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Journal articles on the topic 'Lamprophyre dikes'

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Author: Grafiati

Published: 10 December 2022

Last updated: 28 January 2023

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1

Štemprok, Miroslav, and Thomas Seifert. "An overview of the association between lamprophyric intrusions and rare-metal mineralization." Mineralogia 42, no. 2-3 (January 1, 2011): 121–62. http://dx.doi.org/10.2478/v10002-011-0011-x.

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An overview of the association between lamprophyric intrusions and rare-metal mineralizationGranite-related rare metal districts in orogenic settings are occasionally associated with lamprophyre dikes. We recorded 63 occurrences of lamprophyres in bimodal dike suites of about 200 granite bodies related to rare metal deposits. Most lamprophyres occur in Paleozoic and Mesozoic metallogenic provinces in the northern hemisphere. Lamprophyres which are associated with rare metal deposits are calc-alkaline (kersantites, minettes, spessartites) or more rarely alkaline lamprophyres (camptonites, monchiquites) which occur in the roof zone of complex granitic bodies as pre-granitic, intra-granitic, intra-ore or post-ore dikes. Most lamprophyres are spatially associated with dominant felsic dikes and/or with mafic dikes represented by diorites or diabases. Diorites and lamprophyres occasionally exhibit transitional compositions from one to another. Lamprophyres share common geochemical characteristics of highly evolved granitoids such as enrichment in K and F, increased abundances of Li, Rb, and Cs and enrichment in some HFSE (e.g. Zr, U, Th, Mo, Sn, W). Lamprophyres in rare metal districts testify to accessibility of the upper crust to mantle products at the time of rare metal mineralization and possible influence of mantle melts or mantle-derived fluids in the differentiation of granitic melts in the lower crust.

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2

Vasyukova, Elena A., and Alexander S. Borisenko. "Petrological implications of the Early Mesozoic lamprophyre dikes and related Tarkhata syenites (SE Altai and NW Mongolia)." Mineralogia 44, no. 1-2 (June 1, 2013): 13–30. http://dx.doi.org/10.2478/mipo-2013-0002.

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AbstractThis paper presents new data derived from field sampling and from a thorough description of lamprophyres located in southeastern Altai and northwestern Mongolia in terms of their mineralogy, textures, and chemical composition. The swarms of alkaline mafic dikes in the area coexist with granosyenite-monzodiorite and gabbro-dolerite intrusions and spatially coincide with an ore district of Sb-Hg, Ag-Sb, Ni-Co-As, Cu-Mo-W, and CaF2 hydrothermal mineralization. All lamprophyres belong to the Early Mesozoic Chuya complex formed in an intracontinental enviroment. Their distribution and orientation is controlled by two large fault zones. The Chuya dikes were investigated at two localities, namely, Yustyd and South-Chuya. The Yustyd lamprophyres intrude Middle-Upper Devonian black shale of the Yustyd depression. At South Chuya, lamprophyres, together with the Tarkhata granosyenite-monzodiorite complex, are hosted by Cambrian and Ordovician metamorphic rocks of the South-Chuya Range. Ar-Ar (phlogopite) and U-Pb (SHRIMP, zircon) ages of the lamprophyre dikes indicate long and continuous period of the formation of the Chuya complex (250-235 Ma). Major- and trace-element compositions of the lamprophyres from both localities and of the syenite indicate their origin from the same magma source. The textures and structures of the lamprophyre and plutonic rocks, their mineral assemblages and the chemistry of the rock-forming minerals provide clues to the evolution of the parental alkaline mafic magma and fluid regime.

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3

Kamvisis, Ioannis-Nektarios G. "Lamprophyric rock locations in Greece." Mineralogia 50, no. 1-4 (December 1, 2019): 13–33. http://dx.doi.org/10.2478/mipo-2019-0002.

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AbstractTwenty-four areas with lamprophyric formations have been located through a bibliographic search in Macedonia, Thrace, the islands and Attica. Most lamprophyre types have been identified including rare “alkali minette”. In most localities the dikes/sills appear to be late mantle products associated with deep faulting following extensional activity in granitoids.

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4

Thủy, Nguyễn Thị, Nguyễn Thị Lệ Huyền, Nguyễn Thị Ngọc Trâm, and Lê Hải Nghĩa. "Mineral compositions of magmatic dikes cutting across the Khe Phen granites (Huong Tra, Thua Thien Hue, Central Vietnam)." Hue University Journal of Science: Natural Science 128, no. 1B (June 7, 2019): 21. http://dx.doi.org/10.26459/hueuni-jns.v128i1b.5280.

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The Khe Phen granite quarry located in Huong Tra district (Thua Thien Hue province) has been confirmed as a part of the Ba Na granitoid complex (G/K<sub>2</sub><em>bn</em>), mostly composed of two-mica granite and porphyritic granite. Field survey data show that the granites here are cut across by five distinct narrow dikes (about 50-70 cm wide) including granite pegmatite, granite aplite, aplite, granodiorite and lamprophyre diorite. Mineral compositions of the granite pegmatite and aplite dikes are similar with those of the host granite, which are mainly comprised of quartz (27-35 %), orthoclase (45-58 %), plagioclase (4-15 %), biotite (1-3 %) and a few opaque minerals. Meanwhile, the granodiorite and lamprophyre diorite dikes are melanocratic and compositionally much more mafic, particularly lamprophyre diorite, evidenced by a presence of hornblende (50-55 %), plagioclase (33-40 %), quartz (3-15 %), calcite (5-17 %)... Origin and emplacement age of the latter dikes have not been reported so far, and thus are needed for further studies based on geochemical and isotopic data.

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5

Sun, Yi-Zhan, Kun-Feng Qiu, Mao-Guo An, Shan-Shan Li, Zhen Shang, and Yu Wang. "Geochronological and Geochemical Constraints on the Petrogenesis of Lamprophyre from the Giant Weishan REE Deposit in China." Minerals 12, no. 6 (May 31, 2022): 706. http://dx.doi.org/10.3390/min12060706.

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The Weishan REE deposit is located in the southwest of the Luxi Terrane of the North China Craton (NCC), where a large number of lamprophyre dikes are spatially exposed with the deposit. Here, we report petrology, geochemistry and zircon U-Pb geochronology data for the lamprophyre of the Weishan REE deposit in order to develop constraints for the determination of the petrogenesis, magma source and evolution of the lamprophyre and the tectonic environment. LA-LCP-MS zircon U-Pb dating shows that the crystallization age of the lamprophyre is 125 ± 0.86 Ma. The geochemical data suggest that these lamprophyres have high levels of Al2O3, K2O, MgO and alkalis, moderate level of Na2O and low levels of SiO2, Fe2O3 and TiO2, and that they are enriched with LREEs (La, Ce) and LILEs (Rb, Ba) and depleted with regard to HREEs and HFSEs (Nb, Ta, Ti). They displayed negative εHf(t) values of −14.98 to −9.03, TDM1 ages of 1.1–1.4 Ga and TDM2 ages of 1.7–2.1 Ga, which suggest that the magma source originates from an enriched mantle. Low Rb/Sr and high Dy/Yb ratios suggest that the enriched mantle source was partially melted at the amphibole-bearing lherzolite garnet-facies. The high Ba/Th and Sr/Th ratios indicate that the enriched source was derived from subduction dehydration fluids of the oceanic crust. We propose that the mafic dike intrusions are consistent with an Early Cretaceous alkaline magma emplacement in an extensional setting, in which the magma was not contaminated by crustal material during its emplacement.

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6

Owens, Brent E., and Paul B. Tomascak. "Mesoproterozoic lamprophyres in the Labrieville Massif, Quebec: clues to the origin of alkalic anorthosites?" Canadian Journal of Earth Sciences 39, no. 6 (June 1, 2002): 983–97. http://dx.doi.org/10.1139/e02-010.

