{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/18944"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/18944","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"Numerical hydrologic modeling of the Creede epithermal ore-forming system, Colorado","abstract":"One of the fundamental objectives of the extensive research on Creede district, Colorado, has been to determine the sources, pathways, and interactions of fluids involved in the genesis of the epithermal ores. From the large volume of data on the main period of mineralization, a well-constrained conceptual flow model has evolved. In this model, an intrusion at depth drove hydrothermal convection, and topography drove shallow groundwater flow. Fluids from at least three sources fed the system, and boiling and/or mixing promoted ore deposition. In this study, I examine the qualitative constraints on this model, derive new controls, and then use numerical methods to evaluate the hydrology.","abstract_html":"One of the fundamental objectives of the extensive research on Creede district, Colorado, has been to determine the sources, pathways, and interactions of fluids involved in the genesis of the epithermal ores. From the large volume of data on the main period of mineralization, a well-constrained conceptual flow model has evolved. In this model, an intrusion at depth drove hydrothermal convection, and topography drove shallow groundwater flow. Fluids from at least three sources fed the system, and boiling and/or mixing promoted ore deposition. In this study, I examine the qualitative constraints on this model, derive new controls, and then use numerical methods to evaluate the hydrology.","abstract_has_math":false,"creators":["Hayba, Daniel Owen"],"institution":"University of Illinois at Urbana-Champaign","degree_name":"Ph.D.","degree_level":"Dissertation","degree_discipline":"Geology","degree_department":null,"school":null,"contributors":["Bethke, Craig M."],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2011,"date_issued":"2011-05-07T11:52:11Z","date_published":"2011-05-07T11:52:11Z","updated_at":"2026-07-22T22:25:12Z","subjects":["Geology","Hydrology"],"languages":["eng"],"rights":["Copyright 1993 Hayba, Daniel Owen"],"rights_urls":[],"identifier_entries":[{"key":"dc:identifier","label":"Identifier","values":["AAI9329054","(UMI)AAI9329054"],"render_values":[{"text":"AAI9329054","href":null,"code":true},{"text":"(UMI)AAI9329054","href":null,"code":true}]}]},"links":{"outbound_url":"http://hdl.handle.net/2142/18944","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Bethke, Craig M."]},{"key":"dc:creator","label":"Author","values":["Hayba, Daniel Owen"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2011-05-07T11:52:11Z","10000-01-01","1993"]},{"key":"dc:type","label":"Dc Type","values":["text"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Geology"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Dissertation"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Ph.D."]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["University of Illinois at Urbana-Champaign"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Geology","Hydrology"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["eng"]},{"key":"dc:rights","label":"Dc Rights","values":["Copyright 1993 Hayba, Daniel Owen"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["AAI9329054","(UMI)AAI9329054","http://hdl.handle.net/2142/18944"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["One of the fundamental objectives of the extensive research on Creede district, Colorado, has been to determine the sources, pathways, and interactions of fluids involved in the genesis of the epithermal ores. From the large volume of data on the main period of mineralization, a well-constrained conceptual flow model has evolved. In this model, an intrusion at depth drove hydrothermal convection, and topography drove shallow groundwater flow. Fluids from at least three sources fed the system, and boiling and/or mixing promoted ore deposition. In this study, I examine the qualitative constraints on this model, derive new controls, and then use numerical methods to evaluate the hydrology.","To establish the boundaries of the paleo-system, I determined that the average topographic slope across the district was approximately 10%, and that the depth of hydrothermal circulation was 1.6 to $\\sim$3 km. A detailed fluid inclusion study of growth-banded sphalerite provides another important constraint by conclusively demonstrating that fluid mixing, rather than boiling, was the primary mechanism of ore deposition. Temperature and salinity variations indicate that a 285$\\sp\\circ$C hydrothermal brine ($\\sim$11.5 wt% NaCl eq.) mixed with dilute, 160$\\sp\\circ$C groundwater. I also estimate that the mass flux through the system was approximately 50 kg/sec, and that the size of the granitic heat source was at least 7.5 km$\\sp3$ ($\\sim$2.1 $\\times$ 10$\\sp{13}$ kg). The overall contribution of magmatic fluids to the hydrothermal solution was about 6 wt.