However, Paleogene cooling ages are today exposed locally in the western Southern Alps and specifically in the Ivrea Zone (Figs. 1, 3). This zone exposes basement rocks composed of the Ivrea–Verbano Zone and the adjacent Strona–Ceneri Zone , which are interpreted as representing a cross section of the entire continental crust . They show ZFT ages older than 30 Ma close to the Periadriatic lineament and older than 100 Ma far away from this fault (Siegesmund et al. 2008).

Petrogenesis of the Linxi granitoids, northern Inner Mongolia of China: Constraints on basaltic underplating

The newly emerging continental volcanic arc obviously is continued in the Sunid-Baolidao volcanic arc in Inner Mongolia . However, the analysed Permian sandstones represent early collisional sandstones, because they are tectonically deformed in east-west striking belts . Considering the well pronounced Ordovician-Silurian detrital zircon age population and related positive εHf values, a strong similarity with results from the Hangay-Hentey terrane appears evident . Therefore, a predominant detrital supply from the northern convergent margin of the Mongol-Okhotsk Ocean is probable.

On the whole, the geochemical characteristics of the siliciclastic rocks , including their wacke/greywacke composition , weak degree of source weathering , and the presence of interbedded conglomerate and gravelstone , are evidence that sedimentation proceeded in an active tectonic regime. Exotic blocks are only sporadically found within the Magura Nappe. The available age data include a metadiorite-metagabbro dated at c. 614 Ma , centimeter-scale mica-schist pebbles from the Tylicz and Krynica Zone dated at 310 ± 10 Ma using the U-Th-Pb CHIME method on monazite and the porphyritic granite dated in this study at 315.9 ± 2.6 Ma.

Probability density plot for fission-track grain-age samples

We use synthetic examples to demonstrate how Bayesian statistics allow for the incorporation of the principle of superposition into the analysis of depositional ages, specifically allowing for the calculation of depositional ages and uncertainty estimates from diverse geochronologic constraints . We follow this with a real example from the Magallanes basin of Patagonia (after Schwartz et al., 2017). In this example we demonstrate that the observed chronology of stratigraphy in the Magallanes basin is consistent with the self-similar progradation of a continental shelf-slope system with a topography that is consistent with observations from analagous modern depositional systems. Thus, we show how added geologic context can refine our interpretations of geochronology-based depositional ages. Metamorphic rocks record information on the thermal conditions and tectonic architecture in various tectonic settings. The Baoyintu Group in central-western Inner Mongolia consists of metapelite, quartz schist, quartzite, and marble, with interlayers of amphibolite.

The Napier Complex, East Antarctica, preserves UHT metamorphism, and the timing is still debated. U–Pb zircon geochronology integrated with rare earth element […] Read more. In the present work, we studied zircons from the less foliated granites of the Chail Group, which form a thrust sheet of the Lesser Himalayan Sequences, Garhwal region. Compositionally, these granites are S–type, formed in a collisional tectonic setting.

Populations of detrital zircons are shaped by geologic factors such as sediment transport, erosion mechanisms, and the zircon fertility of source areas. Zircon U-Pb age datasets are influenced both by these geologic factors and by the statistical effects of sampling. Such statistical effects introduce significant uncertainty into the inference of parent population age distributions from detrital zircon samples. This uncertainty must be accounted for in order to understand which features of sample age distributions are attributable to earth processes and which are sampling effects. After detritus are eroded from source area, they are transported and deposited in river, foreland basin or flood plain.

The area contains fine-grained red Palaeozoic sandstone outcrops with variable degrees of weathering and natural variations in the depositional environments. Limestone forms the erosion-resistant cappings on ridges in the region and appears as boulder float near the site. The soil at site 52 is red in colour, similar to that at Site 2. This paper focuses on research conducted at four megalithic jar sites; 1, 2, 52 and one quarry site .

Original figure 2 from Debaille et al. ; An example of Lu/Hf isochron. Ashraf, M.; Chaudhary, M. Petrology of lower Siwalik rocks of Poonch area. Bera, M.; Sarkar, A.; Chakraborty, P.; Loyal, R.; Sanyal, P. Marine to continental transition in Himalayan foreland.

Research paperOn the visualisation of detrital age distributions

The detrital zircon provenance interpretation for the upper Tertiary sequence that was exposed in the Yadgar section needs the U-Pb age data set representative for the litho-tectonic terranes, which were the possible source during the development of the Cenozoic foreland basin. The litho-tectonic terranes included are; Karakoram Block, Lhasa Block, Kohistan–Ladakh Island arc , Greater/Higher Himalaya, Lesser Himalaya and Tethyan Himalaya . These terranes have distinct age spectra that provide an indication of the source region feeding the foreland basin . We make a guess of the age for each sample and then evaluate both its prior and likelihood (e.g., Equation 1, Figure 7). Specifically, we employ a Bayesian, MCMC approach with an affine-invariant ensemble sampler (Foreman-Mackey et al., 2013).

The sedimentary unit cannot be older than the youngest age of the analyzed detrital zircons because the zircon should have existed before the rock formation. This provides useful age information to rock strata where fossils are unavailable, such as the terrestrial successions during Precambrian or pre-Devonian times. Practically, maximum depositional age is averaged from a cluster of youngest age data or the peak in age probability because the youngest U-Pb age within a sample is almost always younger with uncertainty.

The major and trace element data of bulk sediments suggested passive margin settings for the two areas. The trace elemental ratios and chondrite-normalized rare earth element patterns of bulk sediments revealed that the sediments were likely sourced by felsic and intermediate igneous rocks. And the zircon iLove Th/U ratios (mostly more than 0.2) and zircon REE patterns suggested a magmatic origin for both of the beach sediments from these two areas. Two distinct zircon age peaks respectively belonging to the Paleozoic and the Cenozoic were identified both in the Riachuelos and Palma Sola beach sediments.