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Mesoproterozoic lamprophyre dikes occur at four localities within the ~1010 Ma Labrieville anorthosite in the Grenville Province of southern Quebec. All dikes are thin (<20 cm wide), oriented ~N57W, and steeply dipping. Three are biotite lamprophyres, but the fourth is dominated by amphibole. Laser total-fusion 40Ar/39Ar analyses on amphibole or biotite yield minimum ages for the dikes of 945.5 ± 8 Ma, 907.0 ± 5.9 Ma, 892.0 ± 6.2 Ma, and 889.2 ± 9.8 Ma. A crystallization age of ~1 Ga for all dikes is consistent with these data and RbSr isotopic systematics. All lamprophyres contain high levels of Cr (284393 ppm), Ni (101180 ppm), Ba (13805580 ppm), Sr (23593109 ppm), and rare-earth elements (REE; LaN = 191288), with average LaN/LuN = 26 and no Eu-anomalies. At 1 Ga, all lamprophyres have a similar initial Sr isotopic ratio of ~0.7034, similar to Bulk Earth. In contrast, εNd values vary considerably from 4 to 10.2, indicating sources with variable long-term light-REE enrichment. Negative correlations between 143Nd/144Nd and La/Nb and K suggest involvement of at least two source components, probably asthenosphere and metasomatized subcontinental lithosphere. The lamprophyres are only slightly younger than ~1010 Ma Labrieville massif, which is also alkalic and enriched in Sr and Ba relative to most other anorthosites. The lamprophyres provide unequivocal evidence for a Sr- and Ba-rich component in the lithospheric mantle that may have contributed to the parental magmas of Labrieville and other andesine anorthosites in this part of Quebec.

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7

Borradaile, G. J., M. M. Kehlenbeck, and T. W. Werner. "A magnetotectonic study correlating late Archean deformation in northwestern Ontario." Canadian Journal of Earth Sciences 31, no. 9 (September 1, 1994): 1449–60. http://dx.doi.org/10.1139/e94-128.

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Late Archean lamprophyre dikes crop out on both sides of the Quetico–Shebandowan subprovince boundary. They post date F1 folds in late Archean rocks (2690 Ma) but their intrusion overlapped with the waning phase of S1 development. S1 developed to varying degrees or is absent in some dikes. Nevertheless, the dikes show a cryptic tectonic fabric in the ferromagnetic minerals revealed by anisotropy of magnetic susceptibility (AMS). This is parallel to S1 in the host metamorphic rocks. Thus, the S1 fabric-forming episode may be correlated from one subprovince to the other using the dike swarm as a chronological marker.

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8

Ishbaev, Kh D., A. Kh Shukurov, and K. M. Kosbergenov. "Lamprophyres and mineralization of the Koytash ore field (Southern Tien Shan)." LITHOSPHERE (Russia) 20, no. 2 (April 25, 2020): 231–53. http://dx.doi.org/10.24930/1681-9004-2020-20-2-231-253.

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Research subject. The Koytash ore field is located in the potentially productive Au, Ag, W, Mo, Ti, Fe, Cu, Pb, Zn and REE North Nuratau mineralisation zone of Tien Shan. The authors undertook a study of the composition of dikes breaking through the Paleozoic ore-bearing formations, as well as their petro- and ore-generating role in the formation of the Koytash-Ugat sulphide-rare-metal (W, Mo, Fe) specialised mineralisation. Materials and methods. A study of rock and mineral composition was performed at the Institute of Geology and Geophysics named after Kh.M. Abdullaev. The content of petrogenic and rare elements in rocks and sulphides was determined by ICP-MS using an ICPE-9000 mass-spec trometer in the Central Laboratory of the State Committee for Geology of the Republic of Uzbekistan. The chemical analysis of minerals was performed using a Jeol-8800Rh electronic microanalyser at the Institute of Geology and Geophysics named after Kh.M. Abdullaev. The micrographs of transparent sections were obtained using Nikon Optiphot 2 Pol and Polam R-311 microscopes. Results and conclusions. The conducted study showed that, in terms of their structure, the Koytash ore field dike formations can be regarded as lamprophyres. In terms of their chemical composition, these formations are mafic and intermediate rocks of the subalkaline series. It was found that the composition of lamprophyre dikes correlates with the size of the erosion section. Their melanocratic varieties are confined to the southern part of the intrusion (absolute elevations are 1000–1200 m), and leucocratic – to the northern (about 1900 m). This is assumed to be the result of crystallization differentiation of a single initial melt. The dikes of the Koytash ore field lamprophyres break through not only sulphide-rare-metal bodies of the Koytash-Ugat strip, but also skarn and carbonate rocks and, in turn, are broken through by quartz-polymetallic ore-bearing veins, which testifies to their inter-ore character.

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9

Mitchell, Roger H., R. Garth Platt, Maureen Downey, and David G. Laderoute. "Petrology of alkaline lamprophyres from the Coldwell alkaline complex, northwestern Ontario." Canadian Journal of Earth Sciences 28, no. 10 (October 1, 1991): 1653–63. http://dx.doi.org/10.1139/e91-147.

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A suite of alkaline lamprophyre dikes emplaced in centers I and II rocks of the Coldwell alkaline complex is composed of camptonites with calcite ocelli, camptonites with quartz macrocrysts, amphibole camptonites, monchiquites, and sannaites. The camptonites are characterized by phenocrysts of olivine, aluminian pyroxene, kaersutite, and titanian ferropargasite set in a matrix of magnesian hastingsite, augite, plagioclase, biotite, magnetite, sphene, and minor nepheline. Quartz macrocrysts occur as corroded euhedral single crystals. Monchiquites are petrographically similar to the camptonites but are characterized by the presence of an isotropic groundmass. Sannaites contain aluminian and chromian diopside phenocrysts set in a matrix of ferroan pargasite, aluminian diopside, biotite, albitized plagioclase, and epidotized alkali feldspar.Major-element compositions indicate the ocellar camptonites, amphibole camptonites, and monchiquites have affinities with alkali olivine basalt and that monchiquites and camptonites are heteromorphs. None of the dikes represent primitive liquids. Poor correlations between incompatible trace elements (Sr, Ba, Nb, Zr, rare earths), together with the presence of reversely zoned and corroded phenocrysts, suggest that none of the lamprophyres represent single batches of magma. The lamprophyres are considered to be hybrid magmas, formed by the mixing of fragmented cumulates, several generations of phenocrysts, and batches of magma extracted from a continuously replenished evolving magma chamber located within the infrastructure of the complex. Quartz-bearing camptonites are considered to form by contamination of camptonites, although the source of the quartz cannot be determined.

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10

Edgar, A. D., L. A. Pizzolato, and G. M. Butler. "Petrology of the ultramafic lamprophyre and associated rocks at Coral Rapids, Abitibi River, Ontario." Canadian Journal of Earth Sciences 31, no. 8 (August 1, 1994): 1325–34. http://dx.doi.org/10.1139/e94-115.

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An ultramafic lamprophyre sill and dikes, and an olivine–melilite-rich dike rock intrude Lower to Middle Devonian sediments and low- to high-grade Archean metamorphic rocks on the west bank of the Abitibi River, Coral Rapids, Ontario. Although previously considered to be kimberlitic, all these rocks contain olivine + clinopyroxene + phlogopite ± melilite, and hence are ultramafic alkaline rocks. The ultramafic lamprophyre can be distinguished from the dike by its lower SiO2, Na2O, Al2O3, and higher MgO and FeO. In contrast the olivine–melilite dike rock has a more uniform composition, characteristically contains melilite, and has higher Cr and Ni contents. Enriched light rare earth element (LREE) chondrite-normalized patterns are similar for all rocks.Olivine, clinopyroxene, and phlogopite have Mg# (Mg# = 100 Mg/(Mg + Fe) mol) typical of minerals in primitive alkaline rocks. Melilite composition is similar to that of igneous melilites. Phlogopites in all rock types are enriched in Ba and F and the degree of enrichment is distinct for each rock type. Accessory minerals include apatite, carbonates, chlorite, sericite, and sodalite (only in the olivine–melilite-bearing rock).The mineralogy and chemistry of the Coral Rapids rocks suggest that they are derived from a primitive olivine melilitite magma that may have evolved by fractionation of small amounts of olivine and clinopyroxene to form these alkaline ultramafic magmas.Xenoliths in the ultramafic lamprophyre sill and in lesser abundance in the olivine–melilite dike rock include olivine, phlogopite, and clinopyroxene-rich mantle-derived assemblages. The similarity between these xenoliths and their host rocks at Coral Rapids and those from southwest Uganda and West Eifel, Germany, suggests that the Coral Rapids rocks may be derived from magmas that originated from metasomatized mantle sources.

