Economic geology and gold potential of the Occidental patent group, Tumco Mining District, Cargo Muchacho Mountains, Imperial Co, California
by
Donald G. Strachan, Consulting Geologist QP CPG Box 4046, Carson City, NV 89702 [email protected]; [email protected]; www.geostrachan.com; USA cell:+1 775 720-8894 Int'l cell:+1 604 505-2495
30 June 2011
Donald G. Strachan, Consulting Geologist Occidental patents, Imperial County, CA
Abstract The southeast-dipping Pasadena Shear Zone offers bulk-mineable economic gold potential within the Occidental Group of nine, patented contiguous lode claims in the Cargo Muchacho Mountains. Finely stockworked and/or sheeted auriferous veinlets disseminated through the 80-foot average thickness of the Pasadena Shear combined with the occasion thick, equally high-grade veins, may create overall grades averaging 2 gpt (0.06 opt) Au in a manner similar to the nearby American Girl mine and the Oro Cruz deposit. Several similar shear zones may occur in a stacked and block-fault configuration within the Occidental Group. Geologic potential along the northern segment of the Pasadena Shear is 7,300,000 tons containing 440,000 oz Au. This exploration potential occurs over a 2,200-foot strike length, where structural width may average 80 feet down at least 500 feet of dip length. With these dimensions, stripping ratio for an open-pit situation should be economic, subject of course to adequate feasibility studies after discovery and development. Additional segments of the Pasadena Shear Zone along structural strike in the southern portion of the Occidental Group have additional economic potential. The low-angle Pasadena Shear Zone, one of a series of district-scale extensional faults related to regional detachments, may vary up to 140 feet in structural thickness, dips as much as 40º southeast, and projects northeasterly in outcrop and subcrop over at least a mile of strike length. Foliated medium- grained intrusives of the Tumco Formation form the hangingwall and footwall of the Pasadena Shear, along with minor irregular bodies of fine-grained, presumably Cretaceous, felsic intrusives. Post-metamorphic biotite flooding along foliation planes and some vein margins is the most intense hydrothermal alteration observed during this four-day survey. Chlorite-clay alteration was also observed adjacent to some quartz veins. Observed mineralization included limonite after pyrite and other sulfides, and also minor copper oxides, in quartz veins and adjacent veins and fractures.
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Donald G. Strachan, Consulting Geologist Occidental patents, Imperial County, CA
Contents Abstract 2 Contents 3 Introduction 4 Purpose and method 4 Property description 4 Ownership 4 History of the Tumco District and Occidental Group 4 District Geology 5 Economic geology of the Occidental Group 8 Discussion 9 Conclusions 12 Recommendations to the owners 13 References 13 Table 1 – Assays 15
Figure 1 - Location in Southeastern California 4 Figure 2 - Location near San Andreas Fault Zone 5 Figure 3 - Geology and location in Cargo Muchachos Mountains 5 Figure 4 - Location of Occidental Claim Group and May 17th waypoints (blue dots) 6 Figure 5 - Vein trace and sample locations, Dan’s Original Vein Prospect 7 Figure 6a - Occidental Group boundaries, all samples, and topography 8 Figure 6b - Occidental Group boundaries and assay values greater than 5 ppm Au 9 Figure 6c - Occidental Group claims, air photo, and samples greater than 5 ppm Au 10 Figure 7a - Au greater than 5 ppm Au - Pasadena Shear Zone looking South 11 Figure 8b - Au greater than 5 ppm and claim boundaries - Pasadena Shear looking South 12
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Donald G. Strachan, Consulting Geologist Occidental patents, Imperial County, CA
Introduction Purpose and method Dan and Judy Massagli accompanied the author to the Tumco District on the morning of May 17th, 2011, to introduce their patented Occidental claim group for evaluation purposes. Our initial stop was an accessible series of workings on a vein outside of the claim group. This introductory vein is approximately 6,000 feet west-southwest of the Occidental Group. The area initially visited and sampled is indicated in Figures 4, 5a, and 5b below. The author and son Charlie spend the afternoon of May 17th and the next three days determining claim boundaries and sampling dumps, ore piles, outcrops, and portal crops of the Occidental Group and the immediate surroundings. Our primary