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| Chesapeake igneous province | |
|---|---|
| Name | Chesapeake igneous province |
| Type | Large igneous province |
| Location | Mid-Atlantic margin, United States |
| Coordinates | 37°N 76°W |
| Period | Paleocene–Eocene |
| Area | ~150,000 km² (onshore & offshore) |
| Main lithology | Basalt, gabbro, diabase, tephra |
| Named for | Chesapeake Bay region |
Chesapeake igneous province
The Chesapeake igneous province is a Paleocene–Eocene large igneous province associated with extensive intrusions and extrusive magmatism along the Mid-Atlantic margin of the United States. It includes submerged seaward structures, onshore sills and dikes, and submarine volcanic deposits linked to continental rifting and plume-related magmatism during the opening of the North Atlantic. The province has been studied in the contexts of stratigraphy, petroleum geology, paleoclimate, and tectonics by researchers from institutions such as United States Geological Survey, Woods Hole Oceanographic Institution, and Virginia Tech.
The province comprises a network of tholeiitic basaltic sills, dikes, volcanic vents, and intrusive complexes exposed in boreholes, outcrops, and seismic profiles across the coastal plain of Virginia, Maryland, Delaware, and adjacent offshore areas near the Jacksonville Basin and Baltimore Canyon Trough. Key exposures include the Cretaceous–Paleogene sections intersected by the Exmore Formation and deep boreholes like the Chesapeake Bay impact crater-associated drill cores and continental shelf wells tied to the Atlantic Coastal Plain. The distribution of magmatism correlates with regional structures such as the Newark Basin trend and the Appalachian foreland.
Magmatism is dominantly tholeiitic basalt with layered gabbroic bodies and doleritic diabase intrusions occurring as sills and dikes penetrating Paleozoic through Cenozoic strata, including the Potomac Formation and Severn Formation. Petrography shows olivine, clinopyroxene, and plagioclase phenocrysts typical of continental flood basalts described in other provinces like the Deccan Traps and Paraná Basin. Geophysical mapping using seismic reflection and gravity surveys by teams from Lamont–Doherty Earth Observatory and NOAA delineated intrusive geometries and relationships to the Chesapeake Bay impact crater and shelf basalts sampled during expeditions by the RV Knorr and drilling programs associated with Ocean Drilling Program and IODP planning.
Radiometric ages from K–Ar, Ar–Ar, and U–Pb analyses conducted by laboratories at Massachusetts Institute of Technology, USGS, and Smithsonian Institution constrain emplacement primarily to the latest Paleocene and early Eocene, roughly 62–54 Ma, overlapping with the Paleocene–Eocene Thermal Maximum recorded at sites such as Sewell Point and St. Croix Island (U.S.). Correlations have been drawn to seafloor spreading anomalies identified near the Mid-Atlantic Ridge and to continental magmatic pulses related to the North Atlantic Igneous Province. High-resolution stratigraphic ties use biostratigraphy from planktonic foraminifera studies at Yale University and magnetostratigraphy from cores curated at Smithsonian National Museum of Natural History.
Geochemical signatures, including trace elements and isotope ratios (Sr–Nd–Pb), analyzed by researchers at Scripps Institution of Oceanography and Purdue University indicate melting of an enriched mantle source with contributions from lithospheric mantle and possible plume components analogous to models for the Iceland plume. Petrogenetic models invoke low-degree partial melting of a metasomatized subcontinental lithospheric mantle, fractional crystallization, and crustal assimilation documented in studies led by University of California, Berkeley and University of North Carolina at Chapel Hill. Melt generation has been tied to lithospheric thinning and mantle upwelling documented in plate reconstructions by Harvard University geodynamicists.
Emplacement coincides with regional extension related to the opening of the North Atlantic and is spatially associated with transtensional basins such as the Southeast Georgia Embayment and structural elements like the Fall Zone. Thermal effects of sill intrusions altered organic-rich sediments in the Tertiary record, impacting hydrocarbon maturation in play areas studied by ExxonMobil geoscientists and state geological surveys. Volcanic degassing and emplacement timing overlap with recognized climate perturbations including the Paleocene–Eocene Thermal Maximum, prompting interdisciplinary investigations by teams from National Oceanic and Atmospheric Administration and Lamont–Doherty Earth Observatory into links between large igneous provinces and short-term carbon cycle disruptions.
The province is significant for energy and mineral exploration because sill intrusions have thermally matured strata and modified reservoir properties in basins formerly explored by companies such as Chevron and BP, and mapped by state agencies like the Virginia Division of Geology and Mineral Resources. Scientifically, it serves as a natural laboratory for studying mantle processes, continental breakup, and paleoenvironmental change in investigations conducted by International Ocean Discovery Program consortia and university teams at Rutgers University and University of Maryland. Data from the province feed into broader syntheses of large igneous province impacts compiled by the International Association of Volcanology and Chemistry of the Earth's Interior.
Early recognition of onshore igneous rocks in the Mid-Atlantic was reported by investigators affiliated with United States Geological Survey and Smithsonian Institution during the mid-20th century, with systematic drilling and geophysical surveys accelerating in the 1970s and 1980s through collaborations involving National Science Foundation funding and industry partners. Landmark contributions include geochemical syntheses by groups at Scripps Institution of Oceanography and geochronological advances using Ar–Ar dating at California Institute of Technology. Recent multidisciplinary projects integrating seismic imaging by NOAA ships, drilling proposals to IODP, and isotope geochemistry by teams at Columbia University and University of Edinburgh continue to refine models of magmatism, mantle dynamics, and environmental consequences.
Category:Geology of the United States Category:Large igneous provinces