Journal of Archaeological Science: Reports 44 (2022) 103532 2352-409X/© 2022 Elsevier Ltd. All rights reserved. Palynological analysis of an archaeological chinampa in Xochimilco (Basin of Mexico). Construction technology and agricultural production Sara Rosales-Torres a, * , Laura E. Beramendi-Orosco b, c, * , Emily McClung de Tapia d , Guillermo Acosta-Ochoa d a Posgrado en Ciencias de la Tierra, Universidad Nacional Aut´ onoma de M´ exico, Ciudad de M´ exico 04510, Mexico b Instituto de Geología, Universidad Nacional Aut´ onoma de M´ exico, Ciudad de M´ exico 04510, Mexico c Laboratorio Nacional de Geoquímica y Mineralogía, Universidad Nacional Aut´ onoma de M´ exico, Ciudad de M´ exico 04510, Mexico d Instituto de Investigaciones Antropol´ ogicas, Universidad Nacional Aut´ onoma de M´ exico, Ciudad de M´ exico 04510, Mexico A R T I C L E INFO Keywords: Chinampa Construction Agricultural Xochimilco Palynological analysis ABSTRACT In order to better understand the construction techniques used in archaeological chinampas excavated at San Gregorio Atlapulco, Xochimilco (located in the southern Basin of Mexico), modifed standard techniques for the extraction of palynomorphs were applied. The palynological assemblage recovered from the archaeological chinampa and adjacent canal profles suggests that the local and regional vegetation present in the Basin of Mexico consisted of halophilic and aquatic vegetation, grassland, pine-oak forest and Abies forest. The abundant Amaranthaceae pollen observed could come from different species and have diverse origins, however, it may indicate the cultivation of Suaeda sp., a highly prized food plant in Mexican cuisine. The analyses suggest that the construction technique in the archaeological chinampa is similar to the models previously proposed, but this particular variant incorporates some modifcations described in other examples. According to radiocarbon de- terminations, it is suggested that the chinampa was constructed following the Classic period, after around 1640 BP (340–540 cal CE), and was probably utilized initially during the Aztec I-II periods. Therefore, we conclude that the elaboration and maintenance techniques of the SGAX-CH02 chinampa at Xochimilco were more diverse than previous research on archaeological chinampas suggests. 1. Introduction The implementation of highly productive agricultural systems was fundamental to sustaining prehispanic cultural development and sub- sistence needs in the Basin of Mexico. Chinampas were a solution implemented for this purpose (Fig. 1). They have been denominated artifcial islands (Sanders, 1957), foating gardens (Willey and García Prada, 1939; Duran, 1964; Díaz del Castillo, 1965; Moncada Maya, 1982), or raised felds (Morehart and Frederick, 2014; Morehart, 2016). The purpose of their creation was to expand arable land by accessing lakeshore areas and tlatels (islets) (Armillas, 1971a; Armillas, 1971b). Their magnifcent productivity has worldwide recognition (Gonz´ alez- Pozo et al., 2016). This characteristic has aroused the interest of diverse researchers to understand their origin and construction techniques (Table 1). It is unclear when chinampas were frst developed. (Frederick, 2007; Nichols, 2015). Coe (1964) suggested that chinampas were created by the Teotihuacan people, while others pointed to their development during the Aztec period (Armillas, 1971b; Parsons, 1976a; Butzer, 1992). According to Arco and Abrams (2006), the chinampa system intensifed when the population grew between the Aztec III and Early Colonial phases (1400–1600 CE). Also, Cox and Atkins (1979, in Jim´ enez Osornio and G´ omez Pompa, 1983) suggested that their maximum splendor was at this time. Other researchers suggest that their construction dates back to still earlier times (Tolstoy, 1958; Moriarty, 1968); Rojas Rabiela (1995) suggests an even earlier beginning but only small-scale use. Trautmann (1991) argued that their elaboration has gone through different historical stages, culminating in the systems observed today. Therefore, detailed analyses of archaeological examples contribute additional information to the question surrounding chinampa origins. The term chinampa refects intricate aspects of their construction for which there is limited information (Jim´ enez Osornio and G´ omez Pompa, 1983). The name derives from the Nahuatl chin´ amitl - fence or hedged, * Corresponding author. E-mail addresses: rosalestorressara@gmail.com (S. Rosales-Torres), laurab@geologia.unam.mx (L.E. Beramendi-Orosco). Contents lists available at ScienceDirect Journal of Archaeological Science: Reports journal homepage: www.elsevier.com/locate/jasrep https://doi.org/10.1016/j.jasrep.2022.103532 Received 14 September 2021; Received in revised form 14 June 2022; Accepted 17 June 2022