Lamprophyres

1 What are Lamprophyres? - History, Definitions, Classification.- 1.1 A brief history of lamprophyre research.- 1.1.1 The 19th and early 20th centuries: lamprophyres are characterized.- 1.1.2 1940-1960: the wilderness period.- 1.1.3 The late 1960s to the present: lamprophyres come of age.- 1.2 Classification and nomenclature: the Lamprophyre Clan.- 1.3 In defence of the Lamprophyre Clan.- 1.3.1 Further arguments for including lamproites within the lamprophyre clan.- 1.3.2 A brief note on lamproite nomenclature.- 1.3.3 Further arguments for including kimberlites within the lamprophyre clan.- 1.4 Summary of criteria for identifying lamprophyres as a clan.- 1.4.1 Mineral assemblage.- 1.4.2 Texture.- 1.4.3 Mode of occurrence.- 1.4.4 Whole-rock composition.- 1.4.5 Tectono-magmatic association.- 1.4.6 Miscellaneous features.- 1.5 Identification and nomenclature of closely related rock-types.- 1.5.1 Volatile-poor lamprophyre relatives.- 1.5.2 Ultramafic (cumulate) and felsic (differentiated) lamprophyre relatives.- 1.5.3 Plutonic and volcanic lamprophyre equivalents.- 1.6 Distinctions between some petrographically similar rock-types.- 1.6.1 Coexisting lamprophyres from different branches.- 1.6.2 Calc-alkaline lamprophyres versus shoshonites and common calc-alkaline rocks.- 1.6.3 Ultramafic lamprophyres versus melilitites and related rocks.- 1.6.4 Ultramafic lamprophyres versus leucite-bearing ultramafic rocks.- 1.6.5 Alnoites versus aillikites and carbonatites.- 1.6.6 Ultramafic lamprophyres versus Group II kimberlites.- 1.7 Genetic connotations for lamprophyre names: are they reasonable?.- 1.8 A new definition of the term 'lamprophyre'.- 2 When and Where? - Global Distribution, Igneous Associations.- 2.1 A preliminary caveat: metamorphism and lamprophyres.- 2.2 A compilation of worldwide lamprophyre occurrences.- 2.3 Global distribution and abundance of lamprophyres.- 2.3.1 Overall distribution through geological time.- 2.3.2 Overall volumetric abundance.- 2.3.3 Geographical distribution.- 2.4 Tectono-magmatic associations.- 2.4.1 Association A: with calc-alkaline granitoid plutons.- 2.4.2 Association B: with shoshonitic suites.- 2.4.3 Association C: with appinite-breccia pipe-complexes.- 2.4.4 Inter-relationships between Associations A, B and C.- 2.4.5 Association L: lamprophyres with each other alone.- 2.4.6 Association M (mildy alkaline): with alkaline syenite-gabbro plutons.- 2.4.7 Association R: regional lamprophyric magmatism unrelated to other igneous activity.- 2.4.8 Association S (strongly alkaline): with carbonatite-ijolite-nephelinite complexes.- 2.4.9 Some spurious or equivocal associations.- 2.5 Repeated lamprophyre injection in one area over geological time.- 3 Field Geology and Petrography - Macroscopy and Microscopy.- 3.1 Field geology of lamprophyres: diagnostic forms of occurrence.- 3.1.1 Small-scale characteristics of lamprophyre intrusions.- 3.1.2 Composite intrusions of lamprophyres with felsic rock-types.- 3.1.3 Differentiated lamprophyre intrusions.- 3.1.4 Contact metamorphism and metasomatism around lamprophyre intrusions.- 3.1.5 Larger-scale groupings of lamprophyre intrusions.- 3.1.6 Inferred intrusion mechanisms.- 3.1.7 Volcanic lamprophyres: lavas, pyroclastics and tuffs.- 3.2 Petrographical (thin section) characteristics of lamprophyres.- 3.2.1 Modal composition and paragenetic sequence.- 3.2.2 Lamprophyric (panidiomorphic) and related textures.- 3.2.3 Autometasomatic alteration.- 3.2.4 Globular structures.- 3.2.5 Autoliths, lapilli, pellets and related structures.- 4 Cognate Mineralogy.- 4.1 Mineralogical features diagnostic of the whole lamprophyre clan.- 4.2 Minerals and parageneses diagnostic of each lamprophyre branch.- 4.3 Olivines.- 4.4 Monticellites.- 4.5 Garnets.- 4.6 Clinopyroxenes.- 4.7 Amphiboles.- 4.8 Biotite-phlogopites.- 4.9 Feldspars.- 4.9.1 Plagioclases.- 4.9.2 Na-K-Ba feldspars.- 4.9.3 A further note on feldspar assemblages and structural states.- 4.10 Feldspathoids.- 4.10.1 Analcimes.- 4.10.2 Nephelines, cancrinites and sodalite group minerals.- 4.10.3 Leucites.- 4.11 Melilites.- 4.12 Carbonates.- 4.13 Spinels.- 4.14 Ilmenites.- 4.15 Perovskites.- 4.16 Other oxides and sulphides.- 4.17 Miscellaneous primary minerals.- 4.18 Secondary minerals.- 4.19 Glass.- 5 Whole-rock Geochemistry.- 5.1 Major and minor oxides.- 5.1.1 Discrimination between the 5 lamprophyre branches based on major elements.- 5.1.2 Overlap between branches: the effects of accumulation, fractionation and alteration.- 5.1.3 Discrimination between aillikites and kimberlites based on major oxides.