Detrital Zircon Geochronology from the Nueva Segovia Schist, Nicaragua: Evidence for the Tectonic evolution of the Chortis Block?


 The Chortís Block of Central America is a cratonic-type peri-Gondwanan terrane and is commonly included in Neoproterozoic-Paleozoic paleogeographic reconstructions. At present, most research has focused on the Mesozoic evolution of the Chortís block; however its earlier history remains poorly constrained. As a result, there is considerable debate surrounding the internal complexities of the Chortís block and its tectonthermal evolution has not been well established by geochronological and geochemical data. New field investigations from the Nueva Segovia Schist (Northern Nicaragua), considered one of the oldest exposed parts of the Chortis Block, reveal it is composed primarily of deformed sequences of greenschist facies marine clastic and chemical sediments in conformable contact with felsic volcanics. LA-ICP-MS detrital zircon data from two samples taken from the Nueva Segovia Schist reveal a youngest age peak of ca. 250 Ma with other significant peaks at ca. 500 Ma, ca. 1.0 Ga and ca. 1.2 Ga. Taken together with field observations, these data suggest the Nueva Segovia Schist was likely deposited between ca. 250 and 110 Ma proximal to Amazonia during the Late Paleozoic and these data support a Precambrian age for the basement of the East Chortis terrane. Taken together the data support a Pangean position of the Chortis Block adjacent to Amazonia inboard of Oaxaquia.
 
 Supplementary material at
 https://doi.org/10.6084/m9.figshare.c.6351360
