Tectonic Landforms Research Articles

Tectonic landform and geology of the Median Tectonic Line Fault Zone in western Shikoku, southwest Japan

Tectonic landform and geology of the Median Tectonic Line Fault Zone in western Shikoku, southwest Japan

Four major unknown active faults identified, using satellite data, in India and Pakistan portions of NW Himalaya

New mapping through geomorphic analysis of tectonic landforms using a variety of freely available satellite data, including shuttle radar topography and Google Maps, has revealed four major curvilinear ~NW–SE trending faults in NW Himalaya regions of India and Pakistan. From north-west to south-east, these are named as Mawer, Tunda, Gulmarg, and Mughal Road fault zones. Some of these faults show evidence of oblique faulting where thrusting is accompanied by a small component of sinistral strike–slip faulting, and this possibly increases towards south-east. The active nature of deformation on these faults is demonstrated by occurrence of triangular facets, fault rupture scarps, topographic breaks, displaced ridges, shutter ridges, deflected drainages, plus uplift and back tilting of Holocene sedimentary deposits. This is further supported by the fact that these fault traces truncate the previously mapped active structures such as Kashmir basin/Balapore fault and main boundary thrust. The abrupt termination of most of these faults in north-west indicates a strong structural control. These faults are active, and their dimensions and geometrical configurations indicate their potential to host major earthquakes that could be similar or greater than what we witnessed during Kashmir earthquake of 2005. Further, active deformation is also mapped within Udhampur Piggyback basin, which lies within the Riasi fault system in Jammu and Kashmir, NW Himalaya. The emergent thrusting further suggests splay faulting from one of the branches of the Riasi fault system (Mandili-Kishanpur thrust). The structural configuration of the basin indicates a possible structural control on the formation and deformation of the basin. The geomorphic expression of active faulting is manifested in the overall morphology of the oval-shaped basin (similar to Kashmir basin in NW Himalaya). The shape is structurally controlled by faults as the whole of the basin is riding on Riasi fault system. Within the valley, the active faults are only visible on the ~SE portion. This has divided the basin into two distinctive geomorphic divisions: SE and NW domains. These domains are delineated by a structural break that could be ~NE–SW trending fault zone because the mapped faults do not continue beyond this topographic break in the basin. And since the SE tectonic domain is faulted, the streams are deeply incising into the bedrock forming deep canyons. The tributaries are short because their lengths are trimmed by the faults. Thus, the tributaries on the hanging wall have permanently lost their headwater source and are orphaned. Such geomorphic features are not visible in the NW domains, which have not been faulted, and thus, the streams are following the natural slope. All the streams feed the basin merge into a major stream (Tawi River) that cuts through the anticlinal ridge of Suruin–Mastgarh anticline. This river roughly follows the interpreted ~NE–SW trending topographic break, which could mean that it follows a fault. Such an interpretation is backed by the evidence that the anticlinal ridge is only broken at this portion of the ridge.

The surface roughness of Mercury from the Mercury Laser Altimeter: Investigating the effects of volcanism, tectonism, and impact cratering

AbstractSurface roughness is a statistical measure of change in surface height over a given spatial horizontal scale after the effect of broad‐scale slope has been removed and can be used to understand how geologic processes produce and modify a planet's topographic character at different scales. The statistical measure of surface roughness employed in this study of Mercury was the root‐mean‐square deviation and was calculated from 45 to 90°N at horizontal baselines of 0.5–250 km with detrended topographic data from individual Mercury Laser Altimeter tracks. As seen in previous studies, the surface roughness of Mercury has a bimodal spatial distribution, with the cratered terrain (dominated by the intercrater plains) possessing higher‐surface roughness than the smooth plains. The measured surface roughness for both geologic units is controlled by a trade‐off between impact craters generating higher‐surface roughness values and flood‐mode volcanism decreasing surface roughness. The topography of the two terrain types has self‐affine‐like behavior at baselines from 0.5 to 1.5 km; the smooth plains collectively have a Hurst exponent of 0.88 ± 0.01, whereas the cratered terrains have a Hurst exponent of 0.95 ± 0.01. Subtle variations in the surface roughness of the smooth plains can be attributed to differences in regional differences in the spatial density of tectonic landforms. The northern rise, a 1000 km wide region of elevated topography centered at 65°N, 40°E, is not distinguishable in surface roughness measurements over baselines of 0.5–250 km.

