Khanka Massif Research Articles

Revisiting the Late Paleozoic–Mesozoic tectonic evolution of epicontinental eastern Central Asian Orogenic Belt on the basis of detrital zircon

The eastern Central Asian Orogenic Belt (CAOB) is a natural laboratory for studying and interpreting the evolution of accretionary collages. The CAOB contains several micro-landmasses whose tectonic evolution during the Late Paleozoic–Mesozoic is a matter of debate. Here, we revisited detrital zircon data in relevant areas and present new detrital zircon U–Pb age data from the Hulin Complex and Wandashan Accretionary Complex (consisting of the Raohe and Yuejinshan complexes) in the eastern CAOB. The youngest zircon peak age of mica-quartz schist from the Hulin Complex constrains the timing of deposition to after ∼153.5 Ma. Sandy slate and fine sandstone from the Wandashan Accretionary Complex have youngest ages of ∼135.7 and ∼254.7 Ma, respectively. These data, together with detrital zircon data in the epicontinental eastern CAOB, suggest that there was a transformation from an extensional to convergent tectonic setting in the eastern CAOB around the Late Permian–Early Triassic. The Khanka Massif may have been adjacent to the Songnen and Jiamusi massifs to the west and north respectively, during the Late Paleozoic–Mesozoic. Between the Songnen and Jiamusi massifs, the Mudanjiang Ocean initially opened in the Late Paleozoic and closed after the Late Jurassic (∼153.5 Ma) and produced the Heilongjiang Complex. The Paleo-Yuejinshan back-arc basin underwent extension in the Permian and finally closed after ∼216 Ma, forming the Yuejinshan Complex at ∼210–180 Ma. The Raohe Complex was accreted at ∼169–133 Ma and emplaced at ∼133–131 Ma. The large-scale sinistral strike-slip movement of the Dunmi Fault started later than ∼153.5 Ma and partially displaced the Heilongjiang Complex from the Mudanjiang area to the present-day Hulin Complex. The eastern CAOB was under a superimposed tectonic regime of the Paleo-Pacific Ocean and Paleo-Asian Ocean in the Late Paleozoic.

The Khanka Massif: The Heterogeneity of its Basement and Regional Correlations

The Khanka Massif: The Heterogeneity of its Basement and Regional Correlations

The Early Permian assembly of the Jiamusi Massif and Khanka Massif: Evidence from sediment sources

The Jiamusi‐Khanka Massif is an important tectonic unit of the Central Asian Orogenic Belt in North‐east China. Its Late Palaeozoic tectonic properties and the timing of assembly have restricted the understanding of the tectonic evolution process at the eastern segment of the Central Asian Orogenic Belt for a long time. Based on the study of clastic rock petrology and zircon U–Pb chronology of the Early Permian Erlongshan Formation in Mishan, it is clear that the zircon age of the Early Permian Erlongshan Formation in Mishan is mainly Late Palaeozoic, with a major age peak at 300 ± 3 Ma and secondary age peaks at 356 ± 7 Ma and 475 ± 10 Ma. The provenance mainly comes from the magmatic arc source area, and Early Palaeozoic (500–420 Ma) detrital zircons mainly come from the south‐east margin of Jiamusi Massif, Late Palaeozoic (400–270 Ma) detrital zircons mainly come from the eastern margin of Jiamusi Massif and the northern margin of Khanka Massif. Among them, detrital zircons of a special age group 330–310 Ma come from the north of Khanka Massif, while 490–470 Ma detrital zircons which are common in the Early‐Middle Permian strata of Khanka Massif come from Jiamusi Massif. Combined with the evidence of petrology and palaeontology, this paper believes that the Early Permian Jiamusi Massif and Khanka Massif should be a unified Massif, that is, Jiamusi‐Khanka Massif.

