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The Tan-Lu fault zone (TLFZ) along the East China continental margin (ECCM) experienced a change from sinistral to normal faulting in the late Mesozoic. Thirty-four laser ablation (LA)-ICPMS zircon U-Pb dates for plutons and volcanic rocks along the TLFZ indicate that extension-related magmatism started as early as 136 Ma. The development of pre-eruption rift basins along the TLFZ during the earliest Early Cretaceous further constrains the onset time of the Tan-Lu normal faulting to the beginning of Early Cretaceous (ca. 145 Ma). Association of extensive rifts, metamorphic core complexes, and magmatism along the margin with the Tan-Lu normal faulting suggests an Early Cretaceous extensional regime for the ECCM that also started at the beginning of the Early Cretaceous, about 145 Ma. An undeformed granite dike that intrudes the sinistral ductile shear zone yields an LA-ICPMS zircon U-Pb age of 122 Ma. Seven 40Ar/39Ar plateau ages of mica samples from mylonites in the Tan-Lu sinistral ductile shear zone range from 129.5±0.8 to 101.8±0.6 Ma, and these are considered to represent cooling ages related to later normal faulting. A white mica 40Ar/39Ar plateau age of 149.8±0.9 Ma is interpreted as the cooling age of sinistral faulting. It is suggested that the sinistral faulting took place before 150 Ma (Late Jurassic), rather than in the Early Cretaceous, as previously proposed. The Tan-Lu sinistral faulting developed under a transpressive regime along the ECCM during the Late Jurassic. It is inferred that the switch from Late Jurassic transpression to Early Cretaceous extension is due to a shift from oblique, shallow subduction of the Izanagi Plate to orthogonal, steep subduction of the Pacific Plate.

A series of scaled analogue models are used to study (de)coupling between basement and cover deformation. Rigid basal blocks were rotated about a vertical axis in a ‘bookshelf’ fashion, which caused strike-slip faulting along the blocks and in the overlying cover units of loose sand. Three different combinations of cover–basement deformations are modelled: (i) cover shortening before basement fault movement; (ii) basement fault movement before cover shortening; and (iii) simultaneous cover shortening with basement fault movement. Results show that the effect of the basement faults depends on the timing of their reactivation. Pre- and syn-orogenic basement fault movements have a significant impact on the structural pattern of the cover units, whereas post-orogenic basement fault movement has less influence on the thickened hinterland of the overlying belt. The interaction of basement faulting and cover shortening results in the formation of rhombic structures. In models with pre- and syn-orogenic basement strike-slip faults, rhombic blocks develop as a result of shortening of the overlying cover during basement faulting. These rhombic blocks are similar in appearance to flower structures, but are different in kinematics, genesis and structural extent. We compare these model results to both the Zagros fold-and-thrust belt in southwestern Iran and the Alborz Mountains in northern Iran. Based on the model results, we conclude that the traces of basement faults in cover units rotate and migrate towards the foreland during regional shortening. As such, these traces do not necessarily indicate the actual location or orientation of the basement faults which created them.

In the foreland area of western Taiwan, some of the pre-orogenic basement-involved normal faults were reactivated during the subsequent compressional tectonics. The main purpose of this paper is to investigate the role played by the pre-existing normal faults in the recent tectonics of western Taiwan. In NW Taiwan, reactivated normal faults with a strike-slip component have developed by linkage of reactivated single pre-existing normal faults in the foreland basin and acted as transverse structures for low-angle thrusts in the outer fold-and-thrust belt. In the later stage of their development, the transverse structures were thrusted and appear underneath the low-angle thrusts or became tear faults in the inner fold-and-thrust belt. In SW Taiwan, where the foreland basin is lacking normal fault reactivation, the pre-existing normal faults passively acted as ramp for the low-angle thrusts in the inner fold-and-thrust belt. Some of the active faults in western Taiwan may also be related to reactivated normal faults with right-lateral slip component. Some main earthquake shocks related to either strike-slip or thrust fault plane solution occurred on reactivated normal faults, implying a relationship between the pre-existing normal fault and the triggering of the recent major earthquakes. Along-strike contrast in structural style of normal fault reactivation gives rise to different characteristics of the deformation front for different parts of the foreland area in western Taiwan. Variations in the degree of normal fault reactivation also provide some insights into the way the crust embedding the pre-existing normal faults deformed in response to orogenic contraction.

