Phosphoria Formation (Permian) and Its Resource Significance in the Western Interior, U.S.A.

摘要: Abstract The Phosphoria Formation forms part of the Permian in Western Interior United States and includes phosphorite beds associated with two organic carbon-rich mudstone units. was deposited during marine transgressive-regressive cycles Sublett basin, an embayment centered northern Utah southern Idaho extending into adjacent areas broad western shelf North American craton. Westward movement plate assembly Pangean continent developed a foreland basin along its margin time that partially restricted by tectonic highlands probable island arc from open ocean farther west. Geographic conditions were favorable for upwelling currents within entrapment reduced influx terrigenous sediments land to east. configuration depositional system suggests slow subsidence deposition environment abundant biotic production. Sapropelic mud accumulated throughout but highest concentration Corg Idaho-Wyoming border Meade Peak Member Formation, southwestern Montana Retort Member. supply nutrients brought zone photosynthesis enhanced volcanic sources west as well leaching minerals rocks highly alkaline lagoonal eastern fringes basin. Solutes intensely weathered may have supplied additional nutrients. Economic resources are result winnowing left concentrated apatite lags elevated sea floor. petroleum resulted burial organic-rich depths more than 2.5 km, leading hydrocarbon generation. vanadium these beds, possibly other trace metals such silver chromium rocks.