, Mankhan, Yamat, and Nomgon were investigated. For the first time we consider these ...massifs as a single magmatic association and as fragments of Khangai batholith caused by the action of the plume responsible for the formation Permian Khangai LIP. The massifs fractionated from peridotite to gabbro have a similar typomorphic ore mineralogical and geochemical features, which change depending on the degrees of fractionation of magma and evolution of the sulfide melt. The least fractionated Oortsog massif originated from Ni-rich high-Mg basaltic magma. It is characterized by predominance of pyrrhotite mineralization due to exsolution of monosulfide solid solution (MSS). The most fractionated is the Nomgon massif originated from Cu-rich basaltic magma with bornite-chalcopyrite mineralization, formed as an exsolution of intermediate solid solution (ISS). The rest of the massifs have a medium characteristics between these two. The compositions of sulfides in the studied massifs change in accordance with the increase in sulfur fugacity from peridotite to gabbro: enrichment of pentlandite in Ni and pyrrhotite in S. The composition of PGM changes from Pt minerals in Oortsog massif to Pd minerals in Nomgon massif in the same direction. These massifs can be considered as potential for the PGE.
The Yamaat Uul mafic complex with Cu-Ni mineralization is located in the Khangai Mountains of Western Mongolia. We have received new unique data for mafic rocks of the complex: U-Pb dating (SHRIMP ...II), mineralogy (WDS) and geochemistry (XRF, ICP-MS), Sm-Nd and Rb-Sr isotope data and sulphur isotopes. The Yamaat Uul mafic complex consists of two intrusions: Intrusion 1 is represented by rocks of plagioclase cumulates and olivine–pyroxene cumulates; Intrusion 2 consists of monzogabbro. Intrusions 1 and 2 are different in composition of minerals such as olivine, plagioclase and biotite. The monzogabbro has higher contents of incompatible elements (REE, K, Ti, P) than rocks of Intrusion 1. Zircon U-Pb dating of the anorthosite and Bt-Am-Ol gabbronorite shows a Late Permian age (255.8 ± 2.9 Ma and 262.6 ± 3.1 Ma, respectively) for the Yamaat Uul mafic complex. All of the rocks of the complex are derived from a unified parental melt due to different amounts of trapped melts in plagioclase and olivine–pyroxene cumulates and without crustal contamination. The Cu-Ni mineralization of the complex has a low degree of evolution of the sulphide melt, similar to PGE-Cu-Ni mafic–ultramafic intrusions of the Khangai Mountains (Nomgon and Oortsog Uul). The Yamaat Uul mafic complex together with other mafic–ultramafic intrusions of the Khangai Mountains is related to the Khangai LIP and can be considered as potential for the PGE-Cu-Ni. The new geological, petrological, geochemical and isotope–geochronological data can later be used to reconstruct the geotectonics of the Khangai Mountains and the Central Asian orogenic belt as a whole.
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