Post-impact depositional environments as a proxy for crater morphology, Late Devonian Alamo impact, Nevada

摘要: Marine facies of carbonate and siliciclastic sediments deposited on top the upper Devonian Alamo Breccia Member identify shape size impact crater in south-central Nevada (western USA). There are 13 measured sections that record peritidal to deep-subtidal deposition across impacted platform, these correlated three regional depositional sequences above Member. Facies accommodation patterns a concave seafloor we interpret as post-impact legacy crater. Together with isopach lithostratigraphic trends underlying Member, new map is presented showing eastern outer rim fault annular trough. Size estimates were made using newly defined features linear scaling relationships from other marine-target complex craters. Revised dimensions place its transient diameter between 37 65 km, apparent 111 150 km. These more than double previous based biostratigraphy If correct, one largest marine impacts Phanerozoic, conservatively larger well-studied Eocene Chesapeake Bay