{"id":{"repo_id":"colo-mines","oai_identifier":"oai:repository.mines.edu:11124/71537"},"canonical_url":"https://search.dev.ndltd.org/etd/colo-mines/oai:repository.mines.edu:11124/71537","repository":{"repo_id":"colo-mines","name":"Colorado School of Mines","base_url":"https://repository.mines.edu/server/oai/request"},"display":{"title":"El Espino Iron-Oxide Copper Gold District, Coastal Cordillera of North-Central Chile, The","abstract":"The El Espino Iron Oxide Copper Gold (IOCG) mining district is located in the Coastal Cordillera of north-central Chile and includes the El Espino deposit which has a measured plus indicated geologic resource of 145 Mt at 0.55 percent Cu and 0.22 g/t Au. Mineralized bodies are distributed in a 7 x 10 km2 area and range in geometry from single veins to stockworks and breccias to manto-type deposits. The ore bodies are hosted primarily by Early Cretaceous volcanic, volcaniclastic, and sedimentary units, with fewer mineralized zones within a Late Cretaceous multi-phase intermediate pluton. Hydrothermal alteration and mineralization was coeval with plutonism at 88 Ma. Both plutonism and hydrothermal alteration/mineralization were localized within a dilatational jog along a major transtensional north-south fault system that controlled the distribution of alteration and mineralization. Sodic alteration is the most extensive style of alteration in the district and is best developed at stratigraphically deep levels. Sodic-calcic alteration is spatially more restricted and grades inward into a calcic alteration assemblage at intermediate levels, displaying a zoned pattern around the Late Cretaceous pluton. Potassic alteration is relatively restricted in extent and is not always spatially related to sodic, sodic-calcic, and calcic alteration zones. Late hydrolytic alteration is concentrated in the middle and upper portions of the stratigraphis sequence while argillic alteration is restricted to the highest part of the alteration system. Iron oxides and sulfides are largely confined to calcic and hydrolytic alteration assemblages. The fluids responsible for sulfide precipitation ranged in temperature from 350 to 425 degrees C with salinities between 32 and 34 wt. NaCl equivalent. Mineralization probably took place at a minimum depth of 3-4 km. Early high temperature fluids were magmatically derived while later hydrothermal fluids may have contained mixed meteoric fluids with marine-derived sulfate. The close spatial and temporal association of alteration zones with a plutonic suite suggests that plutons provided heat and contributed fluid and sulfur to the hydrothermal system. Lithogeochemical mass balance analyses indicate that early and deep alteration events leached elements that were fixed at later times higher in the stratigraphic sequence during the waning stages of hydrothermal alteration.","abstract_html":"The El Espino Iron Oxide Copper Gold (IOCG) mining district is located in the Coastal Cordillera of north-central Chile and includes the El Espino deposit which has a measured plus indicated geologic resource of 145 Mt at 0.55 percent Cu and 0.22 g/t Au. Mineralized bodies are distributed in a 7 x 10 km2 area and range in geometry from single veins to stockworks and breccias to manto-type deposits. The ore bodies are hosted primarily by Early Cretaceous volcanic, volcaniclastic, and sedimentary units, with fewer mineralized zones within a Late Cretaceous multi-phase intermediate pluton. Hydrothermal alteration and mineralization was coeval with plutonism at 88 Ma. Both plutonism and hydrothermal alteration/mineralization were localized within a dilatational jog along a major transtensional north-south fault system that controlled the distribution of alteration and mineralization. Sodic alteration is the most extensive style of alteration in the district and is best developed at stratigraphically deep levels. Sodic-calcic alteration is spatially more restricted and grades inward into a calcic alteration assemblage at intermediate levels, displaying a zoned pattern around the Late Cretaceous pluton. Potassic alteration is relatively restricted in extent and is not always spatially related to sodic, sodic-calcic, and calcic alteration zones. Late hydrolytic alteration is concentrated in the middle and upper portions of the stratigraphis sequence while argillic alteration is restricted to the