Abstract MVT mineralization in the Appalachian orogen is concentrated in four major paleo aquifers of Lower Cambrian, Lower Ordovician, Lower Silurian and Mississippian age. Deposits are most numerous in the four major embayments along the trend of the orogen in which sediment thickness is greatest, and the nature and continuity of paleoaquifers differs from embayment to embayment. Oil and gas production comes largely from Devonian and younger units to the west of most MVT mineralization. Fluid inclusion homogenization and freezing data, along with Na-Cl-Br leachate, δ 18 O-δD, lead and sulfur isotope compositions, permit delineation of ten Appalachian MVT brine provinces. Only one province, in the foreland basin sediments of the Quebec embayment, is thought to have formed in Taconic (Ordovician) time. Two provinces in the Lower Ordovician paleoaquifer, including the East Tennessee ore field in the Tennessee embayment and the Newfoundland Zinc deposits in the Newfoundland embayment, formed in Acadian (Devonian) time. One province in the Mississippian Windsor paleoaquifer of the Quebec embayment formed in Alleghanian time and another, in the Lower Cambrian paleoaquifer of the Tennessee and Pennsylvania embayments, could have formed at this time. Finally, at least part of one brine province in the Lower Silurian paleoaquifer at Shawangunk in the Pennsylvania embayment probably formed in Jurassic time. These relations confirm that MVT deposits have formed throughout the history of the Appalachian orogen and in response to most of the important orogenic events. Largest MVT districts are found in the most extensive and continuous paleoaquifers, confirming that large amounts of fluid are required to form large deposits. Ore precipitation in the large deposits appears to have taken place in response to mixing of metal-bearing brines with sulfur from a separate reservoir, most of which underwent reduction outside the area of ore deposition.

Prior to about 1963 it was generally accepted that northern New England and adjacent Canada were progressively deglaciated from southeast to northwest during Late Pleistocene time. R. Chalmers and E. Antevs thought differently, but their views were not seriously considered, although their models were basically correct as we understand the deglaciation pattern today. Since about 1963 abundant evidence has accumulated that demonstrates that the Laurentide Ice Sheet was partitioned by a marine calving embayment that advanced up the St. Lawrence Lowland to the Ottawa area at least by 12,800 years B.P. This event left ice sheet remnants over much of Maine, southeastern Quebec, and probably in New Brunswick and western New England as well. Continuing research is needed to delineate the details of the final deglaciation in southeastern Quebec and Maine. Data presently available suggests that the Longfellow, White, and Boundary Mountains emerged as nunataks as early as 15,000 years ago, separating the ice sheet to the north and south. The Frontier Moraine, located on the divide between Quebec and Maine, formed at that time. Subsequently, other moraines formed as the margin of the ice sheet receded northwestward into the St. Lawrence Lowland of Quebec.