Regional Shortening Research Articles

Kinematic Evolution of the Santa Bárbara System in the Foreland of the Central Andes of Northwestern Argentina (26°S)

AbstractCompared to the thin‐skinned Subandean foreland fold‐and‐thrust belt of northern Argentina and Bolivia, the tectonically active morphotectonic province of the Santa Bárbara System in the Andean broken foreland of northwestern Argentina is characterized by a temporally and spatially disparate deformation style. Although there is no well‐defined orogenic deformation front associated with the uplift of these basement‐cored, reverse‐fault bounded mountain ranges, there has been an overall eastward trend in Andean compressional deformation since the Miocene. While reactivation of basement anisotropies, such as early Paleozoic metamorphic fabrics and Cretaceous normal faults, has been proposed to have profoundly affected deformation processes in the Santa Bárbara System, other mechanisms involving Mesozoic and Cenozoic cover rocks may also have played an important role in orogenic deformation in this sector of the Andean foreland. We present structural field observations, interpretations of seismic reflection profiles, and kinematic modeling from the basins bordering the Candelaria Range in the southern sector of the Santa Bárbara System at 26°S. Our analysis features a 110‐km‐long structural cross section that images and links deep‐seated structures with shallow neotectonic faults. We find that regional shortening has been facilitated by several faults associated with a regional detachment at a depth of 23 km, resulting in total horizontal shortening of about 17% (18.4 km). While the deep‐seated first‐order structures seem closely linked to seismogenic processes in the Andean foreland, shallow second‐order structures within the sedimentary cover modify the intermontane landscapes and appear to be associated with aseismic creep.

Patient-specific left atrium contraction quantification associated with atrial fibrillation: A region-based approach

Background and objectivesAtrial fibrillation (AF) is a widespread cardiac arrhythmia that significantly impacts heart function. AF disrupts atrial mechanical contraction, leading to irregular, uncoordinated, and slow blood flow inside the atria which favors the formation of clots, primarily within the left atrium (LA). A standardized region-based analysis of the LA is missing, and there is not even any consensus about how to define the LA regions. In this study we propose an automatic approach for regionalizing the LA into segments to provide a comprehensive 3D region-based LA contraction assessment. LA global and regional contraction were quantified in control subjects and in AF patients to describe mechanical abnormalities associated with AF. MethodsThe proposed automatic approach for LA regionalization was tested in thirteen control subjects and seventeen AF patients. After dividing LA into standard regions, we evaluated the global and regional mechanical function by measuring LA contraction parameters, such as regional volume, global and regional strains, regional wall motion and regional shortening fraction. ResultsLA regionalization was successful in all study subjects. In the AF group compared with control subjects, results showed: a global impairment of LA contraction which appeared more pronounced along radial and circumferential direction; a regional impairment of radial strain which was more pronounced in septal, inferior, and lateral regions suggesting a greater reduction in mechanical efficiency in these regions in comparison to the posterior and anterior ones. ConclusionAn automatic approach for LA regionalization was proposed. The regionalization method was proved to be robust with several LA anatomical variations and able to characterize contraction changes associated with AF.

Migmatite dome as a result of multi-fold interference pattern, in the Damara Belt, Namibia

The western part of the Pan-African Damara Orogen in Namibia is located at the intersection of two highly oblique mobile belts: the coastal NNW-trending Kaoko-Gariep belts and the inland NE-trending Damara Belt. The Namibfontein-Vergenoeg (NV) domes are two, basement-cored, migmatite domes exposed in this orogenic intersection. These domes formed through the superposition of four deformation phases in the presence of melt, giving rise to syn-migmatitic multi-fold interference patterns. Early E-W shortening produced steep N–S striking S1 fabrics linked to km-scale steeply E-inclined F1 folds, likely reflecting the southern continuity of the Kaoko Belt fabrics. The superposition of NE-plunging, NNW-inclined F2 folds formed during NNW-SSE, orogen-perpendicular shortening and produced a Type 1 dome-and-basin fold interference pattern. Progressive with D2, D3 deformation caused localised m-scale folding of steep fabrics into inclined to recumbent, NW-plunging F3 folds, and local top-to-the-S or -SE thrusting. NNW-SSE shortening is correlated with the collision of the Congo and Kalahari cratons during Damara Belt formation. Finally, orogen-parallel NE-SW shortening, produced localised NE-inclined and NE-plunging F4 folds. This weaker shortening phase in the Damara Belt is enigmatic and may reflect tectonic activities further in eastern and western Gondwana. The superposition of F4 folds on F2 folds defines a Type 3 fold interference pattern that established the final 3D architecture of the NV domes. The deformation fabrics at the NV domes document three distinct regional shortening events related to large-scale tectonic switches involved in the western Gondwana Supercontinent assembly.