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11

Wyman, D. A., and R. Kerrich. "Archean lamprophyre dikes of the Superior Province, Canada: Distribution, petrology, and geochemical characteristics." Journal of Geophysical Research: Solid Earth 94, B4 (April 10, 1989): 4667–96. http://dx.doi.org/10.1029/jb094ib04p04667.

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12

Laughlin, A. W., M. J. Aldrich, M. Shafiqullah, and J. Husler. "Tectonic implications of the age, composition, and orientation of lamprophyre dikes, Navajo volcanic field, Arizona." Earth and Planetary Science Letters 76, no. 3-4 (January 1986): 361–74. http://dx.doi.org/10.1016/0012-821x(86)90087-7.

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13

Sarifakioglu, E., Y. Dilek, and M. Sevin. "Jurassic–Paleogene intra-oceanic magmatic evolution of the Ankara Mélange, North-Central Anatolia, Turkey." Solid Earth Discussions 5, no. 2 (November 13, 2013): 1941–2004. http://dx.doi.org/10.5194/sed-5-1941-2013.

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Abstract. Oceanic rocks in the Ankara Mélange along the Izmir–Ankara–Erzincan suture zone (IAESZ) in North-Central Anatolia include locally coherent ophiolite complexes (~179 Ma and ~80 Ma), seamount or oceanic plateau volcanic units with pelagic and reefal limestones (96.6 ± 1.8 Ma), metamorphic rocks with ages of 187.4 ± 3.7 Ma, 158.4 ± 4.2 Ma, and 83.5 ± 1.2 Ma, and subalkaline to alkaline volcanic and plutonic rocks of an island arc origin (~67–63 Ma). All but the arc rocks occur in a shaly-graywacke and/or serpentinite matrix, and are deformed by south-vergent thrust faults and folds that developed in the Middle to Late Eocene due to continental collisions in the region. Ophiolitic volcanic rocks have mid-ocean ridge (MORB) and island arc tholeiite (IAT) affinities showing moderate to significant LILE enrichment and depletion in Nb, Hf, Ti, Y and Yb, which indicate the influence of subduction-derived fluids in their melt evolution. Seamount/oceanic plateau basalts show ocean island basalt (OIB) affinities. The arc-related volcanic rocks, lamprophyric dikes and syeno-dioritic plutons exhibit high-K shoshonitic to medium-to high-K calc-alkaline compositions with strong enrichment in LILE, REE and Pb, and initial &varepsilon;Nd values between +1.3 and +1.7. Subalkaline arc volcanic units occur in the northern part of the mélange, whereas the younger alkaline volcanic rocks and intrusions (lamprophyre dikes and syeno-dioritic plutons) in the southern part. The Early to Late Jurassic and Late Cretaceous epidote-actinolite, epidote-chlorite and epidote-glaucophane schists represent the metamorphic units formed in a subduction channel in the Northern Neotethys. The Middle to Upper Triassic neritic limestones spatially associated with the seamount volcanic rocks indicate that the Northern Neotethys was an open ocean with its MORB-type oceanic lithosphere by the Early Triassic. The Latest Cretaceous–Early Paleocene island arc volcanic, dike and plutonic rocks with subalkaline to alkaline geochemical affinities represent intraoceanic magmatism that developed on and across the subduction-accretion complex above a N-dipping, southward-rolling subducted lithospheric slab within the Northern Neotethys. The Ankara Mélange thus exhibits the record of ~120–130 million years of oceanic magmatism in geological history of the Northern Neotethys.

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14

Jiang, Yao-Hui, Shao-Yong Jiang, Hong-Fei Ling, and Pei Ni. "Petrogenesis and tectonic implications of Late Jurassic shoshonitic lamprophyre dikes from the Liaodong Peninsula, NE China." Mineralogy and Petrology 100, no. 3-4 (September 4, 2010): 127–51. http://dx.doi.org/10.1007/s00710-010-0124-8.

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15

Ishbaev, H. D., D. I. Jumaniyazov, and S. Yu Nematullaev. "Mineragraphy and petrogeochemistry of the lamprophyre dikes of the western flank of the Pistali deposit (Northern Nuratau)." Prospect and protection of mineral resources, no. 5 (2022): 7–17. http://dx.doi.org/10.53085/0034-026x_2022_05_07.

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16

JARGALAN, Sereenen, Hirokazu FUJIMAKI, and Tsukasa OHBA. "Petrologic characteristics and Rb-Sr age dating of lamprophyre dikes of Tsagaan Tsahir Uul gold deposit, Mongolia." Journal of Mineralogical and Petrological Sciences 102, no. 3 (2007): 163–73. http://dx.doi.org/10.2465/jmps.060322b.

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17

Uto, Kozo, Hisatoshi Hirai, Kiyoshi Goto, and Shoji Arai. "K-Ar ages of carbonate- and mantle nodule-bearing lamprophyre dikes from Shingu, central Shikoku, Southwest Japan." GEOCHEMICAL JOURNAL 21, no. 6 (1987): 283–90. http://dx.doi.org/10.2343/geochemj.21.283.

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18

Sarifakioglu, E., Y. Dilek, and M. Sevin. "Jurassic–Paleogene intraoceanic magmatic evolution of the Ankara Mélange, north-central Anatolia, Turkey." Solid Earth 5, no. 1 (February 19, 2014): 77–108. http://dx.doi.org/10.5194/se-5-77-2014.

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Abstract. Oceanic rocks in the Ankara Mélange along the Izmir–Ankara–Erzincan suture zone (IAESZ) in north-central Anatolia include locally coherent ophiolite complexes (~ 179 Ma and ~ 80 Ma), seamount or oceanic plateau volcanic units with pelagic and reefal limestones (96.6 ± 1.8 Ma), metamorphic rocks with ages of 256.9 ± 8.0 Ma, 187.4 ± 3.7 Ma, 158.4 ± 4.2 Ma, and 83.5 ± 1.2 Ma indicating northern Tethys during the late Paleozoic through Cretaceous, and subalkaline to alkaline volcanic and plutonic rocks of an island arc origin (~ 67–63 Ma). All but the arc rocks occur in a shale–graywacke and/or serpentinite matrix, and are deformed by south-vergent thrust faults and folds that developed in the middle to late Eocene due to continental collisions in the region. Ophiolitic volcanic rocks have mid-ocean ridge (MORB) and island arc tholeiite (IAT) affinities showing moderate to significant large ion lithophile elements (LILE) enrichment and depletion in Nb, Hf, Ti, Y and Yb, which indicate the influence of subduction-derived fluids in their melt evolution. Seamount/oceanic plateau basalts show ocean island basalt (OIB) affinities. The arc-related volcanic rocks, lamprophyric dikes and syenodioritic plutons exhibit high-K shoshonitic to medium- to high-K calc-alkaline compositions with strong enrichment in LILE, rare earth elements (REE) and Pb, and initial εNd values between +1.3 and +1.7. Subalkaline arc volcanic units occur in the northern part of the mélange, whereas the younger alkaline volcanic rocks and intrusions (lamprophyre dikes and syenodioritic plutons) in the southern part. The late Permian, Early to Late Jurassic, and Late Cretaceous amphibole-epidote schist, epidote-actinolite, epidote-chlorite and epidote-glaucophane schists represent the metamorphic units formed in a subduction channel in the northern Neotethys. The Middle to Upper Triassic neritic limestones spatially associated with the seamount volcanic rocks indicate that the northern Neotethys was an open ocean with its MORB-type oceanic lithosphere by the early Triassic (or earlier). The latest Cretaceous–early Paleocene island arc volcanic, dike and plutonic rocks with subalkaline to alkaline geochemical affinities represent intraoceanic magmatism that developed on and across the subduction–accretion complex above a N-dipping, southward-rolling subducted lithospheric slab within the northern Neotethys. The Ankara Mélange thus exhibits the record of ~ 120–130 million years of oceanic magmatism in geological history of the northern Neotethys.

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19

Malyutin, S. A. "Western flanks of the Central Asian late paleozoic continental rift system and uranium mineralization." Proceedings of higher educational establishments. Geology and Exploration, no. 1 (June 22, 2022): 17–29. http://dx.doi.org/10.32454/0016-7762-2022-64-1-17-29.