highest part of the alteration system. Iron oxides and sulfides are largely confined to calcic and hydrolytic alteration assemblages. The fluids responsible for sulfide precipitation ranged in temperature from 350 to 425 degrees C with salinities between 32 and 34 wt. NaCl equivalent. Mineralization probably took place at a minimum depth of 3-4 km. Early high temperature fluids were magmatically derived while later hydrothermal fluids may have contained mixed meteoric fluids with marine-derived sulfate. The close spatial and temporal association of alteration zones with a plutonic suite suggests that plutons provided heat and contributed fluid and sulfur to the hydrothermal system. Lithogeochemical mass balance analyses indicate that early and deep alteration events leached elements that were fixed at later times higher in the stratigraphic sequence during the waning stages of hydrothermal alteration.","abstract_has_math":false,"creators":["Lopez Orrego, Gloria P."],"institution":"Colorado School of Mines. Arthur Lakes Library","degree_name":"Doctor of Philosophy (Ph.D.)","degree_level":"Doctoral","degree_discipline":"Geology and Geological Engineering","degree_department":null,"school":null,"contributors":[],"advisors":["Hitzman, Murray Walter"],"committee_chairs":[],"committee_members":["Nelson, Eric P., 1951-","Monecke, Thomas","Humphrey, John D.","Miller, Hugh B."],"year":2012,"date_issued":"2012","date_published":"2012","updated_at":"2026-07-24T01:41:48Z","subjects":["Coastal Cordillera","Chile","Cretaceous","IOCG deposit"],"languages":["eng","English"],"rights":["Copyright of the original work is retained by the author."],"rights_urls":[],"identifier_entries":[{"key":"dc:identifier","label":"Identifier","values":["T 7121"],"render_values":[{"text":"T 7121","href":null,"code":true}]}]},"links":{"outbound_url":"https://hdl.handle.net/11124/71537","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.advisor","label":"Advisor","values":["Hitzman, Murray Walter"]},{"key":"dc:contributor.committeemember","label":"Committee Member","values":["Nelson, Eric P., 1951-","Monecke, Thomas","Humphrey, John D.","Miller, Hugh B."]},{"key":"dc:creator","label":"Author","values":["Lopez Orrego, Gloria P."]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2007-01-03T08:26:15Z","2022-02-03T11:51:07Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2007-01-03T08:26:15Z","2022-02-03T11:51:07Z"]},{"key":"dc:date.issued","label":"Date","values":["2012"]},{"key":"dc:publisher","label":"Institution","values":["Colorado School of Mines. 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Mineralized bodies are distributed in a 7 x 10 km2 area and range in geometry from single veins to stockworks and breccias to manto-type deposits. The ore bodies are hosted primarily by Early Cretaceous volcanic, volcaniclastic, and sedimentary units, with fewer mineralized zones within a Late Cretaceous multi-phase intermediate pluton. Hydrothermal alteration and mineralization was coeval with plutonism at 88 Ma. Both plutonism and hydrothermal alteration/mineralization were localized within a dilatational jog along a major transtensional north-south fault system that controlled the distribution of alteration and mineralization. Sodic alteration is the most extensive style of alteration in the district and is best developed at stratigraphically deep levels. Sodic-calcic alteration is spatially more restricted and grades inward into a calcic alteration assemblage at intermediate levels, displaying a zoned pattern around the Late Cretaceous pluton. Potassic alteration is relatively restricted in extent and is not always spatially related to sodic, sodic-calcic, and calcic alteration zones. Late hydrolytic alteration is concentrated in the middle and upper portions of the stratigraphis sequence while argillic alteration is restricted to the highest part of the alteration system. Iron oxides and sulfides are largely confined to calcic and hydrolytic alteration assemblages. The fluids responsible for sulfide precipitation ranged in temperature from 350 to 425 degrees C with salinities between 32 and 34 wt. NaCl equivalent. Mineralization probably took place at a minimum depth of 3-4 km. Early high temperature fluids were magmatically derived while later hydrothermal fluids may have contained mixed meteoric fluids with marine-derived sulfate. The close spatial and temporal association of alteration zones with a plutonic suite suggests that plutons provided heat and contributed fluid and sulfur to the hydrothermal system. Lithogeochemical mass balance analyses indicate that early and deep alteration events leached elements that were fixed at later times higher in the stratigraphic sequence during the waning stages of hydrothermal alteration."]