High-amplitude lake-level changes in tectonically active Lake Issyk-Kul (Kyrgyzstan) revealed by high-resolution seismic reflection data

A total of 84 seismic profiles, mainly from the western and eastern deltas of Lake Issyk-Kul, were used to identify lake-level changes. Seven stratigraphic sequences were reconstructed, each containing a series of delta lobes that were formed during former lake-level stillstands or during slow lake-level increase or decrease. The lake level has experienced at least four cycles of stepwise rise and fall of 400 m or more. These fluctuations were mainly caused by past changes in the atmospheric circulation pattern. During periods of low lake levels, the Siberian High was likely to be strong, bringing dry air masses from the Mongolian steppe blocking the midlatitude Westerlies. During periods of high lake levels, the Siberian High must have been weaker or displaced, and the midlatitude Westerlies could bring moister air masses from the Mediterranean and North Atlantic regions

Rapid Miocene Exhumation to the East of the Tauern Window

The Eastern Alps were substantially shaped by northward movement of the Dolomites Indenter and eastward extrusion of the orogenic wedge in front of the indenter. A resulting sinistral wrench zone runs through the western Tauern Window (TW) and continues along the Salzach-Ennstal-Mariazell-Puchberg Fault (SEMP) eastward. Low-T thermochronological studies demonstrate rapid Miocene cooling of the TW units from ≥ 350 °C to below ~ 80 °C due to folding and coeval erosion. Thermochronologic ages in the Eastern Tauern Window range between 12 Ma to 22 Ma for the zircon fission track chronometer (partial annealing zone (PAZ) ~ 200 – 350°C, e.g., Tagami et al., 1996) and 5 Ma to 13 Ma for the apatite (U-Th)/He chronometer (partial retention zone (PRZ) ~ 40 – 80°C, Stockli et al., 2000). Ages for the zircon (U-Th)/He and apatite fission track chronometers fall in between. Along the eastern margin of the TW, the extensional Katschberg Fault-System (KFS) decoupled the Gurktal Block (GB) in its hanging wall from folding. The KFS was active between 20 and 17 Ma, in the early Miocene (Scharf et al., 2016). A late reactivation phase is demonstrated by reset or partially reset zircon and apatite fission track ages within the footwall towards the fault, yielding Late Miocene to Pliocene ages (Bertrand et al., 2017). A similar younging trend is observed within the TW towards the Brenner Fault in the western TW. The GB in the hanging wall of the KFS preserves a rapid Cretaceous and Eocene cooling through the zircon fission track PAZ and rapid Oligocene to Miocene cooling through the apatite fission track PAZ (Wölfler et al., 2023). The Niedere Tauern (NT), north of the GB and south of the SEMP line, seem to be structurally closely linked to the TW. They show a similar rapid Miocene cooling history and an intervening Cenozoic structure between the TW and the NT is missing. Published apatite fission track ages range between 14 Ma and 24 Ma (apatite PAZ ~ 60 – 100°C, Wagner et al., 1989). Published apatite (U-Th)/He ages from the southern boundary of the NT range between 6 Ma and 7 Ma, indicating a Late Miocene cooling below ~ 80 °C (Wölfler et al., 2016). Our (U-Th)/He analysis from the interiour of the NT revealed ages of around 20 Ma to 23 Ma (zircon (U-Th)/He), and 11 Ma to 22 Ma (apatite (U-Th)/He). Published apatite fission track ages fall in between and partly overlap with our results. This demonstrates a rapid cooling pulse in the Miocene, exhuming at least the western part of the NT from ≥ 200 °C to below ~ 80 °C. Published AHe ages of ~ 6 Ma along the southern margin of the NT might relate to late Miocene normal faulting along the complex Murtal Fault-System (MFS). A pronounced jump towards older thermochronologic ages in the Seckauer Tauern, east of the Pöls fault and extensional structures along this fault indicate a structural decoupling of the western NT from the Seckauer Tauern. In this contribution, we discuss the linkage between TW and N T and characterize in greater detail the exhumation history along the eastern wrench zone

Exhumation of Basement-cored Uplifts: Example of the Kyrgyz Range Quantified with Apatite Fission-track Thermochronology