Geochronology and Sr-Nd-Pb-Hf isotopic geochemistry of middle-late Permian granitic and volcanic rocks within the eastern margin of the Khanka Massif: petrogenesis and implications for the tectonic nature

ABSTRACT The Khanka Massif forms the easternmost part of the Central Asian Orogenic Belt (CAOB) and represents an ideal location for examination of the timing and processes involved in the transition from the Palaeo-Asian to Palaeo-Pacific Ocean tectonic systems. However, it is obstructed because the late Palaeozoic tectonic attributes of the eastern margin of this massif remain unclear. In this paper, we provide zircon U-Pb ages and Hf isotopic, as well as the whole-rock Sr-Nd-Pb-Hf isotopic data for Permian granitic and volcanic rocks within the eastern margin of the Khanka Massif, with the aim of exploring the petrogenesis and their geodynamics significance. These data suggest that the Permian magmatism within the eastern margin of the Khanka Massif, composed of monzogranites and rhyolites, can be split into two stages; i.e. middle (ca. 264 to ca. 263 Ma) and late (ca. 252 Ma) Permian. The highly fractionated middle Permian monzogranites are formed in an N-S extensional setting and represent the magmatic response to the amalgamation of the Khanka and Jiamusi massifs. Middle-late Permian rhyolites with decoupled Nd-Hf isotopic compositions were derived from partial melting of metasedimentary crustal rocks. Their moderate-high zircon saturation temperatures (796–817°C) are thought to represent the involvement of ridge subduction of the Palaeo-Asian Ocean beneath the western margin of the Khanka Massif. Our findings further reinforce the existence of the ridge subduction of the Palaeo-Asian Ocean at the western margin of Khanka Massif in the Permian, while excluding the possibility of Permian Palaeo-Pacific oceanic plate subduction occurred beneath the eastern margin of the Khanka Massif in the Permian.

ГЕОЭЛЕКТРИЧЕСКИЙ РАЗРЕЗ ЛИТОСФЕРЫ ЦЕНТРАЛЬНОЙ ЧАСТИ ЮГА СИХОТЭ-АЛИНСКОЙ СКЛАДЧАТОЙ СИСТЕМЫ ПО ПРОФИЛЮ Г. ДАЛЬНЕРЕЧЕНСК–ЗАЛ. НАХОДКА ПО ДАННЫМ МАГНИТОТЕЛЛУРИЧЕСКИХ ЗОНДИРОВАНИЙ

The geoelectric section of the lithosphere was constructed down to a depth of 150 km based on the results of magnetotelluric (MT) sounding carried out along the profile that extends along the eastern edge of the Khanka massif to the coast of the Sea of Japan, from the northern part of the massif to the Sikhote-Alin fold system (SASS). Conductive zones in the crust and zones of increased electrical resistivity in the upper mantle were distinguished. Differences in geoelectric characteristics of the Earth’s crust in the Late Proterozoic–Paleozoic Khanka massif and in the Tsentralnaya zone of the Albian-Cenomanian SASS were revealed. The latitudinal zonality of the crust and upper mantle was confirmed. The influence of the coast effect on the behavior of the Wiese vectors was studied and their relationship with conducting zones in the crust and faults was shown.

ХАНКАЙСКИЙ МАССИВ: ГЕТЕРОГЕННОСТЬ ФУНДАМЕНТА И РЕГИОНАЛЬНЫЕ КОРРЕЛЯЦИИ

The results of geochronology studies on metagranitoids (U-Pb SIMS) and ophiolites (Sm-Nb) from the Khanka massif are considered. New and published data define the Early Neoproterozoic Matveevka-Nakhimov terrane with early suprasubduction magmatism of 935 and 915 Ma, intraplate and Pacific-type transform margin magmatism of 850-880 and 757 Ma, and the Late Neoproterozoic-Early Cambrian Dvoryan and Tafuin terranes with suprasubduction magmatism of 543, 520, 517 and 513 Ma. Between these two parts of the massif there is a suture (Voznesenka and Spassk terranes) formed by Ediacaran-Cambrian shelf deposits and a Cambrian accretionary prism with ophiolites older than 514 Ma. The greater part of the Khanka massif formed late in the Cambrian with the Kordonka island arc terrane accreted at the end of the Silurian. The Sergeevka terrane of the Ordovician island arc joined it through Early Cretaceous strike-slip movements. Heterogeneous structures of the main part of the Khanka massif can be traced to the north by the analogous stages of magmatism and metamorphism, where the Jiamusi massif (including the East Bureya terrane) is an Early Neoproterozoic block and the eastern Songnen massif (including the West Bureya terrane) is a Late Neoproterozoic-Cambrian block. Between these two blocks is the Spassk-Wuxingzhen-Melgin suture formed by their collision late in the Cambrian. The Bureya-Songnen-Jiamusi-Khanka superterrane formed as a part of the Gondwana supercontinent about 500 Ma ago through orogeny and accretion of the Rodinia supercontinent fragments.