Fracture distribution along open folds in southern Tunisia: implications for naturally fractured reservoirs

Fracture networks play a critical role in fluid flow within reservoirs, and it is therefore important to understand the interactions and influences of these networks. Our study focuses on the Southern Chotts–Jeffara Basin, which hosts reservoirs within Triassic, Permian and Ordovician units containing significant hydrocarbon accumulations. Recent developments on the structural understanding of the basin have proved that a regional shortening phase occurred between the Permian and Jurassic, forming open folds and a distributed fracture network. Analysis of late Paleozoic and Mesozoic outcrops within the basin has identified several sets of fractures (with dip directions and dip angles of 150/80 and 212/86) and compressional structural features that support this shortening hypothesis. We have integrated fracture data from surface analogues and subsurface analysis of advanced seismic attributes and well data through structural linking to form a 2D hybrid fracture model of the reservoirs in the region. Through analytical aperture modelling and numerical simulation, we found that the fractures orientated 212° in combination with large-scale fractures contribute significantly to the fluid-flow orientation and potential reservoir permeability. Our presented fracture workflow and framework provide an insight into network characterization within naturally fractured reservoirs of Tunisia, and how certain structures form fluid pathways that influence flow and production. Supplementary material: Data and figures detailing fracture characterisation and modelling along open folds in southern Tunisia are available at https://doi.org/10.6084/m9.figshare.c.6904499

Plateau Formation Controlled by Lithospheric Foundering Under a Weak Crust

AbstractLithospheric foundering is hypothesized to contribute to the formation of Earth's largest continental plateaus, but the predicted effects remain poorly constrained, especially considering variations in crustal strength. Here we propose that lithospheric foundering involving a hot, weak crust can explain aspects of topography and crustal deformation in mountain belts. We explore this hypothesis using numerical models of orogenesis and foundering in the Southern Puna Plateau in the Central Andes. Contrary to previous models of foundering involving a strong crust, which are characterized by subsidence and shortening, a weak crust results in surface uplift and upper‐crustal horizontal extension, which is accommodated by horizontal shortening in peripheral regions. Our model explains data such as the timing and location of exhumation and basin sedimentation as a response to foundering. The model also shows that foundering is capable of converting a high‐relief, broken‐foreland region into a high‐elevation, low‐relief plateau in a convergent tectonic setting.

Tectonic evolution of a Paleoproterozoic diffuse cryptic suture zone in northern Fennoscandia and the correlation of northern Fennoscandia and southern Greenland

The boundary between the Karelia and Norrbotten continental blocks in Fennoscandia is a diffuse cryptic suture zone recording c. 200 Ma of tectono-metamorphic evolution between 1.92 and 1.72 Ga. Syn-collisional deposition at 1.92–1.91 Ga was followed by post-collisional deposition at 1.88–1.87 and 1.85–1.84 Ga. The post-collision structural overprint in the suture starts with sinistral movements due to aulacogen inversion (D2) east of the suture. Late-D2 and D orocline extensional stages are followed by NE-vergent basin inversion (D3) of <1.88 Ga rocks and transpressional dextral shear in the suture zone. Nearly orthogonal D4 and D5 deformation events overprint earlier fabrics at c. 1.83 and c. 1.78 Ga, respectively. The youngest (D6, c. 1.73 Ga) structures include sinistral brittle–ductile movements. Northern Fennoscandia and southern Greenland are linked by coeval continent–continent collisions (D1, 1.92–1.89 Ga). The D orocline stage ( c. 1.87 Ga), responsible for oroclinal buckling in central Fennoscandia, is conceivably related to west-directed subduction and subsequent regional shortening in western Greenland. The D3–D4 events in Fennoscandia are comparable to, and the D5–D6 events correlate well with, tectonic events in the suture zone in the eastern Nagssugtoqidian orogen in Greenland. Supplementary material: Analytical methods, data, interpretations of U–Pb data, and structural data on detailed study areas and key locations are available at https://doi.org/10.6084/m9.figshare.c.6675191