%.","Two-dimensional numerical modeling demonstrates that the conceptual flow model for Creede is a viable representation of the ore-forming system. Critical hydrologic elements in this model are a low-permeability ($\\sim$10$\\sp{-12}$ cm$\\sp2)$ horizon overlying a permeable ($\\sim$10$\\sp{-9}$ cm$\\sp2)$ fracture system. This configuration promotes mineralization by focusing and prolonging mixing between topographically-driven groundwater and buoyancy-driven hydrothermal brines. Sensitivity analyses indicate that the conductive heat flux from the pluton was 500 $\\pm$ 200 h.f.u., and that the maximum vertical flow velocity was $\\sim$10$\\sp{-4}$ cm/sec. Modeling results confirm that hydrothermal brines could not have transported the sulfate sulfur found in the ores because of the long residence times within the hydrothermal plume. The model also illustrates problems with determining mineralization depths from fluid inclusion data, and suggests alternative interpretations of such data.","Made available in DSpace on 2011-05-07T11:52:11Z (GMT). No. of bitstreams: 2 license.txt: 4922 bytes, checksum: 910b249b4beec47e7ab768910c8f966f (MD5) 9329054.pdf: 9767086 bytes, checksum: caae4d7faf58b6eae04083f41f612847 (MD5) Previous issue date: 1993","Item marked as restricted to the 'UIUC Users [automated]' Group (id=2) by Howard Ding (hding2@illinois.edu) on 2011-05-07T14:33:36Z Item is restricted indefinitely.","Restriction data tranferred 2014-07-01T11:12:28-05:00 Original Data Group with Access UIUC Users [automated] Release Date: none Reason: ETDs are only available to UIUC Users without author permission","ETDs are only available to UIUC Users without author permission","U of I Only"]},{"key":"dc:title","label":"Title","values":["Numerical hydrologic modeling of the Creede epithermal ore-forming system, Colorado"]}]}],"canonical_facts":{"dc:contributor":["Bethke, Craig M."],"dc:creator":["Hayba, Daniel Owen"],"dc:date":["2011-05-07T11:52:11Z","10000-01-01","1993"],"dc:description":["One of the fundamental objectives of the extensive research on Creede district, Colorado, has been to determine the sources, pathways, and interactions of fluids involved in the genesis of the epithermal ores. From the large volume of data on the main period of mineralization, a well-constrained conceptual flow model has evolved. In this model, an intrusion at depth drove hydrothermal convection, and topography drove shallow groundwater flow. Fluids from at least three sources fed the system, and boiling and/or mixing promoted ore deposition. In this study, I examine the qualitative constraints on this model, derive new controls, and then use numerical methods to evaluate the hydrology.","To establish the boundaries of the paleo-system, I determined that the average topographic slope across the district was approximately 10%, and that the depth of hydrothermal circulation was 1.6 to $\\sim$3 km. A detailed fluid inclusion study of growth-banded sphalerite provides another important constraint by conclusively demonstrating that fluid mixing, rather than boiling, was the primary mechanism of ore deposition. Temperature and salinity variations indicate that a 285$\\sp\\circ$C hydrothermal brine ($\\sim$11.5 wt% NaCl eq.) mixed with dilute, 160$\\sp\\circ$C groundwater. I also estimate that the mass flux through the system was approximately 50 kg/sec, and that the size of the granitic heat source was at least 7.5 km$\\sp3$ ($\\sim$2.1 $\\times$ 10$\\sp{13}$ kg). The overall contribution of magmatic fluids to the hydrothermal solution was about 6 wt.%.","Two-dimensional numerical modeling demonstrates that the conceptual flow model for Creede is a viable representation of the ore-forming system. Critical hydrologic elements in this model are a low-permeability ($\\sim$10$\\sp{-12}$ cm$\\sp2)$ horizon overlying a permeable ($\\sim$10$\\sp{-9}$ cm$\\sp2)$ fracture system. This configuration promotes mineralization by focusing and prolonging mixing between topographically-driven groundwater and buoyancy-driven hydrothermal brines. Sensitivity analyses indicate that the conductive heat flux from the pluton was 500 $\\pm$ 200 h.f.u., and that the maximum vertical flow velocity was $\\sim$10$\\sp{-4}$ cm/sec. Modeling results confirm that hydrothermal brines could not have transported the sulfate sulfur found in the ores because of the long residence times within the hydrothermal plume. The model also illustrates problems with determining mineralization depths from fluid inclusion data, and suggests alternative interpretations of such data.","Made available in DSpace on 2011-05-07T11:52:11Z (GMT). No. of bitstreams: 2 license.txt: 4922 bytes, checksum: 910b249b4beec47e7ab768910c8f966f (MD5) 9329054.pdf: 9767086 bytes, checksum: caae4d7faf58b6eae04083f41f612847 (MD5) Previous issue date: 1993","Item marked as restricted to the 'UIUC Users [automated]' Group (id=2) by Howard Ding (hding2@illinois.edu) on 2011-05-07T14:33:36Z Item is restricted indefinitely.","Restriction data tranferred 2014-07-01T11:12:28-05:00 Original Data Group with Access UIUC Users [automated] Release Date: none Reason: ETDs are only available to UIUC Users without author permission","ETDs are only available to UIUC Users without author permission","U of I Only"],"dc:identifier":["AAI9329054","(UMI)AAI9329054","http://hdl.handle.net/2142/18944"],"dc:language":["eng"],"dc:rights":["Copyright 1993 Hayba, Daniel Owen"],"dc:subject":["Geology","Hydrology"],"dc:title":["Numerical hydrologic modeling of the Creede epithermal ore-forming system, Colorado"],"dc:type":["text"],"thesis:degree_discipline":["Geology"],"thesis:degree_level":["Dissertation"],"thesis:degree_name":["Ph.D."],"thesis:institution_name":["University of Illinois at Urbana-Champaign"]},"updated_at":"2026-07-22T22:25:12Z"}