Igneous Rocks

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Takanori Nakano - One of the best experts on this subject based on the ideXlab platform.

  • Petrogenesis and tectonic setting of Late Paleozoic to Late Mesozoic Igneous Rocks in Cambodia
    Journal of Asian Earth Sciences, 2019
    Co-Authors: Rathborith Cheng, Etsuo Uchida, Masato Katayose, Kosei Yarimizu, Ki Cheol Shin, Sitha Kong, Takanori Nakano
    Abstract:

    Abstract Emplacement of Igneous Rocks from the Carboniferous to the Middle Jurassic of Cambodia was controlled by the Indosinian Orogeny, which was related to the sequence of suturing and collision between the continental fragments from Gondwana. To constrain magma genesis, tectonic setting, and relationship with Igneous Rocks in neighboring countries, we determined the magnetic susceptibility, chemical compositions, Rb-Sr isochron ages and Sr-Nd isotope ratios for Igneous rock samples from Cambodia. Igneous Rocks in Cambodia can be divided by the inferred Mae Ping fault into magnetite series in the NE region and ilmenite series in the SW region. The Igneous Rocks in the NE region showed I-type or A-type and metaluminous signatures, and strong involvement of mantle source materials. They are subdivided into older and younger adakitic Rocks and non-adakitic Rocks. The Igneous Rocks in the SW region showed non-adakitic and slightly metaluminous to peraluminous signatures. These have significant involvement of source materials with relatively uniform Nd isotope ratios but variable Sr isotope ratios, which may have originated from the lower to middle continental crust. The Late Triassic to Middle Jurassic Igneous Rocks were formed by the subduction of the Paleo-Tethys Ocean crust associated with the collision of the Sibumasu Terrane with the Indochina Terrane (the Indosinian Orogeny II). The younger granitic Rocks showed A-type signature and are regarded as post-orogenic, within the plate or rifting zone that intruded in association with the subduction of the Paleo-Pacific Ocean crust beneath Indochina during the Cretaceous to the Paleogene.

M. J. Le Bas - One of the best experts on this subject based on the ideXlab platform.

  • Report of the Working Party on the classification of the lunar Igneous Rocks
    Meteoritics & Planetary Science, 2001
    Co-Authors: M. J. Le Bas
    Abstract:

    — A report is presented for a possible revised classification of lunar Igneous Rocks that still uses the division of Moon Rocks into mare and highland types. It subdivides the mare Rocks into basalts depending on TiO2 content and glasses depending on colour, and subdivides the highland Rocks principally into KREEP basalts and into coarse-grained Igneous Rocks comparable to and using terrestrial Igneous rock terminology.

  • The IUGS systematics of Igneous Rocks
    Journal of the Geological Society, 1991
    Co-Authors: M. J. Le Bas, Albert Streckeisen
    Abstract:

    In order to create a sustainable classification of Igneous Rocks which all geologists might use, an international body was set up by the IUGS: the IUGS Subcommission on the Systematics of Igneous Rocks. In the course of creating the classification, the Subcommission has established ten principles for its construction and for defining an appropriate nomenclature. The principles are: (1) use descriptive attributes; (2) use actual properties; (3) ensure suitability for all geologists; (4) use current terminology; (5) define boundaries of rock species; (6) keep it simple to apply; (7) follow natural relations; (8) use modal mineralogy; (9) if mode not feasible, use chemistry; (10) follow terminology of other IUGS advisory bodies. These principles and their rationale have not previously been enunciated. The classification separates and individually classifies the pyroclastic, carbonatitic, melititic, lamprophyric and charnockitic Rocks before entering the main QAPF classification for plutonic and volcanic Rocks which is based on the modal mineral proportions of quartz (Q), alkali feldspar (A) and plagioclase (P) or of alkali feldspar (A), plagioclase (P) and feldspathoids (F). Rocks with mafic content >90% have their own classification. If the mineral mode cannot be determined as is often the case for volcanic Rocks, then a chemical classification of total alkalis versus silica (TAS) is used. The nomenclature for these classifications necessitates only 297 rock names out of the c . 1500 that exist.

Rathborith Cheng - One of the best experts on this subject based on the ideXlab platform.

