Nd isotope constraints on sources of Neoproterozoic to Early Cambrian siliciclastic sedimentary rocks in northern Sonora

Paleoproterozoic Mojave province in northwestern Mexico? Isotopic and U-Pb zircon geochronologic studies of Precambrian and Cambrian crystalline and sedimentary rocks, Caborca, Sonora

“…Nevertheless, it is generally considered that the siliciclastic sediments were derived from the erosion of Precambrian rocks to the north and/or east (Stewart et al, 1984). Such a conclusion is consistent with the Nd isotopic compositions of siliciclastic sedimentary rocks in the Caborca sequence, which generally match those of Paleoproterozoic crust in southwestern North America (Farmer et al, 2001). Stewart et al (1984) recognized that the miogeoclinal sedimentary sequence in Sonora is similar lithologically to that of Neoproterozoic to Middle Cambrian miogeoclinal sedimentary rocks in the southern Great Basin.…”

“…These similarities could instead simply refl ect accumulation of the original sediments in similar depositional environments (Stewart et al, 1984). This issue remains unresolved despite detailed U-Pb studies of detrital zircons and whole-rock Nd studies of miogeoclinal sedimentary rocks in both Sonora and the southwest United States (Gehrels and Stewart, 1998;Farmer et al, 2001).…”

“…We obtained Nd isotopic data and U-Pb zircon ages from several basement rocks exposed in the Caborca area in northern Sonora ( Fig. 1) and detrital U-Pb zircon age spectra from a set of Neoproterozoic to early Cambrian miogeoclinal sedimentary rocks for which whole-rock Nd isotopic data were already available (Farmer et al, 2001). Our data reveal that Caborca basement rocks may represent a segment of the Mojave province crust, equivalent to Paleoproterozoic rocks in westernmost Arizona and southeastern California, and that these basement rocks could represent the source rocks of the oldest portions of the miogeocline exposed at Caborca.…”

Whole-rock geochemistry and Sr–Nd isotopic composition of the pre-rift sequence of the Camamu Basin, northeastern Brazil

“…Therefore, the measured ratios and calculated parameters in sedimentary rocks will reflect the characteristics of the source rocks. Therefore, 143 Nd/ 144 Nd isotopic ratios, model age (T DM ) and parameters such as ε Nd have been used as provenance tracers in recent sediments (McLennan et al, 1990), Paleozoic turbidites (Gleason et al, 1995), and Neoproterozoic siltstones and sandstones (Farmer et al, 2001).…”

Santa Bárbara Formation (Early Paleozoic, Caçapava do Sul, southern Brazil): Petrographic and Sm–Nd isotopic provenance parameters

“…The Sm-Nd isotopic system has been also applied to provenance studies since the early efforts of Nelson and DePaolo (1988). It has been important in tracing the provenance pattern of recent sediments (McLennan et al, 1990;Négrel and Grosbois, 1999), Paleozoic sedimentary successions (Gleason et al, 1994(Gleason et al, , 1995, and Neoproterozoic sedimentary (Farmer et al, 2001) and metasedimentary successions (Pimentel et al, 2001). The parameters of the Sm-Nd system may be slightly modified during the sedimentary cycle, specially by the following processes: preferential sorting of REE-rich trace minerals (zircon, allanite, sphene, etc.…”