PrimoryeGeology
SHORT  HISTORY  OF  GEOLOGIC  DEVELOPMENT

        Until  recently, the territory of Primorskii Krai was considered a part  of the Sikhote-Alin geosynclinal system that reflects the specific geological conditions of the Eurasia continent-Pacific Ocean transition zone. According to the modern ideas of plate tectonics, that have been  successfully used since the early 1980s for the  paleointerpretation  of geological features of the region (Natalin, 1991; Natalin and others, 1994; Parfenov, 1984; Khanchuk, 1993; Khanchuk and others, 1988, 1996),  the Primorskii Krai  and adjacent  Sea of Japan and Kuril and Japanese Islands (Fig.1)  are a part of the accretionary (transition) zone between Eurasia continent and the Pacific Ocean plate. The territory of Primorskii Krai  is interpreted as a collage of terranes with suturing in between and intrusive rocks and overlapping complexes of volcanic and detrital rocks. Ideas of the nature of terranes, suturing and overlapping them formations are improved as new data appear. The description below is the authors ideas and does not pretend to the absolute certainty and indisputability.

Terranes, Pre-accretionary Magmatism, and Ore Deposits.

       For the  Primorskii Krai (Fig.2)  there are terranes of various ages. The most ancient is, probably, Voznensenka  terrane. It is composed of the Late Proterozoic-Lower Cambrian clastic rocks and limestones that were formed on a shelf, and clastic deposits formed on  the coastal land. In the paleoshelf  units are stratiform polymetallic (essentially zinc) deposits of exhalation-sedimentary genesis. Massive sulphide ores are conformable to the enclosing organogenic bituminous limestones near  contacts with overlapping  of clay rocks. To the north of Voznesenka terrane, e is the Spassk terrane, an accretionary prism or subduction zone composed of Early Paleozoic turbidites with ophiolite, chert, and limestone inclusions of Cambrian age. The Nakhimovsky and Matveevsky terranes  , probably, represent metamorphic cores of greenschist  to granulitic facies of Ordovician age that were formed  on Late Proterozoic and Cambrian sedimentary and volcanic rocks. The Kabargincsky terrane occurs between the Matveevsky and Nakhmovsky  terranes and is composed of Proterozoic-Cambrian limestone, cherty rocks, ophiolite, clastic rocks, and is a fragment of an accretionary prism or subduction zone. In Kabarginsky terrane,   iron ore (with manganese) exhalation-sedimentary deposits are known, mainly magnetite and hematite-magnetite quartzite, and isolated thin beds of marganese ore.
      The Sergeevka terrane is composed of large synkinematic plutons of amphibole gabbro, diorite, and granite. In gabbro and dioriteare large xenoliths of metamorphic rocks derived from clastic  beds. The age of gabbro and granite of the Sergeevka terrane  is Late Cambrian-Early Ordovician. Probably, the Sergeevka terrane was an accretionary prism that underwent melting at the base  of an island arc.
      In  western Primorye, the Laoelin-Grodekovo island-arc terrane, composed of Permian basalt, andesite, rhyolite, volcanoclastic rock, and limestone, occurs. In rhyolite, is the  Komissarovskoye and other epithermal gold-silver deposits.
      In the northeastern part of Primorskii Krai, in the Sikhote-Alin fold belt,  is Samarka terrane, part of an  accretionary prism or subduction zone. It is composed of Jurassic turbidites with the inclusions of the oceanic crust fragments, mainly  Devonian ophiolite, Late Paleozoic and Triassic chert, and Late Paleozoic limestone and basalt. The terrane corresponds to the subduction zone  of the western direction. In the southeast, is the Taukha terrane, a part  of an accretionary prism or subduction zone. This terrane contains a complicated structure and consists of three units. The western unit is composed of basalt from a  spreading zone that is overlapped by Upper Jurassic chert and Neokomian turbidites. The central unit is made up of Neocomian subduction melange with the inclusions of Triassic and Jurassic chert, Triassic limestone and sea-mount basalt. The eastern unit is composed of Late Jurassic-Neocomian subduction melange with the inclusions of Late Paleozoic, Triassic, and Jurassic chert, Devonian, Carboniferous, and Permian limestone and sea-mount basalt, and Triassic clastic rocks. The terrane formed as a subduction zone towards the east.
      To the north-west of Taukha terrane, is Zhuravlevka terrane composed of turbidite basin, formed in a transform continental margin, composed of Early Cretaceous clastic rocks including flysh that encloses rare thin subalkaline basal. To the east, the Kema terrane, an Aptian- Albian island arc occurs and  consists of terrigenous and volcanogenic flysch with basalt and andesite which formed  predominantly under water and more rarely on islands.