Geology of the Shakespeare quadrangle (H03), Mercury

ABSTRACTBy using images acquired by the Mercury dual imaging system (MDIS) on-board the MESSENGER spacecraft during 2008–2015 and available DTMs, a new 1:3,000,000-scale geological map of the Shakespeare quadrangle of Mercury has been compiled. The quadrangle is located between latitudes 22.5°–65.0°N and longitudes 270.0°–180.0°E and covers an area of about 5 million km2. The mapping was based on photo-interpretation performed on a reference monochromatic basemap of reflectance at 166 m/pixel resolution. The geological features were digitized within a geographic information system with a variable mapping scale between 1:300,000 and 1:600,000. This quadrangle is characterized by the occurrence of three main types of plains materials and four basin materials (pertaining to the Caloris basin), whose geologic boundaries have been here redefined compared to the previous map of the quadrangle. The stratigraphic relationships between the craters were based on three main degradation morphologies. Furthermore, previously unmapped tectonic landforms were detected and interpreted as thrusts or wrinkle ridges.

Active Faults in Peninsular Malaysia with Emphasis on Active Geomorphic Features Of Bukit Tinggi Region

In this paper, we summarize the results of recent geomorphic investigations of active faults in Peninsular Malaysia with emphasize on Bukit Tinggi region using IFSAR and field verification. The evidences for active faulting, and their characteristics are discussed. Several fault segments within the Bukit Tinggi fault zone are deemed active. The Bukit Tingg fault zone is considered to be active and is a potential source of future earthquakes. Outside Bukit Tinggi area, the Benus and Karak faults are also deemed active. These fault zones show the following active neotectonic geomorphic features: 1) displays geomorphic features indicative of recent fault activity; 2) show evidence for displacement in young (Late Quaternary) deposits or surfaces; and/or 3) is associated with a pattern of microearthquakes suggestive of an active faults. They were ancient faults that were reactivated in the Quaternary period and continued into the present. The magnitude of paleoearthquake estimated from the activity and stream offsets suggest a minimum of 6 magnitude on the Richter scale have affected the region due to movements along these faults. Over the past decades, Peninsular Malaysia has experienced mild earthquakes. Virtually all earthquakes recorded in Peninsular Malaysia are under magnitude 5.0. However, the regognition of active faults exhibiting active tectonic landforms suggestes that these faults have produced damaging earthquakes before and have potential to trigger similar tremors in the future.

Transverse tectonic structural elements across Himalayan mountain front, eastern Arunachal Himalaya, India: Implication of superposed landform development on analysis of neotectonics