Normal faulting and landsliding in morpho-structural domes related to buried salt stocks, Zagros Mountains, Iran. Insights into salt breakout

Normal faulting in domal structures above diapirs has important implications in hydrocarbon geoscience, but studies on surface faulting on exposed growing domes are scarce. Moreover, there is limited work addressing the erosional processes involved in the unroofing of active diapirs preceding salt emergence. This investigation analyses two morpho-structural domes (Gavbast Dome: GD; Kooh Bedoo Dome: KBD) associated with growing anticlines related to the rejuvenation of precursor buried salt stocks in the Zagros Mountains. The structural relief of the domes (1330 m in GD and 400 m in KBD) and the available chronological data on fold development indicate long-term uplift rates of around 0.1–0.4 mm/yr. GD displays three domains with different fault patterns: (1) fold-normal grabens in one half; (2) polygonal faulting with multiple enclosed graben depressions in the crest; and (3) fold-parallel faulting on the other half. KBD shows a major fold-normal graben restricted to the crest and one flank of the dome. The lack of the typical radial pattern related to multidirectional hoop extension can be attributed the suppression of extension in the fold-normal direction by regional shortening. Other factors such as complexities in the folding structure, outer-arc extension in the anticline crests, and plan geometry seem to play a local control on fault patterns. The studied domes display an extraordinarily high density of large slope movements, indicating that they play an instrumental role in the unroofing process. The slope failures, with sliding planes mainly developed in argillaceous units overlain by thick limestone packages, include incipient planar rock slides more than 5 km2 in area expressed as buckle folds in the lower part of the slopes. The main preparatory factors involved in the development of these slope collapses include rock mass weakening by faulting and slope over-steepening, both related to doming. Our detailed mapping and the examination of a number of salt diapirs in the Fars Arc suggest that episodic landsliding and more gradual fluvial dissection, often controlled by grabens, are the main erosional processes involved in the unroofing of active diapirs leading to salt emergence.

Emplacement of a lamprophyric sheet swarm under ductile transpression in continental crust. Insights from a Variscan magmatic complex in the West Armorican belt, Western France

We present structural data from a Variscan magmatic complex of dominantly lamprophyric (kersantite) and associated felsic (microgranodiorite) sheets - the West Armorican swarm (WAS) - injected into Paleozoic metasedimentary series at the western extremity of a transpressional system in the Armorican belt, Western France. The comparative structural analysis of nearly 100 individual intrusive sheets and their host-rocks demonstrates that the WAS complex is a syntectonic magmatic structure which intruded during the onset of regional shortening via successive pulses alternating with three strain episodes (D1-D2-D3). The moderate/high dipping attitude of a great majority of intrusions, along with their prominent orientation parallel to the regional cleavage (S1), i.e. orthogonal to the direction of shortening, challenge theoretical predictions about magma-filled fractures in contractional settings. These apparently atypical features are reconciled in a kinematic model which emphasizes the influence of both host-rock planar anisotropies (S1 cleavage and D3 shear patterns) and structural inheritance on magma pathways, and instead hypothesizes the negligible role of the ambient stress field. Comparisons are attempted with syncollisional lamprophyre systems present in the European Variscides, and more especially in the SE Bohemian massif.

Provenance analysis of Paleozoic strata in the Falkland/Malvinas Islands: Implications for paleogeography and Gondwanan reconstructions