A Geoelectric Section of the Lithosphere of the Khanka Massif along the Pozharskoye Village–Shkotovo Settlement Profile from MT Soundings

A Geoelectric Section of the Lithosphere of the Khanka Massif along the Pozharskoye Village–Shkotovo Settlement Profile from MT Soundings

Early Ordovician Age of Fluorite-Rare-Metal Deposits at the Voznesensky Ore District (Far East, Russia): Evidence from Zircon and Cassiterite U–Pb and Fluorite Sm–Nd Dating Results

This article presents new isotope-geochronological results for the granites of the Voznesensky ore district (southeastern part of the Khanka massif). The granites are associated with extensive rare-metal–fluorite, tin and tantalum mineralization. Despite the numerous published results of Rb–Sr, Sm–Nd and U–Pb dating of ore-bearing granites and associated ores, the issues of age correlation and the genetic relationship of igneous rocks and mineralization remain unclear. U–Pb zircon SHRIMP dating reveals synchronous ages of 478 ± 4 Ma and 481 ± 7 Ma for two samples of biotite leucogranites as the age of magmatic crystallization of the Voznesensky granites. The composition of the studied zircon demonstrates the typical features of magmatic zircon and has the typical features of zircon exposed to fluids at the late/post-magmatic stage. Sm–Nd ID-TIMS dating of the fluorite of the Voznesenskoe deposit yields an age of 477 ± 9 Ma, and U–Pb ID-TIMS dating of cassiterite from the Yaroslavskoe and Chapaevskoe tin deposits yields an age of 480 ± 4 Ma, which confirms the direct genetic and age relationship of ore formation with granite magmatism.

Tectonic history of the Huangsong tectonic terrains in the Khanka Massif in the easternmost Central Asian Orogenic Belt: Constraints from detrital zircon U–Pb geochronology

The Khanka Massif, as the easternmost micro-massif of the Central Asian Orogenic Belt, its tectonic attributes and Paleozoic tectonic evolution remain controversial. In this paper, we present detrital zircon U–Pb age data for sedimentary rocks from the Huangsong Group, in order to provide constraints in this regard. The Huangsong Group has previously been described as the Precambrian basement of the Khanka Massif, consists of slightly metamorphosed sedimentary rocks, and from bottom to top is divided into the Yangmu and Yanwangdian suites. Unexpectedly, the depositional ages of the Yangmu suite are (from bottom to top) 220–205 Ma, 249–239 Ma, and 509–485 Ma. The depositional ages of the Yanwangdian suite are (from bottom to top) 426–390 Ma and 232–220 Ma. Clearly, the rocks do not have a logical stratigraphic sequence and, therefore, we propose that the “Huangsong Group” represents a stack of tectonic terrains with diverse ages (early Paleozoic to early Mesozoic) rather than a continuous sedimentary sequence. The potential sediment sources were mainly a nearby magmatic arc and batholiths, because the zircons are euhedral–subhedral, exhibit well-developed oscillatory zoning, and have high Th/U ratios. The occurrence of Precambrian detrital zircon grains implies the existence of remnants of Precambrian basement along the western margin of the Khanka Massif in the early Paleozoic. A comparison of magmatism in the regional massifs revealed there was a tectonic affinity between the western margin of the Khanka Massif and eastern margin of the Songnen–Zhangguangcai Range Massif in the Paleozoic. Based on the detrital zircon age populations and trace element contents, we conclude that the western Khanka Massif experienced a change from a stable to an active margin setting during the late Paleozoic, which was caused by subduction of the Paleo-Asian oceanic lithosphere.

АНАЛИТИЧЕСКИЕ ПОДХОДЫ К КОЛИЧЕСТВЕННОМУ ОПРЕДЕЛЕНИЮ СОДЕРЖАНИЙ ХИМИЧЕСКИХ ЭЛЕМЕНТОВ В УГЛЯХ И УГЛИСТЫХ ПОРОДАХ С ИСПОЛЬЗОВАНИЕМ МЕТОДОВ ИСП-МС И ИНАА

