{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/21663"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/21663","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"Potassic alteration of Cambrian-Ordovician sandstones and Precambrian basement rocks of the North American midcontinent","abstract":"In Hole UPH-3 the Mt. Simon Sandstone contains three distinct diagenetic zones: an upper K-feldspar overgrowth zone, an underlying sericite zone, and a lowermost feldspar zone. Uppermost Precambrian basement exhibits potassic alteration similar to the overlying Mt. Simon Sandstone. Sericite in the basement rock was likely formed during the same episode as in the Mt. Simon Sandstone, based on similar $\\delta\\sp{18}$O values. A K/Ar date of 394.6 $\\pm$ 6 Ma (Early Devonian) was obtained from authigenic K-feldspar of the basal Mt. Simon Sandstone. K/AR dates of 271.3 $\\pm$ 4.6 Ma (Permian), 254.4 $\\pm$ 4.6 Ma (Permian), and 214.1 $\\pm$ 4.6 Ma (Triassic) were obtained from authigenic sericite of the Mt. Simon Sandstone. Similar potassic diagenesis of Mt. Simon Sandstone in UPH-3 occurs on a regional scale in the Upper Midcontinent area. Here, two widespread zones of K-feldspar and sericite occur. A K/Ar date of 276 $\\pm$ 10 Ma (Permian) was obtained on sericite from one locality in Iowa, which is separated by 300 km from Hole UPH-3. The episodic K diagenesis of the Mt. Simon Sandstone is attributed to regional migration of basinal brines caused by groundwater recharge on uplifted arches.","abstract_html":"In Hole UPH-3 the Mt. Simon Sandstone contains three distinct diagenetic zones: an upper K-feldspar overgrowth zone, an underlying sericite zone, and a lowermost feldspar zone. Uppermost Precambrian basement exhibits potassic alteration similar to the overlying Mt. Simon Sandstone. Sericite in the basement rock was likely formed during the same episode as in the Mt. Simon Sandstone, based on similar <span class=\"etd-inline-math\">&delta;\\sp{18}</span>O values. A K/Ar date of 394.6 $\\pm$ 6 Ma (Early Devonian) was obtained from authigenic K-feldspar of the basal Mt. Simon Sandstone. K/AR dates of 271.3 $\\pm$ 4.6 Ma (Permian), 254.4 $\\pm$ 4.6 Ma (Permian), and 214.1 $\\pm$ 4.6 Ma (Triassic) were obtained from authigenic sericite of the Mt. Simon Sandstone. Similar potassic diagenesis of Mt. Simon Sandstone in UPH-3 occurs on a regional scale in the Upper Midcontinent area. Here, two widespread zones of K-feldspar and sericite occur. A K/Ar date of 276 $\\pm$ 10 Ma (Permian) was obtained on sericite from one locality in Iowa, which is separated by 300 km from Hole UPH-3. The episodic K diagenesis of the Mt. Simon Sandstone is attributed to regional migration of basinal brines caused by groundwater recharge on uplifted arches.","abstract_has_math":true,"creators":["Duffin, Michael Eugene"],"institution":"University of Illinois at Urbana-Champaign","degree_name":"Ph.D.","degree_level":"Dissertation","degree_discipline":"Geology","degree_department":null,"school":null,"contributors":["Hay, Richard L."],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2011,"date_issued":"2011-05-07T13:15:25Z","date_published":"2011-05-07T13:15:25Z","updated_at":"2026-07-22T22:25:18Z","subjects":["Geochemistry"],"languages":["eng"],"rights":["Copyright 1990 Duffin, Michael Eugene"],"rights_urls":[],"identifier_entries":[{"key":"dc:identifier","label":"Identifier","values":["AAI9021675","(UMI)AAI9021675"],"render_values":[{"text":"AAI9021675","href":null,"code":true},{"text":"(UMI)AAI9021675","href":null,"code":true}]}]},"links":{"outbound_url":"http://hdl.handle.net/2142/21663","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Hay, Richard L."]