Structural and morphotectonic signatures in conjunction with the geomorphic indices are synthesised to trace the role of transverse tectonic features in shaping the landforms developed along the frontal part of the eastern Arunachal sub-Himalaya. Mountain front sinuosity (Smf) index values close to one are indicative of the active nature of the mountain front all along the eastern Arunachal Himalaya, which can be directly attributed to the regional uplift along the Himalayan Frontal Thrust (HFT). However, the mountain front is significantly sinusoidal around junctions between HFT/MBT (Main Boundary Thrust) and active transverse faults. The high values of stream length gradient (SL) and stream steepness (Ks) indices together with field evidence of fault scarps, offset of terraces, and deflection of streams are markers of neotectonic uplift along the thrusts and transverse faults. This reactivation of transverse faults has given rise to extensional basins leading to widening of the river courses, providing favourable sites for deposition of recent sediments. Tectonic interactions of these transverse faults with the Himalayan longitudinal thrusts (MBT/HFT) have segmented the mountain front marked with varying sinuosity. The net result is that a variety of tectonic landforms recognized along the mountain front can be tracked to the complex interactions among the transverse and longitudinal tectonic elements. Some distinctive examples are: in the eastern extremity of NE Himalaya across the Dibang River valley, the NW-SE trending mountain front is attenuated by the active Mishmi Thrust that has thrust the Mishmi crystalline complex directly over the alluvium of the Brahmaputra plains. The junction of the folded HFT and Mishmi Thrust shows a zone of brecciated and pulverized rocks along which transverse axial planar fracture cleavages exhibit neotectonic activities in a transverse fault zone coinciding with the Dibang River course. Similarly, the transverse faults cut the mountain front along the Sesseri, Siluk, Siku, Siang, Mingo, Sileng, Dikari, and Simen rivers. At some such junctions, landforms associated with the active right-lateral strike-slip faults are superposed over the earlier landforms formed by transverse normal faults. In addition to linear transverse features, we see evidence that the fold-thrust belt of the frontal part of the Arunachal Himalaya has also been affected by the neotectonically active NW-SE trending major fold known as the Siang antiform that again is aligned transverse to the mountain front. The folding of the HFT and MBT along this antiform has reshaped the landscape developed between its two western and eastern limbs running N-S and NW-SE, respectively. The transverse faults are parallel to the already reported deep-seated transverse seismogenic strike-slip fault. Therefore, a single take home message is that any true manifestation of the neotectonics and seismic hazard assessment in the Himalayan region must take into account the role of transverse tectonics.

Tectonic landforms and a fault outcrop in the Fujikawa Valley, Central Japan

Tectonic landforms and a fault outcrop in the Fujikawa Valley, Central Japan

Tectonic geomorphology of the Sudetes (Central Europe) – a review and re-appraisal

The Sudetes are a mountain range in Central Europe, which owes its emergence to the Cenozoic rejuvenation of an old Variscan orogen, subject to stresses from the Alps and the Carpathians. The gross morphological features of the Sudetes are typically explained as reflecting the superposition of the effects of long-term, rock-controlled denudation and Late Cenozoic differential uplift and subsidence. In this paper, early conceptual models, developed in the 1950s and 1960s and emphasizing alternating uplift and planation phases, are presented first. A review of more recent work focused on tectonic landforms and geomorphic indicators of tectonic movements follows, with special attention to fault-generated escarpments, valley morphology, stream longitudinal profiles, terraces and fans, drainage basin characteristics and regional geomorphometric studies. Attempts to provide a timeframe of tectonic relief differentiation are also summarized. In the closing part of the paper, the existing approaches and findings are re-evaluated in order to identify challenges and perspectives for future work. The availability of high-resolution digital terrain models creates a unique opportunity to quantify relief features and detect even the subtle topographic signatures of recent tectonics. A need to reconcile the results of geomorphological analysis with those emerging from other studies focused on faults is highlighted.

Reexamination of tectonic landforms and active faults in the northern part of the Kitakami lowland, northeast Japan

Reexamination of tectonic landforms and active faults in the northern part of the Kitakami lowland, northeast Japan

Fault‐bound valley associated with the Rembrandt basin on Mercury

AbstractThe Rembrandt basin is crosscut by the largest fault scarp on Mercury, Enterprise Rupes, and a second scarp complex, Belgica Rupes, extends to the basin's rim. Topographic data derived from MESSENGER orbital stereo images show that these tectonic landforms bound a broad, relatively flat‐floored valley with a mean width of ~400 km. Crosscutting relations suggest that the accumulation of structural relief likely postdates the formation and volcanic infilling of the Rembrandt basin. The valley floor, bound by fault scarps of opposite vergence, is significantly offset below the elevation of the back‐scarp terrains. Along with an offset section of Rembrandt's rim, the elevation differences are evidence that the valley floor was lowered as a result of the formation of bounding fault scarps. The localization of the widely spaced thrust faults of Enterprise and Belgica Rupis and the offset of the valley floor may be the result of long‐wavelength buckling of Mercury's lithosphere.

