+ Resolve Article
+ Follow Us
Follow on FacebookFollow on Facebook
Follow on TwitterFollow on Twitter

+ Translate
+ Subscribe to Site Feed
GeoScience Most Shared ContentMost Shared Content

Mineralogy and mineral chemistry of shear zone-hosted iron deposits from the western Hudson Highlands, NY

, : Mineralogy and mineral chemistry of shear zone-hosted iron deposits from the western Hudson Highlands, NY. Abstracts with Programs - Geological Society of America 36(5): 354

The Proterozoic iron deposits from the western Hudson Highlands, NY are hosted by late Grenville dextral strike-slip shear-zones within a sequence of metasedimentary, metaigneous and quartzofeldspathic gneiss. The shear-zones became dilatational during the terminal phase of activity and were infiltrated by hot, chemically complex fluids that selectively leached iron and other species out from a pre-Grenville Fe-rich protolith and deposited magnetite ore and gangue minerals as concordant/slightly discordant, tabular and lensoidal vein-like bodies within the faults. Dikes of basalt, camptonite and rhyolite cross cut the country rocks, shear-zones and iron ore. Two general mineral sequences were identified within these zones: 1) Oxide sequence associated with amphibolites, calc-silicate and quartzofeldspathic gneiss carrying magnetite (no martite) with spinel (spinel, hercynite, ulvospinel) exsolutions, as granulite facies features, ilmenite, diopside, augite, enstatite, ferrosilite, olivine of hortonolite-hyalosiderite composition (Fo 43 to 61), and almandine (Alm70) + or - calcite or quartz in varying proportions depending upon host rock composition and 2) Sulfide sequence crosscutting the magnetite ore, with pyrrhotite (later replaced by marcasite), chalcopyrite, + or - molybdenite, cobaltite, skutterudite, pentlandite, accompanied by K-Cl and/or F rich amphiboles (ferro-edenite, hastingsite, magnesiohastingsite, pargasite, potassicpargasite, K dominant hastingsite, K and F dominant hastingsite, F dominant tremolite), phlogopite, F dominant phlogopite and marialitic scapolite (Cl up to 0.49% and SO3 up to 1.24%). The K (up to 3.2%) and Cl (up to 3.66%)/F (up to 2.26%) rich amphiboles indicate positive relationship for AK and IVAl versus Cl and a negative one for A[1-(Na+K)] versus Cl. Calculated Fe3+/Fe2+ ratio and mineral composition suggest a crystallization under conditions of relatively low f(O2). The source of both Cl and F is not clear, but the best match is a high salinity, crustal brine. Very coarse-grained pegmatites are primarily around the ore bodies, encapsulate or cross them and contain xenoliths of ore material. They are REE (monazite, allanite)--U (uraninite) alkali-feldspar pegmatites with augite and/or hastingsite and magnesiohastingsite.


Other references

Maniglia, Anthony J., 1993: Symposium on Sleep Apnea and Snoring, Cleveland, Ohio, USA, October 15-16, 1992. Ear Nose & Throat Journal 72(1): 16-90

Haikola, S.; Fortelius, W.; O'hara, R., B.; Kuussaari, M.; Wahlberg, N.; Saccheri, I., J.; Singer, M., C.; Hanski, I., 2001: Inbreeding depression and the maintenance of genetic load in Melitaea cinxia metapopulations. The effects of inbreeding on fitness and the maintenance of genetic load in metapopulations of the endangered Glanville fritillary butterfly (Melitaea cinxia) were examined in four laboratory experiments. In Finland M. cinxia occurs as a large met...

Reitherman, R.W., 1992: Standing up to cancer's challenge. Radiologic Technology 64(2): 109-110

Green, A.L.; Wang, S.; Owen, S.L.F.; Xie, K.; Liu, X.; Paterson, D.J.; Stein, J.F.; Bain, P.G.; Aziz, T.Z., 2005: Deep brain stimulation can regulate arterial blood pressure in awake humans. The periaqueductal grey matter is known to play a role in cardiovascular control in animals. Cardiovascular responses to electrical stimulation of the periventricular/periaqueductal grey matter were measured in 15 awake human study participants fo...

Parker, L.M., 1983: Leukemia after treatment of ovarian cancer with alkylating agents. New England Journal of Medicine 308(23): 1422-1422

Fryczkowski, A.W., 1988: Angioarchitecture of the choroid. IV. The equatorial region. Klinika Oczna 90(2): 46-50

Loreti, F.; Natali, S., 1975: Comparative studies on certain quince rootstocks for pears. Results of 9-year studies on the growth and yield of pears, cv. Coscia, grafted on Quince A, B and F, Lepage B and W, and common quince rootstocks, and trained as palmettes are reported. Lepage B induced least growth and fruit production and Quinc...

Olson, M.S.; Von Korff, R.W., 1967: The effect of depletion of endogenous substrates on the metabolic behavior of isolated rabbit heart mitochondria. Changes in the State 3 respiratory rate and the respiratory control ratio of isolated rabbit heart mitochondria with the use of pyruvate as the substrate parallel changes in, and depletion of, the endogenous substrates. The endogenous substrates o...

Mendoza Wilson, A.; Siller, J.; Bringas, E.; Ojeda, J.; Baez, J.M.; Baez Sanudo, R., 1995: Cuticle differences during ripening of normal and rin tomato fruits. Hortscience 30(4): 825

Wei, H.; Wu, B.; Yang, W.; Luo, T., 2011: Low rainfall-induced shift in leaf trait relationship within species along a semi-arid sandy land transect in northern China. It is unclear whether the shift in leaf traits between species of high- and low-rainfall sites is caused by low rainfall or by species replacement, because leaf traits vary substantially among species and sites. Our objective was to test if the wi...