},{"key":"dc:creator","label":"Author","values":["Duffin, Michael Eugene"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2011-05-07T13:15:25Z","10000-01-01","1990"]},{"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":["Geochemistry"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["eng"]},{"key":"dc:rights","label":"Dc Rights","values":["Copyright 1990 Duffin, Michael Eugene"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["AAI9021675","(UMI)AAI9021675","http://hdl.handle.net/2142/21663"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["In Hole UPH-3 the Mt. Simon Sandstone contains three distinct diagenetic zones: an upper K-feldspar overgrowth zone, an underlying sericite zone, and a lowermost feldspar zone. Uppermost Precambrian basement exhibits potassic alteration similar to the overlying Mt. Simon Sandstone. Sericite in the basement rock was likely formed during the same episode as in the Mt. Simon Sandstone, based on similar $\\delta\\sp{18}$O values. A K/Ar date of 394.6 $\\pm$ 6 Ma (Early Devonian) was obtained from authigenic K-feldspar of the basal Mt. Simon Sandstone. K/AR dates of 271.3 $\\pm$ 4.6 Ma (Permian), 254.4 $\\pm$ 4.6 Ma (Permian), and 214.1 $\\pm$ 4.6 Ma (Triassic) were obtained from authigenic sericite of the Mt. Simon Sandstone. Similar potassic diagenesis of Mt. Simon Sandstone in UPH-3 occurs on a regional scale in the Upper Midcontinent area. Here, two widespread zones of K-feldspar and sericite occur. A K/Ar date of 276 $\\pm$ 10 Ma (Permian) was obtained on sericite from one locality in Iowa, which is separated by 300 km from Hole UPH-3. The episodic K diagenesis of the Mt. Simon Sandstone is attributed to regional migration of basinal brines caused by groundwater recharge on uplifted arches.","A K/Ar date of 448 $\\pm$ 16 Ma (Late Ordovician) was obtained for wholly authigenic K-feldspar from Lower Ordovician Prairie du Chien sandstones in Hole UPH-3. This date if coeval with a Late Ordovician K/Ca date of authigenic K-feldspar from basal St. Peter Sandstone in Wisconsin, suggesting that there may have been a regional episode of K-feldspar authigenesis in the Upper Mississippi Valley during Late Ordovician time.","Authigenic K-feldspar occurs in alteration profiles in uppermost Precambrian basement rocks at several localities of the continent. The K-feldspar has been identified in eight states. It is monoclinic or triclinic by X-ray diffraction, of end-member composition, and may compose 63% of rock volume in altered samples. A sample of wholly authigenic K-feldspar from altered basement in southern Illinois gives a K/Ar date of 549 $\\pm$ 18 Ma (Early Cambrian). This date is in agreement with Early Cambrian Rb/Sr dates for potassic alteration of uppermost Precambrian basement in Ohio. Dated authigenic K-feldspars from both Ohio and Illinois give identical $\\delta\\sp{18}$O values of 17.5%, suggesting formation from similar fluids. Concordancy of both dates and $\\delta\\sp{18}$O values suggest that the K-feldspar formed during an episode of potassic alteration during Early Cambrian time that affected much of continental North America.","Made available in DSpace on 2011-05-07T13:15:25Z (GMT). No. of bitstreams: 2 license.txt: 4922 bytes, checksum: 910b249b4beec47e7ab768910c8f966f (MD5) 9021675.pdf: 5270333 bytes, checksum: 1b55114a91f050e08b71a20a9ce03ca2 (MD5) Previous issue date: 1990","Item marked as restricted to the 'UIUC Users [automated]' Group (id=2) by Howard Ding (hding2@illinois.edu) on 2011-05-07T14:52:22Z Item is restricted indefinitely.","Restriction data tranferred 2014-07-01T11:24:06-05:00 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":["Potassic alteration of Cambrian-Ordovician sandstones and Precambrian