TY - JOUR A1 - Roud, Sophie A1 - Wack, Michael Richard A1 - Gilder, Stuart A. A1 - Kudriavtseva, Anna A1 - Sobel, Edward T1 - Miocene to early pleistocene depositional history and tectonic evolution of the Issyk-Kul Basin, Central Tian Shan JF - Geochemistry, geophysics, geosystems : G 3 ; an electronic journal of the earth sciences N2 - The 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 similar to 22 Ma with average sedimentation rates <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 similar to 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. KW - Central Asia KW - Lake Issyk‐ Kul KW - magnetostratigraphy KW - Neogene KW - Tian KW - Shan Y1 - 2021 U6 - https://doi.org/10.1029/2020GC009556 SN - 1525-2027 VL - 22 IS - 4 PB - Wiley CY - Hoboken, NJ ER - TY - GEN A1 - Lühr, Hermann A1 - Wicht, Johannes A1 - Gilder, Stuart A. A1 - Holschneider, Matthias T1 - General Introduction and Scientific Summary of the German Priority Program "PlanetMag" T2 - Magnetic Fields in the Solar System N2 - This book aims at understanding the diversity of planetary and lunar magnetic fields and their interaction with the solar wind. A synergistic interdisciplinary approach combines newly developed tools for data acquisition and analysis, computer simulations of planetary interiors and dynamos, models of solar wind interaction, measurement of terrestrial rocks and meteorites, and laboratory investigations. The following chapters represent a selection of some of the scientific findings derived by the 22 projects within the DFG Priority Program Planetary Magnetism" (PlanetMag). This introductory chapter gives an overview of the individual following chapters, highlighting their role in the overall goals of the PlanetMag framework. The diversity of the different contributions reflects the wide range of magnetic phenomena in our solar system. From the program we have excluded magnetism of the sun, which is an independent broad research discipline, but include the interaction of the solar wind with planets and moons. Within the subsequent 13 chapters of this book, the authors review the field centered on their research topic within PlanetMag. Here we shortly introduce the content of all the subsequent chapters and outline the context in which they should be seen. Y1 - 2018 SN - 978-3-319-64292-5 SN - 978-3-319-64291-8 U6 - https://doi.org/10.1007/978-3-319-64292-5_1 SN - 0067-0057 VL - 448 SP - 1 EP - 6 PB - Springer CY - Dordrecht ER - TY - GEN A1 - Lühr, Hermann A1 - Wicht, Johannes A1 - Gilder, Stuart A. A1 - Holschneider, Matthias T1 - Preface T2 - Magnetic Fields in the Solar System: Planets, Moons and Solar Wind Interactions Y1 - 2018 SN - 978-3-319-64292-5 SN - 978-3-319-64291-8 SN - 0067-0057 VL - 448 SP - V EP - VI PB - Springer CY - Dordrecht ER - TY - JOUR A1 - Wack, Michael R. A1 - Gilder, Stuart A. A1 - Macaulay, Euan A. A1 - Sobel, Edward A1 - Charreau, Julien A1 - Mikolaichuk, Alexander T1 - Cenozoic magnetostratigraphy and magnetic properties of the southern Issyk-Kul basin, Kyrgyzstan JF - Tectonophysics : international journal of geotectonics and the geology and physics of the interior of the earth N2 - We present paleomagnetic data from the northern flank of the Tianshan range, southeast of Lake Issyk-Kul (Kyrgyzstan). 613 cores were collected in two parallel sections with a total thickness of 960 m (Chon Kyzylsuu, CK) and 990 m Jeti Oguz, JO), as well as 48 cores at six sites in a nearby anticline. Rock magnetic analyses identify both magnetite and hematite in the fluvial-lacustrine sediments. The concentration of both minerals, the magnetite:hematite ratio, and the average magnetite grain size increase upward in both sections. Anisotropy of anhysteretic remanent magnetization defines a tectonic fabric with sub-horizontal maximum axes that parallel the strike direction together with intermediate and minimum axes that streak out