Colorado State University
Trippel, Alan D.
Hydrothermal mineralization and alteration at the Globe Hill deposit, Cripple Creek district, Colorado.
Degree: MS(M.S), Earth Resources, 2018, Colorado State University
The Globe Hill deposit is hosted by a porphyritic, subvolcanic intrusive which is composed of pyroxene-bearing alkali trachyte. It is emplaced within the Oligocene-age Cripple Creek diatreme-intrusive complex, which may be related to the Rio Grande rift system centered 75 km to the west. Four structural events occurred at Globe Hill. The earliest event (stage I) created a zone of upward-flaring hydrothermal breccia bodies which were later cut by a series of tectonic structures (stage II). A dike- or column-like body of intrusive breccia (stage III) subsequently invaded a major stage II shear zone, and a large, separate hydrothermal breccia body (stage IV) formed within the stage I zone. Separate hydrothermal fluids passed through each of the structural systems, and formed epithermal, low-grade, polymetallic mineralization along stage I, II, and IV structures; stage III structures remained unmineralized. Mineralization occurs as veins, breccia-matrix fillings, and disseminations through breccia fragments and adjacent wall rock. Stage I structures were mineralized by an assemblage composed dominantly of chalcedony-celestite-pyrite and trace oxides, telluride, phosphates, and base-metal sulfides. Early stage II veins are composed dominantly of quartzcelestite-pyrite and trace adularia, oxides, telluride, and base-metal sulfides. Wallrock adjacent to later stage II gangue-free structures contains halos of disseminated pyrite and trace oxides, telluride, and base-metal sulfides. The central core zone of the stage IV breccia is cemented by an assemblage of anhydrite-carbonate-celestite-fluorite along with trace pyrite, oxides, and base-metal sulfides; its peripheral halo is partially cemented by montmorillonite and minor amounts of fluorite, quartz, and hematite. Five separate alteration events are recognized. Each of the first four is hypogene and correspond to one of the major structural stages. The fifth event is related to supergene weathering. Alteration associated with the stage I hydrothermal breccias grades from a sericite-dominated zone within the breccia bodies to a chlorite-dominated zone in the surrounding wallrock. Wallrock adjacent to stage II tectonic structures has been altered to a sericite-dominated assemblage. Alteration of the stage III intrusive breccia primarily affected the matrix material and to a lesser extent the fragments, producing a chlorite-dominated assemblage. Stage IV central core zone breccia fragments were altered to a quartz-dominated assemblage which grades to a montmorillonite-dominated assemblage in the peripheral zone and wallrock. The last hypogene event as well as the supergene weathering have partially oxidized the deposit to a depth of over 270 m. The effects of supergene weathering are most pronounced along stage I and II structures where permeability is sufficient to allow for downward percolation of oxidizing surface waters. Mineralization and alteration assemblages associated with each structural stage have been used to infer parentfluid chemistry. Existing data suggest that…
Advisors/Committee Members: Thompson, Tommy B. (advisor), Caddy, Stan W. (committee member), Vaughan, John (committee member).
Subjects/Keywords: Hydrothermal deposits – Colorado – Cripple Creek
to Zotero / EndNote / Reference
APA (6th Edition):
Trippel, A. D. (2018). Hydrothermal mineralization and alteration at the Globe Hill deposit, Cripple Creek district, Colorado. (Masters Thesis). Colorado State University. Retrieved from http://hdl.handle.net/10217/190132
Chicago Manual of Style (16th Edition):
Trippel, Alan D. “Hydrothermal mineralization and alteration at the Globe Hill deposit, Cripple Creek district, Colorado.” 2018. Masters Thesis, Colorado State University. Accessed September 22, 2019.
MLA Handbook (7th Edition):
Trippel, Alan D. “Hydrothermal mineralization and alteration at the Globe Hill deposit, Cripple Creek district, Colorado.” 2018. Web. 22 Sep 2019.
Trippel AD. Hydrothermal mineralization and alteration at the Globe Hill deposit, Cripple Creek district, Colorado. [Internet] [Masters thesis]. Colorado State University; 2018. [cited 2019 Sep 22].
Available from: http://hdl.handle.net/10217/190132.
Council of Science Editors:
Trippel AD. Hydrothermal mineralization and alteration at the Globe Hill deposit, Cripple Creek district, Colorado. [Masters Thesis]. Colorado State University; 2018. Available from: http://hdl.handle.net/10217/190132