Актуальность исследования обусловлена значительным интересом ученых, работающих в области угольной геологии, и специалистов химико-аналитических лабораторий, практикующих элементный количественный анализ объектов окружающей среды, к проблематике высокоточного определения низких содержаний химических элементов в углях и угольных материалах для последующего применения полученных данных при решении научных и различных технологических задач. Цель: рассмотреть и обобщить наиболее часто используемые методические подходы к определению химических элементов в широком диапазоне их содержаний в углях (угольных материалах), а также оценить правильность и точность результатов метода ИСП-МС после открытого кислотного разложения проб и их сплавления с метаборатом лития, сопоставлением получаемых данных с результатами метода ИНАА и статистической обработкой данных. Объекты: угли, углистые алевролиты и углефицированная древесина месторождения германия Спецугли, расположенного на юго-западной окраине Ханкайского массива в восточной части Павловской угленосной впадины, Приморский край. Методы: масс-спектрометрия с индуктивно-связанной плазмой (ИСП-МС), применённая после перевода исследуемых образцов в растворенную форму, и неразрушающий метод количественного инструментального нейтронно-активационного анализа (ИНАА). Для обработки полученных результатов были использованы методы математической статистики. Результаты. Получены результаты ИСП-МС анализа трех стандартных образцов утвержденного типа (СО) состава золы уноса угля КАТЭКа ГСО 9237-2008 (ЗУК-2), золы бурого угля Азейского месторождения ГСО 7177-95 (ЗУА-1) и битуминозного угля CLB-1 Геологической службы США, представленные в виде данных об их микроэлементном составе в сравнении с аттестованными и рекомендованными значениями. Результаты определения части элементов, приведенные нами, дополняют представленные в паспорте данные по этим СО. Проведено сопоставление ИСП-МС результатов анализа для проб углей и углистых пород после различных способов химической пробоподготовки: методики открытого кислотного разложения и сплавления с метаборатом лития. Изучено поведение отдельных элементов во время этих процессов. Выполнено сравнение полученных данных по ИСП-МС и ИНАА методам. Все результаты обработаны метрологически, и показано их допустимое расхождение.

Permian ridge subduction in the easternmost Central Asian Orogenic Belt: Magmatic record using Sr-Nd-Pb-Hf-Mg isotopes

Igneous rocks related to abnormal high heat flow preserved in ancient convergent margins provide direct clues to identify fossil ridge-subduction. The Khanka Massif, as a witness of the final termination of the Paleo-Asian Ocean in Late Paleozoic, provides an ideal opportunity to trace the fossil ridge-subduction. Different types of Permian igneous rocks (282–255 Ma) were identified in composition from mafic to felsic. The mantle-derived mafic rocks are further subdivided into two groups. Group I are arc-featured rocks with normal mantle-like features in Mg isotopes. Permian subduction setting was therefore proposed within western margin of Khanka Massif, supported by the coeval arc-featured granitoids and the detrital zircon cumulative proportion curves. By contrast, Group II are tholeiitic and have more depleted Sr-Nd-Pb-Hf isotopic compositions similar to MORB of Paleo-Asian Ocean. In addition, the decoupling between Sr-Nd-Pb-Hf and Mg isotopes indicate isotope exchange between MORB and magnesite. High heat condition is therefore required because of the decomposition reactions of magnesite. The crust-derived felsic rocks exhibit the prominent difference in Sr-Nd-Pb-Hf-Mg isotopic compositions, implying synchronous melting of the continental and oceanic crusts, which are supported by the high zircon saturation temperatures (855–935 °C). Consequently, an ‘abnormal high-heat condition’ caused by ridge subduction and resultant slab window is the most likely model to reconcile the diversiform magmatism and tectonic evolution along the west margin of the Khanka Massif in the Permian. Sr-Nd-Pb-Hf-Mg isotopes are therefore verified as an integrated tracer to decipher the magmatic response to the ridge-subduction in ancient subduction zone.

ГЕОЭЛЕКТРИЧЕСКИЙ РАЗРЕЗ ЛИТОСФЕРЫ ХАНКАЙСКОГО МАССИВА ПО ПРОФИЛЮ С. ПОЖАРСКОЕ–П. ШКОТОВО ПО ДАННЫМ МАГНИТОТЕЛЛУРИЧЕСКИХ ЗОНДИРОВАНИЙ

The geoelectric section of the lithosphere is constructed down to a depth of 150 km based on the results of MT soundings carried out along the profile crossing the Khanka Massif from north to south. The crust and upper mantle structure of the massif is investigated. It has been found that the Khanka Massif is divided into the northern and southern parts bordered by the northern restriction of the Spassk Zone. A higher resistivity observed in the upper part of the section and the upper mantle is typical of the southern part of the massif. The northern part is characterized by two extended low-resistivity areas located beneath the southern boundaries of the Matveevka and Nakhimovka zones that penetrate from the upper mantle up to the surface. A comparison of the results obtained with the seismic prospecting and gravimetric data has shown their direct or indirect consistency.

