Diagenesis refers to those changes which take place in sediments after sedimentation but before lithification (the conversion to solid rock), while metamorphism is defined as the process whereby alterations to
The lattices of the host minerals are generally strong enough to maintain pressure on the inclusions following uplift and retard their inversion to lower-pressure polymorphs (which involves a volume increase). These rocks went unnoticed for decades because virtually all the host rock had re-...
of temperature that can reach 700–800 °C; the temperature at some depth is higher during the metamorphism than before and after the metamorphism; the thermal gradient is larger than the “normal” period (Figure 8-1); and the physicochemical conditions and characteristic mineral and rock ...
There are several locations in Britain where fine-grained igneous or metamorphic rock was collected from screes or opencast mines, then roughed out locally before trading on to other parts of the country. 不列颠有许多地方可以从岩屑堆(scree)或露天矿中采集细粒度火成岩或变质岩,然后再被交易到该国...
1. Geological sketch map of the North Qaidam Orogenic Belt (a, modified after Zhang et al., 2017a) and the Yuka–Luofengpo terrane with sampling localities (b, modified after Zhang et al., 2005). CAOB, Central Asian Orogenic Belt; NQSZ, North Qilian Suture Zone; EKLOB, East Kunlun ...
1.45 Ga magmatism and metamorphism. Magmatism and granulite facies metamorphism of this age has not previously been recognised in the Gawler Craton. The magmatic rocks have steep LREE-enriched patterns and high Ga/Al values, suggesting they are A-type granites. Calculated metamorphic forward models ...
Situated south of the eastern Himalayan syntaxis at the western margin of the Shan-Thai terrane the high-grade Mogok metamorphic belt (MMB) in Myanmar occupies a key position in the tectonic evolutio...
Relicts of subducted oceanic lithosphere provide key information for the tectonic reconstructions of convergent margins. In the Central Alps, such relicts occur as isolated mafic–ultramafic lenses within the migmatites of the southern Adula nappe and Ci
Various segments of Variscan crust are currently exposed in Iberia in response to successive tectonic events during the Variscan orogeny itself and subsequent extensional and compressive events during the Alpine cycle, all accompanied by surface erosion,
These processes also underpin our understanding of reaction kinetics, fluid-rock interaction processes, elemental transport and partitioning in geodynamic systems, such as collisional orogens and subduction zones. While the pressure–temperature–composition (P–T–X) conditions driving these changes are ...