Stratigraphic implications of palaeomagnetic data from Honduras

Abstract

S U M M A R Y Palaeomagnetic results from mainly Cretaceous rocks in Honduras delineate a distinctive apparent polar wander path (APWP) which is well suited for magnetostratigraphy. T h e A P W P is based o n palaeomagnetic data from palaeontologically dated units in the established stratigraphic column and three radiometrically dated intrusions. T h e ages and stratigraphic positions of sedimentary units whose stratigraphic assignments have been debated, can be inferred by comparing their palaeomagnetic pole postion with the known APWP. T h e results demonstrate the usefulness of magnetostratigraphy for resolving stratigraphic problems in the absence of fossils o r marker beds, and for areas of discontinuous exposures. For regional interpretations, the most important conclusion is that strata in Honduras that have been assigned t o the Todos Santos Formation were not deposited on the same tectonic plate as the Todos Santos Formation of Guatemala and southern Mexico. There is n o evidence that t h e Honduran 'Todos Santos' strata are depositionally related t o the true Todos Santos Formation. T h e name 'Todos Santos Formation' should be abandoned in Honduras and for the entire Chortis Block.

A palaeomagnetic study and age determinations of Tertiary rocks in Nicaragua, Central America

“…The virtual geomagnetic pole (VGP) positions (Fig. 7) calculated from the site means and the grand means of the Highland show the same trend of distribution as poles calculated from Cretaceous rocks in Honduras (Gose 1985;Gose & Finch 1992). The centres of the polar arcs coincide with the sampling region, which means that the distribution of poles may have its origin in local structural rotations as well as plate tectonic rotations (MacDonald 1978(MacDonald , 1990.…”

“… Palaeomagnetic pole positions of Tertiary rocks from the Nicaraguan Highland (this study) (marked by triangles) and Cretaceous rocks from Honduras (Gose 1985; Gose & Finch 1992) (marked by crosses). Open symbols denote poles of reversed polarity and the filled symbols A and B denote the 30 and 60 Myr reference poles for North America.…”

Jurassic volcanic and sedimentary rocks of the La Silla and Todos Santos Formations, Chiapas: Record of Nazas arc magmatism and rift-basin formation prior to opening of the Gulf of Mexico

“…Elsewhere in Mexico, similar lithologies have been assigned to the Huizachal Formation (Mixon et al, 1959). Some confusion exists in the literature because the name Todos Santos has been applied to continental redbeds and other terrigenous sequences across southern Mexico (Chiapas and Oaxaca), Guatemala, and Honduras; the name thus applies to Jurassic and Cretaceous strata in different tectonic settings and in different basins (e.g., Burkart et al, 1973;Blair, 1987;Rueda-Gaxiola, 1998;Gose and Finch, 1992). Clemons et al (1974) assigned a Late JurassicEarly Cretaceous age to Todos Santos strata in Guatemala, at the type locality in the Altos Cuchumatanes.…”

Paleomagnetic data support Early Permian age for the Abor Volcanics in the lower Siang Valley, NE India: Significance for Gondwana-related break-up models

“…In essence, the latitudinal position and/or orientation of a crustal block over moderately long geological intervals is invariably different, thus a primary magnetic direction recorded by a unit will reflect this (e.g. Hanna, 1967;Gose and Finch, 1992;Harlan et al, 1997;Reynolds et al, 1997). Critically, India in the Early Permian occupied a position within central Gondwana and the NE corner of the craton was located at mid-southerly latitudes (Grunow, 1999;Stampfli and Borel, 2002;Torsvik, 2003;Torsvik et al, 2008) -Fig.…”