The Late Permian shoshonitic province of the southern Sydney Basin consists of lavas and intrusions confined to a 140 km long coastal belt, but geophysical and sedimentological data indicate that the province once had a length of at least 340 km.Both petrographic and geochemical data indicate shoshonitic affinities for these Late Permian rocks and, although the compositional range is from 48.4 to 60.6% Si O values range from 5.11 to 2.14 and plot almost exclusively in the mantle array.Similarly, groundwater contained in a limestone aquifer such as the Barkly Tablelands in the Northern Territory will be chemically and isotopically different to that found in a sandstone landscape, such as the Sydney Basin.Nuclear and isotope methods are useful in regions where more traditional hydrologic tools give ambiguous results, or insufficient information.In areas, such as the Perth Basin, researchers within the group are studying how long the water typically takes to travel from surface to underground aquifers.This is called the water residence time or groundwater age.
Considering the errors, the younger ages obtained for Jaguarão lavas overlap the 138–128Ma age of rocks of the Serra Geral Group, and thus indicate that the dacites were erupted prior to the break-up of Gondwana in this region.
K-Ar mineral and Rb-Sr total rock age determinations made on intrusive rocks from southeastern Queensland, Australia, indicate that the Middle Triassic sediments in this area are older than 220 m.y.
This evidence suggests that earlier estimates of the age of the base of the Triassic are too young.
Die spät-permische Schoschonit Provinz des südlichen Sidney Beckens besteht aus Laven und Intrusionen, die in einem 140 km langen Gürtel längs der Küste auftreten.
Geophysikalische und sedimentologische Daten weisen darauf hin, daß diese Provinz ursprünglich eine Länge von mindestens 340 km hatte.