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Introduction. Available information on the occurrences of high alkaline magmatic rocks fixing the position of the western flanks of the southern branches (Gobi Altai and Gobi Tien-Shan) of the Central Asian Late Paleozoic continental rift system in the territory of the North-West of Chingiz (the eastern part of Central Kazakhstan), the Kendyktas-Chu-Ili-Bet-Pak-Dal uranium-bearing province of the Southern Kazakhstan and the Chatkal-Naryn zone of Tien-Shan (Uzbekistan) is reviewed. Data on the confinement of uranium mineralization to these occurrences and its paragenetic relationship with the Late Paleozoic alkaline volcanic-plutonic association is provided.Aim. To study the uranium mineralization of Late Paleozoic alkaline magmatism to clarify metallogenic representations and justify prospects for the ore-bearingness of the western flanks of the southern branches of the Central Asian continental rift system.Materials and methods. The largest part of materials was obtained in the process of geological surveys and prospecting works of various scales in the regions of Central Kazakhstan in the period 1965–1985 with the participation of the author. Published materials concerning the subdivision of magmatic formations in the uranium ore fields of Southern Kazakhstan and the Chatkal-Naryn zone were also used.Results. Subvolcanic bodies of comendites and small masses of alkaline granites of the Late Paleozoic were identified across the area of uranium ore occurrences in the South-Western Chingiz and some deposits of South Kazakhstan confined to Devonian volcanic structures, which indicates their relationship with the southern branches of the Central Asian continental rift system. Rare-metalalbite, uranium-phosphorus and uranium-molybdenum formations are confined to alkaline rocks. Rare-metal mineralization is closely associated with alkaline rocks, while uranium mineralization occurred after the introduction of the most recent microgabbrodiorite and lamprophyre dikes. Similar correlations of rare-metal and uranium mineralization with alkaline granites and of microgabbrodiorite and lamprophyre dikes are observed in the uranium deposits of the Chatkal-Naryn zone located among the early Permian bimodal trachybasalt-trachyolite formation.Conclusion. The establishment of ore mineralization on the western flanks of the Gobi Altai and Gobi Tien-Shan branches in the territory of Southern and Central Kazakhstan allows these areas to be distinguished as metallogenic zones, promising in terms of rare-metal and uranium mineralization.

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20

Noblett, Jeffrey B., and Margaret W. Staub. "Mid-Proterozoic lamprophyre commingled with late-stage granitic dikes of the anorogenic San Isabel batholith, Wet Mountains, Colorado." Geology 18, no. 2 (1990): 120. http://dx.doi.org/10.1130/0091-7613(1990)018<0120:mplcwl>2.3.co;2.

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21

Martina, Federico, Horacio N. Canelo, Federico M. Dávila, María Helena M. de Hollanda, and Wilson Teixeira. "Mississippian lamprophyre dikes in western Sierras Pampeanas, Argentina: Evidence of transtensional tectonics along the SW margin of Gondwana." Journal of South American Earth Sciences 83 (April 2018): 68–80. http://dx.doi.org/10.1016/j.jsames.2018.02.006.

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22

Dostal, Jaroslav, Susan M. Karl, J. Duncan Keppie, Daniel J. Kontak, and J. Gregory Shellnutt. "Bokan Mountain peralkaline granitic complex, Alexander terrane (southeastern Alaska): evidence for Early Jurassic rifting prior to accretion with North America." Canadian Journal of Earth Sciences 50, no. 6 (June 2013): 678–91. http://dx.doi.org/10.1139/cjes-2012-0139.

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The circular Bokan Mountain complex (BMC) on southern Prince of Wales Island, southernmost Alaska, is a Jurassic peralkaline granitic intrusion about 3 km in diameter that crosscuts igneous and metasedimentary rocks of the Alexander terrane. The BMC hosts significant rare metal (rare earth elements, Y, U, Th, Zr, and Nb) mineralization related to the last stage of BMC emplacement. U–Pb (zircon) and 40Ar/39Ar (amphibole and whole-rock) geochronology indicates the following sequence of intrusive activity: (i) a Paleozoic basement composed mainly of 469 ± 4 Ma granitic rocks; (ii) intrusion of the BMC at 177 ± 1 Ma followed by rapid cooling through ca. 550 °C at 176 ± 1 Ma that was synchronous with mineralization associated with vertical, WNW-trending pegmatites, felsic dikes, and aegirine–fluorite veins and late-stage, sinistral shear deformation; and (iii) intrusion of crosscutting lamprophyre dikes at >150 Ma and again at ca. 105 Ma. The peralkaline nature of the BMC and the WNW trend of associated dikes suggest intrusion during NE–SW rifting that was followed by NE–SW shortening during the waning stages of BMC emplacement. The 177 Ma BMC was synchronous with other magmatic centres in the Alexander terrane, such as (1) the Dora Bay peralkaline stock and (2) the bimodal Moffatt volcanic suite located ∼30 km north and ∼100 km SE of the BMC, respectively. This regional magmatism is interpreted to represent a regional extensional event that precedes deposition of the Late Jurassic – Cretaceous Gravina sequence that oversteps the Wrangellia and Alexander exotic accreted terranes and the Taku and Yukon–Tanana pericratonic terranes of the Canadian–Alaskan Cordillera.

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Scarrow, Jane H., José Francisco Molina, Fernando Bea, Pilar Montero, and Alan P. M. Vaughan. "Lamprophyre dikes as tectonic markers of late orogenic transtension timing and kinematics: A case study from the Central Iberian Zone." Tectonics 30, no. 4 (August 2011): n/a. http://dx.doi.org/10.1029/2010tc002755.

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Guzmics, Tibor, János Kodolányi, István Kovács, Csaba Szabó, Enikő Bali, and Theodoros Ntaflos. "Primary carbonatite melt inclusions in apatite and in K-feldspar of clinopyroxene-rich mantle xenoliths hosted in lamprophyre dikes (Hungary)." Mineralogy and Petrology 94, no. 3-4 (August 15, 2008): 225–42. http://dx.doi.org/10.1007/s00710-008-0014-5.

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25

Windom, Kenneth E., W. Randall Van Schmus, Karl E. Seifert, E. Timothy Wallin, and Raymond R. Anderson. "Archean and Proterozoic tectono-magmatic activity along the southern margin of the Superior Province in northwestern Iowa, United States." Canadian Journal of Earth Sciences 30, no. 6 (June 1, 1993): 1275–85. http://dx.doi.org/10.1139/e93-109.

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A Precambrian igneous body of ultramafic and mafic rocks, named the Otter Creek layered igneous complex, occurs within the basement of northwestern Iowa, United States. It is marked by a circular magnetic anomaly, one of several that lie north and west of an inferred suture between the Archean Superior Province and Early Proterozoic juvenile crust. Sm–Nd whole-rock analyses for several rock types from the Otter Creek complex yield an isochron age of 2890 ± 90 Ma, with an εNd(t) of −0.9 ± 2.4. A block of older banded iron formation, itself intruded by lamprophyre dikes, is contained within the layered sequence. The iron formation – lamprophyre block has undergone high-temperature metamorphism followed by a retrograde event. A quartz monzodiorite gneiss, with a U–Pb age of 2523 ± 5 Ma, occurs near the layered complex, but the contact relations are not known. The layered series is overlain by Proterozoic keratophyre with a U–Pb age of 1782 ± 10 Ma. These felsic pyroclastic rocks are extremely depleted in K, Rb, Ba, and Cs. Our data are consistent with Archean greenstone-belt formation, including chemical sedimentation followed by mafic–ultramafic magmatism at approximately 2.9 Ga, followed by two later episodes of magmatism, one at approximately 2.5 Ga and the other at approximately 1.78 Ga. The Otter Creek complex is the first Archean greenstone reported south of the Great Lakes Tectonic Zone (GLTZ); its 2.9 Ga age is older than those reported for the granite–greenstone rocks north of the GLTZ. The southern portion of the Superior Province thus appears to have formed later, and in a different tectonic environment, than the high-grade gneisses of the Minnesota River Valley, but before the bulk of the granite–greenstone rocks exposed in northern Minnesota, Ontario, and eastern Manitoba.

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Ibrahim, Mohamed El-Ahmady, Koichiro Watanabe, Gehad Mohamed Saleh, and Waleed Saad Ibrahim. "Abu Rusheid lamprophyre dikes, South Eastern Desert, Egypt: as physical-chemical traps for REEs, Zn, Y, U, Cu, W, and Ag." Arabian Journal of Geosciences 8, no. 11 (March 31, 2015): 9261–70. http://dx.doi.org/10.1007/s12517-015-1882-8.

