U-Pb geochronology and Hf isotopes of the Grenvillian Río Hondo gneisses, Puebla: redefining the western edge of Oaxaquia
In situ Río Hondo (Puebla, southern Mexico) gneiss samples, as well as clastic samples recovered from the nearby-outcropping latest Paleozoic Matzitzi Formation, a fluvial unit mainly sourced by Grenvillian rocks, were historically interpreted as representative of the northernmost exposures of the...
Saved in:
| Main Authors: | , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Universidad Nacional Autónoma de México
2024-03-01
|
| Series: | Revista Mexicana de Ciencias Geológicas |
| Subjects: | |
| Online Access: | https://rmcg.unam.mx/index.php/rmcg/article/view/1760 |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| _version_ | 1849336822015983616 |
|---|---|
| author | Luigi A. Solari Mariano Elías Herrera Guillermo Espejo-Bautista Mariana Jaramillo-Jaramillo María del Consuelo Macías Romo Carlos Ortega-Obregón |
| author_facet | Luigi A. Solari Mariano Elías Herrera Guillermo Espejo-Bautista Mariana Jaramillo-Jaramillo María del Consuelo Macías Romo Carlos Ortega-Obregón |
| author_sort | Luigi A. Solari |
| collection | DOAJ |
| description |
In situ Río Hondo (Puebla, southern Mexico) gneiss samples, as well as clastic samples recovered from the nearby-outcropping latest Paleozoic Matzitzi Formation, a fluvial unit mainly sourced by Grenvillian rocks, were historically interpreted as representative of the northernmost exposures of the Oaxacan Complex, the largest outcrop of ortho and metasedimentary units, made up of mostly 1.0–1.3 Ga protoliths, affected cfby local migmatization (ca. 1.1 Ga) and granulite facies metamorphism at ca. 0.98 Ga, constituting the most prominent outcrop of the Oaxaquia microcontinent.
U-Pb geochronology and Lu-Hf isotopic determinations in zircon by LA-(MC)-ICP-MS were performed on both in situ and clast samples. In situ basement samples record a ca. 1.2 crystallization event, together with a younger one at ca. 1.02 Ga. both lacking inherited >1.3 Ga components. The clasts have an unimodal zircon U-Pb age distribution, recording a crystallization event at ca. 1.2–1.27 Ga. Scarce inherited zircon cores between ca. 1.4–1.6 Ga were found, with only a few samples with a broader age distribution, suggesting a detrital protolith with zircon cores as old as ca. 1.8 and 2.4 Ga. No zircon overgrowths or geochemical-petrographic evidences are indicative of granulite metamorphism. Furthermore, all the studied metaigneous samples show discordant zircon ages produced by Pb loss events barely constrained between the latest Paleozoic to the Mesozoic.
Hf isotopes reveal that zircon crystals from clasts have a range of εHf (1.25 Ga) ≈+1 to +5 and yield Hf model ages from 1.7 to 1.9 Ga. On the other hand, the The zircon Hf isotopes of one analyzed basement sample reveal a higher range of εHf (1.25 Ga) ≈+7 to +9, and Hf model ages from 1.5 to 1.6 Ga.
Both ≈1.2 Ga and 1.02 Ga events are consistent with magmatic ages previously documented elsewhere in Oaxaquia, interpreted as indicating portions of the NW Amazonia-Oaxaquia arc system with cratonic influence or to slices of Baltica thrust over Oaxaquia during the Grenville orogeny. However, the absence of granulite facies indicators, such as zircon metamorphic ages and/or granulite paragenesis (typically, in other Oaxaquia samples, orthopyroxene and garnet) are interpreted as prime evidence that the studied samples didn’t undergo such high grade of metamorphism. Río Hondo gneisses, as this sequence is informally named, must belong to a source that had the influence of an older continental crust and can be tentatively associated either with rocks recently described in the Sierra de Juárez, or those belonging to the central basement of the Maya block, currently exposed farther to the SE in Chiapas.
|
| format | Article |
| id | doaj-art-d7cae06cb1854301972bed3f9534cf73 |
| institution | Kabale University |
| issn | 1026-8774 2007-2902 |
| language | English |
| publishDate | 2024-03-01 |
| publisher | Universidad Nacional Autónoma de México |
| record_format | Article |
| series | Revista Mexicana de Ciencias Geológicas |
| spelling | doaj-art-d7cae06cb1854301972bed3f9534cf732025-08-20T03:44:52ZengUniversidad Nacional Autónoma de MéxicoRevista Mexicana de Ciencias Geológicas1026-87742007-29022024-03-0141110.22201/cgeo.20072902e.2024.1.1760U-Pb geochronology and Hf isotopes of the Grenvillian Río Hondo gneisses, Puebla: redefining the western edge of OaxaquiaLuigi A. Solari0Mariano Elías Herrera1Guillermo Espejo-Bautista2Mariana Jaramillo-Jaramillo3María del Consuelo Macías Romo4Carlos Ortega-Obregón5Instituto de Geociencias, Universidad Nacional Autónoma de México, Campus Juriquilla, 76230 Juriquilla, Querétaro (QRO), Mexico.Instituto de Geología, Universidad Nacional Autónoma de México, Ciudad Universitaria, 04510 Del. Coyoacán, Mexico City, Mexico.Instituto de Geociencias, Universidad Nacional Autónoma de México, Campus Juriquilla, 76230 Juriquilla, Querétaro (QRO), Mexico.Instituto de Geociencias, Universidad Nacional Autónoma de México, Campus Juriquilla, 76230 Juriquilla, Querétaro (QRO), Mexico.Instituto de