intent was to observe geological characteristics and to sample mineralized outcrops and historical workings within the Figure 9 - Location in Southeastern California boundaries of the Occidental Group to ascertain tenor and Au distribution (Figure 6c). Outcrop maapping was not attempted during the limited time available. Nevertheless, geologic observations made during this introductory sampling, along with assay results and published references are the main basis of this report. Property description The Occidental Group consists of nine contiguous patented claims located in the Tumco mining district in the central Cargo Muchacho Mountains, 18 miles southeast of the operating Mesquite gold mine (New Gold Inc.) and a half mile southeast of the reclaimed American Girl gold mine (428,000 oz Au production). Access to the Occidental Group, via paved highway, and gravel the last few miles, takes approximately 50 minutes of driving time from Yuma, Arizona. Ownership The Occidental Group is owned 100% by Dan and Judy Massaglli of Southern California. Their contact information is: office (909) 987-6624; cell (951) 315-8776; email [email protected]. History of the Tumco District and Occidental Group High grade veins in the Cargo Muchachos were mined by independent Mexican nationals until the mid-1800’s. Unfortunately, this early activity was abruptly ended by an attack by Yuma Indians on July
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Donald G. Strachan, Consulting Geologist Occidental patents, Imperial County, CA
17, 1781, when 50 men were killed and 67 women and children taken into slavery. Mining activity was not resumed until the establishment of the Mexican Republic in 1823 (California Gold, 2011). American miners entered the district soon after the Mexican War ended in 1848, becoming firmly established when the Southern Pacific Railroad was completed to Yuma. Large scale activity continued from 1890 to 1916, from 1932 to 1941, and intermittently in the years after World War II. Names of the mines during this era included the American Boy, American Girl, Big Bear, Blossom, Butterfly, Cargo Muchacho, Coffee
Pot, Colorado, Desert King, Golden Cross, Figure 10 - Location near San Andreas Fault Zone Golden Queen, Guadeloupe, Little Bear, Madre and Padre, Ogilby Group, Pasadena, Sovereign, Vitrafax, and White Cap. Several of these mines were re-explored during the 1980’s, and the American Girl and American Boy were operated as an open pit. Large, reclaimed, and depleted heap leach pads and waste dumps (in brown, Figure 4) dominate the small east-west valley a few thousand feet north and northwest of the Occidental Group. District Geology Basement rocks in the Cargo Muchacho Mountains consist of Jurassic (?) gneiss and schist of the Tumco Formation. The Tumco Formation is intruded by large bodies of Cretaceous (?) hornblende-biotite quartz monzonite and later Cretaceous (?) biotite granite bodies and associated pegmatite dikes. Cretaceeous (?) porphyritic aplite seems to cut all earlier metamorphic and intrusive lithologies. The structural fabric underlying most of the range appears to be low- angle extensional faults related to one or more Tertiary listric detachments. On-going listric faulting produced shear zone strikes varying from west- Figure 11 - Geology and location in Cargo Muchachos Mountains northwest to northeast. Additional high-angle northwesterly faults are Page 5 of 15 July 4, 2011
Donald G. Strachan, Consulting Geologist Occidental patents, Imperial County, CA secondary but important components of the overall extensional Tertiary fabric of the Cargo Muchacho Mountains (Rozelle, 2010, page 2).
Figure 12 - Location of Occidental Claim Group and May 17th waypoints (blue dots)
Alteration is metamorphic and later hydrothermal. Regional developpment of gneiss and amphibolite preceded Cretaceous (?) intrusion. Gneiss, schist and granitics are hydrothermally altered along fractures and some veins, and appear to be associated wwith granitic and/or aplite dikes. Coarse hydrothermal biotite is common in mesothermally altered wallrocks. Some of the coarse biotite zones consist of aggregations of individual, chaotically-oriented crystals up to 3 mm across with much open space between. These occurrences of hydrothermal biotitee might be called veins or veinlets, although their boundaries are somewhat irregular. Individual quartz veins sometimes have up to several feet of chlorite-clay alteration and limonite (after sulfide) in their hangingwalls or footwalls.
