Global deformation on the surface of Venus

Large-scale mapping of tectonic structures on Venus shows that there is an organized global distribution to deformation. The structures we emphasize are linear compressive mountain belts, extensional rafted zones, and the small-scale but widely distributed wrinkle ridges. Ninety percent of the area of the planet's compressive mountain belts are concentrated in the northern hemisphere whereas the southern hemisphere is dominated by extension and small-scale compression. We propose that this striking concentration of fold belts in the northern hemisphere, along with the globe-encircling equatorial rift system, represents a global organization to deformation on Venus

Surface effects of active folding, illustrated with examples from the TianShan intracontinental mountain belt (China)

Understanding the irregularity of seismic cycles: A case study in Turke

fault gouge graphitization as evidence of past seismic slip

One moderate- to large-magnitude earthquake (M > 6) nucleates in Earth's crust every three days n average, but the geological record of ancient fault slip at meters-per-second seismic velocities (as opposed to subseismic slow-slip creep) remains debated because of the lack of established fault-zone evidence of seismic slip. Here we show that the irreversible temperature-dependent transformation of carbonaceous material (CM, a constituent of many fault gouges) into graphite is a reliable tracer of seismic fault slip. We sheared CM-bearing fault rocks in the laboratory at just above subseismic and at seismic velocities under both water-rich and water-deficient conditions and modeled the temperature evolution with slip. By means of micro-Raman spectroscopy and focused-ion beam transmission electron microscopy, we detected graphite grains similar to those found in the principal slip zone of the A.D. 2008 Wenchuan (Mw 7.9) earthquake (southeast Tibet) only in experiments conducted at seismic velocities. The experimental evidence presented here suggests that high-temperature pulses associated with seismic slip induce graphitization of CM. Importantly, the occurrence of graphitized fault-zone CM may allow us to ascertain the seismogenic potential of faults in areas worldwide with incomplete historical earthquake catalogues

Proto-South China Sea plate tectonics using subducted slab constraints from tomography

The past size and location of the hypothesized proto-South China Sea vanished ocean basin has important plate-tectonic implications for southeast Asia since the Mesozoic. Here we present new details on proto-South China Sea paleogeography using mapped and unfolded slabs from tomography. Mapped slabs included: the Eurasia-South China Sea slab subducting at the Manila trench; the northern Philippine Sea plate slab subducting at the Ryukyu trench; and, a swath of detached, sub-horizontal, slab-like tomographic anomalies directly under the South China Sea at 450 to 700 km depths that we show is subducted ‘northern proto-South China Sea’ lithosphere. Slab unfolding revealed that the South China Sea lay directly above the ‘northern Proto-South China Sea’ with both extending 400 to 500 km to the east of the present Manila trench prior to subduction. Our slab-based plate reconstruction indicated the proto-South China Sea was consumed by double-sided subduction, as follows: [1] The ‘northern proto-South China Sea’ subducted in the Oligo-Miocene under the Dangerous Grounds and southward expanding South China Sea by in-place 'self subduction' similar to the western Mediterranean basins; [2] Limited southward subduction of the proto-South China Sea under Borneo occurred pre-Oligocene, represented by the 800-900 km deep 'southern Proto-South China Sea' slab.Earth and Atmospheric Sciences, Department o

The Quaternary fault in Jiamu area, the Xinjiang Uygur Autonomous Region

peer reviewedThe Quaternary Tailan River fault has been found in the Tianshan foothills area, the Xinjiang Uygur Autonomous Region. It is the recent boundary fault of the Tarim Basin coupling with the West Tianshan Mountains. In the light of measurement data of the slip which cuts the Quaternary deposits of different ages, the Quaternary kine- matic figures of the Tailan River fault are estimated as fol- lows: crustal shortening 3.7 km and shortening rate 1.59 mm/a, uplift of Tianshan Mountains 1.34 km and uplift rate 0.56 mm/a, and additional relief of 900 m. Considering the contribution of the Gumubiezi anticline close to the south of the Tailan River fault, the Quaternary crustal shortening and shortening rate of the Jiamu area are 4.8 km and 2 mm/a respectively. The above-mentioned data coincide with the crustal shortening rate calculated from the growth strata in the Kuqa area, as well as the GPS measurements in the Lake Issyk area and the Korla-Urumqi area, reflecting the fast thrusting period within the shortening tectonic processes of the rejuvenation foreland basin in front of the southern foothill of the West Tianshan Mountains since Neogene