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27

Symons, D. T. A., and A. D. Chiasson. "Paleomagnetism of the Callander Complex and the Cambrian apparent polar wander path for North America." Canadian Journal of Earth Sciences 28, no. 3 (March 1, 1991): 355–63. http://dx.doi.org/10.1139/e91-032.

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The 7 km2 circular Callander alkaline complex was emplaced into anorthositic and granitic gneisses of the Grenville Province in the Canadian Shield about 575 ± 5 Ma ago at the start of the Cambrian. The complex has not been subsequently metamorphosed or tilted. Detailed alternating-field and thermal step demagnetization of 252 specimens from 29 sites led to the identification of a characteristic A magnetization component with a direction of D = 82.2°, I = 82.7° (α95 = 3.1°, k = 83, N = 26 sites) in 5 sites of mesocratic to leucocratic syenite from the core of the complex, in 5 sites of fenitized host rock from its aureole, and in 16 sites of lamprophyre from radiating dikes. Isothermal remanent-magnetization tests show that the A component is retained by both magnetite and hematite in a complete spectrum of domain sizes. A reversals test suggests and a contact test shows the A component to be primary. Its pole position at 46.3°S, 121.4°E(dp = 5.9°, dm = 6.1°) does not fall on published but poorly defined Cambrian apparent polar wander paths, leading to speculation on an alternative Cambrian path.

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28

Wyman, D. A., and R. Kerrich. "Correction [to “Archean lamprophyre dikes of the Superior Province, Canada: Distribution, petrology, and geochemical characteristics” by D. A. Wyman and R. Kerrich]." Journal of Geophysical Research 97, B12 (1992): 17439. http://dx.doi.org/10.1029/89jb02888.

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29

Sazonova, L. V., A. A. Nosova, E. V. Yutkina, I. A. Kondrashov, and L. V. Shumlyanskyy. "Genesis and evolution of the mantle melts of the devonian mafic-ultramafic rocks from the Eastern Azov region (Dnieper-Donetsk rift, Ukraine) based on the clinopyroxene geochemistry study." Петрология 27, no. 6 (December 16, 2019): 690–714. http://dx.doi.org/10.31857/s0869-5903276690-714.

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The Devonian magmatic association of the Eastern Azov region, which is part of the Pripyat-Dnieper-Donetsk rift zone, was studied. The association includes gabbroids, peridotites, pyroxenites, and lamprophyre dikes of the Pokrovo-Kireevsky massif (PKM) and picrites, picrobasalts and basalts of the Anton-Taramskaya suite (ATS). The clinopyroxenes of different generations from the micaceous PCM gabbro and the alkaline ATS picrite were studied. It was obtained the information on the mantle source composition and the evolution of melts, who determined the close spatial-temporal location of kimberlites, basites, ultramafic rocks, including alkaline ones, in the Eastern Azov region. Clinopyroxenes from micaceous gabbro are composed of Cpx1 (Mg# = 0.870.88) or Сpx2 (Mg# = 0.800.81) cores and Cpx3 external zones (Mg# = 0.700.76). Clinopyroxenes in alkaline picrite are composed of Сpx2 cores (Mg # = 0.800.84) and external Cpx3 zones (Mg# = 0.710.78). The multielement spectra of clinopyroxenes are generally dome-shaped in nature, with enrichment with LREE, depletion of Ba, Nb, TREE, Zr-Hf negative anomaly, a negative Sr-anomaly appears in Cpx2 and Cpx3 also. The resulting compositions of the model melt for Сpx2 from the micaceous gabbro are very close to the composition of this gabbro, and the compositions of the model melt for Cpx2 from the alkaline picrite coincide with those of this picrite. The high Mg# value and concentrations of Cr in Cpx1 cores indicate that the earliest weakly differentiated composition close to the primary could serve as the equilibrium melt. The presence in the Cpx1 geochemical spectra of a negative Zr-Hf anomaly at ZrPM HfРМ may be evidence of the origin of melts that once contained these clinopyroxenes, due to the melting of metasomatized, possibly carbonated garnet-contained peridotites. Probably, the Cpx1 cores are relics of phenocrysts crystallized from the earliest melt during the formation of the PCM and the ATS. An important feature of the Eastern Azov rocks is a very high content of Ti (up to 7.3 wt.% TiO2) in the high-Mg (Mg# = 0.480.65) and deep (CaO/Al2O3 0.8) melts, which formed picrobasalts and lamprophyres. The geochemical features of the early Cpx1 cores compared with the geochemistry of clinopyroxenes from ilmenite-containing mantle metasomatites are consistent with the assumption that carbonated ilmenite-containing peridotites, possibly also phlogopite-containing (PIC), are the source of ultrahigh-Ti primary melts for the Eastern Azov lamprophyres.

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Artemenko, G. V., L. M. Stepanyuk, D. K. Wozniak, V. G. Bakhmutov, and Yu O. Lytvynenko. "U-Pb age and ore mineralization of dike lamprophires of the Roсa Islands (Wilhelm Archipelago, West Antarctica)." Geochemistry and ore formation, no. 43 (2022): 31–40. http://dx.doi.org/10.15407/gof.2022.43.031.

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The dike of lamprophyres of the Roсa Islands chemically correspond to the basic rocks of the calc-alkaline series with high magnesian #mg 0.56. They have an increased content of Y (41.6 ppm) and Yb (11.5 ppm), which indicates the absence of garnet in the magmatic source. Rare earth elements are weakly differentiated — (La/Yb)N = 3.64). A deep negative European anomaly is distinguished — Eu/Eu*=0.36, which is probably due to the fractionation of plagioclase in the crustal magmatic source. Polymetallic mineralization for copper (445 g/t), zinc (207 g/t), lead (123 g/t) and tungsten (28.7 g/t) was found. Zircon from lamprophyres is represented by two types of crystals. The first type – transparent yellowish-pink individuals with a pyramidal-prismatic habit. In terms of quantity, it dominates; the second type is the formation of a flat outline. Dimensions are usually 0.3—0.7 mm along the L4 axis. Crystals of the first type were selected for geochronological research. It was found that the lamprophyre zircon contains very little lead, and a significant part of it is the lead isotope 204Pb. For this reason, age values for uranium-lead ratios of 238U/206Pb are more reliable. It was determined that the uranium-lead age of zircon from lamprophyres is within 50—60 Ma. Primary melt inclusions and less often mineral inclusions were found in zircon crystals. The former can sometimes occupy up to 30% of the crystal volume. Among the mineral inclusions, potassium feldspar, albite and potassium-sodium feldspar, apatite, and quartz were diagnosed. One primary inclusion of CO2 fluid was detected, the remaining inclusions are represented by primary crystallized melt inclusions. Rooting of the lamprophyre dyke is probably associated with the stress stresses experienced by the granodiorite plutons as a result of later tectonic movements.

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Sacks de Campos, Roberto, Ruy Paulo Philipp, Hans-Joachim Massonne, and Farid Chemale. "Early post-collisional Brasiliano magmatism in Botuverá region, Santa Catarina, southern Brazil: Evidence from petrology, geochemistry, isotope geology and geochronology of the diabase and lamprophyre dikes." Journal of South American Earth Sciences 37 (August 2012): 266–78. http://dx.doi.org/10.1016/j.jsames.2012.02.005.

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32

Belyaev, V. A., M. A. Gornova, I. V. Gordienko, A. A. Karimov, A. Ya Medvedev, A. V. Ivanov, S. I. Dril, D. A. Grigoriev, and O. Yu Belozerova. "Late Cambrian calc-alkaline magmatism during transition from subduction to accretion: Insights from geochemistry of lamprophyre, dolerite and gabbro dikes in the Dzhida terrain, Central Asian orogenic belt." Lithos 386-387 (April 2021): 106044. http://dx.doi.org/10.1016/j.lithos.2021.106044.

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33

McDowell, F. W., M. F. Roden, and D. Smith. "Comments on “Tectonic implications of the age, composition, and orientation of lamprophyre dikes, Navajo volcanic field, Arizona”, by A.W. Laughlin, M.J. Aldrich, Jr., M. Shafiqullah and J. Husler." Earth and Planetary Science Letters 80, no. 3-4 (November 1986): 415–17. http://dx.doi.org/10.1016/0012-821x(86)90121-4.

