10 Geochemistry and Mineralogy (Posters)

Sunday, 22 March 2026
8:00 AM - 12:00 PM
CCC, Ballroom C

Geological Aspects of the Mesozoic Gold Skarn and Porphyry Occurrence Guayzim Alto Concession Nambiji District Zamora Province Ecuador

Paper number: 10-9
Program: Technical Sessions
Time: 8:00 AM – 8:00 AM

Authors

Abstract

 

Worldwide attention of the significant increase in gold prices (> 4000 $ oz.) have lead to geological evaluations of old mining locations. The purpose of this presentation is to explore the geology Guayzim Alto gold concession, Nambiji District, Zamora Province, Ecuador. The Nambija and supergiant Fruta del Norte gold mines serve as our exploration analogues.   

This presentation is based upon Volcan  Holdings Corporations attained reports of Guayzimi Alto  (1990, 1995, 2024), 6893 m of cores, 2000 m underground mine samples ,25000 geochemical assays ,geological maps and cross sections( 29) , and Fruta del Norte Lundin  NI-43-101 ( 2016) ,Voclan plans to reactivate mining.

  The Guayzimi Alto concession located at the western margin of the Amazon craton is largely underlain by crystal – lithic tuff and welded tuffs, ash, massive volcanic flows, flow breccia’s, and sedimentary rocks. The hydrothermal alteration is oxodized retrograde skarn with K enrichment ( orhoclase)  Nambija hemicrothermometric data (Th from 513°C to 318°C and salinity from 1.0 to 23 wt.% eq. NaCl) and δ18O values between 6.2‰ and 11.5‰ for gold-bearing milky quartz from the retrograde stage suggest ore-forming fluid was dominantly magmatic.Coarse native gold occurs in granular garnetite with K feldspar  and Na-rich plagioclase at the walls and milky quarz in  the core with vuggy veinlets, and fine grained  gold between garnet grains. The major stockwork, skarn deposits, demonstrate  fracturing and quartz veining., Target areas ,garneitite mineralization,  where north – south mineralized faults intersect east – west (90°) and N70°E (70°) as well as N55° W (125°) zones ..

 Skarnification has increased  rock competency  ( brittleness) and faulting  . The skarn deposits are  1) Mine Skarn( endoskarn), protolith latite porphory, calc-silicate skarn, with free gold with later quartz ,sulphide, and orthoclase veinlets (up to several ounces per ton)  in proximity to faulting within a 50 x 150-meter zone trending WNW. .2) Buenaventura (Or Camp) Skarn. an epidote –diopside – garnet skarn intercalated with calc – silicate skarn (tremolite –actinolite) A one-meter chip sample taken there assayed 10 Au g/t. 3) Escondida Skarn, containing garnet-orthoclase skarn wih quartz and pyrite 

Guayzim Alto.contains 3 areas of deeper unexplored  gold potential ( depth 200-700m) exhibited in cross-section.  

  In  addition, the northern area, the multiphase sub volcanic intrusions and hydrothermal systems including the Cerro Banderas porphyry ( Au-Cu+/- Mo), offer unexplored potential. .

 

Geological Society of America Abstracts with Programs. Vol. 58, No. 2

doi: 10.1130/abs/2026NE-411101

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