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Donald G. Strachan, Consulting Geologist Occidental patents, Imperial County, CA
Judging from our samples and our observations of historic workings, veins and shears of all orientations host gold in the Tumco District, but low-angle detachment structures have been responsible for most production since the 1980’s. Continuous and discontinuous crystalline, mesothermal quartz veins occur throughout the district ranging from a few inches to several feet in width. The single vein at Dan’s Original Prospect (Figure 5) is white, crystalline, with scattered grey metallic up to 1.5 feet wide, striking northeast and dipping steeply Figure 13 - Vein trace and sample locations, Dan’s Orriginal Vein Prospect northwest, with assay values up to 87 ppm Au (Table 1). Dan’s Original appears to be typical of the high-grade quartz veins in mineralized areas of the Tumco District. Many of these gold-bearing veins and veinlets seem to occur in hangingwalls of low-angle shear zone segments. The Oro Cruz (Golden Cross) deposit, located 3 milles northwest of the Occidental Group, is currently being developed by Lincoln Mining Corporation. Lincoln has announced an inferred resource of 341,800 oz Au in 4,835,000 tons grading 2.20 gpt Au and intends to restart development drilling in late 2011. Mesothermal mineralization at Oro Cruz occurs in multtiple brown to brownish gray siliceous zones containing hematite, magnetite, quartz, mica, feldspar, chlorrite, and blue copper oxides. Native gold and very low silver are associated with iron oxides. Most gold is very fine with ±64% <1 to 5 microns in size (Rozelle, 2010, page 2). Oro Cruz is a detachment-related shear dippiing 25 degrees. The tabular Oro Cruz deposit strikes northwest and dips 25º to the south.
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Donald G. Strachan, Consulting Geologist Occidental patents, Imperial County, CA
Figure 14a - Occidental Group boundaries,, all samples, and topography
Economic geology of the Occidental Group A low-angle shear zone (Pasadena Shear Zone), part of series of district-scale extensional faults related to regional detachments, passes through the center of the Occidental Group. The Pasadena Shear Zone, which may vary up to 140 feet in structural thickness, dips 40º southeast and projects northeasterly in outcrop and subcrop over at least a milee of strike length (Figure 6c). The Tumco Formation makes up the hangingwall and footwall of the Paasadena Shear, with minor irregular bodies of fine-grained, presumably Cretaceous, felsic intrusives. Post-metamorphic biotite flooding along foliation planes and some vein margins was the most intense hydrothermal alteration observed during this survey. Chlorite-clay alteration was also observed adjacent to some quartz veins. Observed mineralization during this May, 2011, survey included limonite after pyrite and other sulfides, and also minor amounts of copper oxides, in quartz veins and adjacent veins and fractures.
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Donald G. Strachan, Consulting Geologist Occidental patents, Imperial County, CA
Figure 6b - Occidental Group boundaries and assay values greater than 5 ppm Au
A total of 37 samples taken from mine portal ore piles, mine dumps, portal crop, and outcrop during this survey were analyzed for Au and Ag (Figure 6a and Taabble 1). Most portals and pits were collapsed or filled intentionally by absent miners throughout this part of the district, obviously to preserve the values in the workings for their anticipated return. Au asssay values ranged up to 87.7. Sixteen of 37 samples assayed over 3.0 ppm Au. Ten samples assayed over 10.0 ppm Au. Two samples exceeded 34 ppm Au. Gold values seem to increase with the limonite (after sulfide) abundance, especially in samples of quartz vein material from dumps along the trace of the Pasadena Shear Zone (cover and Figures 6 and 7). Discussion Once the location and boundaries of the Occidental Grouup had been determined, observations of the general geology of known gold occurrences had been madde, and the extent of historic mining activity better ascertained, the primary purpose of our planned four-day survey became apparent. We would determine the tenor of gold within the larger volumes of historically-mined zones of favorable mineralization, alteration, structure, and lithologies.
