Large igneous province

Large igneous province
Williamborg · CC BY-SA 3.0 · source
Name	Large igneous province
Caption	Satellite image of the Deccan Traps flood basalt province
Type	Igneous province
Period	Various
Region	Global

Contents

Large igneous province Large igneous provinces are vast accumulations of igneous rock formed by high-volume volcanism over short geologic timescales, exemplified by provinces such as the Siberian Traps, Deccan Traps, and Columbia River Basalt Group. These provinces have played central roles in Earth history, interacting with events like the Permian–Triassic extinction event, the Cretaceous–Paleogene extinction event, and the paleoclimatic shifts recorded across the Paleozoic and Mesozoic. Studies of provinces link to work by institutions such as the United States Geological Survey, Geological Survey of India, and research projects at universities like Cambridge University, Stanford University, and the University of Oxford.

Definition and Characteristics

A large igneous province is defined by criteria developed in literature from groups including the International Association of Volcanology and Chemistry of the Earth's Interior and researchers at Geological Society of America, typically involving emplacement of >100,000 km2 of magmatic rock or >0.1 million km3 in a geologically brief interval, judged using stratigraphy from formations like the Deccan Traps and the Bryah Basin. Characteristic features include extensive flood basalts such as the Siberian Traps, layered intrusive complexes like the Bushveld Complex, and associated dike swarms as in the Mackenzie dike swarm. Provinces are often bounded by tectonic provinces recognized by agencies like the British Geological Survey and recorded in databases curated by the National Aeronautics and Space Administration and the International Union of Geological Sciences.

Hypotheses for province formation include mantle plume heads proposed by researchers following the plume hypothesis originally advanced by advocates studying the Hawaii hotspot and the Iceland hotspot, lithospheric extension models linked to events like the breakup of Pangaea and the rifting around the North Atlantic Ocean, and edge-driven convection tied to cratonic margins such as the Kaapvaal Craton and the Baltica margin. Geodynamic modeling from groups at MIT, ETH Zurich, and the Max Planck Institute for Chemistry integrates seismic tomography of features beneath provinces like the Siberian Traps and geochemical signatures compared to samples from expeditions by the Ocean Drilling Program and the Integrated Ocean Drilling Program.

Large igneous provinces manifest as continental flood basalt provinces (e.g., Deccan Traps, Siberian Traps, Columbia River Basalt Group), oceanic plateaus (e.g., Ontong Java Plateau, Shatsky Rise, Manihiki Plateau), and intrusive-dominant provinces such as the Gondwana-age Bushveld Complex and the Stillwater Complex. The global distribution spans cratons like the Yilgarn Craton and the Superior Province and extends to island arcs adjacent to the Kurile Islands and Aleutian Islands, with chronology tied to events like the Cretaceous Normal Superchron and the opening of the South Atlantic Ocean.

Geologically, provinces display thick sequences of mafic to ultramafic lavas, sill provinces exemplified by the Karoo-Ferrar system, and large intrusive bodies such as layered intrusions studied at the Bushveld Complex and the Stillwater Complex. Geochemical fingerprints include incompatible element enrichments, isotopic ratios of strontium and neodymium used in provenance studies by teams at Caltech and Lehigh University, and platinum-group element anomalies investigated in samples from the Siberian Traps and Deccan Traps by researchers affiliated with the Smithsonian Institution and the Natural History Museum, London.

Temporal correlations link major province eruptions to mass extinctions such as the Permian–Triassic extinction event associated with the Siberian Traps and the Cretaceous–Paleogene extinction event proximate to the Deccan Traps, with climatic consequences modeled by groups at the National Center for Atmospheric Research and the British Antarctic Survey. Volcanogenic gas release, including sulfur dioxide and carbon dioxide, affected ocean anoxia recorded in sections studied at the Geological Survey of Canada and contributed to biotic crises documented in fossil records curated by institutions like the American Museum of Natural History and the National Museum of Natural History, Paris.

Economic interest arises from metallogenic associations: the Bushveld Complex hosts major platinum and chromium resources mined by companies such as Anglo American and Impala Platinum, while layered intrusions and associated hydrothermal systems yield copper, nickel, and PGE mineralization targeted by firms listed on exchanges like the Johannesburg Stock Exchange and the New York Stock Exchange. Sedimentary basins modified by provinces, for example around the Karoo Basin and the Siberian Platform, influence hydrocarbon maturation assessed by national energy agencies including the U.S. Energy Information Administration.

Research employs field mapping by crews linked to institutions such as the British Geological Survey and Geological Survey of India, geochronology via ^40Ar/^39Ar and U–Pb zircon dating performed at laboratories at Arizona State University and the ETH Zurich, paleomagnetic studies coordinated with the European Geosciences Union, and geochemical analysis using mass spectrometers at facilities like Woods Hole Oceanographic Institution and the Lamont–Doherty Earth Observatory. Integrated approaches use seismic imaging from the USGS and plate reconstructions by research groups at Paleomap Project and the University of Chicago to place province emplacement in tectonic context.

Category:Igneous petrology Category:Volcanism