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Key information on sedimentary or tectonic events is recorded in deformation structures formed in unlithified and lithified sediments. Disputes about the classification and identification of the two types of deformation have become increasingly relevant. The present study systematically summarizes, based on consolidation states, the genetic mechanisms of deformation. Consolidation conditions may affect deformation patterns and morphology; this can be a clue to distinguish soft-sediment deformation from tectonic deformation. Liquefaction is a typical state of unconsolidated sediment and can create clastic dikes, liquefied breccia, convolute laminae, load cast, and water-escape structures. Synsedimentary faults may be formed in weakly consolidated sediments. Most deformation structures of lithified sediments are large-scale folds and faults, but small-scale structures – especially microfolds – are difficult to distinguish from slump folds. Tectonic folds can be formed in different strata and induced by tectonic events; they differ from slump folds in morphology, distribution, and related structures. We demonstrated that consideration of liquefaction, folds in different strata – matched with the regional geological regime, related deformation structures, and micro-deformation structures – can be clues to the identification of deformation origins. [ABSTRACT FROM AUTHOR]

The Mesozoic to Cenozoic mountain uplift, exhumation, and deformation of the SW Tianshan Mountains (Kyrgyzstan and Northwest China) offer an important window to understand the intra-continental rejuvenation mechanism of the Central Asian Orogenic Belt (CAOB), as response to the far-field effects of the India-Asia collision. This article presents new observation and data for the planation surface and sedimentation and deformation features of the regional intermountain basins to rebuild the orogenic history in Mesozoic to Cenozoic. Three planation surfaces were recognized by field observation, showing that the mountain may have experienced lengthy erosion since the end Cretaceous, and a continuous planation surface may have formed at the Eocene to Oligocene. The filling sequences and deformation character revealed that the orogenic disintegrate and intermountain basin formation likely began in the end of Oligocene. Subsequently, the uniform planation surface in Western Tianshan may have begun to disintegrate, leading to the basin-and-range landform formation. Folds and nappes in the Cenozoic basins, large-scale thrusting of Palaeozoic rocks over Cenozoic sediments at the basin margin associated with the rapid mountain uplift may have occurred at the end of Early Pleistocene, suggesting a tectonic inversion. The Mesozoic-Cenozoic Tianshan uplift and deformation were likely induced by the collision/accretion along the southern margin of Eurasia. Both the northward propagation of the Parmir syntaxis to the SW Tianshan and the oblique dextral faulting of the Talas-Fergana fault have likely played an important role on the formation and deformation of the Cenozoic basins in the SW Tianshan. [ABSTRACT FROM AUTHOR]

In order to constrain the timing and petrogenesis of both the hosting rocks and the inner mafic microgranular enclaves (MMEs) of the Liangnong pluton, SE China, we have performed a series of bulk-rock geochemistry, zircon U–Pb, and Hf isotopic analysis, respectively. Zircon laser ablation–inductively coupled plasma–mass spectrometry U–Pb isotopic analysis yielded ages of 106.3 ± 1.1 Ma for the granodiorite and 103.9 ± 1.6 to 105 ± 1.8 Ma for monzogranite phases within the hosting pluton, as well as an age of 104.7 ± 0.8 Ma for the associated MMEs. The host rocks are metaluminous, have A/CNK values of 0.91–1.09, contain relatively high concentrations of SiO2and K2O, are enriched in Rb, Th, Ba, Zr, and Hf, are depleted of Sr, P, Ti, Nd, and Ta, contain high concentrations of the rare earth elements (REE) and the light REE, and have moderately negative Eu anomalies (Eu /Eu = 0.6–0.8). In comparison, the MMEs contain high concentrations of Al2O3, FeO, MgO, and TiO2, are relatively enriched in Ba, U, and Sr, and are depleted in Th, Nd, and Zr. They have lower total REE concentrations and higher Eu /Eu values than the hosting granites. The zircons within the hosting granites have Hf crustal model ages (TDMC) that show a peak at 1.29–1.85 Ga. Zircons within the MMEs have different εHf(t) values (–3.7 to +4.9) than the zircons within the hosting granites (–10.8 to –1.9). The results indicate that the MMEs and the hosting granites crystallized from magmas with different sources, thereby showing that the Early Cretaceous magmatism in the coastal areas of SE China was generated by the widespread injection of mantle-derived magmas caused by rollback of the subducting palaeo-Pacific Plate. [ABSTRACT FROM AUTHOR]