Robert W. Metsger, 2001. "Evolution of the Sterling Hill Zinc Deposit, Ogdensburg, Sussex County, New Jersey", Part I. Proterozoic Iron and Zinc Deposits of the Adirondack Mountains of New York and the New Jersey Highlands Part II. Environmental Geochemistry and Mining History of Massive Sulfide Deposits in the Vermont Copper Belt, John F. Slack, Jane M. Hammarstrom, Robert R. Seal
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Structural and textural evidence within the Mesoproterozoic Sterling Hill Zn-Fe-Mn orebody suggests that it is a metamorphosed stratiform deposit, part of a subducting assemblage that was folded and subjected to sufficiently high pressure and temperature conditions to induce viscous or pseudoviscous flow in the carbonate host rock. This resulted in a high-density ore deposit sinking as an inverted diapir through the enclosing marble.
During Phanerozoic time a possibly large part of the orebody was lost due to major faulting. The occurrence of an extensive rubble breccia body in the mine is evidence that a probable Cambro-Ordovician kars-tification event extended down into underlying Proterozoic rocks.
Most recently saprolites, as much as 240 m deep, developed within the marble/amphibolite core of the orebody and also in rocks above in the hanging wall.
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Part I. Proterozoic Iron and Zinc Deposits of the Adirondack Mountains of New York and the New Jersey Highlands Part II. Environmental Geochemistry and Mining History of Massive Sulfide Deposits in the Vermont Copper Belt
This First day of the field trip visits Proterozoic iron deposits at the Podunk and Skiff Mountain iron mines, in the eastern Adirondack Mountains of New York state. Included are roadcuts to see representative lithologies and structures in the region surrounding the iron deposits. The origin of these iron deposits has been controversial, but studies by Foose and McLelland (1995) and more recently by McLelland et al. (2001b, 2001c) provide strong evidence for a high-temperture, intramagmatic origin related to late stages the Lyon Mountain Granite and correlative intrusions during the latter part of the 1090 to 1030 Ma Ottawan orogeny. The great majority of the deposits consist of low Ti magnetite ore accompanied by apatite and aegerine-augite. The apatite has high concentrations of rare-earth elements (REE) indicating to Foose and McLelland (1995) that the deposits are of Kiruna (REE-Au-U-Cu) type. This is further supported by persistent sodic (i.e., albitic) alteration associated with the ores. Most of the iron ores appear to be undeformed although they may occur in strained host rocks. Deposits are intimately associated with late tectonic to post-tectonic Lyon Mountain Granitic Gneiss that was emplaced at ca. 1055 Ma, during the waning stages of the ca. 1090 to 1030 Ma Ottawan Orogeny.