The collision of India with Asia

Abstract

a b s t r a c tWe review the relative motion of India and Asia for the last 100 million years and present a revised reconstruction for the India-Antarctica-Africa-North America-Eurasia plate circuit based on published motion histories. Deformation of these continental masses during this time introduces uncertainties, as does error in oceanic isochron age and location. Neglecting these factors, the data ipso facto allow the inference that the motion of India relative to Eurasia was distinctly episodic. Although motion is likely to have varied more smoothly than these results would allow, the geological record also suggests a sequence of distinct episodes, at about the same times. Hence we suggest that no single event should be regarded as the collision of India with Asia. The deceleration of the Indian plate commencing at ∼65 Ma is matched by an equally significant prior acceleration and this aspect must be taken into account in geodynamic scenarios proposed to explain the collision of India with Asia.

Petrogenesis of the Early Eocene adakitic rocks in the Napuri area, southern Lhasa: Partial melting of thickened lower crust during slab break-off and implications for crustal thickening in southern Tibet

“…Detailed investigation of upper Cretaceous strata in the Tethys Himalaya also indicated that the initial contact between India and Asia occurred during the Maastrichtian (~70-65 Ma) (Cai et al, 2011). The magnetic anomalies on the Central Indian Ridge and Southeast Indian Ridge (Sclater and Fisher, 1974) and palaeomagnetic data (e.g., Lee and Lawver, 1995;White and Lister, 2012) both indicate an India-Eurasia collision in the Paleocene epoch (65-55 Ma). In addition, slab detachment commonly causes a decrease in convergence rates (e.g., Chung et al, 2005;Lee and Lawver, 1995).…”

“…In addition, slab detachment commonly causes a decrease in convergence rates (e.g., Chung et al, 2005;Lee and Lawver, 1995). The deceleration of the Indian continent relative to Eurasia occurred approximately 50 Ma (e.g., Molnar and Stock, 2009;White and Lister, 2012), broadly coeval with a break-off of the Neo-Tethyan slab at ca. 51-46 Ma.…”

Early Late Cretaceous (ca. 93Ma) norites and hornblendites in the Milin area, eastern Gangdese: Lithosphere–asthenosphere interaction during slab roll-back and an insight into early Late Cretaceous (ca. 100–80Ma) magmatic “flare-up” in southern Lhasa (Tibet)

“…Most paleomagnetic data imply that the acceleration in the rate of convergence between Indian and Asian continents (Fig. 7) occurred at approximately 85 Ma (e.g., Klootwijk et al, 1992;White and Lister, 2012). Acceleration of the northward drift rate and change of convergence angle occurred in the final stage of the early Late Cretaceous Gangdese magmatic "flare up" event and slightly later than the age peak (95-85 Ma) of southern Lhasa magmatic rocks (Fig.…”

Deciphering orogenic evolution

“…The general image provided by the tectonic plate approach is that of mostly rigid plates deforming at narrow boundaries. Recent geodetic measurements have evidenced annual "instantaneous" deformation rates similar to geological-scale rates, especially in very active tectonic settings such as the Indian-Asian convergence zone (Zhang et al, 2004). However, it remains difficult to reconcile these plate-scale approaches with those undertaken at the centimeter scale.…”