Detrital zircon dating

Posted by / 27-Aug-2017 09:35

The Katangan Supergroup sequence commences with the Roan Group, composed of an early, oxidised, mainly clastic, rift phase, including the Lower Roan Subgroup, deposited in a number of connected intracontinental rift basins in Zambia.The rift-stage rocks were overlain by a thermal sag phase sequence of largely reduced, mixed evaporitic carbonate and finer clastic rocks of the Upper Roan Subgroup in Zambia. Subgroup unit is interpreted to represent the residue following later dissolution of a thick salt/evaporite unit, overlain by largely reduced, transgressive, mixed evaporitic carbonate and finer clastic rocks enclosing a number of regressive phases, which together constitute the Mines and Dipeta Subgroups.The uppermost of the three Roan Group units in the DRC is the Dipeta Subgroup, comprising a lower regressive suite, including oxidised, evaporitic rocks, followed by transgressive carbonate rocks with some reduced intervals.During deposition of the late Upper Roan and Dipeta subgroups, a period of 'renewed extension' commenced, reflected by a ~30 to 100 km wide by ~500 km long corridor of gabbroic and lesser felsic intrusions, and an associated volcanic belt of thin mafic lavas and tuffs emplaced from ~765 to 735 Ma.Sedimentología, reconstrucción paleoambiental y significado tectónico de las sucesiones clásticas del Jurásico Medio en el área de Texcalapa, Puebla-Huajuapan de León, Oaxaca: Revisión de las formaciones Ayuquila y Tecomazúchil Sedimentology, paleoenvironmental reconstruction and tectonic significance of Middle Jurassic clastic successions in the Texcalapa, Puebla– Huajuapan de León, Oaxaca area: review of the Ayuquila and Tecomazúchil formations Departamento de Ingeniería Geológica, Facultad de Ingeniería, Universidad Nacional Autónoma de México, Circuito Interior, Ciudad Universitaria, Delegación Coyoacán, 04510 México D. *[email protected] propone subdividir la sucesión clástica pre-Oxfordiano de la cuenca Ayuquila en dos unidades litoestratigráficas, con base en el reconocimiento de una discordancia angular mayor en el análisis de facies, así como en fechamientos de circones magmáticos y detríticos.Se documenta que la sucesión se acumuló mediante sistemas fluviales trenzados con drenaje principal hacia el sur, bajo un clima inicialmente semiárido durante el Bajociano-Bathoniano y que se tornó más húmedo en el Calloviano, tal vez como respuesta del desplazamiento de la región meridional de México a una posición más ecuatorial.The majority of the pre-Neoproterozoic zircons underwent Pb loss, possibly as a consequence of the Pan-African orogeny resetting their provenance.

These were overlain by the widespread glacial (Sturtian) and post-glacial deposits of the Nguba Group from ~750 to ~630 Ma and similar rocks of Kundelungu Group to ~560 Ma.400 km long Central African Copperbelt, that continues south into neighbouring Zambia, to become the Zambian Copperbelt.Although part of the same curvilinear trend, the Congolese Copperbelt is hosted by carbonate-rich rocks deposited in an evaporitic environment, in contrast to the Zambian Copperbelt deposits, which are hosted by non-evaporitic, rift facies siliciclastic rocks, which are not temporally or lithologically equivalent to the hosts in the DRC.Voluminous Paleozoic sandstone sequences were deposited in northern Africa and Arabia following an extended Neoproterozoic orogenic cycle that culminated in the assembly of Gondwana.We measured sensitive high-resolution ion microprobe (SHRIMP) U-Pb ages of detrital zircons separated from several Cambrian units in the Elat area of southern Israel in order to unravel their provenance.

detrital zircon dating-49detrital zircon dating-36detrital zircon dating-2