  • Petrogenesis and tectonic setting of Late Paleozoic to Late Mesozoic Igneous Rocks in Cambodia
    Journal of Asian Earth Sciences, 2019
    Co-Authors: Rathborith Cheng, Etsuo Uchida, Masato Katayose, Kosei Yarimizu, Ki Cheol Shin, Sitha Kong, Takanori Nakano
    Abstract:

    Abstract Emplacement of Igneous Rocks from the Carboniferous to the Middle Jurassic of Cambodia was controlled by the Indosinian Orogeny, which was related to the sequence of suturing and collision between the continental fragments from Gondwana. To constrain magma genesis, tectonic setting, and relationship with Igneous Rocks in neighboring countries, we determined the magnetic susceptibility, chemical compositions, Rb-Sr isochron ages and Sr-Nd isotope ratios for Igneous rock samples from Cambodia. Igneous Rocks in Cambodia can be divided by the inferred Mae Ping fault into magnetite series in the NE region and ilmenite series in the SW region. The Igneous Rocks in the NE region showed I-type or A-type and metaluminous signatures, and strong involvement of mantle source materials. They are subdivided into older and younger adakitic Rocks and non-adakitic Rocks. The Igneous Rocks in the SW region showed non-adakitic and slightly metaluminous to peraluminous signatures. These have significant involvement of source materials with relatively uniform Nd isotope ratios but variable Sr isotope ratios, which may have originated from the lower to middle continental crust. The Late Triassic to Middle Jurassic Igneous Rocks were formed by the subduction of the Paleo-Tethys Ocean crust associated with the collision of the Sibumasu Terrane with the Indochina Terrane (the Indosinian Orogeny II). The younger granitic Rocks showed A-type signature and are regarded as post-orogenic, within the plate or rifting zone that intruded in association with the subduction of the Paleo-Pacific Ocean crust beneath Indochina during the Cretaceous to the Paleogene.

F H Kattan - One of the best experts on this subject based on the ideXlab platform.

  • distribution and significance of pre neoproterozoic zircons in juvenile neoproterozoic Igneous Rocks of the arabian nubian shield
    American Journal of Science, 2010
    Co-Authors: Robert J Stern, Kamal A Ali, Jeanpaul Liegeois, Peter R Johnson, W Kozdroj, F H Kattan
    Abstract:

    Igneous Rocks of the Arabian-Nubian Shield (ANS) have lithologic associations (ophiolites, calc-alkaline Igneous Rocks, immature sediments) and radio- genic isotopic compositions consistent with formation as juvenile continental crust as a result of accreting intraoceanic arc systems during 880 to 630 Ma, with crustal differentiation continuing until 570 Ma. ANS Igneous Rocks locally contain zircons with ages that are much older than this, leading some researchers to infer the presence of pre-Neoproterozoic crust at depth in spite of Nd isotopic evidence that ANS crust is overwhelmingly juvenile. The ANS is flanked by pre-Neoproterozoic crust but geo- chronology and isotopic compositions readily identify such tracts. We have compiled U-Pb zircon ages for 302 samples of ANS Igneous Rocks that have been analyzed for the age of individual zircons (2372 ages) and find that a significant proportion (5%) of these have ages older than 880 Ma (zircon xenocrysts). Zircon xenocrysts are more common in volcanic than plutonic Rocks and mafic relative to felsic Igneous Rocks. Four explanations are considered: 1) contamination during sample processing; 2) involve- ment of pre-Neoproterozoic crust; 3) incorporation of detrital zircons from sediments; and 4) inheritance from a mantle source. Possibilities 1 and 2 are discounted, and we conclude that the presence of pre-880 Ma zircon xenocrysts in ANS Igneous Rocks with mantle-like isotopic compositions indicates either incorporation of sediments or inheritance from the mantle source region, or both.

David I. Groves - One of the best experts on this subject based on the ideXlab platform.

  • Tectonic Settings of Potassic Igneous Rocks
    2016
    Co-Authors: Daniel Müller, David I. Groves
    Abstract:

    Modern potassic Igneous Rocks occur in a wide range of tectonic settings, from continental to oceanic and within-plate, some of which are not apparently associated with subduction (Joplin 1968; Morrison 1980; Muller et al. 1992b). It is therefore important, whether improving exploration models for ancient mineral deposits, or reconstructing ancient terranes, to be able to distinguish the tectonic settings in which ancient potassic Igneous Rocks were generated. The following chapter seeks to provide such a distinction.

  • Potassic Igneous Rocks and Associated Gold-Copper Mineralization
    1995
    Co-Authors: Daniel Müller, David I. Groves
    Abstract:

