Stratigraphy and Structure of West-Central Vermont

Abstract

Introduction Acknowledgments • 517 Previous work 519 Stratigraphy • 524 The present classification Lower Cambrian series General correlation Formations Distribution and genetic relations Upper Cambrian series 53,4 General correlation Formations Distribution and genetic relations Ordovician-Beekmantown "group" General correlation Formations Distribution and genetic relations Ordovician-Chazy group General correlation Formations , Distribution and genetic relations Ordovician-Black River group General correlation and Uthology Distribution and genetic relations Ordovician-Trenton group General correlation Formations Distribution and genetic relations Succeeding groups Structural geology Major structures General setting 562 Synclinoria Anticlinoria Thrust faults '. 564 Normal fault system 570 Lesser structures 572 General relations Detailed description 572 Summary statement 575 Structural details 575 General scope 575 515 516 W. M. CADY-STRATIGRAPHY AND STRUCTURE OF WEST-CENTRAL VERMONT Foliation 575 Flow structure 575 Flexures 576 Ruptures 576 Mechanism of deformation 577 Diastrophic relations General statement 579 Taconic Allochthone 579 Foreland thrusts and associated folds 580 Adirondack normal faults 580 References cited 581 ILLUSTRATIONS Figure Page 1. Geographic location of west-central Vermont 518 2. Wing's manuscript sketch map, and cross sections of Middlebury synclinorium 520 3. Stratigraphic correlation of west-central Vermont and adjoining areas 522 4. Columnar sections of strata in west-central Vermont 527 5. Regional geologic map 563 6. Palinspastic map of the region of western New England, eastern New York, and southern Quebec 568 Plate Facing page 1. Major topographic features 515 2. Lower Cambrian strata 526 3. Upper Cambrian and Beekmantown strata 527 4. Chazy strata 548 5. Trenton strata 549 6. Major structures 562 7. Cleavage-bedding relations 563 8. Flow structure 576 9. Folds 577 10. Areal geology and structure of west-central Vermont ;.. In pocket ABSTRACT The lithologic units recognizable in the fossiliferous succession along southern Lake Champlain are structurally continuous with and traceable eastward into the "marble belt" of west-central Vermont immediately west of the Green Mountain Front. They are also traceable northward through west-central Vermont into a succession in northwestern Vermont bounded on the east and west by major thrusts, where they pass laterally northeastward into fossiliferous shales, the faunal zones of which are correlated with those along southern Lake Champlain and in the Hudson and Mohawk valleys. The Cambrian strata are traced into west-central from northwestern Vermont whereas the Ordovician correlation is with rocks in the Mohawk-Hudson-Champlain region. Certain of the Upper Cambrian strata can be correlated with established formations of this age in both of the outlying areas. The structural pattern reflects movements dependent upon the original distribution of sedimentary facies. Interbedded Carnbro-Ordovician limestones and dolomites grade westward into fo...

Geologic, geochemical, and isotopic studies of a carbonate- and siliciclastic-hosted Pb-Zn deposit at Lion Hill, Vermont

“…Metasedimentary rocks in the vicinity of Lion Hill contain chlorite, epidote, and, locally, rare, pale-green to green-brown biotite (Cady, 1945;Clark, 1990), indicating greenschist facies conditions. Pyrophyllite is not present in the pelitic rocks (Zen, 1960), and the limestones and dolomites do not contain talc, wollastonite, graphite, or other minerals that form by decarbonation reactions; the dolomites show only minor recrystallization.…”

“…Textures of the mineralized rocks can be grouped into four types: metamorphic segregations, intergranular fillings, layered sui-~ Cady (1945), New Jersey Zinc Company (unpub. data, 1952-54), Labradex Corporation (unpub.…”

“…Dur-ing Middle Ordovician time, prior to Taconic thrusting and deformation, at least 1,000 m of sedimentary rock overlay the Monkton Quartzite in the vicinity of Lion Hill (Cady, 1945). Medium-pressure regional metamorphic environments generate lithostatic pressures of about 2-4 kbar at temperatures of around 400°C.…”

“…1 ). Lower Cambrian Monkton Quartzite (Cady, 1945) is the host for the largest stratabound Zn-Pb-Cu sulfide zones found at Lion Hill, 3-4 km north of the town of Brandon, Vt., (fig. 1); lesser amounts of base-metal sulfide minerals occur in Winooski Dolomite.…”

Petrology and geochemistry of selected talc-bearing ultramafic rocks and adjacent country rocks in north-central Vermont

“…Geologic maps of the Montpelier and Hyde Park quadrangles, embracing much of the Waterbury-Waitsfield and nearby areas, have recently been published (Cady, 1956;Albee, 1957). Plate 2, a sketch map of the area based upon those publications and upon U.S. Geological Survey studies in progress, shows the distribution of formations, metamorphic zones, and chief structural features.…”