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The Himalaya are among the youngest and highest mountains in the world, but the exact timing of their uplift and origins of their biodiversity are still in debate. The Himalayan region is a relatively small area but with exceptional diversity and endemism. One common hypothesis to explain the rich montane diversity is uplift-driven diversification—that orogeny creates conditions favoring rapid in situ speciation of resident lineages. We test this hypothesis in the Himalayan region using amphibians and reptiles, two environmentally sensitive vertebrate groups. In addition, analysis of diversification of the herpetofauna provides an independent source of information to test competing geological hypotheses of Himalayan orogenesis. We conclude that the origins of the Himalayan herpetofauna date to the early Paleocene, but that diversification of most groups was concentrated in the Miocene. There was an increase in both rates and modes of diversification during the early to middle Miocene, together with regional interchange (dispersal) between the Himalaya and adjacent regions. Our analyses support a recently proposed stepwise geological model of Himalayan uplift beginning in the Paleocene, with a subsequent rapid increase of uplifting during the Miocene, finally giving rise to the intensification of the modern South Asian Monsoon. [ABSTRACT FROM AUTHOR]

Abstract: The Early–Middle Miocene exhumation of the crystalline core of the Himalaya is a relatively well-understood process compared to the preceding phase of burial and prograde metamorphism in the Eocene–Oligocene. Highly deformed rocks of the Greater Himalayan Sequence (GHS) dominate the crystalline core, and feature a strong metamorphic and structural overprint related to the younger exhumation. The Tethyan Sedimentary Series was tectonically separated from the underlying GHS during the Miocene by the South Tibetan Detachment, and records a protracted and complex history of Cenozoic deformation. Unfortunately these typically low-grade or unmetamorphosed rocks generally yield little quantitative pressure–temperature–time information to accompany this deformation history. In parts of the western Himalaya, however, the basal unit of the Tethyan Sedimentary Series (the Haimanta Group) includes pelites metamorphosed to amphibolite facies. This presents a unique opportunity to explore the tectono-thermal evolution of crystalline rocks which record the early history of the orogen. Pressure–temperature–time–deformation (P–T–t–d) paths modelled for two Haimanta Group pelitic rocks reveal three distinct stages of metamorphism: (1) prograde Barrovian metamorphism to 610–620 °C at c. 7–8 kbars, with garnet growing over an early tectonic fabric (S1); (2) initial decompression during heating to 640–660 °C at c. 6–7 kbars, with development of a pervasive crenulation cleavage (S2) and staurolite and kyanite porphyroblast growth; (3) further exhumation during cooling, with minor retrograde metamorphism and modification of the pervasive S2 fabric. Monazite growth ages constrain the timing of initial garnet growth (>34 Ma), the start of D2 and maximum burial (c. 30 Ma), and the termination of garnet growth (c. 28 Ma). Muscovite Ar/Ar ages indicate cooling through c. 300 °C at c. 13 Ma, from which we derive an initial exhumation rate of c. 1.3 mm year−1 for the Haimanta Group. The underlying GHS was exhumed at a rate of 2.2 to 3 mm year−1 during this time. The difference in exhumation rate between these two units is considered to reflect Early Miocene displacement on the intervening South Tibetan Detachment. Slower exhumation (c. 0.6 mm year−1) of both units after c. 13 Ma followed the cessation of major displacement on this structure, after which time the Haimanta Group and the GHS were exhumed as one relatively coherent tectonic block. [Copyright &y& Elsevier]

The geodynamic system of Earth is controlled by the horizontal motion of fragmented tectonic plates due to complex interaction between the mantle and the crust. Land and marine paleomagnetic signatures, along with extensive petrochronological and structural data, suggest non-continuous, multi-directional convergence histories for modern orogenic belts, as seen in the Himalayas and Betic Cordillera, among others. The consequences of radical changes in the direction of plate motions are obscured by complex structural settings and repeated cycles of metamorphism in orogenic belts. Although, subduction was operational on Earth in the Paleoproterozic, one of the major questions is: how far back in geological time can we trace the scale of modern-style subduction, collisional tectonics and poly-metamorphism? The metasedimentary and volcanic rocks (2.5 to 2.05 Ga) of the Sodankylä belt of northern Finland were deformed and metamorphosed during a prolonged period, now represented by the Svecofennian orogen (ca. 1.92–1.77 Ga). The orogenic belt represents a window into the deep levels of a Paleoproterozoic crust, where the interplay between deformation and metamorphism can be compared with the modern orogenic settings. In this study, five discrete heterogeneously developed superimposed, near-orthogonal, deformation events (D1 to D5) have been identified and mapped based on the high-resolution aeromagnetic data and field studies. Regional correlation of tectonic fabrics, along with metamorphic textures across the Sodankylä belt and northern Finland, suggest that each deformation event was a regional-scale phenomenon rather than a local one. Previous geochronological data obtained from the Sodankylä belt and adjacent Central Lapland Granitoid Complex on different Paleoproterozoic deformed rocks allow us to propose a time-constrained tectono-metamorphic model for the Sodankylä belt. The sequence of near-orthogonal deformation history and the polymetamorphic evolution offer comparisons with modern-style orogenic settings. The most notable aspect is the occurrence of Mesoarchean and Paleoproterozoic eclogitic high-pressure granulites reported from the Belomorian belt of Fennoscandian Shield, which lies to the east of the Sodankylä belt. From a tectono-metallogenic viewpoint, the Sodankylä belt is located in the centre of Ni-Cu-PGE, orogenic gold-cobalt deposits of the northern part of Fennoscandian Shield, therefore, the tectonic processes and overprinting role of multiple deformation phases need to be well understood as they directly link mineral exploration to the timing and controls on mineralization. [ABSTRACT FROM AUTHOR]