The Kyrgyz Range, the northernmost portion of the Kyrgyzstan Tien Shan, displays topographic evidence for lateral propagation of surface uplift and exhumation. The highest and most deeply dissected segment lies in the center of the range. To the east, topography and relief decrease, and preserved remnants of a Cretaceous regional erosion surface imply minimal amounts of bedrock exhumation. The timing of exhumation of range segments defines the lateral propagation rate of the range-bounding reverse fault and quantifies the time and erosion depth needed to transform a mountain range from a juvenile to a mature morphology. New apatite fission-track (AFT) data from three transects from the eastern Kyrgyz Range, combined with published AFT data, demonstrate that the range has propagated over 110 km eastwards over the last 7-11 Myr. Based on the thermal and topographic evolutionary history, we present a model for a time-varying exhumation rate driven by rock uplift and changes in erodability and the time scale of geomorphic adjustment to surface uplift. Easily eroded, Cenozoic sedimentary rocks overlying resistant basement control early, rapid exhumation and slow surface upliftrates. As increasing amounts of resistant basement are exposed, exhumation rates decrease while surface uplift rates are sustained or increase, thereby growing topography. As the range becomes high enough to cause ice accumulation and develop steep river valleys, fluvial and glacial erosion become more powerful and exhumation rates once again increase. Independently determined range-noma1 shortening rates have also varied over time, suggesting a feedback between erosional efficiency and shortening rate

Importance of continued activation of thrombin reflected by fibrinopeptide A to the efficacy of thrombolysis

Factors responsible for initial success or failure of coronary thrombolysis and persistent recanalization or early reocclusion have not been thoroughly elucidated. Both adequate initial clot lysis and preclusion of rethrombosis are required. Failure may reflect clot lysis followed immediately or somewhat later by rethrombosis. To determine whether differences in the intensity and persistence of the activation of thrombin are determinants of success or failure of recanalization, plasma fibrinopeptide A, a fibrinogen product liberated by thrombin, was serially assayed in 19 patients treated with intravenous streptokinase. In patients exhibiting recanalization (n = 9), plasma fibrinopeptide A decreased after administration of streptokinase but before administration of heparin. In patients without initially apparent recanalization, fibrinopeptide A increased, suggesting ongoing thrombosis, and subsequently decreased promptly after heparin. In patients with initial recanalization followed by overt reocclusion the pattern was different. Despite recanalization, fibrinopeptide A continued to rise markedly. Elevations persisted despite administration of heparin. Thus, inhibition of activation of thrombin is associated with successful recanalization. Conversely, persistent activation of thrombin may be a predisposing factor to both apparent initial failure of recanalization and nvprt early reocclusion

Geochronology, Geochemistry, and Geodynamic Implications of Permo-Triassic Back-Arc Basin Successions in the North Pamir, Central Asia

AbstractThe Permo-Triassic period marks the time interval between Hercynian (Variscan) orogenic events in the Tien Shan and the North Pamir, and the Cimmerian accretion of the Gondwana-derived Central and South Pamir to the southern margin of the Paleo-Asian continent. A well-preserved Permo-Triassic volcano-sedimentary sequence from the Chinese North Pamir yields important information on the geodynamic evolution of Asia’s pre-Cimmerian southern margin. The oldest volcanic rocks from that section are dated to the late Guadalupian epoch by a rhyolite and a dacitic dike that gave zircon U-Pb ages of ~260 Ma. Permian volcanism was largely pyroclastic and mafic to intermediate. Upsection, a massive ignimbritic crystal tuff in the Chinese Qimgan valley was dated to 244.1±1.1 Ma, a similar unit in the nearby Gez valley to 245±11 Ma, and an associated rhyolite to 233.4±1.1 Ma. Deposition of the locally ~200 m thick crystal tuff unit follows an unconformity and marks the onset of intense, mainly mafic to intermediate, calc-alkaline magmatic activity. Triassic volcanic activity in the North Pamir was coeval with the major phase of Cimmerian intrusive activity in the Karakul-Mazar arc-accretionary complex to the south, caused by northward subduction of the Paleo-Tethys. It also coincided with the emplacement of basanitic and carbonatitic dikes and a thermal event in the South Tien Shan, to the north of our study area. Evidence for arc-related magmatic activity in a back-arc position provides strong arguments for back-arc extension or transtension and basin formation. This puts the Qimgan succession in line with a more than 1000 km long realm of extensional Triassic back-arc basins known from the North Pamir in the Kyrgyz Altyn Darya valley (Myntekin formation), the North Pamir of Tajikistan and Afghanistan, and the Afghan Hindukush (Doab formation) and further west from the Paropamisus and Kopet Dag (Aghdarband, NE Iran)

