Evolution of fractures and alteration in the Sierrita-Esperanza hydrothermal system, Pima County, Arizona

Titley, Spencer R.; Thompson, R. C.; Haynes, Frederick M.; Manske, S. L.; Robison, Laurent; White, Joshua

doi:10.2113/gsecongeo.81.2.343

Cited by 40 publications

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“…The mineralizing magmas may have been emplaced into the upper crust only where compressional stress was locally accommodated by extension during these specific windows of time. Similar extensional features at other Laramide magmatic centers, with ages corresponding to these mineralization windows, may serve as a favorable indication of new deposits (37).…”

Section: Lntradeposit Relations and Regional Timing Of Mineralizationmentioning

confidence: 68%

“…More likely, normal convergence of the Farallon plate imposed a constant compressional regime throughout the area (36). Accomodation for this compression is expressed locally at several porphyry deposits in the form of oriented dike swarms, elongated stocks, and oriented fracture density patterns (36,37). The mineralizing magmas may have been emplaced into the upper crust only where compressional stress was locally accommodated by extension during these specific windows of time.…”

Section: Lntradeposit Relations and Regional Timing Of Mineralizationmentioning

confidence: 99%

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Rhenium-Osmium Evidence for Regional Mineralization in Southwestern North America

McCandless

Ruíz

1993

Science

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More than 40 base metal porphyry ore deposits in southwestern North America are associated with the Laramide orogeny (about 90 million to 50 million years ago). Rhenium-osmium dates on molybdenite, a rhenium-enriched sulfide common in many of the deposits, reveal that in individual deposits mineralization occurs near the final stages of magmatic activity irrespective of the time of inception, magnitude, or duration of magmatism. Deposits that differ widely in location and in the extent and timing of magmatism have nearly identical ages for mineralization. Rhenium-osmium-ages suggest that mineralization occurred during two distinct intervals from about 74 million to 70 million years ago and from 60 million to 55 million years ago. Most deposits that formed in the oldest interval are within the older Precambrian basement of northwestern Arizona, whereas the younger deposits are restricted to the younger Precambrian basement in southern Arizona and northern Mexico. Synchronous, widespread mineralization indicates that similar crust-mantle interaction occurred on a regional scale for ore deposits once thought to be the product of localized processes.

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Section: Lntradeposit Relations and Regional Timing Of Mineralizationmentioning

confidence: 68%

Section: Lntradeposit Relations and Regional Timing Of Mineralizationmentioning

confidence: 99%

Rhenium-Osmium Evidence for Regional Mineralization in Southwestern North America

McCandless

Ruíz

1993

Science

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“…As a qualitative assessment of hydrothermal fluid controls at the Yaxcopoil-1 site, we estimated fracture densities (after the method of Titley et al [1986] and Titley [1990]) from visual inspection of scanned color images of the Yaxcopoil-1 core. For this analysis, we considered only those fractures filled with alteration products (i.e., veins and stockworks).…”

Section: Fracturingmentioning

confidence: 99%

“…In addition to mineralogies susceptible to hydrothermal replacement, high permeability in the host rock plays an important role in providing the channels and traps for hydrothermal fluids (i.e., Newhouse 1969). As a qualitative assessment of hydrothermal fluid controls at the Yaxcopoil-1 site, we estimated fracture densities (after the method of Titley et al [1986] and Titley [1990]) from visual inspection of scanned color images of the Yaxcopoil-1 core. For this analysis, we considered only those fractures filled with alteration products (i.e., veins and stockworks).…”

Section: Fracturingmentioning

confidence: 99%

Hydrothermal alteration in the core of the Yaxcopoil‐1 borehole, Chicxulub impact structure, Mexico

Zürcher

Kring

2004

Meteorit & Planetary Scien

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Abstract-Petrographic, electron microprobe, and Raman spectrometric analyses of Yaxcopoil-1 core samples from the Chicxulub crater indicate that the impact generated a hydrothermal system. Relative textural and vein crosscutting relations and systematic distribution of alteration products reveal a progression of the hydrothermal event in space and time and provide constraints on the nature of the fluids. The earliest calcite, halite, and gaylussite suggest that the impactite sequence was initially permeated by a low temperature saline brine. Subsequent development of a higher temperature hydrothermal regime is indicated by thermal metamorphic diopside-hedenbergite (Aeg 3 Fs 18-33 En 32-11 Wo 47-53 ) after primary augite and widespread Na-K for Ca metasomatic alkali exchange in plagioclase. Hydrothermal sphene, apatite, magnetite ± (bornite), as well as early calcite (combined 3 to 8 vol%) were introduced with metasomatic feldspar. A lower temperature regime characterized by smectite after probable primary glass, secondary chlorite, and other pre-existing mafic minerals, as well as very abundant calcite veins and open-space fillings, extensively overprinted the early hydrothermal stage. The composition of early and late hydrothermal minerals show that the solution was chlorine-rich (Cl/F >10) and that its Fe/Mg ratio and oxidation state increased substantially (4 to 5 logƒO 2 units) as temperature decreased through time. The most altered zone in the impactite sequence occurs 30 m above the impact melt. The lack of mineralogical zoning about the impact melt and convective modeling constraints suggest that this unit was too thin at Yaxcopoil-1 to provide the necessary heat to drive fluids and implies that the hydrothermal system resulted from the combined effects of a pre-existing saline brine and heat that traveled to the Yaxcopoil-1 site from adjacent areas where the melt sheet was thicker. Limonite after iron oxides is more common toward the top of the sequence and suggests that the impactite section was subjected to weathering before deposition of the Tertiary marine cover. In addition, scarce latest anatase stringers, chalcopyrite, and barite in vugs, francolite after apatite, and recrystallized halite are the likely products of limited post-hydrothermal ambient-temperature diagenesis, or ocean and/or meteoric water circulation.

