vintage 1981 merrimack publ corp railroad story book

#Vintage 1981 merrimack publ corp railroad story book series

Youngest detrital zircons in the terrane, however, are as young as the Early to Middle Ordovician. Samples from the Nashoba terrane yielded major age populations between ~560 and ~540 Ma, consistent with input from local sources formed during the Ediacaran–Cambrian Penobscot orogenic cycle and its basement rocks. U–Pb detrital zircon laser ablation inductively coupled plasma mass spectrometry analysis were conduced on six samples from the Nashoba terrane in Massachusetts and seven samples associated with the Merrimack belt in Massachusetts and SE New Hampshire to investigate their depositional ages and provenance. The fault-bounded Nashoba–Putnam terrane, a metamorphosed early Paleozoic, Ganderian arc/back-arc complex in SE New England, lies between rocks of Avalonian affinity to the southeast and middle Paleozoic sedimentary rocks, interpreted as cover on Ganderian basement, in the Merrimack belt to the northwest. 1983 Pb/ 206 Pb ages for zircon >800 Ma to be consistent with most previous U-Pb detrital zircon studies in the Appalachians. Deformation and metamorphism in the Merrimack belt resulted from Acadian, Neoacadian and/or Alleghanian events (Zen et al. , 2021Charnock 2015) and is deformed by at least four generations of folds, including large recumbent folds (Peck 1975(Peck, 1976Hepburn 1976 Robinson 1978Robinson, 1981Goldstein 1992Goldstein, 1994Goldsmith 1991b Hussey and Bothner 1993 Kopera and Walsh 2014 Kuiper et al. , 2009Fargo and Bothner 1995 Lyons et al. 1983 Zartman and Naylor 1984 Robinson and Goldsmith 1991 Wones and Goldsmith 1991 Zartman and Marvin 1991 Bothner et al.

#Vintage 1981 merrimack publ corp railroad story book series

The Merrimack belt has been intruded by a series of Silurian to Devonian granitic to dioritic plutons (Gore 1976 Zen et al. 1983 Goldsmith 1991b Robinson and Goldsmith 1991 Lyons et al. The metamorphic grade of the sedimentary rocks of the Merrimack belt in central Massachusetts varies from lower greenschist facies in the southeast to upper amphibolite facies in the northwest (Thompson and Norton 1968 Zen et al.