TY - JOUR A1 - Pedoja, Kevin A1 - Husson, Laurent A1 - Johnson, Markes E. A1 - Melnick, Daniel A1 - Witt, Cesar A1 - Pochat, Stephane A1 - Nexer, Maelle A1 - Delcaillau, Bernard A1 - Pinegina, Tatiana A1 - Poprawski, Yohann A1 - Authemayou, Christine A1 - Elliot, Mary A1 - Regard, Vincent A1 - Garestier, Franck T1 - Coastal staircase sequences reflecting sea-level oscillations and tectonic uplift during the Quaternary and Neogene JF - Earth science reviews : the international geological journal bridging the gap between research articles and textbooks N2 - Many coasts feature sequences of Quaternary and Neogene shorelines that are shaped by a combination of sea-level oscillations and tectonics. We compiled a global synthesis of sea-level changes for the following highstands: MIS 1, MIS 3, MIS 5e and MIS 11. Also, we date the apparent onset of sequences of paleoshorelines either from published data or tentatively extrapolating an age for the uppermost, purported oldest shoreline in each sequence. Including the most documented MIS 5e benchmark, we identify 926 sequences out of which 185 also feature Holocene shorelines. Six areas are identified where elevations of the MIS 3 shorelines are known, and 31 feature elevation data for MIS 11 shorelines. Genetic relationships to regional geodynamics are further explored based on the elevations of the MIS 5e benchmark. Mean apparent uplift rates range from 0.01 0.01 mm/yr (hotspots) to 1.47 0.08 mm/yr (continental collision). Passive margins appear as ubiquitously uplifting, while tectonic segmentation is more important on active margins. From the literature and our extrapolations, we infer ages for the onset of formation for -180 coastal sequences. Sea level fingerprinting on coastal sequences started at least during mid Miocene and locally as early as Eocene. Whether due to the changes in the bulk volume of seawater or to the temporal variations in the shape of ocean basins, estimates of eustasy fail to explain the magnitude of the apparent sea level drop. Thus, vertical ground motion is invoked, and we interpret the longlasting development of those paleoshore sequences as the imprint of glacial cycles on globally uplifted margins in response to continental compression. The geomorphological expression of the sequences matches the amplitude and frequency of glacial cyclicity. From middle Pleistocene to present-day, moderately fast (100,000 yrs) oscillating sea levels favor the development of well identified strandlines that are distinct from one another. Pliocene and Lower Pleistocene strandlines associated with faster cyclicity (40,000 yrs) are more compact and easily merge into rasas, whereas older Cenozoic low-frequency eustatic changes generally led to widespread flat-lying coastal plains. KW - Cenozoic KW - Coastal sequence of shorelines KW - Strandlines KW - Rasa KW - Geodynamic Y1 - 2014 U6 - https://doi.org/10.1016/j.earscirev.2014.01.007 SN - 0012-8252 SN - 1872-6828 VL - 132 SP - 13 EP - 38 PB - Elsevier CY - Amsterdam 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 -