New U-Pb geochronological, Hf isotopic, heavy mineral, and sandstone petrographic results for Paleozoic clastic deposits of the Falkland/Malvinas Islands help address renewed debates on the plate tectonic history, regional paleogeography, and basin evolution of this geologic enigma prior to Mesozoic breakup of Gondwana. The Falkland/Malvinas Islands have been considered either an autochthonous part of the South American continent or part of an independent microplate displaced from the southeastern corner of Africa. We report detrital zircon U-Pb results (n = 1306 LA-ICPMS ages) for 11 sandstone samples from the Silurian-Devonian West Falkland Group (N = 7 samples, n = 837 grains) and Carboniferous-Permian Lafonia Group (N = 4 samples, n = 469 grains). Detrital zircon age distributions for the West Falkland Group point to consistent contributions from Neoproterozoic-Cambrian (650–520 Ma) and Mesoproterozoic (1100–1000 Ma) sources. Heavy mineral assemblages and sandstone petrographic data from these samples indicate significant input from recycled sediments. A potential shift in sediment sources during deposition of the Lafonia Group is indicated by the appearance of late Paleozoic (350–250 Ma) and Proterozoic (2000–1200 Ma) age populations, decreased proportions of stable heavy minerals, and a shift to juvenile Hf values for < 300 Ma zircons. The provenance change can be attributed to the onset of subduction-related arc magmatism and potential regional shortening and crustal thickening in southwestern Gondwana during the Permian transition of a passive margin into an active, retro-arc foreland basin. The detrital zircon age distributions identified here reflect potential source regions in southern Africa and/or the Transantarctic Mountains in Antarctica. These results are most readily accommodated within a Gondwana reconstruction that includes the Falkland/Malvinas Islands as a rotated microplate originating on the eastern side of southern Africa as part of the Gondwanide fold-thrust belt spanning from the Ventania region of Argentina through the Cape region of South Africa and into the Ellsworth and Pensacola mountains of Antarctica.

Myocardial Regional Shortening from 4D Cardiac CT Angiography for the Detection of Left Ventricular Segmental Wall Motion Abnormality.

To investigate whether endocardial regional shortening computed from four-dimensional (4D) CT angiography (RSCT) can be used as a decision classifier to detect the presence of left ventricular (LV) wall motion abnormalities (WMAs). One hundred electrocardiographically gated cardiac 4D CT studies (mean age, 59 years ± 14 [SD]; 61 male patients) conducted between April 2018 and December 2020 were retrospectively evaluated. Three experts labeled LV wall motion in each of the 16 American Heart Association (AHA) segments as normal or abnormal; they also measured peak RSCT across one heartbeat in each segment. The data set was split evenly into training and validation groups. During training, interchangeability of RSCT thresholding with experts to detect WMA was assessed using the individual equivalence index (γ), and an optimal threshold of the peak RSCT (RSCT*) that achieved maximum agreement was identified. RSCT* was then validated using the validation group, and the effect of AHA segment-specific thresholds was evaluated. Agreement was assessed using κ statistics. The optimal threshold, RSCT* of -0.19, when applied to all AHA segments, led to high agreement (agreement rate = 92.17%, κ = 0.82) and interchangeability with experts (γ = -2.58%). The same RSCT* also achieved high agreement in the validation group (agreement rate = 90.29%, κ = 0.76, γ = -0.38%). The use of AHA segment-specific thresholds (range: 0.16 to -0.23 across AHA segments) slightly improved agreement (1.79% increase). RSCT thresholding was interchangeable with expert visual analysis in detecting segmental WMA from 4D CT and may be used as an objective decision classifier.Keywords: CT, Left Ventricle, Regional Endocardial Shortening, Wall Motion Abnormality Supplemental material is available for this article. © RSNA, 2023.

Palaeostress analysis using fault-slip data from the Xiangdong tungsten deposit in the central south China continent: Evolution of intraplate stress in the Middle Mesozoic

In the central South China continent, the Xiangdong tungsten deposit associated with Late-Jurassic granitic intrusion offers an opportunity to examine the evolution of intraplate stress between the Late Jurassic and Early Cretaceous, which was a time of transition from regional shortening to regional extension. NE–ENE-striking, steeply-dipping, opening-mode tungsten-bearing quartz veins constitute the deposit. Favorable conditions for vein formation where densely spaced arrays have non-curving tips occur under remote stress with a large stress difference and hence in this case probably aligned with the horizontal maximum principal stress axis. Palaeostress analysis using fault-slip data measured on the side walls of underground mine levels yielded the optimal solution of two stresses characterized by an NNW–SSE-shortening strike-slip regime and an NNW–SSE extensional regime. Based on field observations, the first tectonic phase existed during meso- and epi-thermal mineralization, probably owing to the collision between the Siberia and Mongolia–Sino-Korean continents far to the north at the time, and the second tectonic phase appeared after hydrothermal mineralization, as a result of Cretaceous regional rifting. Therefore, multiple strike-slip deformations would have involved the study area during hypo- and epi-thermal mineralization in the Late Jurassic. This evidence does not support the mainstream extension model for Mesozoic tungsten mineralization in central South China.