Formation age and provenance of the Iman Group in the Khanka Massif: Evidence from U-Pb geochronology of detrital and magmatic zircons

本文对出露在兴凯地块南部伊曼群的变沉积岩和侵入其中的火成岩进行了系统的锆石LA-ICP-MS U-Pb定年和Hf同位素研究，旨在查明伊曼群的形成时代与物源，并讨论侵入岩的成因和构造背景。伊曼群二云母片岩中锆石呈自形-半自形，显示典型的岩浆生长环带，暗示其岩浆成因。定年结果表明：100个碎屑锆石分析点给出了555~1322Ma的年龄区间，主要峰值年龄为555Ma、612Ma、700Ma、739Ma、769Ma、839Ma、936Ma；其中约533Ma的锆石eHf（t）值介于-4.1~+3之间，二阶段模式年龄tDM2介于1305~1755Ma之间；700~839Ma的锆石eHf（t）值介于-3.7~+7.8之间，二阶段模式年龄tDM2介于1246~1907Ma之间。侵入伊曼群的白云母二长花岗岩的定年结果显示为443±3Ma，此年龄对应eHf（t）值介于-17.6~-4.2之间，二阶段模式年龄tDM2介于1688~2529Ma之间。结合二云母片岩中碎屑锆石的最小年龄以及穿切其中花岗岩的形成时代，可以判定伊曼群二云母片岩的形成时代介于443~555Ma之间，应为新元古代晚期至晚奥陶世之间。基于伊曼群中碎屑锆石的年龄众数及与区域岩浆事件的对比，伊曼群的沉积物源主要来自松嫩地块和佳木斯地块的新元古代火成岩。此外，白云母二长花岗岩显示出埃达克岩的地球化学属性，岩浆源于加厚下地壳的部分熔融，暗示晚奥陶世研究区可能发生了陆壳加厚事件。

Detrital Zircon U‐Pb Dating of Nanshuangyashan Formation in the Jiamusi Massif, NE China and its Tectonic Implications

A suite of the fossil‐rich marine‐land interbedded strata (Nanshuangyashan Formation) is distributed at the eastern margin of the Jiamusi massif in the eastern Heilongjiang Province, NE China. The authors had recently discovered a suite of arkose beneath the marine‐land interbedded strata, which overlays unconformably on the Permain granite in the eastern margin of the Jiamusi massif. The LA‐ICP‐MS zircon U‐Pb dating indicate that all detrital zircons from the analysed four arkose samples show the four population ages of >800 Ma, 538–481 Ma, 269–250 Ma and 223–215 Ma. The former three population ages are widely recorded in the Jiamusi‐Khanka massif and the Songnen massif. The later group is the minimal age population in the analyzed samples, limiting the sedimentation time of the arkoses occurred after the Late Triassic. At present, the minimal age population is not recorded in the Jiamusi massif, but the granites with the ages of 228–210 Ma are widely distributed in the Songnen‐Zhangguangcai Range massif and the Khanka massif. The predominantly Permian zircons are characterized by oscillatory zoning and euhedral shapes, with variable zircon εHf(t) values (–5.5 to +11.2), indicating that they were derived from mixture sources, possibly mixed with components of the Songnen‐Zhangguangcai Range massif and the Jiamusi‐Khanka massif. These results, combined with regional analyses, indicate that the closing of Mudanjiang ocean and Panthalassa ocean possibly existed from Early Permian to Late Triassic.

Magmatic control of gold mineralization in Western Primorye (by geophisical data)

An analysis of the regional gravitational field of the north-east of China, Korea and Western Primorye was carried out. The distribution of gold deposits was compared with the development of Mesozoic magmatism and negative anomalies of the gravitational field. Based on the analysis of geological, mineragenic, petrophysical and geophysical materials, geological and geophysical zoning of the western part of the Khanka massif was performed, and a scheme for interpreting geological and geophysical data with elements of minerageny was drawn up. A connection was established between the anomalies of the magnetic and gravitational fields and the position of the supposed gold-bearing ore regions and nodes located in the zone of joints of the North China Triassic-Jurassic volcanic-plutonic belt with the Proterozoic substrates of the Khanka massif. According to geophysical data, Early Jurassic intrusions were identified as, controlling the location of the gold nodes. It was concluded that the gold mineralization is related to the Jurassic magmatism, which increases the prospects for the discovery of gold mineralization in the Khanka district of the Western Primorye.

