Geochemistry and age of the complex of alkaline metasomatic rocks and carbonatites of the Gremyakha-Vyrmes massif, Kola Peninsula
N. V. SorokhtinaL. N. KogarkoA. K. ShpachenkoM. V. GroznovaYu. A. KostitsynI. A. RoshchinaI. V. Gredina
7
Citation
7
Reference
10
Related Paper
Citation Trend
Keywords:
Carbonatite
Metasomatism
Massif
Ultramafic rock
Kola peninsula
Abstract The Turiy Massif, on the southern coast of the Kola Peninsula, consists of five intrusive complexes containing a variety of carbonatites, phoscorites, melilitolites, ijolites and pyroxenites. Petrographic and mineralogical studies of the different rocks show that the samples are texturally heterogeneous. Minerals including apatite, garnet, magnetite, melilite, mica and pyroxene, show systematic variations in composition relating to the rock type in which they occur. Compositional similarities and/or distinct trends are seen in the mineral compositions within the each of the pyroxenite-melilitolite, and melteigite-ijolite rock series, indicating linked petrogenetic histories within each of the two series. The carbonatites from the northern complex may be related to nearby melilitolites, but the central complex carbonatites and phosocorites do not bear any mineralogical (or isotopic) similarities to any of the silicate rocks within the massif.
Carbonatite
Massif
Kola peninsula
Ultramafic rock
Melilite
Pyroxene
Baddeleyite
Cite
Citations (21)
The 650–621 Ma plume which impinged beneath the Siberian craton during the breakup of Rodinia caused the formation of several alkaline carbonatite massifs in craton margins of the Angara rift system. The Beloziminsky alkaline ultramafic carbonatite massif (BZM) in the Urik-Iya graben includes alnöites, phlogopite carbonatites and aillikites. The Yuzhnaya pipe (YuP) ~ 645 Ma and the 640–621 Ma aillikites in BZM, dated by 40Ar/39Ar, contain xenoliths of carbonated sulfide-bearing dunites, xenocrysts of olivines, Cr-diopsides, Cr-phlogopites, Cr-spinels (P ~ 4–2 GPa and T ~ 800–1250 °C) and xenocrysts of augites with elevated HFSE, U, Th. Al-augites and kaersutites fractionated from T ~ 1100–700 °C along the 90 mW/m2 geotherm. Higher T trend for Al-Ti augite, pargasites, Ti-biotites series (0.4–1.5 GPa) relate to intermediate magma chambers near the Moho and in the crust. Silicate xenocrysts show Zr-Hf, Ta-Nb peaks and correspond to carbonate-rich magma fractionation that possibly supplied the massif. Aillikites contain olivines, rare Cr-diopsides and oxides. The serpentinites are barren, fragments of ore-bearing Phl carbonatites contain perovskites, Ta-niobates, zircons, thorites, polymetallic sulphides and Ta-Mn-Nb-rich magnetites, ilmenites and Ta-Nb oxides. The aillikites are divided by bulk rock and trace elements into seven groups with varying HFSE and LILE due to different incorporation of carbonatites and related rocks. Apatites and perovskites reveal remarkably high LREE levels. Aillikites were generated by 1%–0.5% melting of the highly metasomatized mantle with ilmenite, perovskite apatite, sulfides and mica, enriched by subduction-related melts and fluids rich in LILE and HFSE. Additional silicate crystal fractionation increased the trace element concentrations. The carbonate-silicate P-bearing magmas may have produced the concentration of the ore components and HFSE in the essentially carbonatitic melts after liquid immiscibility in the final stage. The mechanical enrichment of aillikites in ore and trace element-bearing minerals was due to mixture with captured solid carbonatites after intrusion in the massif.
Carbonatite
Ultramafic rock
Metasomatism
Massif
Columbite
Cite
Citations (23)
The Tomtor massif is a polychronous ring zonal complex of alkaline ultramafic and carbonatite rocks containing unique Nb and REE deposits. Mineralogical and geochemical studies of minerals from different types of silicate rocks and carbonatites of the Tomtor massif were performed. For excluding traces of the interaction between silicate and carbonatite melts, we limited ourselves to the study of independent small secant bodies located in the immediate vicinity of the massif itself. The presence of through mineral series in various silicate igneous rocks and carbonatite ores of high-titanium chromium spinels, rare-metal, ore and other exotic phases with similar compositional trends was defined. Such studies will help reveal the mineralogical criteria for the genetic relationship between silicate melts and associated carbonatite derivatives, which can form rich rare elements mineralization. Also, such studies help to improve the petrochemical and mineralogical criteria for dividing potentially diamond-bearing magmatites (typical kimberlites) from non-diamond-bearing kimberlites, alpicrites and other non-diamond-bearing rocks convergent to kimberlites, which are formed under different physicochemical conditions. The existence of polychronous complex ore–magmatic ring complexes, such as the Tomtor massif, indicates the existence of large deep intraplate magma-generating chambers in the lithospheric mantle.