Matrix deformation and fracture network in minibasins in a foreland fold and thrust belt: The Sivas Basin, Turkey

We use a multiscale study to investigate the strain record in the continental sandstones-filled minibasins of the Sivas Basin. Located on the central Anatolian Plateau, the Sivas basin is a foreland fold-and-thrust belt characterized in its central part by a wall and basin province in which two generations of Oligocene minibasins develop. We collected 399 oriented cores and 2504 fractures in the lower and middle members of the continental Karayün Formation from four minibasins (Emirhan, Karayün, Egribuçak and Ilkindi). Integrated analyses support several observations: (i) an early fracture set, striking NS, occurs in all minibasins. These fractures developed prior to macroscopic halokinetic structures formation (such as megaflap) and prior to minibasin tilting, during Layer Parallel Shortening (LPS). (ii) A preferential orientation of matrix texture, estimated using anisotropy of magnetic susceptibility, is related to the LPS direction only in the Emirhan minibasin. (iii) A second, younger, fracture set, oriented parallel to the tilting axes of the minibasins and to the thrust faults, developed prior to minibasin tilting or folding of minibasin edge structures (known as megaflaps, megahooks and composite halokinetic sequences). The existence of the carapace above raising salt bodies enables the propagation of the LPS deformation in response to regional shortening. However, once the carapace is broken due to the salt rise, there is no evidence of deformation at the meter and matrix scales in relation with FTB shortening affecting the wall and basin domain. The large bodies of evaporites preferentially accommodate compression in between minibasins through internal diapir squeezed. Salt bodies inhibit matrix and mesoscale deformation within the minibasins.

Alpine tectono‐metamorphic evolution of the Corsica basement

AbstractThe Alpine orogenic edifice of Corsica (northern Tyrrhenian Sea) offers the possibility to investigate the mode through which continental crust responds to the propagation of regional shortening at convergent plate margins. The geology of Corsica has been traditionally described as separating domains affected by the Alpine tectonism (Alpine Corsica) from those that did not experience the Alpine tectono‐metamorphic overprint (Hercynian Corsica), but recent studies show that most of Hercynian Corsica was thermally reset in post‐Eocene times, questioning this paradigm. The continental units formed at the expenses of the stretched continental margin of the European plate and consist of Hercynian granitoid basement rocks and cover sequences (Permian volcaniclastics and Mesozoic sedimentary successions). By integrating meso‐ and microstructural investigations with metamorphic thermobarometry and 40Ar–39Ar geochronology along three E–W trending structural transects running across the basement section exposed below the Alpine orogenic wedge, we document middle‐late Eocene (c. 50–33 Ma) westward‐verging syn‐metamorphic (low‐grade blueschist facies) thick‐skinned, basement‐involved thrusting. Significantly, crustal shortening in the continental basement predated of c. 15–10 Ma the subduction zone metamorphism in the oceanic‐derived Schistes Lustrés Complex. When the P–T–t–deformation history as reconstructed from the Corsica basement is integrated with the regional scenario of the Alpine–Apennine orogeny, a tectonic reconstruction is proposed, which frames the Alpine orogeny in Corsica within the Apennine–Maghrebian subduction system in the retroside (retrowedge) of the Apennine orogenic wedge.

Detection of left ventricular wall motion abnormalities from volume rendering of 4DCT cardiac angiograms using deep learning.