Recent tectonic activity on Mercury revealed by small thrust fault scarps

The planet Mercury has contracted over its history. The identification of small thrust fault scarps suggests the occurrence of tectonic activity on Mercury within the past 50 million years and thus a slow-cooling planetary interior. Large tectonic landforms on the surface of Mercury, consistent with significant contraction of the planet, were revealed by the flybys of Mariner 10 in the mid-1970s1. The MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) mission confirmed that the planet’s past 4 billion years of tectonic history have been dominated by contraction expressed by lobate fault scarps that are hundreds of kilometres long2,3,4,5. Here we report the discovery of small thrust fault scarps in images from the low-altitude campaign at the end of the MESSENGER mission that are orders of magnitude smaller than the large-scale lobate scarps. These small scarps have tens of metres of relief, are only kilometres in length and are comparable in scale to small young scarps on the Moon6,7,8. Their small-scale, pristine appearance, crosscutting of impact craters and association with small graben all indicate an age of less than 50 Myr. We propose that these scarps are the smallest members of a continuum in scale of thrust fault scarps on Mercury. The young age of the small scarps, along with evidence for recent activity on large-scale scarps, suggests that Mercury is tectonically active today and implies a prolonged slow cooling of the planet’s interior.

Late Quaternary tectonic landforms and fluvial aggradation in the Saryu River valley: Central Kumaun Himalaya

The present study has been carried out with special emphasis on the aggradational landforms to explain the spatial and temporal variability in phases of aggradation/incision in response to tectonic activity during the late Quaternary in the Saryu River valley in central Kumaun Himalaya. The valley has preserved cut-and-fill terraces with thick alluvial cover, debris flow terraces, and bedrock strath terraces that provide signatures of tectonic activity and climate. Morphostratigraphy of the terraces reveals that the oldest landforms preserved south of the Main Central Thrust, the fluvial modified debris flow terraces, were developed between 30 and 45ka. The major phase of valley fill is dated between 14 and 22ka. The youngest phase of aggradation is dated at early and mid-Holocene (9–3ka). Following this, several phases of accelerated incision/erosion owing to an increase in uplift rate occurred, as evident from the strath terraces. Seven major phases of bedrock incision/uplift have been estimated during 44ka (3.34mm/year), 35ka (1.84mm/year), 15ka (0.91mm/year), 14ka (0.83mm/year), 9ka (1.75mm/year), 7ka (5.38mm/year), and around 3ka (4.4mm/year) from the strath terraces near major thrusts. We postulate that between 9 and 3ka the terrain witnessed relatively enhanced surface uplift (2–5mm/year).

Geomorphic features of active faults around the Kathmandu Valley, Nepal, and no evidence of surface rupture associated with the 2015 Gorkha earthquake along the faults