Carbonatite
Massif
Ultramafic rock
Metasomatism
Silicate minerals
Cite
Citations (0)
Изучены кристаллы циркона из щелочных и нефелиновых сиенитов массива Сахарйок, образованные на магматическом (2645 ± 7 млн лет), гидротермальном (1832 ± 7 млн лет) и метаморфическом (1784 ± 22 млн лет) этапах кристаллизации. Циркон из щелочных сиенитов по сравнению с цирконом из базальтов океанических островов (OIB) имеет более низкие значения ɛHf и ɛNd, определяющие его принадлежность к мантийным производным протолитов, по изотопному составу близких к CHUR. Предполагается, что формирование неоархейской щелочной Кейвской провинции происходило в результате плюм-литосферного взаимодействия, вызванного поднятием неоархейского плюма, обусловившего процессы метасоматического изменения и последующего парциального плавления пород субкратонной литосферной мантии и коры. Исходные расплавы Сахарйокского массива могли быть образованы при возобновлении плюмовой активности, происходившей на 20—30 млн лет позже образования щелочных гранитов провинции при селективном плавлении пород метасоматически измененной литосферной мантии.
Kola peninsula
Massif
Peninsula
Cite
Citations (0)
Massif
Ultramafic rock
Carbonatite
Kola peninsula
Cite
Citations (23)
Carbonatite
Ultramafic rock
Massif
Fluorite
Kola peninsula
Metasomatism
Cite
Citations (13)
Carbonatite
Massif
Radiogenic nuclide
Metasomatism
Ultramafic rock
Petrogenesis
Cite
Citations (11)
1125 Alkaline magmatism has been widely abundant on the territory of the Kola Peninsula with the maximal activity in the Paleozoic, when most of the alkaline– ultrabasic complexes, alkaline intrusions of the agpaitic series, and rocks of the dyke series were formed [1–3]. Paleozoic dykes of alkaline rocks were registered (1) in the Khibiny and Lovozero agpaitic massifs and their frames; (2) in the massifs of alka� line–ultrabasic rocks with carbonatite (Kovdor, Turii Mys, Vuorijarvi, Afrikanda, Kandaguba, etc.); (3) in autonomous swarms, which are not spatially related to alkaline intrusions (dykes on the coast of the Kan� dalaksha Bay, swarms of pipes and dykes of kimberlite and melilitite of the Tersk coast, etc.) [3]. A new occurrence of alkaline dyke magmatism was discovered in 2010 during the geological works per� formed by the Murmansk Geological Prospecting Expedition in the “Mokhnatye Roga” area located 55 km to the southeast of the Kovdor massif ( 67°15′ N, 31°30′ E) (Fig. 1). The “Mokhnatye Roga” area is located in the Ensk segment of the northwestern part of the Belomorian mobile belt. We performed a complete petrological and geochemical description of the sections in Holes 19 and 24, which reveal one of the largest dykes in the area. The dyke, with a length of ≈4 km and a width of ≈160 m, has an eastern orientation with steep dipping (60°–90°) to the north. The thickness of Quaternary deposits ranges from 0.8 to 4.0 m; alkaline rocks occur in the range of 4.0–93.9 m being followed by host amphibole–biotite gneiss with interbeds of plagioam� phibolite (AR2 mt) along the section. The contacts with host rocks are sharp, secant, magmatic; there are no
Massif
Kola peninsula
Carbonatite
Ultramafic rock
Prospecting
Nepheline
Cite
Citations (0)
Massif
Kola peninsula
Pegmatite
Metasomatism
Nepheline
Nepheline syenite
Paragenesis
Carbonatite
Peralkaline rock
Cite
Citations (1)
Kiruna-type iron oxide–apatite associations occur in a variety of rock types and their origin has remained controversial. Most of the Kiruna-type deposits are associated with intermediate to felsic rocks, and in rare cases with ultramafic rocks. Here we investigate the Seruwila iron oxide–apatite deposit at the contact between the Highland and Vijayan complexes that has been defined as the "eastern suture" in Sri Lanka, which formed during the late Neoproterozoic assembly of the Gondwana supercontinent. The ore deposit is hosted in an ultramafic intrusion and comprises massive and disseminated mineralization. The ore-bearing rocks are mainly composed of low-Ti magnetite and chlor-fluorapatite. Our petrological and geochemical studies suggest a magmatic–hydrothermal model for the mineralization wherein: (1) the Cl-rich magmatic–hydrothermal fluid scavenged iron and P from the ultramafic magma, transported iron to shallower levels in the crust and deposited along the suture zone to form the massive type magnetite and apatite; and (2) the cooling of the hydrothermal fluids resulted in the growth of disseminated magnetite and the precipitation of sulfide minerals, followed by a calcic metasomatism (scapolitization and actinolitization). This model is in conformity with the genetic relation between Kiruna-type deposits and iron oxide–copper–gold (IOCG) deposits. We also report LA-ICP-MS zircon U–Pb ages from the host ultramafic intrusion suggesting its emplacement at ca. 530 Ma, which is younger than the regional high-grade metamorphism associated with the collisional assembly of the crustal blocks in Sri Lanka at ca. 540 Ma. By analogy with the common occurrence of Kiruna-type deposits in extensional tectonic settings, and the geochemical features of the studied rocks including low silica, high Mg, Fe, Ca with high field strength elements (HFSEs such as Nb, Ta, Zr, Hf, Ti) depletion and strong LREE and F enrichment, we theorize that the ultramafic magmatism occurred in a post-collisional extensional setting derived from a volatile- and LREE-rich metasomatized lithospheric mantle.
Ultramafic rock
Metasomatism
Felsic
Ore genesis
Cite
Citations (11)