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Show ic Study of the Emplacement of the Alta Stock, Brighton, Utah B. l>idciirkwn .1 M Hirffey J>t [>;i rniw nT HJ t C. t.u hi^y i f j t-< tji Ei j si pa, |U rrf varsity nf t tfth The AJta sfocl^ neai1 Bn^hi^m. Utnh. is ;i nud-r^iJutjyf^Ol M^J ^1^1)1^ ijsmsion T.A.Vogel jindoihers *i^£es( that the Alta stock and related tnftorusions wste emplaced jmo shear zones duiijia cnistal eMteiision, Topical crustal extension raDes C< 1 cnifyt} and thermal modeling indicate thai synkineitiatic iiumdons diould fonti corapositely by diking. Crosscutting mafic-layers on the rnargiit of the stodc suggest at least three episodes of diking, but the core of the stock appears homogeneous in the field. Theiefoca. forty samples collected at intervals of ca. 100 meters along oriented travel's^ supplemented hy published data, are being studied for subtle compositional and textual evident ofs^iJdjifimatic-shjeeted eni|jiacejnent. PreLiniinaiy textui'aJ KSUB* indicate ttuee intrusive phases: porphyritic, sub-porphyritic, andnon-porphyritic; which may recoi'd evolving thermal conditions. At least one stage of synkinematic crystallization is recognized by feldspar overgrowths that truncate growth zones and intraciystalline faults within the coces of the grains. When ongoing data collection is complete, the spatial distribution of modal and textural variations in the intnsion will be known over length of 100 meters and greater. Thess variation* may be a feey mdetemiidng the cleeiee to which die Alta stock and otJier synfeinematic intnKions ire composite. Acknowledgements: Funding provided by: UROP & CoDege of Mines and Edith Sciences.. University of Utah Fieldwctk andphotauici'ogTaphs: Joseph Chhstophei'son Eric Petetsen Auflioi1 Emails: Brad Diclaiehseji (h,diderickMn@.utakedD> John M. 32 |