The 1000 km long NW-SE-striking, left-lateral Ailao Shan-Red River shear zone runs from the southeastern corner of Tibet to the Gulf of Tonkin and the South China Sea. It has been used as the prime example of a lithospheric-scale strike-slip fault that has accommodated between 500 and 1000 km of southeastwards extrusion of Indo-China away from the Indian plate indentor. Central to the model of continental extrusion is that such faults cut through the entire lithosphere, that shear heating resulted in high-grade metamorphism and local anatexis, and that the ages of sheared granites along the fault also date the timing of strike-slip shearing. However, structural data from the Red River shear zone clearly show that vertical strike-slip faulting post-dated metamorphism and granite emplacement. Most granites along the shear zone are mantle-related granodiorites or within-plate alkali granites formed prior to shearing along the Red River shear zone. Left-lateral kinematic indicators are ubiquitous within the Red River mylonites, but they are always lower-temperature fabrics, formed after peak sillimanite metamorphism and after granite crystallization. It is suggested that left-lateral strike-slip shearing along the Red River shear zone started after 21 Ma, not at 35 Ma as previously thought, and the fault was purely a crustal structure. None of the geological features used to propose the 500-1000 km offsets are robust, and the total finite offset remains unknown.

Within the San Andreas system of southern California, vertical-axis clockwise rotations have been attributed to (1) capture of the Monterey microplate, during which oceanic lithosphere beneath North America was transferred to the Pacific plate imparting basal traction and inducing northwestward motion of overlying North American crust, and (2) torsional force couples imposed at the ends of rotating panels. In contrast, some crustal blocks that are smaller and/or weaker than crust on opposite sides of faults have experienced clockwise transrotation as they have moved through restraining double bends: (1) rapid 40° clockwise rotation of the eastern Transverse Ranges (6–0 Ma), starting with the southernmost parts and progressing northward; (2) rapid 23° clockwise rotation of the Morales Formation in the Cuyama Valley (3–0 Ma); and (3) continuing clockwise rotation of the westernmost Transverse Ranges. The magnitude of rotation matches the angle between the strikes of fault segments on either side of the corresponding left bend. The oblique path of the San Andreas fault (SAf) across the disrupted Cretaceous batholith created a large-scale restraining double bend. As the rigid Sierra Nevada and Peninsular Ranges batholiths have converged along opposite sides of the SAf, the intervening SAf has rotated counterclockwise, thus tightening the restraining double bends. As a result, the magnitude of rotation of blocks moving through these bends has increased through time. Counterclockwise rotation of this segment of the SAf may also have caused 8°–16° counterclockwise rotation of the San Gabriel block. Our resulting palinspastic reconstructions not only satisfy kinematic and geologic constraints but also suggest a dynamic basis for transrotation of discrete crustal blocks, independent of microplate-capture events.

Ultramafic to felsic, potassic alkaline igneous rocks along the Ailo Shan-Red River (ASSR) shear zone share similar trace element patterns and radiogenic isorope ratios. Structures and outcrop outline suggest a genetic relationship to the ASSR shear zone. About 400 zircons separated from 12 potassic alkaline bodies have been dated to temporally constrain left-lateral movements along the shear zone. Analyses of 29Si, 31P, 91Zr, 177Hf, 206Pb, 207Pb, 208Pb, 232Th, 235U, 238U and six REE were performed in the LA-ICP-MS laboratory at the Research School of Earth Sciences, Australian National University. The zircon ages range from 34.0 to 36.3 Ma which, when combined with previous data, suggest that the onset of the left-lateral movements began at or slightly before 36 Ma and lasted from ≥ 36 to 17 Ma. Taking uncertainties into account, the duration of motion on the ASSR shear zone coincides with the opening of the South China Sea; this implies a genetic relationship.

Composite tectonic emplacement of the world's largest outcropping body of subcontinental mantle rocks, the Ronda peridotites, occurred during Early Miocene continental subduction and as a result of oblique plate convergence. Partitioning of transpressional deformation between coeval orogen-parallel wrenching and orogen-perpendicular, pure thrusting components is recorded by shear zone kinematics and dynamothermal metamorphism in the footwall to the ultramafic rocks. Left-lateral shear, characterizing the deeper, high-pressure (eclogitic) portions of the continental subduction system, propagated through the mantle into the overlying continental crust of the overriding plate, whereas top-to-the-foreland frontal thrusting dominated at the leading edge of the hot peridotite body. Top-to-the-hinterland shear along the upper contact of the peridotites is consistent with the kinematics expected for an extrusion wedge consisting of subcontinental mantle rocks. On the other hand, coeval strike-parallel extension and thinning of the crustal rocks overlying the peridotites confirms that, similarly to other Alpine-Mediterranean examples, partitioned transpression resulted in the development of a complex deformation pattern, with kinematically linked shear zones aiding exhumation. The proposed model provides a new, coherent scenario for syn-convergence peridotite emplacement and exhumation in the western Betic Cordillera.