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Donald G. Strachan, Consulting Geologist Occidental patents, Imperial County, CA
Figure 6c - Occidental Group claims, air photo, and samples greater than 5 ppm Au
In the Tumco District, prime candidates for geologically favorable volumes are planar, horizontally- extensive, low-angle, moderate-grade shear zones similar to the American Girl mine (428,000 oz Au in 6,114,286 tons grading 2.38 gpt [0.07 opt] Au) and the proposed Oro Crruz (341,800 oz Au in 4,835,000 tons grading 2.20 gpt [0.07 opt] Au) deposit. With this structural model in mind, 30 mineralized outcrops and mine dumps in the vicinity of the Occidental claim group were located, observed, and sampled. At least one well-developed structural shear of permissive size and geometry, the Pasadena Shear, was recognized during this survey. The Pasadena Shear projects through the Pasaadena, Robert E. Lee, Tip Top, and Delphi patent claims (Figures 6c and 7c) and appears to have a structural thickness of as much as 140 feet. Seventeen of the 30 samples were taken along the surface trace of this shear, scattered evenly over a strike length of 2,200 feet, and they averaged 6.92 ppm Au. Structural thickness of the Pasadena Shear may average about 80 feet over this hoorizontal distance.
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Donald G. Strachan, Consulting Geologist Occidental patents, Imperial County, CA
Figure 15a - Au greater than 5 ppm Au - Pasaadena Shear Zone looking South
Fourteen of the Pasadena Shear samples carried more than 1 ppm Au. Twelve of the Pasadena Shear samples were taken within the boundaries of the Robert E. Lee or Pasadena patents (Figures 6c and 7c). These samples were from all the significant portal crops, dudumps, and ore piles on the Shear within the later patents. Their average value of 9.10 ppm (0.3 opt) Au may represent a lower limit for the expected average grade for veins contained within the Pasadena Shear Zone. Many larger vein segments grading better than 17 gpt (0.5 opt) Au were undoubtedly mined from the southernmost portions of the Pasadena and the northernmost portions of the Occidental and Tip Top lodes through the Occidental Mine (Figure 6c) before World War II. High-grade veins similar to those historically mined underground may be preserved along unmined strike and dip extensions of the Pasadena Shear within the Occidental, Pasadena, Tip Top, Delphi, and Henrietta lodes, and beneath unpatented ground east of Pasadena lode (Figure 6c). Fine auriferous veinlet stockworks and/or sheeted auriferous veinlets may also be disseminated throughout much of the postulated 80-foot average thickness of the Pasadena Shear Zone. These veinlet masses will add substantially to overall Au grade within the shear, creating bulk-mineable economic potential. This postulated economic potential will be especially high in areas of the shear faulted off or otherwise less accessible to historic high-grade underground miners.
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Donald G. Strachan, Consulting Geologist Occidental patents, Imperial County, CA
Figure 16b - Au greater than 5 ppm and claim boundaries - Pasadena Shear Zone looking South.
Conclusions The bulk-mineable character of the southeast-dipping Pasadena Shear Zone offers the best economic gold potential within the Occidental Group. Finely stockworked and/or sheeted auriferous veinlets disseminated through the 80-foot average thickness of the Pasadena Shear may create grades averaging 2 gpt (0.06 opt) Au in a manner similar to the American Girl mine and the Oro Cruz deposit (above). Given this grade, the minimum 2,200-foot strike length of the mineralized northern segment of the Pasadena Shear Zone, an average 500 feet dip length, and 80 feet of average structural width, geologic potential of the northern half of the Occidental Group is 7,300,000 tons containing 440,000 oz Au. With these dimensions, stripping ratio for an open-pit situation under present economic conditions should not be too onerous, subject of course to adequate feasibility studies after discovery and development. Additional portions of the Pasadena Shear Zone with equal economic potential may be projected along structural strike into the southern portion of the Occidental Group, and further east down structural dip across northerly block faults of variable throw.