    1 Introduction.- 1.1 Preamble: Potassic Igneous Rocks and Their Importance.- 1.2 Scope of Book.- 2 Definitions and Nomenclature.- 2.1 Historical Perspective of Potassic Igneous Rocks.- 2.2 Potassic Igneous Rocks as an Umbrella Term.- 2.3 Shoshonites.- 2.4 Shoshonitic and Alkaline Lamprophyres.- 2.5 Ultrapotassic Rocks.- 2.5.1 Introduction.- 2.5.2 Lamproites.- 2.5.3 Kamafugites.- 2.5.4 Orogenic Ultrapotassic Rocks.- 2.6 Group II Kimberlites.- 2.7 Potassic Igneous Rocks as Considered in this Book.- 2.8 Field Recognition of Potassic Igneous Rocks.- 3 Tectonic Settings of Potassic Igneous Rocks.- 3.1 Introduction.- 3.2 Tectonic Settings of Potassic Igneous Rocks.- 3.2.1 Continental Arc.- 3.2.2 Postcollisional Arc.- 3.2.3 Oceanic (Island) Arc.- 3.2.4 Within-Plate.- 3.2.5 Problems with Tectonic Classification.- 3.3 History of Discrimination of Tectonic Setting by Geochemical Means.- 3.4 Erection of Databases SHOSH1 and SHOSH2.- 3.5 Discrimination of Tectonic Setting by Multivariate Statistical Methods.- 3.6 Discrimination via Simple Geochemical Diagrams.- 3.7 Theoretical Basis for Discrimination Between Potassic Igneous Rocks in Different Tectonic Settings.- 3.8 Conclusions.- 4 Selected Type-Localities of Potassic Igneous Rocks from the Five Tectonic Settings.- 4.1 Roman Province (Italy): Example from a Continental Arc Setting.- 4.1.1 Introduction.- 4.1.2 Regional Geology.- 4.1.3 Mineralogy and Petrography of the Potassic Igneous Rocks.- 4.1.4 Geochemistry of the Potassic Igneous Rocks.- 4.2 Kreuzeck Mountains, Eastern Alps (Austria): Example from a Postcollisional Arc Setting.- 4.2.1 Introduction S.- 4.2.2 Regional Geology.- 4.2.3 Mineralogy and Petrography of the Lamprophyres.- 4.2.4 Geochemistry of the Lamprophyres.- 4.3 Northern Mariana Arc (West Pacific): Example from an Initial Oceanic Arc Setting.- 4.3.1 Introduction.- 4.3.2 Regional Geology.- 4.3.3 Mineralogy and Petrography of the Potassic Igneous Rocks.- 4.3.4 Geochemistry of the Potassic Igneous Rocks.- 4.4 Vanuatu (Southwest Pacific): Example from a Late Oceanic Arc Setting.- 4.4.1 Introduction.- 4.4.2 Regional Geology.- 4.4.3 Mineralogy and Petrography of the Potassic Igneous Rocks.- 4.4.4 Geochemistry of the Potassic Igneous Rocks.- 4.5 African Rift Valley (Rwanda, Uganda, Zaire): Example from a Within-Plate Setting.- 4.5.1 Introduction.- 4.5.2 Regional Geology.- 4.5.3 Mineralogy and Petrography of the Potassic Igneous Rocks.- 4.5.4 Geochemistry of the Potassic Igneous Rocks.- 5 Primary Enrichment of Precious Metals in Potassic Igneous Rocks.- 5.1 Introduction.- 5.2 Theoretical Discussion.- 5.3 Case Study: Potassic Alkaline Lamprophyres with Elevated Gold Concentrations from the Karinya Syncline, South Australia.- 5.3.1 Introduction.- 5.3.2 Regional Geology and Tectonic Setting.- 5.3.3 Mineralization in the Vicinity of the Lamprophyres.- 5.3.4 Nature of the Lamprophyres.- 5.3.5 Petrology and Geochemistry of the Lamprophyres.- 5.3.6 Precious Metal Abundance and Significance.- 5.4 Comparison of Precious Metal Abundances for Lamprophyres from the Karinya Syncline and Kreuzeck Mountains.- 6 Direct Associations Between Potassic Igneous Rocks and Gold-Copper Deposits.- 6.1 Direct Associations in Specific Tectonic Settings: Introduction.- 6.2 Erection of Database GOLD 1.- 6.3 Late Oceanic Arc Associations.- 6.3.1 Ladolam Gold Deposit, Lihir Island, Papua New Guinea.- 6.3.2 Emperor Gold Deposit, Viti Levu, Fiji.- 6.3.3 Dinkidi Copper-Gold Deposit, Didipio, Phillipines.- 6.3.4 Goonumbla Copper-Gold Deposit, New South Wales, Australia.- 6.4 Continental Arc Associations.- 6.4.1 Bajo de la Alumbrera Copper-Gold Deposit, Catamarca Province, Argentina.- 6.4.2 Bingham Copper Deposit, Utah, USA.