Magmatic Control of Gold Mineralization in Western Primorye

The article analyzes the regional gravitational field of northeastern China, Korea, and Western Primorye. The distribution of gold deposits is compared with the development of Mesozoic magmatism and negative gravitational field anomalies. Based on an analysis of geological, minerogenic, petrophysical, and geophysical materials, geological and geophysical zoning of the western part of the Khanka massif was carried out and a scheme was compiled for interpreting geological and geophysical data with minerogenic elements. The authors have determined the relationship between magnetic and gravitational field anomalies and the position of prospective gold-bearing ore districts and clusters in the junction zone of the North China Triassic–Jurassic volcanoplutonic belt with Proterozoic substrates of the Khanka massif. Based on geophysical data, early Jurassic intrusions were identified, which controlled the location of gold ore clusters. A conclusion is drawn about the relationship between gold mineralization and Jurassic magmatism, which increases the prospects for discovering gold mineralization in the Prikhankaysky region of Western Primorye.

Tectonic affinity of the Khanka Massif in the easternmost Central Asian Orogenic Belt: evidence from detrital zircon geochronology of Permian sedimentary rocks

ABSTRACTThe tectonic affiliation of the Khanka Massif, in the easternmost section of the Central Asian Orogenic Belt (CAOB), is still a matter of debate. Here, we provide new constraints on the provenance and timing of deposition of Permian strata in the western margin of the Khanka Massif. The results, which include U–Pb dating of detrital zircon grains using laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS), provide evidence regarding the tectonic position of the Khanka Massif and its role in the late Palaeozoic evolution of the eastern CAOB. Detrital zircon grains from a sublitharenite (Pingyangzhen Formation), a litharenite (Liangzichuan Formation), and a metamorphic siltstone (Qinglongcun Group) yielded multiple age populations ranging from Neoproterozoic (~914 Ma) to Permian (~272 Ma). Combined with age constraints from overlying/late-stage igneous rocks and other magmatism of the Khanka Massif, we conclude that the dated strata were deposited during the early–middle Permian and were sourced from the Khanka Massif. A comparison between the detrital zircon age populations and the history of magmatic activity in the neighbouring areas suggests that the Khanka Massif was tectonically linked to the Songnen–Zhangguangcai Range Massif. Based on tectonic discrimination diagrams, we conclude that the western margin of the Khanka Massif was positioned in a convergent-boundary basin during the early–middle Permian. Strike-slip faulting along the Dunhua–Mishan Fault, in response to ridge subduction of the Paleo-Asian Ocean Plate, resulted in a north-eastward movement of the Khanka Massif. The occurrence of Precambrian detrital zircon grains (with ages of 1900–1700 and 900–700 Ma) implies the presence of an ancient basement within the Khanka Massif.

Crustal Accretion and Reworking within the Khanka Massif: Evidence from Hf Isotopes of Zircons in Phanerozoic Granitoids

This paper presents a synthesis and analysis of geochronological, geochemical, and zircon Hf isotopic data of Phanerozoic granitoids within the Khanka massif, with the aim of revealing the accretion and reworking processes of continental crust within the massif. Zircon U-Pb dating indicates that Phanerozoic granitic magmatism within the Khanka massif can be subdivided into eight stages: Late Cambrian, Middle–Late Ordovician, Middle Silurian, Late Carboniferous, Early Permian, Middle–Late Permian to Early Triassic, Late Triassic–Early Jurassic, and Early Cretaceous. The zircon Hf isotopic compositions reveal that crustal accretionary events took place mainly in the Mesoproterozoic and Neoproterozoic. Through time, the zircon eHf(t) values gradually increase, indicating that the Phanerozoic granitic magmas were derived from the melting of progressively less ancient and more juvenile crust. The zircon eHf(t) values exhibit a gradual decrease with the increases in latitude, which implies that the amounts of ancient crustal components within the lower continental crust of the Khanka massif increased from south to north. At the same latitude range, the zircon Hf isotopic compositions also display some variations. We conclude, therefore, that significant horizontal and vertical heterogeneities existed in the lower continental crust of the Khanka massif during the Phanerozoic.