BackgroundThe presence of left ventricular (LV) wall motion abnormalities (WMA) is an independent indicator of adverse cardiovascular events in patients with cardiovascular diseases. We develop and evaluate the ability to detect cardiac wall motion abnormalities (WMA) from dynamic volume renderings (VR) of clinical 4D computed tomography (CT) angiograms using a deep learning (DL) framework.MethodsThree hundred forty-three ECG-gated cardiac 4DCT studies (age: 61 ± 15, 60.1% male) were retrospectively evaluated. Volume-rendering videos of the LV blood pool were generated from 6 different perspectives (i.e., six views corresponding to every 60-degree rotation around the LV long axis); resulting in 2058 unique videos. Ground-truth WMA classification for each video was performed by evaluating the extent of impaired regional shortening visible (measured in the original 4DCT data). DL classification of each video for the presence of WMA was performed by first extracting image features frame-by-frame using a pre-trained Inception network and then evaluating the set of features using a long short-term memory network. Data were split into 60% for 5-fold cross-validation and 40% for testing.ResultsVolume rendering videos represent ~800-fold data compression of the 4DCT volumes. Per-video DL classification performance was high for both cross-validation (accuracy = 93.1%, sensitivity = 90.0% and specificity = 95.1%, κ: 0.86) and testing (90.9, 90.2, and 91.4% respectively, κ: 0.81). Per-study performance was also high (cross-validation: 93.7, 93.5, 93.8%, κ: 0.87; testing: 93.5, 91.9, 94.7%, κ: 0.87). By re-binning per-video results into the 6 regional views of the LV we showed DL was accurate (mean accuracy = 93.1 and 90.9% for cross-validation and testing cohort, respectively) for every region. DL classification strongly agreed (accuracy = 91.0%, κ: 0.81) with expert visual assessment.ConclusionsDynamic volume rendering of the LV blood pool combined with DL classification can accurately detect regional WMA from cardiac CT.

Kinematic evolution of the central Andean retroarc thrust belt in northwestern Argentina and implications for coupling between shortening and crustal thickening

Abstract The Andes are the culmination of shortening and crustal thickening that commenced during Late Cretaceous time. First-order questions regarding the tectonic evolution of the central Andes include the magnitude and timing of shortening, and controls on the along-strike variability in observed styles of shortening and deformation. Along-strike differences in the time of surface uplift have spawned two contrasting hypotheses: (1) uplift is related to dynamic and isostatic processes accompanying lithospheric removal and is decoupled in space and time from crustal thickening and shortening, and (2) uplift is directly coupled with shortening and crustal thickening. Although considerable work has been done in Bolivia to address these hypotheses, work in northern Argentina has not yet produced a transorogenic balanced structural cross section from which the total amount and kinematic history of shortening can be evaluated. To help understand the evolution of the thrust belt in northernmost Argentina, we present a regional, retrodeformable cross section at 23°–24°S across the Puna and Eastern Cordillera. New apatite fission-track thermochronological data integrated with other geochronological, sedimentological, and structural data constrain incremental retrodeformation of the cross section between ca. 45 and 6.5 Ma. Regional shortening was facilitated by at least 12 major thrust systems, linked to a regional mid-crustal décollement. Deformation generally propagated eastward through time and involved two major episodes of eastward advance of the orogenic front, separated by periods of internal out-of-sequence shortening and kinematic stagnation of the orogenic front. A new minimum estimate of ∼271 km of total shortening from the Cordillera de Domeyko to the eastern orogenic front explains crustal thickening at northern Puna latitudes. Together with previously published paleoaltimetry data, our new structural and thermochronologic data indicate that regional uplift in the northern Argentine Puna and Eastern Cordillera was synchronous with, and thus directly linked to, crustal shortening and thickening.

Abstract 11402: Targeting RyR2 to Suppress Ventricular Arrhythmias and Improve Left Ventricular Function in Chronic Ischemic Heart Disease