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34

Laughlin, A. W., M. J. Aldrich, M. Shafiqullah, and J. Husler. "A reply to “Comments on ‘Tectonic implications of the age, composition, and orientation of lamprophyre dikes, Navajo volcanic field, Arizona’ ” by F.W. McDowell, M.F. Roden and D. Smith." Earth and Planetary Science Letters 80, no. 3-4 (November 1986): 418–20. http://dx.doi.org/10.1016/0012-821x(86)90122-6.

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35

Wu, Fei, Yilin Xiao, Lijuan Xu, M. Santosh, Shuguang Li, Jian Huang, Zhenhui Hou, and Fang Huang. "Geochronology and geochemistry of felsic xenoliths in lamprophyre dikes from the southeastern margin of the North China Craton: implications for the interleaving of the Dabie–Sulu orogenic crust." International Geology Review 57, no. 9-10 (February 13, 2015): 1305–25. http://dx.doi.org/10.1080/00206814.2015.1009182.

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36

Azzone, Rogério Guitarrari, Lina Maria Cetina Tarazona, Mariana Robertti Ambrosio, Vincenza Guarino, Luanna Chmyz, Nicholas Machado Lima, and Excelso Ruberti. "The Hidden Magmatic Chamber from the Ponte Nova Mafic–Ultramafic Alkaline Massif, SE Brazil: Clues from Clinopyroxene and Olivine Antecrysts." Minerals 12, no. 6 (June 18, 2022): 775. http://dx.doi.org/10.3390/min12060775.

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Clinopyroxene and olivine primocrysts in the intrusions of the Ponte Nova mafic–ultramafic alkaline massif (SE Brazil) present several textures and zoning that indicate open-system processes. Important compositional differences were found in the clinopyroxene. Diopside relict cores (mostly partially corroded) present higher Mg, Cr and Ni and lower Ti, Na, Al, REE and Sr than Ti-augite mantling and rims. Subordinately, two types of olivine crystals were recognized, one related to very zoned crystals with high Mg (Fo up to 86 mol.%) and Ni cores (mostly with corroded rims), and other almost without clear zonation and with lower Mg contents. Relict cores of high-Mg clinopyroxene and olivine crystals are representative of antecrysts formed in deeper chamber environments. Temperature and pressure estimates based on clinopyroxene-liquid geothermobarometers indicate crystallization of the antecrysts at ~1171 ± 10 °C and ~5.7 ± 0.3 kbar, pointing to a deeper hidden magmatic chamber, whereas mantling and rim compositions indicate a shallow chamber environment. Clinopyroxenes of this hidden chamber have progressive enrichments of incompatible elements with the Mg# decrement and inflection points in Sr and REE due to the starting of co-precipitation of apatite. The evolution trend of clinopyroxene antecrysts indicates that the main intrusions in the Ponte Nova shallow chamber were fed by a single deeper hidden chamber mainly controlled by typical fractional crystallization processes. These antecrysts indicate the presence of a complex plumbing system, which is also supported by similar antecrysts found in the lamprophyre and alkali basalt dikes of this region. The preferred petrological model for the Ponte Nova massif could be summarized as repeated influxes of antecryst-laden basanite magmas that deposited most of their suspended crystals on the floor of the upper-crust magma chamber.

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Pivarunas, Anthony F., and Joseph G. Meert. "Protracted magmatism and magnetization around the McClure Mountain alkaline igneous complex." Lithosphere 11, no. 5 (June 27, 2019): 590–602. http://dx.doi.org/10.1130/l1062.1.

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Abstract The McClure Mountain–Iron Mountain igneous complex is an alkalic intrusive center in the northern Wet Mountains of southern Colorado. It was emplaced in early Cambrian time into gneissic/granitic 1.75–1.45 Ga Proterozoic host rocks. Numerous dikes are associated with the complex, primarily along the western side. Although the main intrusive nepheline-syenite body is well dated, the ages of the surrounding dikes are poorly known. Crosscutting relationships and poorly defined K-Ar dates suggest that the dikes are younger than the main intrusion. Paleomagnetic samples were collected from dikes associated with the McClure Mountain igneous complex. Geochronologic samples were also collected from two dikes sampled for their paleomagnetism. We obtained U-Pb zircon ages of 526 ± 8 Ma for a lamprophyric extracomplex dike and 483 ± 2 Ma for a trachytic extracomplex dike. These ages suggest either multistage or protracted dike intrusion around the ca. 524 Ma McClure Mountain complex. Our paleomagnetic data are consistent with previously published results. Dikes of the complex primarily exhibit southeast and shallow paleomagnetic directions, with variable declinations. Results from several baked contact tests indicate that the magnetizations are secondary. A steeply inclined magnetization is pervasive and was acquired over a protracted interval from late Laramide time to the present day.

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Barrie, C. Tucker, and Steven B. Shirey. "Nd- and Sr-isotope systematics for the Kamiskotia–Montcalm area: implications for the formation of late Archean crust in the western Abitibi Subprovince, Canada." Canadian Journal of Earth Sciences 28, no. 1 (January 1, 1991): 58–76. http://dx.doi.org/10.1139/e91-006.

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Geochemistry and Nd isotopic compositions are used to characterize mantle and crustal sources and to provide constraints on petrogenetic models for tholeiitic, calc-alkalic, and lamprophyric suites in the Kamiskotia–Montcalm area. The Kamiskotia gabbroic complex (KGC) and cogenetic, bimodal volcanic rocks have εNd(t) = +2.2 to +2.6, consistent with a direct derivation from a long-term, light rare-earth element (LREE)-depleted mantle. The Montcalm gabbroic complex has decreasing εNd(t) upsection from +2.8 to +1.0, consistent with contamination by long-term, LREE-enriched (with respect to the long-term, LREE-depleted Abitibi mantle) crust during fractionation. Two calc-alkalic lamprophyre samples, characterized by large-ion lithophile element (LILE) and LREE enrichment and high MgO, Ni, and Cr contents, have εNd(t) of +2.5 and +2.8, indicating a derivation from a depleted mantle source that had undergone recent trace-element enrichment. A different lamprophyre suite is extremely LILE and LREE enriched and has an εNd(t) of +1.0, indicating a derivation from a slightly different source that had earlier LREE enrichment. Granitoid rocks internal and external to greenstone belt rocks have εNd(t) = +2.5 to +3.8 and +0.6 to −0.4, respectively. The lower values provide additional evidence for the existence of LREE-enriched crust in this area.Considering these data along with other radiogenic isotope studies, a petrogenetic and tectonic model is suggested for the crustal development of the southern Abitibi Subprovince. From >2740 to 2698 Ma—the major period of volcanic activity—komatiitic and tholeiitic suites and one lamprophyre suite were derived from a uniformly LREE-depleted mantle reservoir with εNd(t) = +2 to +3. Calc-alkalic granitoids were emplaced generally after 2700 Ma. Their long-term, LREE-depleted and LREE-enriched Nd isotopic signatures are similar to signatures in continental-arc settings (e.g., the Coastal Batholith of Peru). Form 2690 to 2670 Ma, when transpressional tectonism prevailed, mantle-derived magmatism was represented by long-term, LREE-enriched (εNd(t) = +1 to +2) lamprophyric and alkalic volcanic suites.The Kamiskotia suite has a seven-point, whole-rock – mineral isochron Sm–Nd age of 2710 ± 30 Ma, identical to U–Pb zircon ages for the suite, indicating closed-system behavior. An Rb–Sr mineral – whole-rock isochron age from one KGC sample is 2450 ± 30 Ma, identical to U–Pb ages for the Hearst–Matachewan dike swarm, a prominent feature in the KGC area. Regression of whole-rock and mineral-isotope data for one granitoid sample with a U–Pb zircon age of 2696 ± 1.5 Ma gives identical ages of 2530 ± 30 Ma in the Sm–Nd and Rb–Sr systems. The latter data add to an increasing body of evidence for cryptic, late thermal events after granitoid–greenstone belt development in the southern Abitibi Subprovince.

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Barrie, C. Tucker. "U–Pb garnet and titanite age for the Bristol Township lamprophyre suite, western Abitibi Subprovince, Canada." Canadian Journal of Earth Sciences 27, no. 11 (November 1, 1990): 1451–56. http://dx.doi.org/10.1139/e90-153.

