Fluid Inclusion Analysis and Conditions of Microfracturing in the Southwestern Adirondacks

Fluid Inclusion Analysis and Conditions of Microfracturing in the Southwestern Adirondacks

John-Luke Henriquez, Dr. Gayle Gleason, and Dr. Bob DarlingGeology Department, State University of New York College at Cortland, Cortland, NY

SCOP CORELAREA INCLUZIUNILOR FLUIDE DIN MILONITE ------- ISTORIA DEFORMRII in munii ADIRONDACK cu APARIIA fisurilor

Incadrare geografica

Zona studiata NW stat NY , ru Moose

Litologie gnais granitic /granite

metamorfozate tectonic P,T mari

Milonitele (nou) sint incadrate intr-un filon pegmatitic (vechi 1100ma) prins in gnaisurile granitice (cel mai vechi)

IF din milonite provin dintr-un eveniment hidrofracturare post cristalizare filon pegmatitic

INCLUZIUNI FLUIDE = BULE DE AP I GAZ FORMATE N INTERIORUL CRISTALELOR (QUART) - PRIMARE, SECUNDARE

PRIMARE formate in geneza cuarului sau recristalizarea lui (blasteza)

SECUNDARE lichide HT cu Q dizolvat circul pe fracturi ( cazul nostru)

METODOLOGIE

- Probe din milonite taiate perpendicular pe fabricul de forfecare i paralel cu planul de incluziune --- seciuni subiri + microscop petrografic

- inclzite(vapori dispar) i racite succesiv (reapar)----pt aflarea determinarea Th (temp de omogenizare = T min la care

fluidul trapped in incluziune) = densitatea fluid

T min= densitatea IF

Micrographs of A. quartz ribbon in the mylonite. B. fluid inclusions from section indicated.

IF cu vapori

- T trapping min = densitatea IF = constant fa de T (volum i mas de ap constante)

Izocore= P i T pt ap la diferite densitati (T min de capturare IF)

Fluidul a fost captat de-a lungul unei izocore

Ex. O fractura apare in pct A (350T i 350P), se inchide i fluidul este captat AB (punct B= Th omogenizare).

Incalzind IF la T camerei(C) boiling curve CB se determin B (vaporii dispar = T omogenizare=T min trapping

T-urile min captare fluide = 152-270 (210 media)

IF trec prin banda de Q in zona de forfecare, deci hidrofracturile sint post aparitie zona de forfecare. Limitele T in zona de forfecare au fost dedusedin chimia feldspatilor recristalizati i microstructurile Q (Gleason and DeSisto) . P min a fost estimat considernd 250MPa necesari i suficieni n suppressing brittle failure contracararea comportamentului casant din zona de forfecare. P max corespunde cu condiiie maxime de metamorfoz a gnaissurilor din Adirondacks(Darling et al., 2004)

As the rocks of the Adirondacks cooled and were uplifted to their current elevation, they had to have passed through each of the shaded regions .

Micrographs of A. quartz ribbon in the mylonite. B. fluid inclusions from section indicated.

A.

B.

References:

Darling, R.S., Florence, F.P., Lester, G.W., and Whitney, P.R., 2004, Petrogenesis of prismatine-bearing metapelitic gneisses along the Moose River, west-central Adirondacks, New York, in Tollo, R.P., Corriveau, L., McLelland, J., and Bartholomew, M.J., eds., Proterozoic tectonic evolution of the Grenville orogen in North America: Boulder, Colorado, Geological Society of America Memoir 197, 325-336.

Gleason, G.C., and DeSisto, S., in review, A natural example of crystal-plastic deformation enhancing the incorporation of water into quartz.