basement rocks of the North American midcontinent"]}]}],"canonical_facts":{"dc:contributor":["Hay, Richard L."],"dc:creator":["Duffin, Michael Eugene"],"dc:date":["2011-05-07T13:15:25Z","10000-01-01","1990"],"dc:description":["In Hole UPH-3 the Mt. Simon Sandstone contains three distinct diagenetic zones: an upper K-feldspar overgrowth zone, an underlying sericite zone, and a lowermost feldspar zone. Uppermost Precambrian basement exhibits potassic alteration similar to the overlying Mt. Simon Sandstone. Sericite in the basement rock was likely formed during the same episode as in the Mt. Simon Sandstone, based on similar $\\delta\\sp{18}$O values. A K/Ar date of 394.6 $\\pm$ 6 Ma (Early Devonian) was obtained from authigenic K-feldspar of the basal Mt. Simon Sandstone. K/AR dates of 271.3 $\\pm$ 4.6 Ma (Permian), 254.4 $\\pm$ 4.6 Ma (Permian), and 214.1 $\\pm$ 4.6 Ma (Triassic) were obtained from authigenic sericite of the Mt. Simon Sandstone. Similar potassic diagenesis of Mt. Simon Sandstone in UPH-3 occurs on a regional scale in the Upper Midcontinent area. Here, two widespread zones of K-feldspar and sericite occur. A K/Ar date of 276 $\\pm$ 10 Ma (Permian) was obtained on sericite from one locality in Iowa, which is separated by 300 km from Hole UPH-3. The episodic K diagenesis of the Mt. Simon Sandstone is attributed to regional migration of basinal brines caused by groundwater recharge on uplifted arches.","A K/Ar date of 448 $\\pm$ 16 Ma (Late Ordovician) was obtained for wholly authigenic K-feldspar from Lower Ordovician Prairie du Chien sandstones in Hole UPH-3. This date if coeval with a Late Ordovician K/Ca date of authigenic K-feldspar from basal St. Peter Sandstone in Wisconsin, suggesting that there may have been a regional episode of K-feldspar authigenesis in the Upper Mississippi Valley during Late Ordovician time.","Authigenic K-feldspar occurs in alteration profiles in uppermost Precambrian basement rocks at several localities of the continent. The K-feldspar has been identified in eight states. It is monoclinic or triclinic by X-ray diffraction, of end-member composition, and may compose 63% of rock volume in altered samples. A sample of wholly authigenic K-feldspar from altered basement in southern Illinois gives a K/Ar date of 549 $\\pm$ 18 Ma (Early Cambrian). This date is in agreement with Early Cambrian Rb/Sr dates for potassic alteration of uppermost Precambrian basement in Ohio. Dated authigenic K-feldspars from both Ohio and Illinois give identical $\\delta\\sp{18}$O values of 17.5%, suggesting formation from similar fluids. Concordancy of both dates and $\\delta\\sp{18}$O values suggest that the K-feldspar formed during an episode of potassic alteration during Early Cambrian time that affected much of continental North America.","Made available in DSpace on 2011-05-07T13:15:25Z (GMT). No. of bitstreams: 2 license.txt: 4922 bytes, checksum: 910b249b4beec47e7ab768910c8f966f (MD5) 9021675.pdf: 5270333 bytes, checksum: 1b55114a91f050e08b71a20a9ce03ca2 (MD5) Previous issue date: 1990","Item marked as restricted to the 'UIUC Users [automated]' Group (id=2) by Howard Ding (hding2@illinois.edu) on 2011-05-07T14:52:22Z Item is restricted indefinitely.","Restriction data tranferred 2014-07-01T11:24:06-05:00 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":["AAI9021675","(UMI)AAI9021675","http://hdl.handle.net/2142/21663"],"dc:language":["eng"],"dc:rights":["Copyright 1990 Duffin, Michael Eugene"],"dc:subject":["Geochemistry"],"dc:title":["Potassic alteration of Cambrian-Ordovician sandstones and Precambrian basement rocks of the North American midcontinent"],"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":"2026-07-22T22:25:18Z"}