Introduction: Sarcoplasmic reticulum Ca +2 leak from RyR2 is a common finding in chronic ischemic heart disease (CIHD) and may be a key driver for ventricular arrhythmias and reduced excitation-contraction coupling in failingm myocytes. Here, we test the hypothesis that targeting Ca +2 leak using the non-selective RyR inhibitor, Dantrolene, suppresses ventricular arrhythmias and improves left ventricular contractile function in CIDH. Methods: CHID was induced in 24 C57BL/6J mice by left coronary artery ligation. Four weeks after myocardial infarction (MI), subcutaneous osmotic pumps were placed to deliver continuous dantrolene (20 mg/kg/day) or vehicle (0.9% Saline). Left ventricular (LV) function was assessed by echocardiogram at 4-, 7- and 10-weeks post-MI. Peripheral muscle strength was assessed by provoked electromyogram at 6 weeks. Inducibility of ventricular tachycardia (VT) was assessed by rapid transesophageal pacing with isoproterenol at 10 weeks. Results: Dantrolene reduced the peripheral muscle strength in mice (0.014±0.001 vs 0.010±0.001 N, P&lt;0.05), but had no adverse effects on weight loss or mortality. Dantrolene increased fractional shortening (18.7±1.3% vs 22.1±1.6%, P&lt;0.001) and mean velocity fiber shortening (mVcfc 1.37±0.09 vs 1.74±0.1 circ/sec, P&lt;0.002) in non-infarcted regions at 10 weeks. This prevented the progression in LV ejection fraction reduction from 4 to 10 weeks (Saline: 35.6±3.4% to 30.6%±3.4%; Dantrolene 34.6±2.4% to 38.1±1.9% vs, P&lt;0.01). Dantrolene reduced VT frequency per animal (0.083±0.04 vs 0.028±0.02 VT/pacing train, P&lt;0.02) and the total duration of inducible VT per animal (59.2±24 secs vs 1.2±0.6 sec, P&lt;0.04). Dantrolene significantly prolonged the ventricular effective refractory period (VERP) (35.1±1.6 msec vs 42.0±0.9 msec, P&lt;0.005). Conclusion: Dantrolene suppression of RyR2 diastolic Ca +2 leak in chronic ischemic heart failure improves the systolic function of surviving myocardium and reduces VT burden by prolonging the VERP, preventing the re-entry circuit for VT in this model. RyR2 inhibition may represent a new therapeutic target for the treatment of CIDH with ventricular arrhythmias.

The Alps-Apennines Interference Zone: A Perspective from the Maritime and Western Ligurian Alps

In SW Piemonte the Western Alps arc ends off in a narrow, E-W trending zone, where some geological domains of the Alps converged. Based on a critical review of available data, integrated with new field data, it is concluded that the southern termination of Western Alps recorded the Oligocene-Miocene activity of a regional transfer zone (southwestern Alps Transfer, SWAT) already postulated in the literature, which should have allowed, since early Oligocene, the westward indentation of Adria, while the regional shortening of SW Alps and tectonic transport toward the SSW (Dauphinois foreland) was continuing. This transfer zone corresponds to a system of deformation units and km-scale shear zones (Gardetta-Viozene Zone, GVZ). The GVZ/SWAT developed externally to the Penninic Front (PF), here corresponding to the Internal Briançonnais Front (IBF), which separates the Internal Briançonnais domain, affected by major tectono-metamorphic transformations, from the External Briançonnais, subjected only to anchizonal metamorphic conditions. The postcollisional evolution of the SW Alps axial belt units was recorded by the Oligocene to Miocene inner syn-orogenic basin (Tertiary Piemonte Basin, TPB), which rests also on the Ligurian units stacked within the adjoining Apennines belt in southern Piemonte. The TPB successions were controlled by transpressive faults propagating (to E and NE) from the previously formed Alpine belt, as well as by the Apennine thrusts that were progressively stacking the Ligurian units, resting on the subducting Adriatic continental margin, with the TPB units themselves. This allows correlation between Alps and Apennines kinematics, in terms of age of the main geologic events, interference between the main structural systems and tectonic control exerted by both tectonic belts on the same syn-orogenic basin.

Migration of Late Miocene to Quaternary alkaline magmatism at the Alpine-Pannonian transition area: Significance for coupling of Adria plate motion with the Alpine-Carpathian front

Within-plate migration of alkaline basaltic centers is generally related to translation of the lithosphere with a hot spot above a largely stationary mantle plume. Here, we report, for the first time, a hitherto unrecognized migration of small-sized Late Miocene to Early Quaternary alkali-basaltic volcanic centers at the transition from Eastern Alps to Pannonian Basin. The volcanic centers migrated along the South Burgenland High in a regular sequence over a 95 km distance from NNE to SSW between 11 Ma and 1.7 Ma. The basaltic magmatism was also associated with thinning of the crust and lithosphere and an increase of the thermal gradient. In detail, three stages of migration are recognized as follows: (i) Stage 1 with a 55 km SSW-towards shift of volcanism between 11 and 5 Ma; (ii) Stage 2 with a ~ 35 km-WSW shift and enlargement of the distribution of volcanic centers between ca. 5 and 3.5 Ma; and (iii) Stage 3 with a S-directed shift of ca. 25 km between 3.5 and 1.7 Ma. The Stage 1 shift of alkali-basaltic volcanism can be also observed in the Little Hungarian Plain and South Slovakia–Nógrád volcanic fields, and the Stage 2 in the Balaton-Bakony of the Pannonian Basin (north of Lake Balaton). We propose that this pattern and mechanism of migration of the volcanic centers along the South Burgenland High resulted from thermally induced progressive thinning of the lithosphere over a mantle plume underneath the ALCAPA block, which was moving from SSW to the NNE between 11 and 1.7 Ma. The migration was interrupted by a marked eastward shift between 5 and 3.5 Ma (Stage 2). The migration of volcanic centers correlates with orientation and timing of regional shortening phases and inversion of the Alpine-Carpathian-Pannonian system although the overall amount of shortening remains uncertain. The deformation events allow to correlate Adria motion with deformation along the frontal parts of Eastern Alps, and Western and Eastern Carpathians across the western Pannonian Basin.

