Provenance and paleogeography of post-Middle Ordovician, pre-Devonian sedimentary basins on the Gander composite terrane, eastern and east-central Maine: implications for Silurian tectonics in the northern Appalachians

Recent mapping in eastern and east-central Maine addresses long-standing regional correlation issues and permits reconstruction of post-Middle Ordovician, pre-Devonian paleogeography of sedimentary basins on the Ganderian composite terrane. Two major Late Ordovician-Silurian depocenters are recognized in eastern Maine and western New Brunswick separated by an emergent Miramichi terrane: the Fredericton trough to the southeast and a single basin comprising the Central Maine and Aroostook-Matapedia sequences to the northwest. This Central Maine/Aroostook-Matapedia (CMAM) basin received sediment from both the Miramichi highland to the east and highlands and islands to the west, including the pre-Late Ordovician Boundary Mountains, Munsungun-Pennington, and Weeksboro-Lunksoos terranes. Lithofacies in the Fredericton trough are truncated and telescoped by faulting along its flanks but suggest a similar basin that received sediment from highlands to the west (Miramichi) and east (St. Croix).Deposition ended in the Fredericton trough following burial and deformation in the Late Silurian, but continued in the CMAM basin until Early Devonian Acadian folding. A westward-migrating Acadian orogenic wedge provided a single eastern source of sediment for the composite CMAM basin after the Salinic/Early Acadian event, replacing the earlier, more local sources. The CMAM, Fredericton, and Connecticut Valley-Gaspé depocenters were active immediately following the Taconian orogeny and probably formed during extension related to post-Taconian plate adjustments. These basins thus predate Acadian foreland sedimentation.Structural analysis and seismic reflection profiles indicate a greater degree of post-depositional crustal shortening than previously interpreted. Late Acadian and post-Acadian strike-slip faulting on the Norumbega and Central Maine Boundary fault systems distorted basin geometries but did not disturb paleogeographic components drastically

Lawson criterion for ignition exceeded in an inertial fusion experiment

For more than half a century, researchers around the world have been engaged in attempts to achieve fusion ignition as a proof of principle of various fusion concepts. Following the Lawson criterion, an ignited plasma is one where the fusion heating power is high enough to overcome all the physical processes that cool the fusion plasma, creating a positive thermodynamic feedback loop with rapidly increasing temperature. In inertially confined fusion, ignition is a state where the fusion plasma can begin "burn propagation" into surrounding cold fuel, enabling the possibility of high energy gain. While "scientific breakeven" (i.e., unity target gain) has not yet been achieved (here target gain is 0.72, 1.37 MJ of fusion for 1.92 MJ of laser energy), this Letter reports the first controlled fusion experiment, using laser indirect drive, on the National Ignition Facility to produce capsule gain (here 5.8) and reach ignition by nine different formulations of the Lawson criterion

Earthquakes in Maine

Maine Geological Survey. Map of Maine showing all earthquakes since 1814 for which magnitudes were measured or have been estimated. Also includes discussion of Maine\u27s earthquake history, what happens during an earthquake, regional seismicity, and causes and risks of Maine earthquakes.https://digitalmaine.com/mgs_maps/1018/thumbnail.jp

Historical Bedrock Maps of Maine, Part I: The Hitchcock (1885) Map

Maine Geological Survey, Geologic Facts and Localities, Circular GFL-85https://digitalmaine.com/mgs_publications/1376/thumbnail.jp

The Big Eddy of the Kennebec, Skowhegan, ME

Maine Geological Survey, Geologic Facts and Localities, Circular GFL-197https://digitalmaine.com/mgs_publications/1488/thumbnail.jp

Beach pebbles

Brimstone Islandhttps://digitalmaine.com/mgs_geologic_field_photos/9561/thumbnail.jp

Portland Head Light, Cape Elizabeth, Maine

Maine Geological Survey, Geologic Facts and Localities, Circular GFL-6.https://digitalmaine.com/mgs_publications/1297/thumbnail.jp

Long glacial groove, Bald Mountain summit

Prominent gouge at the summit of Bald Mountain, one of many glacial grooves heading 161 degrees. Glacially sculpted and smoothed summit. Owls Head in the distance. Rock is gray migmatitic schist of Megunticook Formation. Prominent fracture trends 104 degrees. Project Name: Bald Mountain, Camdenhttps://digitalmaine.com/mgs_geologic_field_photos/9503/thumbnail.jp

Beach pebbles

Brimstone Islandhttps://digitalmaine.com/mgs_geologic_field_photos/9557/thumbnail.jp

Sillimanite schist, Megunticook Formation

Sheaves of coarse-grained prismatic sillimanite in quartz-muscovite-garnet schist. At inside of sharp left curve in trail. Project Name: Bald Mountain, Camdenhttps://digitalmaine.com/mgs_geologic_field_photos/9494/thumbnail.jp