Accretion of Terranes, Collision  and Post-accretion Magmatism, and Ore Mineralization

      Paleobiogeographical data suggest the  ancient Voznesenka terrane  was a part of Cambrian Gondwana supercontinent. In Ordovician time, the Spassky, Nakhimovsky, Kabarginsky, and Matveevsky  terranes were accreted to the Gondwana margin. Initially they were the parts of the Paleoasia Ocean. Collision of the terranes with the continent margin was accompanied by strong metamorphism and granite formation. With biotite granites (Ordovician-Silurian?), that intruded the Cambrian deposits of Voznesenka terrane, are  veined tin with tungsten deposits,  lithium-fluorine protolithionite granites, with fluorine deposits in Cambrian limestones. Micaceous-fluorite ores contain also beryllium, rubidium, lithium and caesium  and  rare-metal granites contain  tantalum-niobium and  weak tin deposits.
      Devonian-Carboniferous magmatic complexes of ancient terranes of Primorskii Krai  are riftogenic and, probably connected with the Gondwana decay. This stage of magmatism is represented by bimodal volcanites that contain up to 95%  rhyolite and sparse  high-titanium and high-alumina basalt and andesite. Plutonic rocks are represented by intrusions and subvolcanic bodies of alkaline gabbro, diorite, and plumasite  granite. Volcanic rocks contain molybdenum-uranium vein deposits.
      In Permian , the Voznesenka, Spassky, Nakhimovsky, Kabarginsky, and Matveevsky terranes made up the Khanka continental superterrane  that was located near the equator. The Sergeevka terrane has a similar Permian island-arc geological history, but it accreted to the Khanka superterrane along a large-amplitude, left-lateral fault only in Early Cretaceous. In the Permian , along the margin of Khanka superterrane , the Laoelin-Grodekovo island arc was formed. The fragments of the accretionary prism of this arc subduction zone  are in  North Korea and China. At the same time, within Khanka superterrane, riftogenic  back-arc basin deposits formed, including  high-titanium basalt and andesite, more rarely dacite and rhyolite. Plutonic rocks are represented by gabbro-syenite and subalkaline granites (magnetite series).
      In the Early Triassic, the Khanka superterrane and Laoelin-Grodekovo island arc collided with the North-China craton. Probably, this event was marked by small bodies of Triassic collision granites  near the southwest boundary of Primorye. Their composition and ore mineralization have not been studied.
      In the Triassic , the Khanka superterrane together with the North-China Craton  moved to the north. In the Middle Jurassic, along the continent margin, a westward  subduction zone was generated, and the  Samarka terrane of accretionary prism formed.  Outcrops of Jurassic volcanic rocks are known within Sergeevka terrane, but Jurassic supra-subduction volcanoplutonic belt has not been found.
      In the Early Cretaceous, in Valanginian time, after the Late Jurassic spreading ridge was accreted to the margin of Eurasia continent,  subduction evolved into left-lateral sliding between the continental and oceanic plates. Turbidites of the Zhuravlevka terrane formed along the Early Cretaceous  continent-ocean boundary. The fragments of the Late Jurassic spreading ridge crop out in the western part of the Taukha terrane and, probably, in the South-West Japan in Sambagawa terrane. The Taukha terrane of (accretionary prism) corresponds to a subduction zone, that dipped to the east towards Paleopacific,  and was presumably related with the Early Cretaceous island arc in Kitakami-Oshima of Honshu and Hokkaido islands. The geodynamic history of the  Kema terrane of the Early Cretaceous island arc has not been studied well.
      At the initial stage of  development of the Early Cretaceous transform boundary of  Primorskii Krai,  alkaline ultrabasic rocks, gabbro, and nepheline syenites intruded the Samarka accretionary prism. In gabbro the large Ariadnenskoye and other deposits of ilmenite and copper-nickel sulphide ores formed. In syenite small deposits of zirconium, niobium, and rare earths of cerium group  formed, in some cases lanthanum and yttrium are found (Sobolikha, Shumnoye, and other).
