37 Cordilleran Margin Evolution and Supercontinent Tectonics: From Pangea Assembly to North American Orogenesis (Posters)
This session integrates tectonics, petrology, geochronology, stratigraphy, and paleontology to illuminate how Paleo-Pacific plates drove subduction dynamics, crustal evolution, and paleogeographic reconstructions across the complex geological architecture of the American Cordilleras.
Friday, 24 April 2026
8:00 AM - 5:30 PM
LMH, 5th Floor Chapel
Jurassic paleoflora on the western margin of equatorial Pangea: a comparative approach.
Paper number: 37-11
Program: Technical Sessions
Time: 8:00 AM – 8:00 AM
Authors
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Erika OrtizUniversidad Nacional Autonoma de México, Mexico
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Miguel FloresUniversidad Nacional Autónoma de México, Circuito de la Investigación Científica, Avenida Universidad 3000
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Diego LozanoUniversidad Nacional Autónoma de México, Ex Fábrica de San Manuel 8-A, San Miguel Contla, Tlaxcala
Abstract
The current study of the western fragmentation of Pangea allows proposing the tectono-stratigraphic domains North (ND) and South (SD). The DN includes the Otlaltepec, Ayuquila and Tecomazúchil formations in a stratigraphic range from Bajocian to Callovian; while the SD includes the Rosario, Cualac, Zorrillo and Zorrillo-Taberna undifferentiated units from Toarcian to Bajocian. The paleoenvironmental proposal for both domains is supported by geomorphological and sedimentary factors. In the DN a dry environment prevailed in contrast to the DS where the environment was humid. The present study aims to analyze the paleobotanical data available in both domains to contrast with previous paleoenvironmental proposals. For this purpose, taxonomic richness was quantified, understanding that the foliar anatomy reflects the environmental conditions in which the different plant communities were established. The proxy used for this analysis was leaf area. The databases of the Paleontology Collection of the Facultad de Estudios Superiores Zaragoza (which includes 1311 leaf elements) were used and complemented with bibliographic information. The paleofloristic richness recorded in the DN consists of 17 species, 11 genera and four orders. The leaf area of vegetative structures is dominated by the category Microphilous I (0.082 to 1.36cm2). While in the DS, a richness of 40 species was recorded, grouped in 15 genera and seven orders. The leaf area is mainly represented by the categories Microphyll I and II, with a range of 0.082-3.4835 cm2 with the exception of the genus Mexiglossa that presents the category Notophyll reaching up to 57cm2. Therefore, these data indicate that the DN presented a lower richness and leaf area compared to the DS. In this sense, the paleobotanical results agree with the paleoenvironmental estimation based on geomorphological and sedimentary factors. It should be noted that the differences in richness and leaf area between the two domains display how the tectonic processes can be determinant in the distribution of the speciessince both widely distributed and endemic species were recorded.
Geological Society of America Abstracts with Programs. Vol. 58, No. 3
doi: 10.1130/abs/2026CD-410775
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