Frequent coexistence of anti-topoisomerase I and anti-U1RNP autoantibodies in African American patients associated with mild skin involvement: a retrospective clinical study

Introduction: The presence of anti-topoisomerase I (topo I) antibodies is a classic scleroderma (SSc) marker presumably associated with a unique clinical subset. Here the clinical association of anti-topo I was reevaluated in unselected patients seen in a rheumatology clinic setting.Methods: Sera from the initial visit in a cohort of unselected rheumatology clinic patients (n = 1,966, including 434 systemic lupus erythematosus (SLE), 119 SSc, 85 polymyositis/dermatomyositis (PM/DM)) were screened by radioimmunoprecipitation. Anti-topo I-positive sera were also tested with immunofluorescence and RNA immunoprecipitation.Results: Twenty-five (15 Caucasian, eight African American, two Latin) anti-topo I positive patients were identified, and all except one met the ACR SSc criteria. Coexistence of other SSc autoantibodies was not observed, except for anti-U1RNP in six cases. When anti-topo I alone versus anti-topo I + U1RNP groups were compared, African American (21% vs. 67%), overlap with SLE (0 vs. 50%; P = 0.009) or PM/DM (0 vs. 33%; P = 0.05) or elevated creatine phosphokinase (CPK) (P = 0.07) were more common in the latter group. In comparison of anti-topo I-positive Caucasians versus African Americans, the latter more frequently had anti-U1RNP (13% vs. 50%), mild/no skin changes (14% vs. 63%; P = 0.03) and overlap with SLE (0 vs. 38%; P = 0.03) and PM/DM (0 vs. 25%; P = 0.05).Conclusions: Anti-topo I detected by immunoprecipitation in unselected rheumatology patients is highly specific for SSc. Anti-topo I coexisting with anti-U1RNP in African American patients is associated with a subset of SLE overlapping with SSc and PM/DM but without apparent sclerodermatous changes. \ua9 2011 Satoh et al.; licensee BioMed Central Ltd

Negative affect and ruminative self-focus during everyday goal pursuit

Models of self-regulation propose that negative affect is generated when progress towards goals is perceived to be inadequate. Similarly, ruminative thinking is hypothesised to be triggered by unattained goals (Martin & Tesser, 1996). We conducted an experience-sampling study in which participants recorded their negative affect, ruminative self-focus, and goal appraisals eight times daily for one week. Negative affect and ruminative self-focus were each associated with low levels of goal success and (with the exception of sadness) high levels of goal importance. As predicted, the combination of low goal success and high goal importance was associated with the highest levels of negative affect, and this interaction was marginally significant for ruminative self-focus. Decomposition of the ruminative self-focus measure revealed that the success by importance interaction was significantly associated with focus on problems but not focus on feelings. Findings did not differ for individuals reporting high versus low levels of depressive symptoms or trait rumination. These results suggest that self-regulatory models of goal pursuit provide a useful explanatory framework for the study of affect and ruminative thinking in everyday life

Indentation of the Pamirs with respect to the northern margin of Tibet: constraints from the Tarim basin sedimentary record

The Pamirs represent the indented westward continuation of the northern margin of the Tibetan Plateau, dividing the Tarim and Tajik basins. Their evolution may be a key factor influencing aridification of the Asian interior, yet the tectonics of the Pamir Salient are poorly understood. We present a provenance study of the Aertashi section, a Paleogene to late Neogene clastic succession deposited in the Tarim basin to the north of the NW margin of Tibet (the West Kunlun) and to the east of the Pamirs. Our detrital zircon U-Pb ages coupled with zircon fission track, bulk rock Sm-Nd, and petrography data document changes in contributing source terranes during the Oligocene to Miocene, which can be correlated to regional tectonics. We propose a model for the evolution of the Pamir and West Kunlun (WKL), in which the WKL formed topography since at least ~200 Ma. By ~25 Ma, movement along the Pamir-bounding faults such as the Kashgar-Yecheng Transfer System had commenced, marking the onset of Pamir indentation into the Tarim-Tajik basin. This is coincident with basinward expansion of the northern WKL margin, which changed the palaeodrainage pattern within the Kunlun, progressively cutting off the more southerly WKL sources from the Tarim basin. An abrupt change in the provenance and facies of sediments at Aertashi has a maximum age of 14 Ma; this change records when the Pamir indenter had propagated sufficiently far north that the North Pamir was now located proximal to the Aertashi region