Miocene to Early Pleistocene Depositional History and Tectonic Evolution of the Issyk‐Kul Basin, Central Tian Shan

AbstractThe Issyk‐Kul Basin (Kyrgyzstan), situated in the central Tian Shan Mountains, hosts the largest and deepest mountain lake in Central Asia. Erosion of the surrounding Terskey and Kungey ranges led to the accumulation of up to 4 km of sediment in the adjacent depression. Creation of the basin from regional shortening and uplift likely initiated around the Oligocene‐Miocene, yet precise age control is sparse. To better understand the timing of these processes, we obtained magnetostratigraphic age constraints on fossil‐poor, fluvio‐lacustrine sediments exposed south of Lake Issyk‐Kul, that agree well with previous age constraints of the equivalent strata outside the Issyk‐Kul Basin. Two 500–650 m thick sections comprised mainly of Chu Group sediments were dated at 6.3–2.8 Ma and 7.0–2.4 Ma (late Miocene to early Pleistocene). Together with reinterpreted magnetostratigraphic constraints from underlying strata, we find that syn‐tectonic deposition commenced at ∼22 Ma with average sedimentation rates &lt;10 cm/ka. Sedimentation rates increased to 10–30 cm/ka at 7 Ma, concurrent with accelerated uplift in the Terskey Range to the south. A deformation event in one section (Kaji‐Say) between 5 and 3 Ma together with concurrent shifts of depositional centers throughout the basin signal the onset of substantial uplift of the Kungey Range to the north at ∼5 Ma. This uplift and deformation transformed the Issyk‐Kul area into a closed basin that facilitated the formation of a deep lake. Lacustrine facies deposited around 3 Ma mark the existence of Lake Issyk‐Kul by that time.

Formation and Forward Propagation of the Indosinian Foreland Fold‐Thrust Belt and Nanpanjiang Foreland Basin in SW China

AbstractOrogenic growth, characterized by formation and forward propagation of fold‐thrust belts and foreland basins, is predicted by wedge models of thrust systems. The growth of the Nanpanjiang fold‐thrust belt and foreland basin system of the Indosinian orogenic belt in the southwestern South China remains poorly understood. The development of the Indosinian foreland system remains underappreciated due to few constraints on structural styles, kinematics and ages. Surface cross sections, seismic profiles and detrital zircon data are presented to address the structural styles and evolution of the Indosinian foreland system. The results reveal that the fold‐thrust belt is characterized by fault‐related folds with deeper duplexes and shallower imbricates, which yield a NNE‐SSW regional shortening magnitude of ∼36%. Our new constraints indicate that the Nanpanjiang region experienced multi‐staged thrusting during the Indosinian orogeny (D1). The D11affected the southernmost southern fold‐thrust belt, producing thick‐skinned thrusts involving Neoproterozoic basement and initiating the Nanpanjiang foreland basin. During the D12, NNE‐verging thick‐skinned thrusting continued and was followed by thin‐skinned thrusting in the northern fold‐thrust belt. Locally preserved foreland basin deposits at the northernmost Nanpanjiang Basin define D13. The progressive D14co‐axially deformed the residual basin into a wide and gentle syncline. Thus, the progressive D11to D14deformation sequence of NNE‐verging in‐sequence thrusting and foreland basin migration describe the kinematic and dynamic relationship between fold‐thrust belt and foreland basin during the Indosinian tectonic event. Indosinian D1structures were subsequently refolded by the Yanshanian tectonic event (D2), forming N‐ to NE‐striking cleavage and arcuation of D1fold axes.