Geología, Universidad Nacional Autónoma de México, Ciudad Universitaria, 04510 Del. Coyoacán, Mexico City, Mexico.Instituto de Geociencias, Universidad Nacional Autónoma de México, Campus Juriquilla, 76230 Juriquilla, Querétaro (QRO), Mexico. In situ Río Hondo (Puebla, southern Mexico) gneiss samples, as well as clastic samples recovered from the nearby-outcropping latest Paleozoic Matzitzi Formation, a fluvial unit mainly sourced by Grenvillian rocks, were historically interpreted as representative of the northernmost exposures of the Oaxacan Complex, the largest outcrop of ortho and metasedimentary units, made up of mostly 1.0–1.3 Ga protoliths, affected cfby local migmatization (ca. 1.1 Ga) and granulite facies metamorphism at ca. 0.98 Ga, constituting the most prominent outcrop of the Oaxaquia microcontinent. U-Pb geochronology and Lu-Hf isotopic determinations in zircon by LA-(MC)-ICP-MS were performed on both in situ and clast samples. In situ basement samples record a ca. 1.2 crystallization event, together with a younger one at ca. 1.02 Ga. both lacking inherited >1.3 Ga components. The clasts have an unimodal zircon U-Pb age distribution, recording a crystallization event at ca. 1.2–1.27 Ga. Scarce inherited zircon cores between ca. 1.4–1.6 Ga were found, with only a few samples with a broader age distribution, suggesting a detrital protolith with zircon cores as old as ca. 1.8 and 2.4 Ga. No zircon overgrowths or geochemical-petrographic evidences are indicative of granulite metamorphism. Furthermore, all the studied metaigneous samples show discordant zircon ages produced by Pb loss events barely constrained between the latest Paleozoic to the Mesozoic. Hf isotopes reveal that zircon crystals from clasts have a range of εHf (1.25 Ga) ≈+1 to +5 and yield Hf model ages from 1.7 to 1.9 Ga. On the other hand, the The zircon Hf isotopes of one analyzed basement sample reveal a higher range of εHf (1.25 Ga) ≈+7 to +9, and Hf model ages from 1.5 to 1.6 Ga. Both ≈1.2 Ga and 1.02 Ga events are consistent with magmatic ages previously documented elsewhere in Oaxaquia, interpreted as indicating portions of the NW Amazonia-Oaxaquia arc system with cratonic influence or to slices of Baltica thrust over Oaxaquia during the Grenville orogeny. However, the absence of granulite facies indicators, such as zircon metamorphic ages and/or granulite paragenesis (typically, in other Oaxaquia samples, orthopyroxene and garnet) are interpreted as prime evidence that the studied samples didn’t undergo such high grade of metamorphism. Río Hondo gneisses, as this sequence is informally named, must belong to a source that had the influence of an older continental crust and can be tentatively associated either with rocks recently described in the Sierra de Juárez, or those belonging to the central basement of the Maya block, currently exposed farther to the SE in Chiapas. https://rmcg.unam.mx/index.php/rmcg/article/view/1760Grenville orogenOaxacan ComplexMexicoU-Pb geochronologyHf isotopes |
| spellingShingle | Luigi A. Solari Mariano Elías Herrera Guillermo Espejo-Bautista Mariana Jaramillo-Jaramillo María del Consuelo Macías Romo Carlos Ortega-Obregón U-Pb geochronology and Hf isotopes of the Grenvillian Río Hondo gneisses, Puebla: redefining the western edge of Oaxaquia Revista Mexicana de Ciencias Geológicas Grenville orogen Oaxacan Complex Mexico U-Pb geochronology Hf isotopes |
| title | U-Pb geochronology and Hf isotopes of the Grenvillian Río Hondo gneisses, Puebla: redefining the western edge of Oaxaquia |
| title_full | U-Pb geochronology and Hf isotopes of the Grenvillian Río Hondo gneisses, Puebla: redefining the western edge of Oaxaquia |
| title_fullStr | U-Pb geochronology and Hf isotopes of the Grenvillian Río Hondo gneisses, Puebla: redefining the western edge of Oaxaquia |
| title_full_unstemmed | U-Pb geochronology and Hf isotopes of the Grenvillian Río Hondo gneisses, Puebla: redefining the western edge of Oaxaquia |
| title_short | U-Pb geochronology and Hf isotopes of the Grenvillian Río Hondo gneisses, Puebla: redefining the western edge of Oaxaquia |
| title_sort | u pb geochronology and hf isotopes of the grenvillian rio hondo gneisses puebla redefining the western edge of oaxaquia |
| topic | Grenville orogen Oaxacan Complex Mexico U-Pb geochronology Hf isotopes |
| url | https://rmcg.unam.mx/index.php/rmcg/article/view/1760 |
| work_keys_str_mv | AT luigiasolari upbgeochronologyandhfisotopesofthegrenvillianriohondogneissespueblaredefiningthewesternedgeofoaxaquia AT marianoeliasherrera upbgeochronologyandhfisotopesofthegrenvillianriohondogneissespueblaredefiningthewesternedgeofoaxaquia AT guillermoespejobautista upbgeochronologyandhfisotopesofthegrenvillianriohondogneissespueblaredefiningthewesternedgeofoaxaquia AT marianajaramillojaramillo upbgeochronologyandhfisotopesofthegrenvillianriohondogneissespueblaredefiningthewesternedgeofoaxaquia AT mariadelconsuelomaciasromo upbgeochronologyandhfisotopesofthegrenvillianriohondogneissespueblaredefiningthewesternedgeofoaxaquia AT carlosortegaobregon upbgeochronologyandhfisotopesofthegrenvillianriohondogneissespueblaredefiningthewesternedgeofoaxaquia |