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A U–Pb age of 2687 ± 3 Ma has been determined for a garnetite dike, using melanite garnet and titanite mineral separates. This is the first primary igneous U–Pb age reported using garnet. The garnetite dike is part of the Bristol Township lamprophyre suite, which is extremely enriched in large-ion lithophile elements and light rare earth elements and which is located within the Destor Porcupine fault zone of the western Abitibi Subprovince. The age represents an upper limit for late-stage gold mineralization found along brittle fractures that cut the lamprophyre suite and it coincides with regional transpression documented in several locations in the southern Superior Province.

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40

Macrae, Neil D., Allan E. Armitage, Adrienne L. Jones, and Allan R. Miller. "A Diamondiferous Lamprophyre Dike, Gibson Lake Area, Northwest Territories." International Geology Review 37, no. 3 (March 1995): 212–29. http://dx.doi.org/10.1080/00206819509465401.

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41

Lipman, Peter W., and Matthew J. Zimmerer. "Magmato-tectonic links: Ignimbrite calderas, regional dike swarms, and the transition from arc to rift in the Southern Rocky Mountains." Geosphere 15, no. 6 (September 30, 2019): 1893–926. http://dx.doi.org/10.1130/ges02068.1.

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Abstract Radial and linear dike swarms in the eroded roots of volcanoes and along rift zones are sensitive structural indicators of conduit and eruption geometry that can record regional paleostress orientations. Compositionally diverse dikes and larger intrusions that radiate westward from the polycyclic Platoro caldera complex in the Southern Rocky Mountain volcanic field (southwestern United States) merge in structural trend, composition, and age with the enormous but little-studied Dulce swarm of trachybasaltic dikes that continue southwest and south for ∼125 km along the eastern margin of the Colorado Plateau from southern Colorado into northern New Mexico. Some Dulce dikes, though only 1–2 m thick, are traceable for 20 km. More than 200 dikes of the Platoro-Dulce swarm are depicted on regional maps, but only a few compositions and ages have been published previously, and relations to Platoro caldera have not been evaluated. Despite complications from deuteric alteration, bulk compositions of Platoro-Dulce dikes (105 new X-ray fluorescence and inductively coupled plasma mass spectrometry analyses) become more mafic and alkalic with distance from the caldera. Fifty-eight (58) new 40Ar/39Ar ages provide insight into the timing of dike emplacement in relation to evolution of Platoro caldera (source of six regional ignimbrites between 30.3 and 28.8 Ma). The majority of Dulce dikes were emplaced during a brief period (26.5–25.0 Ma) of postcaldera magmatism. Some northeast-trending dikes yield ages as old as 27.5 Ma, and the northernmost north-trending dikes have younger ages (20.1–18.6 Ma). In contrast to high-K lamprophyres farther west on the Colorado Plateau, the Dulce dikes are trachybasalts that contain only anhydrous phenocrysts (clinopyroxene, olivine). Dikes radial to Platoro caldera range from pyroxene- and hornblende-bearing andesite to sanidine dacite, mostly more silicic than trachybasalts of the Dulce swarm. Some distal andesite dikes have ages (31.2–30.4 Ma) similar to those of late precaldera lavas; ages of other proximal dikes (29.2–27.5 Ma) are akin to those of caldera-filling lavas and the oldest Dulce dikes. The largest radial dikes are dacites that have yet younger sanidine 40Ar/39Ar ages (26.5–26.4 Ma), similar to those of the main Dulce swarm. The older andesitic dikes and precaldera lavas record the inception of a long-lived upper-crustal magmatic locus at Platoro. This system peaked in magmatic output during ignimbrite eruptions but remained intermittently active for at least an additional 9 m.y. Platoro magmatism began to decline at ca. 26 Ma, concurrent with initial basaltic volcanism and regional extension along the Rio Grande rift, but no basalt is known to have erupted proximal to Platoro caldera prior to ca. 20 Ma, just as silicic activity terminated at this magmatic locus. The large numbers and lengths of the radial andesitic-dacitic dikes, in comparison to the absence of similar features at other calderas of the San Juan volcanic locus, may reflect location of the Platoro system peripheral to the main upper-crustal San Juan batholith recorded by gravity data, as well as its proximity to the axis of early rifting. Spatial, temporal, and genetic links between Platoro radial dikes and the linear Dulce swarm suggest that they represent an interconnected regional-scale magmatic suite related to prolonged assembly and solidification of an arc-related subcaldera batholith concurrently with a transition to regional extension. Emplacement of such widespread dikes during the late evolution of a subcaldera batholith could generate earthquakes and trigger dispersed small eruptions. Such events would constitute little-appreciated magmato-tectonic hazards near dormant calderas such as Valles, Long Valley, or Yellowstone (western USA).

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42

Zel, Ivan, Bekhzodjon Abdurakhimov, Sergey Kichanov, Olga Lis, Elmira Myrzabekova, Denis Kozlenko, Mannab Tashmetov, Khalbay Ishbaev, and Kuatbay Kosbergenov. "Neutron Tomography Studies of Two Lamprophyre Dike Samples: 3D Data Analysis for the Characterization of Rock Fabric." Journal of Imaging 8, no. 3 (March 19, 2022): 80. http://dx.doi.org/10.3390/jimaging8030080.

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The rock fabric of two lamprophyre dike samples from the Koy-Tash granitoid intrusion (Koy-Tash, Jizzakh region, Uzbekistan) has been studied, using the neutron tomography method. We have performed virtual segmentation of the reconstructed 3D model of the tabular igneous intrusion and the corresponding determination of dike margins orientation. Spatial distributions of inclusions in the dike volume, as well as further analysis of size distributions and shape orientations of inclusions, have been obtained. The observed shape preferred orientations of inclusions as evidence of the magma flow-related fabric. The obtained structural data have been discussed in the frame of the models of rigid particle motion and the straining of vesicles in a moving viscous fluid.

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Cooper, A. F., B. A. Barreiro, D. L. Kimbrough, and J. M. Mattinson. "Lamprophyre dike intrusion and the age of the Alpine fault, New Zealand." Geology 15, no. 10 (1987): 941. http://dx.doi.org/10.1130/0091-7613(1987)15<941:ldiata>2.0.co;2.

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44

Udoratina, O. V., A. M. Shmakova, D. A. Varlamov, and A. S. Shuisky. "Alkaline-ultrabasic rocks of Novobobrovsky ore field (Middle Timan): mineralogy, petrography." Proceedings of the Komi Science Centre of the Ural Division of the Russian Academy of Sciences 3 (2021): 14–21. http://dx.doi.org/10.19110/1994-5655-2021-3-14-21.

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Minerals of disintegrated alkaline-ultrabasic dike rocks exposed by wells within the rare-metal–rare earth Novobo-brovsky ore field (Middle Timan) were studied. Microprobe studies were conducted in CCU "Geoscience" (Syktyvkar) and the Institute of Experimental Geology, RAS (Chernogolovka). Primary mineral parage-neses are difficult to diag-nose due to strong secondary alteration of rocks. The primary minerals are phlogopite (XMg = 0.64–0.89) and minerals of the chromespinelides group (the central parts are represented by chrompicotite, and the marginal zones – by ferrich-romite); the secondary minerals are represented by the chlorites group (talcochlorite, clinochlorite, pennine). The rock is saturated with numerous xenoliths of quartzite sandstones, and has also undergone fenitization processes, which is why the development of rare metal–rare earth mineralization is observed in the rock: columbite, rutile ↔ Nb-rutile ↔ ilme-norutil, monazite, Th-monazite, more rare phosphates (complex phosphates and hydroaluminophosphates of lead similar in composition to dragmanite, differing by the presence of Mn, Ba, K). The studied primary mineral parageneses are typical for the picrite-lamprophyre Chetlas dike complex developed here; the superimposed rare-metal–rare-earth mineralization is specific for dike rocks developed within the ore fields of the Kosyu ore cluster.

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Gomes, Celso de Barros, Francisco Rubens Alves, Rogério Guitarrari Azzone, Gaston Eduardo Enrich Rojas, and Excelso Ruberti. "Geochemistry and petrology of the Búzios Island alkaline massif, SE, Brazil." Brazilian Journal of Geology 47, no. 1 (January 2017): 127–45. http://dx.doi.org/10.1590/2317-4889201720160121.