The M7.8 April 25, 2015, Gorkha earthquake in Nepal was produced by a slip on the low-angle Main Himalayan Thrust, a decollement below the Himalaya that emerges at the surface in the south as the Himalayan Frontal Thrust (HFT). The analysis of the SAR interferograms led to the interpretations that the event was a blind thrust and did not produce surface ruptures associated with the seismogenic fault. We conducted a quick field survey along four active faults near the epicentral area around the Kathmandu Valley (the Jhiku Khola fault, Chitlang fault, Kulekhani fault, Malagiri fault and Kolphu Khola fault) from July 18–22, 2015. Those faults are located in the Lesser Himalaya on the hanging side of the HFT. Based on our field survey carried out in the area where most typical tectonic landforms are developed, we confirmed with local inhabitants the lack of any new surface ruptures along these faults. Our observations along the Jhiku Khola fault showed that the fault had some definite activities during the Holocene times. Though in the past it was recognized as a low-activity thrust fault, our present survey has revealed that it has been active with a predominantly right-lateral strike-slip with thrust component. A stream dissecting a talus surface shows approximately 7-m right-lateral offset, and a charcoal sample collected from the upper part of the talus deposit yielded an age of 870 ± 30 y.B.P, implying that the talus surface formed close to 870 y.B.P. Accordingly, a single or multiple events of the fault must have occurred during the last 900 years, and the slip rate we estimate roughly is around 8 mm/year. The fault may play a role to recent right-lateral strike-slip tectonic zone across the Himalayan range. Since none of the above faults showed any relationship corresponding to the April 25 Gorkha earthquake, it is possibility that a potential risk of occurrence of large earthquakes does exist close to the Kathmandu Valley due to movements of these active faults, and more future work such as paleoseismological survey is needed to assess the risk.

Tectonic landforms associated with recent activities of the Minobu fault in the Fujikawa Valley and its implications, South Fossa Magna, Central Japan

Tectonic landforms associated with recent activities of the Minobu fault in the Fujikawa Valley and its implications, South Fossa Magna, Central Japan

Caloris basin, Mercury: History of deformation from an analysis of tectonic landforms

The 1640km diameter Caloris basin is the largest impact basin on Mercury and hosts three distinct suites of tectonic structures in its substantially deformed smooth plains, indicative of the basin’s complex history. These structures, i.e. radial graben comprising Pantheon Fossae, concentric graben/troughs arranged in an irregular pattern, and wrinkle ridges, are found at various regions throughout the basin and occasionally interact. We document the locations, orientations, and cross-cutting relationships of these structures using high-resolution MESSENGER images. We suggest that Caloris shows a history of continuous deformation, resulting from the contemporaneous formation of sets of strain compatible tectonic structures, rather than discrete stages of deformation producing each suite independently in temporal sequence. We propose that radial graben formed continuously in the basin’s early deformational history, following initial wrinkle ridge formation possibly representative of a multi-ring basin structure, overlapping with continued wrinkle ridge formation, and persisting with the formation of concentric graben after contraction ceased.

The tectonics of Titan: Global structural mapping from Cassini RADAR

The Cassini RADAR mapper has imaged elevated mountain ridge belts on Titan with a linear-to-arcuate morphology indicative of a tectonic origin. Systematic geomorphologic mapping of the ridges in Synthetic Aperture RADAR (SAR) images reveals that the orientation of ridges is globally E–W and the ridges are more common near the equator than the poles. Comparison with a global topographic map reveals the equatorial ridges are found to lie preferentially at higher-than-average elevations. We conclude the most reasonable formation scenario for Titan’s ridges is that contractional tectonism built the ridges and thickened the icy lithosphere near the equator, causing regional uplift. The combination of global and regional tectonic events, likely contractional in nature, followed by erosion, aeolian activity, and enhanced sedimentation at mid-to-high latitudes, would have led to regional infilling and perhaps covering of some mountain features, thus shaping Titan’s tectonic landforms and surface morphology into what we see today.

Tectonic landforms along the coast of Shakotan peninsula, Hokkaido, Northern Japan

Tectonic landforms along the coast of Shakotan peninsula, Hokkaido, Northern Japan

Global thrust faulting on the Moon and the influence of tidal stresses

Lunar Reconnaissance Orbiter Camera images reveal a vast, globally distributed network of over 3200 lobate thrust fault scarps, making them the most common tectonic landform on the Moon. Based on their small scale and crisp appearance, crosscutting relations with small-diameter impact craters, and rates of infilling of associated small, shallow graben, these fault scarps are estimated to be younger than 50 Ma and may be actively forming today. The non-random distribution of the scarp orientations is inconsistent with isotropic stresses from late-stage global contraction as the sole source of stress. We propose that tidal stresses contribute significantly to the current stress state of the lunar crust. Orbital recession stresses superimposed on stresses from global contraction with the addition of diurnal tidal stresses result in non-isotropic compressional stress and thrust faults consistent with lobate scarp orientations. The addition of diurnal tidal stresses at apogee result in peak stresses that may help trigger coseismic slip events on currently active thrust faults on the Moon.