      At the closing stage of transform margin development, in the Aptian-Senomanian,  Mesozoic terranes collided  with the continental margin. Apt-Senomanian deformation of the Sikhote-Alin terranes  is younger from west to east. Collisional  processes resulted in terrane clustering, formation of a granite-metamorphic layer, and formation of continental  crust about 30-40 km thick. The continental crust of the Sikhote-Alin fold belt was formed over a short time interval, about 60 m.y. (middle Jurassic-Senomanian), and involved (1) the formation  of accretionary prism terranes, turbidite basin and island arc terranes, and (2)  collision with the continent margin..
     Collision stage magmatism of the Early-Late Cretaceous transform continental  margin shows complicated pattern of  alternating zones of extension and compression in time and space, and by different composition of terranes. Along the margin of  the Khanka superterrane and on the Sergeevka terrane, with Paleozoic continental crust,   Albian bimodel volcanic series occurs in pull-apart basins. In the northwest Primorye,  Albian rhyolite contains  gold and silver  in quartz-sericite metasomatites, propilites,  and  secondary quartzite.  The Paleozoic continental margin is characterized by magnetite granitoids with gold-quartz veins with pyrite and arsenopyrite, that in the Sergeevka terrane  contain gold deposits  Krinichnoye and Askold. In the Sergeevka terrane, is an  Albian metamorphic  zone with gold-quartz veins in Paleozoic crystalline rocks. In the zones of greenschist metamorphism, are gold and gold-copper deposits.
      In  Jurassic accretionary prism and Early Cretaceous turbidite basin terranes are  Albian-Senomanian granitoids of the compression zones of the  Hungariiskaya series (about 130-110 m.y.) and similar granites of the Sandinsky complex (about 100 m.y.), mainly two-mica, cordierite-bearing  granite and granodiorite. Mafic rocks  in this association show mantle participation. Petrochemical and mineralogical data for the granites  of the Hungariiskaya series and Sandinsky  complex indicate  S-type granites.  The crustal nature of granitoids is confirmed by the initial strontium ratio   0.07975+0.00154 (Simanenko and others, 1997). These granitoids  belong to the ilmenite series and show low oxidation of iron. The ore deposits  of the granitoids of the Hungariiskaya series and the Sandinsky complex  are poorly studied.. Small manifestations of tin, tungsten, and gold may be related. A single large deposit, related to  granites of the Hungariiskaya series is Lermontovskoye of scheelite-bearing skarn deposit.
      Another group of intrusive rocks, formed on the transform margin,  is the Tatibinskaya intrusive series. The intrusions of this series are localized mainly in the area of the Central Sikhote-Alin fault, a  co-wrench extension fault. Complex composition of intrusive bodies, composed of diorite to leucocratic granite and aplite indicates possible formation of  melts at  different generation levels. Numerous potassium-argon ages range from 145 to 95 m.y., with maximum values 115-105 m.y. Rb-Sr age of diorite and quartz diorite is about  130 m.y. and for biotite and leucocratic granites  is about 100 m.y. Petrochemical, geochemical, and mineralogical features indicate the  Tatibinsky granitoids  as I-type  ilmenite series or transitional I(?)-S type. The initial Sr ratios are close: 0.7047  -  0.7048. In granitoids of the Vostok-2 stock, the largest deposit of tungsten-bearing skarn  with copper, gold, and apatite, it increases to 0.70675. The granitoids of  the Tatibinskaya series contain abundant ore manifestations  and some related deposits of complex tin-tungsten ores. As a rule, they occur in small late-stage stocks of leucocratic granite and granite-porphyry and are localized in granites near theirroof. Ores consist of greisen, quartz veins and stockwerks with cassiterite, wolframite, scheelite, molybdenite, and arsenopyrite, more rarely pyrite, chalcopyrite, sphalerite, and galena. An example  is Rudnoye  deposit. Many researchers include lithium-fluorine granites of about 85 m.y. in age in the Tatibinskaya series that are associated with large bodies of Tatibinsky granitoids. Best known are the  stocks at Tigrinyi and Zabytyi containing greisen deposits  with complex tin-tungsten-rare-earth ores.