Geochronology and geochemistry of early Paleozoic intrusive rocks from the Khanka Massif in the Russian Far East: Petrogenesis and tectonic implications

This paper presents new geochronological and geochemical data for early Paleozoic intrusive rocks from the Khanka Massif in the Russian Far East, with the aim of elucidating the Paleozoic evolution and tectonic attributes of the Khanka Massif. New U–Pb zircon data indicate that early Paleozoic magmatism within the Khanka Massif can be subdivided into at least four stages: ~502, ~492, 462–445, and ~430Ma. The ~502Ma pyroxene diorites contain 58.28–59.64wt% SiO2, 2.84–3.69wt% MgO, and relatively high Cr and Ni contents. Negative εHf(t) values (−1.8 to −0.4), along with other geochemical data, indicate that the primary magma was derived from partial melting of mafic lower crust with the addition of mantle material. The ~492Ma syenogranites have high SiO2 and K2O contents, and show positive Eu anomalies, indicating the primary magma was generated by partial melting of lower crust at relatively low pressure. The ~445Ma Na-rich trondhjemites display high Sr/Y ratios and positive εHf(t) values (+1.8 to +3.9), indicating the primary magma was generated by partial melting of thickened hydrous mafic crust. The ~430Ma granitoids have high SiO2 and K2O contents, zircon εHf(t) values of −5.4 to +5.8, and two-stage model ages of 1757–1045Ma, suggesting the primary magma was produced by partial melting of heterogeneous Proterozoic lower crustal material. The geochemistry of these early Paleozoic intrusive assemblages indicates their formation in an active continental margin setting associated with the subduction of a paleo-oceanic plate beneath the Khanka Massif. The εHf(t) values show an increasingly negative trend with increasing latitude, revealing a lateral heterogeneity of the lower crust beneath the Khanka Massif. Regional comparisons of the magmatic events indicate that the Khanka Massif in the Russian Far East has a tectonic affinity to the Songnen–Zhangguangcai Range Massif rather than the adjacent Jiamusi Massif.

Formation of the Permian Taipinggou igneous rocks, north of Luobei (Northeast China): implications for the subduction of the Mudanjiang Ocean beneath the Bureya–Jiamusi Massif

ABSTRACTControversy has long surrounded the tectonic framework and evolution of the Mudanjiang Ocean between the Bureya–Jiamusi–Khanka Massif and Songnen–Zhangguangcai Range Massif, which are located in the easternmost segment of the Central Asian Orogenic Belt. To address these issues, we present zircon U-Pb ages, geochemical data, and zircon Hf isotopic compositions of the Taipinggou amphibolite and metagabbro exposed along the boundary area of Bureya–Jiamusi Massif and Songnen–Zhangguangcai Range Massif. Magmatic zircons from the amphibolite and metagabbro yield 206Pb/238U ages of 267 ± 2 Ma and 264 ± 2 Ma, respectively, which are interpreted as protolith ages. The geochemical data of the amphibolite samples show transitional characteristics of calcalkaline to tholeiitic series, with high MgO concentrations (9.44–10.48 wt.%) and Mg-numbers (73–75). These samples are enriched in large ion lithophile elements (e.g. Rb, Ba, and K) and light rare earth elements and are depleted in high-field-strength elements (e.g. Nb, Ta, and Ti) and heavy rare earth elements, with εHf(t) values of −6.63 to −3.26. It is inferred that the parental magma originated from an enriched lithospheric mantle that had been metasomatized by fluids derived from subducted oceanic slab. During magma evolution, the magma that formed the amphibolite mainly experienced accumulation with a shallow-level evolutionary process involving fractional crystallization. The Taipinggou metagabbro samples are subalkaline series and also characterized by enrichment in large ion lithophile elements (e.g. Rb, Ba, and K) and light rare earth elements and by depletion in Nb–Ta–P–Ti, with εHf(t) values of −3.09 to +1.16. The Taipinggou metagabbro and amphibolite have similar geochemical and Hf isotopic compositions, indicating a common parental magma source but with different degrees of magmatic differentiation. Based on the new geochronological and geochemical data presented in this study, we propose that both the Taipinggou metagabbro and amphibolite formed in a Middle Permian continental arc setting, closely related to eastward subduction beneath the Bureya–Jiamusi Massif. Combined with previous studies and regional geological observations, we suggest that a double-side subduction model is favoured for the Late Palaeozoic–Early Mesozoic geodynamic processes along the boundary area of Bureya–Jiamusi–Khanka Massif and Songnen–Zhangguangcai Range Massif.