Philippine Sea and East Asian plate tectonics since 52 Ma constrained by new subducted slab reconstruction methods

We reconstructed Philippine Sea and East Asian plate tectonics since 52 Ma from 28 slabs mapped in 3-D from global tomography, with a subducted area of ~25% of present-day global oceanic lithosphere. Slab constraints include subducted parts of existing Pacific, Indian, and Philippine Sea oceans, plus wholly subducted proto-South China Sea and newly discovered ñEast Asian Sea.î Mapped slabs were unfolded and restored to the Earth surface using three methodologies and input to globally consistent plate reconstructions. Important constraints include the following: (1) the Ryukyu slab is ~1000 km N-S, too short to account for ~20Á Philippine Sea northward motion from paleolatitudes; (2) the Marianas-Pacific subduction zone was at its present location (±200 km) since 48 ± 10 Ma based on a \u3e1000 km deep slab wall; (3) the 8000 _ 2500 km East Asian Sea existed between the Pacific and Indian Oceans at 52 Ma based on lower mantle flat slabs; (4) the Caroline back-arc basin moved with the Pacific, based on the overlapping, coeval Caroline hot spot track. These new constraints allow two classes of Philippine Sea plate models, which we compared to paleomagnetic and geologic data. Our preferred model involves Philippine Sea nucleation above the Manus plume (0Á/150ÁE) near the Pacific-East Asian Sea plate boundary. Large Philippine Sea westward motion and post-40 Ma maximum 80Á clockwise rotation accompanied late Eocene-Oligocene collision with the Caroline/Pacific plate. The Philippine Sea moved northward post-25 Ma over the northern East Asian Sea, forming a northern Philippine Sea arc that collided with the SW Japan-Ryukyu margin in the Miocene (~20_14 Ma). ©2016. The Authors

The Chimei Submarine Canyon and Fan: A Record of Taiwan Arc-Continent Collision on the Rapidly Deforming Overriding Plate

The Chimei Canyon is a large, uplifting wedge‐top submarine canyon offshore eastern Taiwan that has delivered sediment since ~1‐2 Ma from the rapidly eroding Taiwan orogen to the Chimei Fan in the Huatung Basin, east of the colliding Luzon Arc. In this study, we document the depositional record of the Taiwan arc‐continent collision on the adjacent oceanic Philippine Sea plate using multichannel seismic reflection data together with high‐resolution bathymetry data to study the morphology, seismic sequences, and structures of the Chimei Canyon‐Fan system. The sedimentary strata are separated into three seismic sequences. The lowest sequence overlies oceanic crust, showing Cenozoic‐Cretaceous pelagic seismic facies that we interpret as pre‐collisional, whereas the middle and upper sequences are syn‐collisional. We propose a model for the development of the Chimei Canyon‐Fan in which the middle sequence first developed ~1‐2 Ma while the main depocenter was to the west in the forearc basin, west of the Luzon Arc. The upper sequence records a shift of depocenter after ~1 Ma from the forearc basin to the Chimei Fan east of the Luzon Arc. At the same time, this antecedent paleo channel‐fan system was deformed rapidly (~60 mm/yr; 62 km minimum shortening) by a complex imbricate thrust belt with the emergence of the arc and forearc basin as the west‐vergent Coastal Range thrust belt and the Chimei Canyon incising the active east‐vergent Offshore East Taiwan thrust belt. The thrust belt underlying the wedge‐top Chimei Canyon‐Fan has undergone >19 km shortening and ~2.6 km structure uplift

The timescale of plume-driven cratonization: A complete record from Tarim

ABSTRACT: Cratonization of the Tarim block in central Asia is finalized by the Permian Tarim plume that welded two cratonic nuclei together. Hence, the over-10-km-thick Tarim basin preserves a complete record of deformation and growth strata before, during, and after the plume-driven cratonization. Here we use seismic reflection data from the central Tarim basin to quantify the timing and style of the Paleozoic–Mesozoic deformation. The thrust and strike-slip faults there all underwent an early, intense deformation stage in the earliest Ordovician–Middle Devonian, a hiatus stage from Late Devonian to Late Permian, and a newly-discovered stage of weak activity throughout the Mesozoic. The intracontinental deformation is controlled by the subduction and accretion surrounding the Tarim block. The minor, but non-zero, Mesozoic strains reflect the ongoing adjustment to far-field compressions during the cooling and strengthening of the plume-stitched continental lithosphere. The cessation of interior deformation marks that the Tarim cratonization is finally attained ~200 Myr after the plume waned