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ABSTRACT: The Late Cretaceous Búzios Island alkaline massif intrudes Precambrian charnockites and consists dominantly of syenitic rocks that are cut by a large number of dikes, mostly NE-trending, and representing two distinct suites, a felsic one and a mafic-ultramafic one. Alkali feldspar is the most abundant mineral; other constituents are clinopyroxene, commonly replaced by amphibole/biotite, and opaques. Accessory minerals include occasionally rare phases bearing Zr, Ti, Nb and Rare Earth Elements (REE). The felsic dikes may also have nepheline (sodalite). The mafic-ultramafic suite, in particular the lamprophyres, shows a primary mineral assemblage with olivine, clinopyroxene and amphibole in addition to a groundmass having glassy material and carbonates (ocelli). The Búzios rocks are chemically evolved, mostly of potassic affinity and mainly belong to the miaskitic series. Variation diagrams for major and trace elements show a bimodal distribution, suggesting an origin from different magmatic pulses. The rocks are interpreted as having been derived by fractional crystallization processes from a basanitic parental magma. The SiO2-undersaturated and SiO2-oversaturated associations present in the massif are apparently not linked to a single magmatic source, and in the petrogeny residual system two trends are evident: the first one towards the phonolitic minimum and the second one towards the rhyolitic minimum, possibly pointing to amphibole fractionation.

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Dalton, Hayden, Andrea Giuliani, Hugh O’Brien, David Phillips, Janet Hergt, and Roland Maas. "Petrogenesis of a Hybrid Cluster of Evolved Kimberlites and Ultramafic Lamprophyres in the Kuusamo Area, Finland." Journal of Petrology 60, no. 10 (October 1, 2019): 2025–50. http://dx.doi.org/10.1093/petrology/egz062.

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Abstract Kimberlites are often closely associated, both in time and space, with a wide variety of alkaline ultramafic rock types, yet the question of a genetic relationship between these rock types remains uncertain. One locality where these relationships can be studied within the same cluster is the Karelian craton in Finland. In this study we present the first petrographic, mineral and whole-rock geochemical results for the most recently discovered kimberlite cluster on this craton, which represents an example of the close spatial overlap of kimberlites with ultramafic lamprophyres. The Kuusamo cluster incorporates seven bodies [Kasma 45, Kasma 45 south, Kasma 47, Kalettomanpuro (KP), Kattaisenvaara (KV), Dike 15 and Lampi] distributed along a 60 km NE–SW corridor. Hypabyssal samples from KV, KP, Kasma 45 and Kasma 47 consist of altered olivine macrocrysts and microcrysts and phlogopite phenocrysts in a groundmass of perovskite, apatite, spinel, ilmenite, serpentine, and calcite. These petrographic features combined with mineral (e.g. Mg-rich ilmenite, Al–Ba-rich, Ti–Fe-poor mica) and whole-rock incompatible trace element compositions (La/Nb = 0·8 ± 0·1; Th/Nb = 0·07 ± 0·01; Nb/U = 66 ± 9) are consistent with these rocks being classified as archetypal kimberlites. These Kuusamo kimberlites are enriched in CaO and poor in MgO, which, combined with the absence of chromite and paucity of olivine macrocrysts and mantle-derived xenocrysts (including diamonds), suggests derivation from differentiated magmas after crystal fractionation. Samples from Lampi share similar petrographic features, but contain mica with compositions ranging from kimberlitic (Ba–Al-rich cores) to those more typical of orangeites–lamproites (increasing Si–Fe, decreasing Al–Ti–Ba), and have higher bulk-rock SiO2 contents than the Kuusamo kimberlites. These features, combined with the occurrence of quartz and titanite in the groundmass, indicate derivation from a kimberlite magma that underwent considerable crustal contamination. This study shows that crustal contamination can modify kimberlites by introducing features typical of alkaline ultramafic rock types. Dike 15 represents a distinct carbonate-rich lithology dominated by phlogopite over olivine, with lesser amounts of titaniferous clinopyroxene and manganoan ilmenite. Phlogopite (Fe–Ti-rich) and spinel [high Fe2+/(Fe2+ + Mg)] compositions are also distinct from the other Kuusamo intrusions. The petrographic and geochemical features of Dike 15 are typical of ultramafic lamprophyres, specifically, aillikites. Rb–Sr dating of phlogopite in Dike 15 yields an age of 1178·8 ± 4·1 Ma (2σ), which is considerably older than the ∼750 Ma emplacement age of the Kuusamo kimberlites. This new age indicates significant temporal overlap with the Lentiira–Kuhmo–Kostomuksha olivine lamproites emplaced ∼100 km to the SE. It is suggested that asthenospheric aillikite magmas similar to Dike 15 evolved to compositions akin to the Karelian orangeites and olivine lamproites through interaction with and assimilation of MARID-like, enriched subcontinental lithospheric mantle. We conclude that the spatial coincidence of the Kuusamo kimberlites and Dike 15 is probably the result of exploitation of similar trans-lithospheric corridors.

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Adams, C. J., and Alan F. Cooper. "K‐Ar age of a lamprophyre dike swarm near Lake Wanaka, west Otago, South Island, New Zealand." New Zealand Journal of Geology and Geophysics 39, no. 1 (March 1996): 17–23. http://dx.doi.org/10.1080/00288306.1996.9514691.

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Palke, Aaron C., Nathan D. Renfro, and Richard B. Berg. "Origin of sapphires from a lamprophyre dike at Yogo Gulch, Montana, USA: Clues from their melt inclusions." Lithos 260 (September 2016): 339–44. http://dx.doi.org/10.1016/j.lithos.2016.06.004.

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Craddock, John P., Jennifer Anziano, Karl Wirth, Jeffrey D. Vervoort, Brad Singer, and Xifan Zhang. "Structure, geochemistry and geochronology of a Penokean Lamprophyre Dike Swarm, Archean Wawa Terrane, Little Presque Isle, Michigan, USA." Precambrian Research 157, no. 1-4 (August 1, 2007): 50–70. http://dx.doi.org/10.1016/j.precamres.2007.02.010.

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50

Kepezhinskas, Pavel K., Glenn M. D. Eriksen, and Nikita P. Kepezhinskas. "Geochemistry of Ultramafic to Mafic Rocks in the Norwegian Lapland: Inferences on Mantle Sources and Implications for Diamond Exploration." Earth Science Research 5, no. 2 (July 28, 2016): 148. http://dx.doi.org/10.5539/esr.v5n2p148.

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Geology of the Norwegian Lapland is dominated by diverse Archean crystalline basement complexes superimposed with Proterozoic greenstone belts. Isotopic dating of detrital zircons from basement gneisses in the Kirkenes area establishes presence of Early Archean (3.69 Ga) crustal component as well as three major episodes of crustal growth at 3.2 Ga, 2.7-2.9 Ga and 2.5 Ga. Precambrian terranes are intruded by ultramafic-mafic dikes and sills that range in composition from komatiites and ultramafic-mafic lamprophyres to high-Mg basalts and low-Ti subalkaline basalts. Geochemical characteristics of these rocks fall into three principal groups: 1) enriched compositions with high Nd, Nb, Hf, Zr and Th concentrations and elevated La/Th and Nb/Th coupled with low La/Nb, Ba/Nb and U/Nb ratios; 2) compositions depleted in Th, Hf and Nb together with low LREE/HFSE (such as La/Nb) and LILE/HFSE (such as Ba/Nb and U/Nb) ratios; 3) transitional group clearly identified by marked depletions in Ti, Nb and Ta contents coupled with enrichment in Th and U and other large-ion lithophile elements (LILE). These geochemical characteristics are interpreted within the framework of two principal source models: 1) derivation of parental ultramafic-mafic melts from multiple mantle sources (depleted to enriched) inherited from Archaean lithospheric tectonics and 2) a single primitive mantle source which underwent several depletion and enrichment episodes, at least partially associated with subduction zone processes. Subduction modification of depleted lithospheric mantle was assisted by accretion of subducted sediment to depleted mantle source at Archean, Proterozoic or Early Paleozoic convergent margin. Alkaline ultramafic rocks such as lamprophyres and mica picrites display geochemical characteristics supportive of their origin within stability field of diamond in a deep mantle beneath Norwegian Arctic margin which, together with other lithospheric characteristics, suggests its high potential for hosting economic diamond mineralization.

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