Print Email Facebook Twitter Neogene transpression in the Gobi-Altai (Southern Mongolia) did not involve significant rotations: no deviation from the reference APWP Title Neogene transpression in the Gobi-Altai (Southern Mongolia) did not involve significant rotations: no deviation from the reference APWP Author Straathof, G. Project Molengraaff Fonds Date 2005 Abstract A paleomagnetic study has been carried out to discriminate between two end-member scenarios on the intra-continental, transpressional strike-slip system in the Gobi-Altai, southern Mongolia. The first suggests that these strike-slip faults utilise obliquely oriented weak Paleozoic or Mesozoic zones in the basement. The second scenario suggests that initial strike-slip faults become transpressional as a result of vertical axis rotations, caused by increased shortening from east to west. We sampled lower Cretaceous basalts, and some younger lavas and basalt plugs. Approximately 1040 samples were drilled in 17 localities in lower Cretaceous and Cenozoic lavas, each subdivided into 4-15 sites of 7 samples each. These were then demagnetised using alternating field (AF) and thermal demagnetisation techniques. Rock magnetic analysis includes determination of Curie temperatures (560- 580°C) and indicates magnetite as the main carrier of the magnetic signal. Three positive foldtests give us confidence that our high temperature-component is the primaiy magnetisation. The results show a mean direction of declination/inclination (D/I) = 12.3/66.5 (a95=2.3; k=43.4), which does not statistically deviate from the published average Eurasian paleomagnetic direction for this time window (D/I = 13,6/63.0; a95 = 1.7, from Besse and Courtillot, 2002). We thus conclude that Neogene transpressional mountain building in the Gobi Altai of southern Mongolia was not associated with rotation of strike-slip faults. Moreover, we show that southern Mongolia has belonged to the Eurasian continent since at least the early Cretaceous. To reference this document use: http://resolver.tudelft.nl/uuid:2461f90f-afe2-4822-afe7-7d286078fa54 Publisher Utrecht University Part of collection Geoscience Reports Document type report Rights (c) the author Files PDF Straathof (2005).pdf 1.78 MB Close viewer /islandora/object/uuid:2461f90f-afe2-4822-afe7-7d286078fa54/datastream/OBJ/view