      In the Late Cretaceous, in the Sikhote-Alin fold basement formed  the volcano-plutonic belt along an active continental margin at the base of which are tuff-conglomerates, tuffite, tuff, and lava of andesite-basalt, and more rarely basalt of Senomanian-Turonian age. Spatially associated extrusions and dikes of pyroxene-hornblende andesite also occur.. Intrusive formations consist of small bodies of gabbro-diorite and diorite. Volcanic rocks  typically calc-alkaline series. The main part of the volcanic belt is made up of aerial fields of tuff and ignimbrite of rhyolite with co-magmatic  small-depth and subsurface intrusions calc-alkaline  diorite-granite. Effusive formations are characterized by normal alumina content and alkalinity with potassium predominance. Intrusive bodies have a porphyry appearance and  sometimes show a gradual transition from granite to granite-porphyry in apical parts of the massifs.
      The formation of ores at this stage of the active continental margin development  was influenced by the composition of the terranes , heterogeneous composition  of magmatic formations connected with geochemical zoning usual for such geodynamic regimes, and change of magmatism nature according to a gradual  changing  geodynamic  regime. A  predominance of tin mineralization occurs in a back zone, adjacent to the Central Sikhote-Alin fault, with increasing polymetal  ores towards the east. Most of the deposits show a complex composition of ores formed in several stages.
      In the frontal zone of the volcano-plutonic belt, in the  Taukha terrane, the unique Dalnegorsk skarn borosilicate deposit occurs in a large inclusion of paleooceanic Triassic limestone within the accretionary prism. The deposit was formed in Turonian-Santonian time. At the same stage,  zones of veinlet-impregnated tin-polymetallic mineralization were formed in silicified  tourmalinized tuffs. Where allochthonous bodies of limestones occur, small veined lead-zinc deposits are developed. Some ores are confined to apical parts of the intrusion (Lidovskoye deposit) or to volcanites (Krasnogorskoye deposit).
      In the  early Paleogene, collision of the terranes of Sakhalin Island and the Okhotsk Sea bottom with the margin of Eurasia continent occurred and the transform boundaries between the continental lithosphere microplates appeared along Sakhalin Island, and between the  Eurasia continent and the Pacific plate along Japan. Right lateral displacements on the continent margin resulted in the opening of the Sea of Japan at about 21-15 m.y. ago. On the territory of Primorskii Krai, geodynamic evolution of the plate transform boundary was responsible for the formation of sublatitudinal pull-apart basins with intensive magmatism.
     In Danian-Paleocene time, a series of ultrapotash rhyolite and subvolcanic leucogranite  formed along with   skarn lead-zinc deposits of the Dalnegorsk ore district. All skarn deposits are confined to the allochthonous blocks of Triassic limestones. Paleovolcanic  control of distribution of the deposits is seen in their restriction to the edges of volcano-tectonic depressions. The gold-silver (mainly silver) deposit at Salyut and others  occur in rhyolite. At the same time, in the north-eastern part of Primorye, near the eastern boundary of the Zhuravlevka terrane,   tin-sulphide deposits Zvezdnoye, Zolotoye, Ledyanoye, and others,  formed  with the extrusions of porphyry rhyolites and andesites. In the Eocene-Miocene, bimodal volcanic associations, with high-alumina and high-titanium basalt and andesite and subordinate dacite and rhyolite formed. Common are subalkaline granites of the magnetite series. Epithermal gold-silver ores are related with the Paleogene bimodal volcanoplutonic series.

  A. KHANCHUK, corresponding member of Russian Acad. Sci., Director, Far East Geological Institute, Far Eastern Branch of Russian Acad. Sci.

 V. GONEVCHUK, candidate of geological and mineralogical sciences, chief, Laboratory of metallogenesis of ore districts, Far East Geological Institute, Far Eastern Branch of Russian Acad. Sci.

 V. SIMANENKO, candidate of geological and mineralogical sciences, leading research worker, Laboratory of regional geology, Far East Geological Institute, Far Eastern Branch of Russian Acad. Sci.
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