The Weibei sag is a Cenozoic sag located within the Tan-Lu strike-slip fault zone southeast of the Bohai Bay Basin, China. The sag is controlled by two branches of the Tan-Lu right-lateral strike-slip fault zone (strike N30°E) and the Gucheng-Weihekou normal fault (strike E-W). This sag was thought to be a promising exploration area after several oil fields were found there. However, the most highly productive oil and gas wells are located on traps far from the source rocks, a situation thought to be related to the tectonic evolution of this sag. Thus, a regional study of the Weibei sag, involving three-dimensional seismic data sets and drilling cores, has been undertaken to document the sag's evolution. Five groups of secondary faults are distinguished within the Weibei sag: WNW-, E-W-, and ENE-striking normal faults and NNW- and NNE-striking strike-slip faults. Except for the preexisting WNW-striking faults, the other four groups of faults developed under Cenozoic tectonic movement. The combined analysis, including seismic profiles, drilling cores, and structure-contour and isopach maps, reveals that the Weibei sag is a simple right-lateral pull-apart basin, associated with right-stepping of the main displacement zones of the Tan-Lu fault zone, that experienced three stages of tectonic evolution: a right-lateral pull-apart stage (66-41.2 Ma), an uplift and erosion stage (41.2-23 Ma), and a depression stage (23 Ma-present). Based on the vertical and antithetic shear restorations, the minimum amounts of right-lateral strike-slip displacement along the Tan-Lu fault zone are 5.3 and 9.5 km, respectively. Our results suggest that it is important to take tectonic evolution, such as the dip direction and activity of secondary faults, into consideration to target a potential petroleum reservoir.

Two preferred textures were observed in the Alhama de Murcia Fault rocks: (a) foliated bands (>100 µm thick) rich in well-crystallized dioctahedral micas, quartz, hematite and dolomite; and (b) ultrafine-grained bands (<100 µm thick) made of patches composed of small mica crystals (<15 µm) and dispersed Fe-oxides. In both textures, kaolinite forms intergrowths or patches of randomly oriented crystals filling gaps or opening layers of presumably inherited detrital mica crystals, which is interpreted as an epitaxial growth from fluids. The Na/K ratio of mica crystals in the thin ultrafine-grained bands shows a wider range than the micas from the foliated bands including muscovitic, intermediate Na/K and paragonitic compositions. The absence of the 0.98 nm intermediate peak in the diffractograms indicates that the small micas are submicroscopically paragonite and phengite intergrowths. The d001 values of the K-dioctahedral micas in the <2 µm and whole fractions are clearly different from each other. The d001 values of micas of the <2 µm fraction are larger, indicating a higher K and lower Na content in the small micas. Their composition corresponds to lower temperatures, suggesting their growth during a genetic episode in the fault. The textural relationships indicate a late growth of kaolinite, probably due to the fluid-rock interaction along fault planes and fractures. The neoformed clay minerals might alter the stability of the fault plane. The absence of expandable clay minerals and the relatively high frictional strength of kaolinite under wet conditions might explain the observed velocity-neutral behaviour of this gouge and earthquake propagation towards the surface.

Postcollisional extrusion and tectonic evolution in the eastern Tianshan orogenic belt (ETOB) remains poorly known, especially the mechanism of dextral strike-slip motion and associated tectonic exhumation. To better constrain this development, a structural and 40Ar/39Ar geochronological study was carried out on a syndextral strike-slip intrusion the Jueluotag batholith-as well as on other granitic plutons in the ETOB. 40Ar/39Ar analyses of hornblende, biotite, K-feldspar, and plagioclase from quartz-mica diorite, granodiorite, and dioritic porphyry dykes were used to construct cooling histories of the ETOB. Hornblendes have cooling ages of 277-272 Ma, similar to the syntectonic granitic intrusions, but biotite ages are 261-254 Ma along the syndextral strike-slip pluton from east to west. The dextral strike-slip motion cuts through ∼268-Ma dioritic porphyry dikes as well. From these data we conclude that dextral strike-slip motion occurred from ∼270 to 245 Ma. Based on the syntectonic granitic intrusions, structural features, and cooling ages along or outside of the dextral strike-slip belt, we demonstrate that a positive flower structure is the main structural framework for the Paleozoic northern segment of the ETOB. Rapid cooling and tectonic exhumation occurred during ∼240-220 Ma along the ETOB but did not occur in the western Tianshan orogen. The central Tianshan crystalline belt along the Gangou-Aqikekuduk fault zone was cut and offset southeastward by the dextral strike-slip motion. This suggests that dextral strike-slip motion occurred later than sinistral strike-slip along the southern margin of the ETOB. Geological features and age constraints suggest that the postcollisional eastward extrusion occurred at ∼270-245 Ma with dextral strike-slip motion, syntectonic granitic intrusions, and synextrusion tectonic exhumation.