},{"key":"dc:format.medium","label":"Dc Format Medium","values":["born digital","doctoral dissertations"]},{"key":"dc:title","label":"Title","values":["El Espino Iron-Oxide Copper Gold District, Coastal Cordillera of North-Central Chile, The"]}]}],"canonical_facts":{"dc:contributor.advisor":["Hitzman, Murray Walter"],"dc:contributor.committeemember":["Nelson, Eric P., 1951-","Monecke, Thomas","Humphrey, John D.","Miller, Hugh B."],"dc:creator":["Lopez Orrego, Gloria P."],"dc:date.accessioned":["2007-01-03T08:26:15Z","2022-02-03T11:51:07Z"],"dc:date.available":["2007-01-03T08:26:15Z","2022-02-03T11:51:07Z"],"dc:date.issued":["2012"],"dc:description":["2012 Fall.","Includes illustrations (some color), maps (some color).","Includes bibliographical references."],"dc:description.abstract":["The El Espino Iron Oxide Copper Gold (IOCG) mining district is located in the Coastal Cordillera of north-central Chile and includes the El Espino deposit which has a measured plus indicated geologic resource of 145 Mt at 0.55 percent Cu and 0.22 g/t Au. Mineralized bodies are distributed in a 7 x 10 km2 area and range in geometry from single veins to stockworks and breccias to manto-type deposits. The ore bodies are hosted primarily by Early Cretaceous volcanic, volcaniclastic, and sedimentary units, with fewer mineralized zones within a Late Cretaceous multi-phase intermediate pluton. Hydrothermal alteration and mineralization was coeval with plutonism at 88 Ma. Both plutonism and hydrothermal alteration/mineralization were localized within a dilatational jog along a major transtensional north-south fault system that controlled the distribution of alteration and mineralization. Sodic alteration is the most extensive style of alteration in the district and is best developed at stratigraphically deep levels. Sodic-calcic alteration is spatially more restricted and grades inward into a calcic alteration assemblage at intermediate levels, displaying a zoned pattern around the Late Cretaceous pluton. Potassic alteration is relatively restricted in extent and is not always spatially related to sodic, sodic-calcic, and calcic alteration zones. Late hydrolytic alteration is concentrated in the middle and upper portions of the stratigraphis sequence while argillic alteration is restricted to the highest part of the alteration system. Iron oxides and sulfides are largely confined to calcic and hydrolytic alteration assemblages. The fluids responsible for sulfide precipitation ranged in temperature from 350 to 425 degrees C with salinities between 32 and 34 wt. NaCl equivalent. Mineralization probably took place at a minimum depth of 3-4 km. Early high temperature fluids were magmatically derived while later hydrothermal fluids may have contained mixed meteoric fluids with marine-derived sulfate. The close spatial and temporal association of alteration zones with a plutonic suite suggests that plutons provided heat and contributed fluid and sulfur to the hydrothermal system. Lithogeochemical mass balance analyses indicate that early and deep alteration events leached elements that were fixed at later times higher in the stratigraphic sequence during the waning stages of hydrothermal alteration."],"dc:format.medium":["born digital","doctoral dissertations"],"dc:identifier":["T 7121"],"dc:identifier.uri":["https://hdl.handle.net/11124/71537"],"dc:language":["English"],"dc:language.iso":["eng"],"dc:publisher":["Colorado School of Mines. Arthur Lakes Library"],"dc:rights":["Copyright of the original work is retained by the author."],"dc:subject":["Coastal Cordillera","Chile","Cretaceous","IOCG deposit"],"dc:title":["El Espino Iron-Oxide Copper Gold District, Coastal Cordillera of North-Central Chile, The"],"dc:type":["Text"],"thesis:degree_discipline":["Geology and Geological Engineering"],"thesis:degree_level":["Doctoral"],"thesis:degree_name":["Doctor of Philosophy (Ph.D.)"],"thesis:institution_name":["Colorado School of Mines"]},"updated_at":"2026-07-24T01:41:48Z"}