Research Article| March 01, 1995 Nd isotopic study of Precambrian basement of South Korea: Evidence for Early Archean crust? Ching-Ying Lan; Ching-Ying Lan 1Institute of Earth Sciences, Academia Sinica, Nangkang, Taipei, Taiwan, China Search for other works by this author on: GSW Google Scholar Typhoon Lee; Typhoon Lee 1Institute of Earth Sciences, Academia Sinica, Nangkang, Taipei, Taiwan, China Search for other works by this author on: GSW Google Scholar Xin-Hua Zhou; Xin-Hua Zhou 2Institute of Geology, Academia Sinica, Beijing, China Search for other works by this author on: GSW Google Scholar Sung-Tack Kwon Sung-Tack Kwon 3Department of Geology, Yonsei University, Seoul, Republic of Korea Search for other works by this author on: GSW Google Scholar Author and Article Information Ching-Ying Lan 1Institute of Earth Sciences, Academia Sinica, Nangkang, Taipei, Taiwan, China Typhoon Lee 1Institute of Earth Sciences, Academia Sinica, Nangkang, Taipei, Taiwan, China Xin-Hua Zhou 2Institute of Geology, Academia Sinica, Beijing, China Sung-Tack Kwon 3Department of Geology, Yonsei University, Seoul, Republic of Korea Publisher: Geological Society of America First Online: 02 Jun 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (1995) 23 (3): 249–252. https://doi.org/10.1130/0091-7613(1995)023<0249:NISOPB>2.3.CO;2 Article history First Online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation Ching-Ying Lan, Typhoon Lee, Xin-Hua Zhou, Sung-Tack Kwon; Nd isotopic study of Precambrian basement of South Korea: Evidence for Early Archean crust?. Geology 1995;; 23 (3): 249–252. doi: https://doi.org/10.1130/0091-7613(1995)023<0249:NISOPB>2.3.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract We carried out a Sm-Nd isotopic reconnaissance study of South Korea. Eight river sediments gave crustal residence ages (TDM) between 1.7 and 2.7 Ga, implying that, on average, the crust of South Korea was formed in Early to Middle Proterozoic time. Twenty-six Precambrian basement rocks yielded TDM between 1.4 and 3.8 Ga. More than half of them exceed 2.5 Ga, indicating that South Korea has a long history of crustal evolution. Four of the samples have TDM from 3.2 to 3.8 Ga suggesting the possibility that there may be ancient continental crust in Korea having ages comparable to those of the oldest cratons in the world. However, these samples also have preferentially higher Sm/Nd, so their old ages could be artifacts, thus requiring confirmation. The large variation in TDM of South Korea is reminiscent of that for the South China block. However, the existence of Early Archean ages better matches that of the North China block, because the basement of south China was thought to be mostly Proterozoic in age. The recent discovery of rare Archean basement rocks in the South China block may favor models that attempt to correlate South Korea with south China. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.
Determining the timing, magnitude, and location of deformation due to the Indo‐Asian collision is widely acknowledged as an important step in understanding how the lithosphere responds during continental collision. A puzzling result of geological investigations of the Lhasa Block over the past 2 decades has been the apparent lack of significant Tertiary deformation there. Perhaps the most important structural feature of the Lhasa Block is the south directed Gangdese Thrust System, which developed along its southern edge. The thrust system, which separates the Andean‐type batholith of southern Asia from rocks of Indian affinity, is obscured at most locations across southeastern Tibet by back thrusts of the younger, north directed Renbu Zedong Thrust System. The best documented site where both thrusts are exposed occurs near Zedong (Zedong Window). Systematic geochronologic analyses were conducted in this area. U‐Pb zircon dating of three samples of a synkinematically to postkinematically deformed hanging wall granitoid (the Yaja granodiorite) cut by the Gangdese Thrust indicates a crystallization age of 30.4±0.4 Ma (2σ), thus placing an upper bound on the initiation of the thrust. U‐Pb zircon dating of granitoid samples structurally higher in the Gangdese hanging wall yields emplacement ages of 42.5±1.0 Ma and 48.9±0.8 Ma (2σ), similar to other magmatic complexes within the Gangdese arc. Geochemical results are consistent with these plutons forming in the same environment as precollisional intrusions within the Gangdese batholith, suggesting a significant post‐collisional input of juvenile heat. The 40 Ar/ 39 Ar thermochronology of samples from a vertical section through the hanging wall within the Yaja granodiorite, coupled with results of a numerical thermal model, indicate an average slip rate along the Gangdese Thrust of 7 mm/yr between 30 and 23 Ma and a minimum displacement of ∼50 km. Farther east in the Zedong Window, thermal effects produced by later north directed thrust sheets of the Renbu Zedong system appear to have obscured thermal history signatures in the Gangdese hanging wall related to earlier south directed thrusting. Thermochronological results from this region indicate that thermal overprinting related to the north directed thrusting occurred between 25 and 10 Ma, consistent with previous estimates.
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