Strike-slip fault systems have been central to Cordilleran assembly, redistributing accreted terranes, dismembering suture zones, and translating arc and oceanic fragments over hundreds to thousands of kilometers along continental margins. In Central America, the North America–Caribbean plate boundary is defined by parallel, east–west–trending, left-lateral strike-slip fault systems that have accommodated at least ~1100 km of lateral displacement since the opening of the Cayman oceanic spreading center, directly controlling the transfer and present configuration of Pacific-margin fragments—including enigmatic Paleo-Pacific radiolarites—within the southern Guatemala Suture Zone (GSZ).

The southern GSZ forms an east–west–elongate belt extending from central Guatemala to the Bay Islands of Honduras and consists of tectonically juxtaposed continental and oceanic crustal slivers. These include (i) Precambrian–Cambrian low-grade to greenschist-facies metasediments; (ii) Carboniferous and Jurassic–Cretaceous high-grade gneiss, migmatite, metasediment, and meta-igneous sequences; (iii) serpentinite-matrix mélange enclosing eclogite, blueschist, jadeitite, omphacitite, and albitite; and (iv) phyllitic metasediments associated with low-grade to amphibolite-facies metabasites, metagabbros, and Upper Jurassic Pacific-type radiolarian cherts. These sequences are locally intruded by metaplagiogranite dikes.

New geochemical data from metabasites and metaplagiogranites reveal contrasting ocean-floor (MORB, OIB) and arc (IAT, CAB) signatures, with enrichment in fluid-mobile elements (Rb, Ba, K, U), strong Nb depletion, and moderate Th and Ti depletion. Zircon U–Pb analyses from metaplagiogranite yield a crystallization age of ~90 Ma and Jurassic to Mesoproterozoic inherited cores with maximum ages of ~1262 Ma, providing direct constraints on arc construction and crustal inheritance within the suture.

This unusual juxtaposition of continental basement, arc-derived crust, accreted oceanic lithosphere, and exhumed high-pressure metamorphic rocks closely resembles Pacific–Cordilleran margins, where continental rocks are exposed along trenchward zones and spatially associated with accreted oceanic complexes and exhumed metamorphic belts. The absence of this configuration along the modern southern Mexican margin, which is characterized by a lack of oceanic assemblages, suggests that a segment of its former Pacific margin has been removed. We propose that the southern GSZ represents this “stolen” margin: a fragment of the southern Mexican plate boundary that was translated eastward and stacked into its present position during the formation and eastward migration of the Caribbean Plate.