- 5.2 CIPW normative composition.- 5.3 Trace elements.- 5.4 Rare-earth elements (REE).- 5.5 Precious metals (PGE, Au).- 5.6 Radiogenic isotopes.- 5.7 Stable isotopes.- 6 Inclusion Suites - Macrocrysts, Xenocrysts, Xenoliths, etc.- 6.1 Type B (largely cognate): inclusions derived from host melt at high-P.- 6.2 Type C (semi-cognate): inclusions derived from evolved melt.- 6.3 Type D (partly cognate): inclusions derived for related melts.- 6.4 Type E (related or foreign): mantle-type mafic-ultramafic inclusions.- 6.5 Type F: True xenocrysts and xenoliths of unrelated crustal rocks.- 6.6 The discrete nodule (macrocryst, megacryst) suite.- 6.6.1 Megacrysts of one mafic mineral.- 6.6.2 "Megacrystalline rocks" and intergrowths of two or more mafic minerals.- 6.6.3 Feldspar megacrysts and feldspar intergrowths.- 6.7 Abundance of different inclusion types in different lamprophyres.- 6.8 P-T significance of inclusion suites.- 7 Plutonic and Volcanic Equivalents of Lamprophyres.- 7.1 Plutonic and volcanic equivalents of calc-alkaline lamprophyres.- 7.1.1 The appinite suite: plutonic spessartites and vogesites.- 7.1.2 The vaugnerite series: plutonic minettes and kersantites.- 7.1.3 Calc-alkaline lamprophyres versus plutonic and volcanic shoshonitic rocks.- 7.1.4 Calc-alkaline lamprophyres versus volcanic boninites.- 7.1.5 Minettes versus volcanic olivine-leucitites (ugandites).- 7.1.6 Minettes versus volcanic selagites.- 7.2 Plutonic and volcanic equivalents of alkaline lamprophyres.- 7.3 Plutonic and volcanic equivalents of ultramafic lamprophyres.- 7.3.1 Ultramafic lamprophyres versus volcanic melilitites.- 7.3.2 Ultramafic lamprophyres versus plutonic melilitolites.- 7.3.3 Ultramafic lamprophyres versus volcanic meimechites.- 7.3.4 Ultramafic lamprophyres versus volcanic ankaratrites.- 7.3.5 Ultramafic lamprophyres versus volcanic katungites.- 8 Nature, Origin and Evolution of Lamprophyre Melts.- 8.1 Do 'lamprophyre magmas' exist?.- 8.2 How many distinct lamprophyre magma-types are there?.- 8.2.1 Calc-alkaline lamprophyres.- 8.2.2 Alkaline lamprophyres.- 8.2.3 Ultramafic lamprophyres.- 8.2.4 Kimberlites.- 8.2.5 Lamproites.- 8.2.6 Seven lamprophyre magma-types.- 8.3 What parameters can we use to deduce lamprophyres' origins?.- 8.3.1 Indications of primary magmatic status from whole-rock geochemistry.- 8.3.2 High LILE and HFSE enrichments.- 8.3.3 Coupled negative Ta-Nb-Ti (TNT) anomalies.- 8.3.4 Radiogenic isotopes - crust v. mantle, contamination v. metasomatism.- 8.3.5 Experimental petrology.- 8.3.6 Mantle-type inclusions.- 8.3.7 Oceanic versus continental settings.- 8.3.8 Lamprophyre mineral assemblages - what do they represent?.- 8.4 Petrogenesis of individual lamprophyre magma-types.- 8.4.1 M1 magma-type (AL/UML): volatile-enriched alkali basaltic to melilititic melts?.- 8.4.2 M2 magma-type (UML): primary carbonatite affiliates?.- 8.4.3 M3 and M4 magma-types (KIL and olivine-lamproites): deep mantle melts?.- 8.4.4 M5 magma-type (LL): multi-reservoir, multi-stage mantle melts?.- 8.4.5 M6 magma-type (Navajo minettes, etc.): slightly contaminated mantle melts?.- 8.4.6 M7 magma-type (CAL): heavily contaminated mantle melts?.- 8.5 Evolution (differentiation) of lamprophyre melts.- 8.5.1 Evidence of evolution within single lamprophyre bodies.- 8.5.2 Evidence of evolution within regional dyke-suites.- 8.5.3 Role of liquid immiscibility in the evolution of lamprophyre melts.- 8.6 Lamprophyres as parental melts to other igneous rock-suites.- 8.6.1 M7 (CAL) magma-type and calc-alkaline suites.- 8.6.2 M2 (AL) magma-type and alkaline gabbro-syenite plutons.- 8.6.3 M3 (UML) magma-type and carbonatite-ijolite-nephelinite complexes.- 8.7 Petrogenetic overview.- 9 Economic Geology.- 9.1 Lamprophyres and diamond.- 9.2 Calc-alkaline lamprophyres and gold.- 9.3 Lamprophyres and miscellaneous mineral deposits.- 10 A Selective Lamprophyre Bibliography.- Appendix A Abbreviations and Symbols.- Appendix B Glossary of lamprophyres and ambiguous petrological terms.- Appendix C Global Compilation of Lamprophyre Occurrences.- Table C1 Confirmed occurrences of calc-alkaline lamprophyres.- Table C2 Confirmed occurrences of alkaline lamprophyres.- Table C3 Confirmed occurrences of ultramafic lamprophyres.- Table C4 Confirmed occurrences of lamproites.- Table C5 Additional documentation for the appinite suite and vaugnerite series.- Table C6 Confirmed mixed or transitional occurrences (covering two or more branches).- Table C7 Unconfirmed occurrences of "lamprophyres".- Table C8 Apocryphal occurrences of "lamprophyres".- Appendix D The computerized lamprophyre database LAMPDA.