- 6.4.3 El Indio Gold Deposit, Chile.- 6.4.4 Twin Buttes Copper Deposit, Arizona, USA.- 6.5 Postcollisional Arc Associations.- 6.5.1 Grasberg Copper-Gold Deposit, Indonesia.- 6.5.2 Misima Gold Deposit, Misima Island, Papua New Guinea.- 6.5.3 Porgera Gold Deposit, Papua New Guinea.- 6.6 Synthesis of Direct Genetic Associations.- 7 Indirect Associations Between Lamprophyres and Gold-Copper Deposits.- 7.1 Introduction.- 7.2 Shoshonitic Lamprophyres with Elevated Gold Concentrations from the Goodall Gold Deposit, Northern Territory, Australia (Proterozoic).- 7.2.1 Introduction.- 7.2.2 Regional Geology.- 7.2.3 Nature of Mesothermal Gold Mineralization.- 7.2.4 Mineralogy of the Lamprophyres.- 7.2.5 Geochemistry of the Lamprophyres.- 7.2.6 Direct or Indirect Link Between Potassic Lamprophyres and Mineralization.- 7.3 Shoshonitic Lamprophyres from the Tom's Gully Gold Deposit, Northern Territory, Australia (Proterozoic).- 7.3.1 Introduction.- 7.3.2 Regional Geology.- 7.3.3 Nature of Mesothermal Gold Mineralization.- 7.3.4 Petrology and Geochemistry of the Lamprophyres.- 7.3.5 Indirect Link Between Lamprophyres and Gold Mineralization.- 7.4 Shoshonitic Lamprophyres from the Eastern Goldfields, Yilgarn Block, Western Australia (Archaean).- 7.4.1 Introduction.- 7.4.2 Regional Geology.- 7.4.3 Nature of Mesothermal Gold Mineralization.- 7.4.4 Lamprophyres and Their Association with Mineralization.- 7.4.5 Petrology and Geochemistry of the Lamprophyres.- 7.5 Shoshonitic Lamprophyres from the Superior Province, Canada (Archaean).- 7.5.1 Introduction.- 7.5.2 Nature of Mesothermal Gold Mineralization.- 7.5.3 Lamprophyres and Their Association with Mineralization.- 7.5.4 Petrology and Geochemistry of the Lamprophyres.- 7.6 Indirect Link Between Lamprophyres and Archaean Gold Mineralization.- 7.7 Synthesis of Indirect Associations.- 8 Halogen Contents of Mineralized Versus Unmineralized Potassic Igneous Rocks.- 8.1 Introduction.- 8.2 Erection of Database MICA1.- 8.3 Discussion.- 8.3.1 Behaviour of Halogens in Magmatic Hydrothermal Systems.- 8.3.2 Halogen Contents of Mica in Potassic Igneous Rocks.- 8.3.3 Significance of Halogen Data.- 9 Implications for Mineral Exploration.- 9.1 Introduction.- 9.2 Area Selection.- 9.2.1 Composition of Host Rocks.- 9.2.2 Tectonic Setting.- 9.3 Prospect Evaluation.- 9.3.1 Favourable Tectonic Elements on the Prospect Scale.- 9.3.2 High Oxidation State of the Magmas.- 9.3.3 Elevated Halogen Contents of the Magmas.- 10 Characteristics of Some Gold-Copper Deposits Associated with Potassic Igneous Rocks.- 10.1 Abbreviations.- 10.2 Tables of Deposit Characteristics.- 10.2.1 Andacollo, Chile.- 10.2.2 Bajo de la Alumbrera, Catamarca Province, Argentina.- 10.2.3 Bingham, Utah, USA.- 10.2.4 Cadia, New South Wales, Australia.- 10.2.5 Choquelimpie, Chile.- 10.2.6 Cripple Creek, Colorado, USA.- 10.2.7 Dinkidi, Didipio, Philippines.- 10.2.8 El Indio, Chile.- 10.2.9 Emperor, Viti Levu, Fiji.- 10.2.10 Goonumbla, New South Wales, Australia.- 10.2.11 Grasberg, Indonesia.- 10.2.12 Kirkland Lake, Superior Province, Canada.- 10.2.13 Ladolam, Lihir Island, Papua New Guinea.- 10.2.14 Maricunga Belt, Chile.- 10.2.15 Misima, Misima Island, Papua New Guinea.- 10.2.16 Mount Kare, Papua New Guinea.- 10.2.17 Mount Morgans, Eastern Goldfields, Western Australia.- 10.2.18 Ok Tedi, Papua New Guinea.- 10.2.19 Porgera, Papua New Guinea.- 10.2.20 Summitville, Colorado, USA.- 10.2.21 Tom's Gully, Northern Territory, Australia.- 10.2.22 Twin Buttes, Arizona, USA.- 10.2.23 Wiluna, Eastern Goldfields, Western Australia.- 10.2.24 Woodlark Island, Papua New Guinea.- References.

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