about a great circle orthogonal to the maximum axes suggestive of a tectonic fabric emplaced during folding. Stepwise thermal demagnetization isolates interpretable magnetization components in 284 samples that define 26 polarity chrons in CK and 19 in JO. A positive fold test, dual polarities and systematic changes in rock-magnetic parameters with depth suggest that the high temperature magnetization component was acquired coevally with deposition. An age model based on a visual magnetostratigraphic correlation of both sections with the geomagnetic polarity time scale defines absolute ages from 26.0 to 13.3 Ma, with a fairly constant sedimentation rate of 9-10 cm/ka. A correlation based on a numerical algorithm arrives at a slightly different conclusion, with deposition ages from 25.2 to 11.0 Ma and sedimentation rates from 5 to 8 cm/ka. In comparison with sedimentation rates found at other magnetostratigraphic sections in the Tianshan realm, we infer that the sedimentary record in this part of the Issyk-Kul Basin precedes the more rapid phase of uplift of the Kyrgyz Tianshan. The onset of deposition and concomitant erosion of the adjacent Terskey Range is in good agreement with independent assessments of the exhumation history of this mountain range, with erosion increasing at 25-20 Ma and accelerating after 11-13 Ma. (C) 2014 Elsevier B.V. All rights reserved. KW - Cenozoic KW - Magnetostratigraphy KW - Rock magnetism KW - Issyk-Kul KW - Anisotropy of magnetic remanence Y1 - 2014 U6 - https://doi.org/10.1016/j.tecto.2014.03.030 SN - 0040-1951 SN - 1879-3266 VL - 629 SP - 14 EP - 26 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Macaulay, Euan A. A1 - Sobel, Edward A1 - Mikolaichuk, Alexander A1 - Wack, Michael A1 - Gilder, Stuart A. A1 - Mulch, Andreas A1 - Fortuna, Alla B. A1 - Hynek, Scott A1 - Apayarov, Farid T1 - The sedimentary record of the Issyk Kul basin, Kyrgyzstan: climatic and tectonic inferences JF - Basin research N2 - A broad array of new provenance and stable isotope data are presented from two magnetostratigraphically dated sections in the south-eastern Issyk Kul basin of the Central Kyrgyz Tien Shan. The results presented here are discussed and interpreted for two plausible magnetostratigraphic age models. A combination of zircon U-Pb provenance, paleocurrent and conglomerate clast count analyses is used to determine sediment provenance. This analysis reveals that the first coarse-grained, syntectonic sediments (Dzhety Oguz formation) were sourced from the nearby Terskey Range, supporting previous thermochronology-based estimates of a ca. 25-20 Ma onset of deformation in the range. Climate variations are inferred using carbonate stable isotope (delta O-18 and delta C-13) data from 53 samples collected in the two sections and are compared with the oxygen isotope compositions of modern water from 128 samples. Two key features are identified in the stable isotope data set derived from the sediments: (1) isotope values, in particular delta C-13, decrease between ca. 26.0 and 23.6 or 25.6 and 21.0 Ma, and (2) the scatter of delta O-18 values increased significantly after ca. 22.6 or 16.9 Ma. The first feature is interpreted to reflect progressively wetter conditions. Because this feature slightly post-dates the onset of deformation in the Terskey Range, we suggest that it has been caused by orographically enhanced precipitation, implying that surface uplift accompanied late Cenozoic deformation and rock uplift in the Terskey Range. The increased scatter could reflect variable moisture source or availability caused by global climate change following the onset of Miocene glaciations at ca. 22.6 Ma, or enhanced evaporation during the Mid-Miocene climatic optimum at ca. 17-15 Ma. Y1 - 2016 U6 - https://doi.org/10.1111/bre.12098 SN - 0950-091X SN - 1365-2117 VL - 28 SP - 57 EP - 80 PB - Wiley-Blackwell CY - Hoboken ER -