Identification of a suspected Quaternary fault in eastern Korea: Proposal for a paleoseismic research procedure for the mapping of active faults in Korea

In terms of seismic hazard in the Korean Peninsula, the occurrence of destructive earthquakes has long been overlooked because of no serious modern instrumental seismicity and lack of historical earthquake records of large earthquakes. In recent years, although the importance and uses of paleoseismological studies has significantly increased in seismic hazard assessments of critical facilities, there is still a huge lack of paleoseismological data to improve our knowledge for Korean active tectonics and relevant seismic hazards. In this study, we identified and characterized a suspected Quaternary fault in the eastern part of the Korea Peninsula based on lineament analyses, field observations, and trench surveys. We focus on a prominent lineament around the northern part of the previously reported, but not sufficiently studied, Maeup Fault. Firstly, a potential fault lineament is recognized by geomorphic expressions in a mountainous area from satellite and digital elevation model (DEM)-generated images. Then, fault-related geomorphic and hydrologic features, such as disconnected drainages, sag ponds, and asymmetric water leaking out on an artificial ditch, were observed along the lineament in the field studies. Finally, the existence of the fault is confirmed by an exposure of a 2.5m wide fault core in trench surveys. The internal structures of the fault core (i.e., slip surfaces, slickenlines, and S-C fabrics) indicate that the fault evolved via a series of slip events under a variety of tectonic settings, probably leading up to the current stress regime sustained during Quaternary. Thus our results suggest that the newly identified fault could be a Quaternary fault, and hence it is necessary to perform more paleoseismic investigations around the study region. This case study emphasizes the importance of the careful interpretation of tectonic landforms and fault zone structures in the study of active faults, and proposes a suitable research procedure for the identification of active faults in Korea.

Active faults and dip slip rates along the northern margins of the Huashan Mountain and Weinan loess tableland in the southeastern Weihe Graben, central China

Two active faults, including the Huashan piedmont fault (HPF) along the northern margin of Huashan Mountain and the north margin fault of the Weinan loess tableland (NMF-WLT), were developed in the southeastern Weihe Graben, in central China. HPF, which is the most active fault in the Weihe Graben, is known throughout the world for the M81/4 great Guanzhong earthquake in 1556 AD. Through field investigation, AMS 14C, and OSL dating in this paper, in combination with previous studies, the following results are obtained: (i) Tectonic landforms, such as triangular fault facets, waterfalls and fault scraps of proluvial fans, were developed in the HPF, but these features were not developed in the NMF-WLT. (ii) HPF experienced three intensive seismic activities in 5920–7670Cal yr BP, 2215±95–3105±105Cal yr BP and 1556 AD during the Holocene, but there has only been one seismic event noted for the NMF-WLT since the Holocene (6865±80Cal yr BP). (iii) The dip-slip rate of the HPF was approximately 0.64mm/yr since the mid-Pleistocene and approximately 1.67–2.71mm/yr in the Holocene. In contrast, the dip-slip rate of NMF-WLT was approximately 0.32–0.42mm/yr since the early Pleistocene and was approximately 0.39–0.58mm/yr from the late Pleistocene to the Holocene. (iv) The seismic activity at the HPF has been more intense than at the NMF-WLT; the HPF was the triggering seismic fault of the M81/4 great Guanzhong earthquake in 1556 AD, whereas the NMF-WLT was not the seismogenic fault of this event. These results provide new information for the study of active tectonics of the Weihe Graben.