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Donald G. Strachan, Consulting Geologist Occidental patents, Imperial County, CA
Recommendations to the owners Phase One steps should be accomplished to prepare the Occidental Group for discovery drilling: 1) peripheral and internal unpatented claims should be staked, 2) outcrop geology should be thoroughly mapped at an appropriate scale, 3) a comprehensive rock chip and soil sampling program should be completed, and 4) a geophysics program adequate for projecting the Pasadena and other, potentially stacked, shear zones should be completed. A budget to accomplish this preparatory work over a six- month period should be considered. Once strike, dip, and depth of the Pasadena Shear and similar structures are mapped and projected beneath the surface, a Phase Two discovery drilling program to intersect mineralized structures should be designed, budgeted, and carried out. A Phase Three drill program would follow to infer economic resources. References Booth & Sons, 1920, The Occidental group of mines: private report, 1 page. California Gold blog, 15 May 2011, Spanish miners: http://www.goldcalifornia.net/tag/spanish-miners- in-california/ Decker, C., 1 July, 1939, Letter to Henry Merdinck relating mine activities and including 15 July Koppea report. Dillon, J.T., 1976, Geology of the Chocolate and Cargo Muchacho Mountains, southeastern-most California: Santa Barbara, University of California, Ph.D. thesis, 405 p. Duke, N. and M. Pazner, March 2008, Field Trip – Gold mineralization related to extensional tectonics, Nevada, Arizona, and SE California: University of Western Ontario website http://instruct.uwo.ca/earth-sci/fieldlog/cargo/indexcargo.htm#day5 Henshaw, Paul Carrington (1942), Geology and mineral resources of the Cargo Muchacho Mountains, Imperial County, California: California Journal of Mines and Geology, California Division Mines (Report 38): 117. Koppea, A.D., 15 July, 1925, Report of examination of the Occidental group of mines in the Cargo Muchacho mining district, Imperial County, California: private report, 5 pages. Lashar, M., 30 April 1940, Report on Pasadena Mine, Ogilby, California: 1108 Park Central Building, Los Angeles, California, Vandike 0923, 7 pages. Morton, P.K., 1977, Geology and mineral resources of Imperial County, California: California Division of Mines and Geology, County Report 7, 104 p., scale 1:125,000. Owens, E.O., and Hodder, R.W., 1994, Aluminosilicate mineral assemblages in the Cargo Muchacho Mountains, southern California: metasomatism and gold concentration associated with magmatism and deformation in mesozonal environments: Canadian Journal of Earth Sciences, v. 31, p. 310-322. Perez, J, 14 December, 2009, Press release: USA Uranium Acquires Pasadena/Occidental Mine and Consummates Comstock Royalty LLC Financing: Marketwire http://www.marketwire.com/press- release/usa-uranium-acquires-pasadena-occidental-mine-consummates-comstock-royalty-llc- financing-1180440.htm.
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Perez, J, 29 March 2010, Entry into definitive agreement: Form 8-K: Securities and Exchange Commission, Washington, D.C., 4 pages. Rozelle, J.W., 21 September 2010, 43-101 technical report, Oro Cruz gold project resource estimate, Imperial County CA, USA: for Lincoln Mining Corporation, 116 pages, 28 figures, 29 tables, 1 appendix. Strand, R.G., 1962, Geologic map of California: San Diego-El Centro sheet: California Division of Mines and Geology, scale 1:250000. Van Wormer, S.R and J.D. Newland, Spring 1996, The History of Hedges and the Cargo Muchacho Mining District Parts I and II: The Journal of San Diego History, Volume 42, Number 2.
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Table 1 – Assays
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