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“…Although there is no question that the thermal effects of intrusive igneous activity have been important and probably essential, no specific relationship of occurrence of silver and gold in epigenetic ores of this region with any specific kind or group of potential igneous metal "progenitors" has yet been convincingly demonstrated or recognized, notwithstanding the existence of a complex pattern of intrusions of different compositions as detailed by Westra and Keith (1981). Further, abundant field evidence reveals that large volumes of crustal rocks, beyond intrusive centers, have been involved in the hydrothermal mineralizing processes and have themselves been hosts to ores (Heidrick and Titley 1982;Titley et al 1986). Indeed, in many districts of this region, the apparent volume of igneous rocks at the level of exposed ore deposits is trivial and in many cases a direct association of ores with igneous rocks is unknown.…”

Section: Discussionmentioning

confidence: 99%

Correspondence of ores of silver and gold with basement terranes in the American southwest

Titley

1991

Mineral. Deposita

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Abstract. The ratios of silver to gold produced from epigenetic ore districts of the American southwest reveal a consistency of value ranges, differing by an order of magnitude, that may be identified with either one or the other of two geologic terranes in which the ores occur. A discriminating value of the ratio is about 17.5 : 1, the ratio of crustal abundance given by Ahrens (1965). (No further significance is attributed to this value, at this time, beyond the fact that it appears to establish a reasonable separation of values on the basis of geographic occurrence.) Ores relatively enriched in Ag occur in terranes floored by thick Proterozoic clastic and Paleozoic marine successions, and ores relatively enriched in Au lie above or within a Proterozoic basement dominated by maficfelsic volcanic (arc) successions. Proterozoic granites occur in each region. The values of the ratio are broadly consistent within each terrane, irrespective of the age of ore formation, the ore deposit style, associated igneous rocks, structural control, differing interpreted styles of subduction, and weathering histories. These characteristics and associations support a hypothesis that metallogenic signatures of ore districts in this region are fundamentally related to the crust in which the ores occur.Regional analysis of metals in Arizona ore deposits has led to a hypothesis that the silver and gold of districts may be inherited from the crust (Titley 1987(Titley , 1989. Limiting values of ratios of Ag:Au produced from ores of districts correspond geographically to the distribution of different ages and compositions of subjacent Proterozoic basement. The correspondence with basement compositions transcends the genetic style of ores, the tectonic environment and setting of ore districts, apparent associated igneous rock types and the ages of metallogenesis. Further, the orders of magnitude of the values of the ratio correspond in a general way to those values inferred from published data for known basement lithologies.The original regional analysis (Titley /987) was restricted to the State of Arizona because of limited data. This report extends that metallogenic data in New Mexico from information recently published by North and McLemore (1988) and into parts of Nevada and California from some data of Wilkins (1984). Boundaries of Proterozoic basement lithologies and corresponding ages in Arizona have been extended into adjoining New Mexico. The results of this expansion of basement and precious metal characteristics show that the correspondence of the Ag:Au ratios with distinctive Proterozoic basement of the American Southwest appears to be regionwide. Values of the Ag : Au ratio from districts within or above the older, volcanic-dominated Proterozoic basement are relatively enriched in gold (< 17.5), those above the younger Proterozoic, clastic rock-dominated basement, relatively enriched in Ag.

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Evolution of fractures and alteration in the Sierrita-Esperanza hydrothermal system, Pima County, Arizona

Cited by 40 publications

References 0 publications

Rhenium-Osmium Evidence for Regional Mineralization in Southwestern North America

Rhenium-Osmium Evidence for Regional Mineralization in Southwestern North America

Hydrothermal alteration in the core of the Yaxcopoil‐1 borehole, Chicxulub impact structure, Mexico

Correspondence of ores of silver and gold with basement terranes in the American southwest

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