Marine Geology xxx (xxxx) xxx–xxx Contents lists available at ScienceDirect Marine Geology journal homepage: www.elsevier.com/locate/margo Invited research article Controls on modern erosion and the development of the Pearl River drainage in the late Paleogene ⁎ Chang Liua, Peter D. Clifta,b, , Andrew Carterc, Philipp Böningd, Zhaochu Hue, Zhen Sunf, Katharina Pahnked a Department of Geology and Geophysics, Louisiana State University, Baton Rouge 70803, USA b School of Geography Science, Nanjing Normal University, Nanjing 210023, China c Department of Earth and Planetary Sciences, Birkbeck College, University of London, London WC1E 7HX, UK d Max Planck Research Group for Marine Isotope Geochemistry, Institute of Chemistry and Biology of the Marine Environment (ICBM), University of Oldenburg, 26129, Germany e State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Wuhan 430074, China f Key Laboratory of Marginal Sea Geology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, 164 Xingangxi Road, Guangzhou 510301, China ARTICLE INFO ABSTRACT Keywords: The Pearl River and its tributaries drains large areas of southern China and has been the primary source of Zircon sediment to the northern continental margin of the South China Sea since its opening. In this study we use a Nd isotope combination of bulk sediment geochemistry, Nd and Sr isotope geochemistry, and single grain zircon U-Pb Erosion dating to understand the source of sediment in the modern drainage. We also performed zircon U-Pb dating on Provenance Eocene sedimentary rocks sampled by International Ocean Discovery Program (IODP) Expedition 349 in order to Pearl River constrain the source of sediment to the rift before the Oligocene. A combination of Nd and Sr isotopes shows that South China Sea International Ocean discovery program the Gui, Liu and Dong Rivers are likely not important sources. Single grain zircon dates emphasize the im- IODP site U1435 portance of the westernmost tributaries (Hongshui and Yu Rivers), which drain the highest topography and tectonically active areas, as the primary sediment producers. Our data indicate that climate is not the primary control on erosion patterns and intensities. Zircon dating also shows that the Gui and Liu Rivers are not gen- erating large sediment yields. Discrepancies between these new data and earlier samples make the role of the Dong River hard to determine, although Nd isotopes suggest that it is not dominant. The source of sediment during the Eocene at IODP Site U1435 appears to have been a relatively local basement source, or a regionally restricted river only draining nearby areas of the Cathaysia Block, similar, but not identical, to the modern Dong River. There is no evidence for a large regional river and we exclude sediment transport from the southwest (Indochina). Our data are consistent with small drainage systems dominating the basin until the end of the Oligocene (~24 Ma), after which the Pearl River expanded towards its modern state as a result of headwater capture largely towards the west. 1. Introduction the uplift of the Tibetan plateau (Clark et al., 2004; Clift et al., 2006; Zheng et al., 2013). In this respect the Pearl River (Fig. 1) has typically Drainage systems are born and develop in response to interactions been considered anomalous in that it is generally not thought to have between climate and tectonic processes. As new ocean basins open or been involved in major headwater capture during plateau uplift, but mountain ranges rise, drainages reorganize in response to the changing may be more closely tied to the development of the South China Sea topography and discharge supplied as result of precipitation (Clark et al., 2004). In this study we assess the geographic diversity of (Brookfield, 1998; Clark et al., 2004). In so doing they can be sensitive sources within the modern river in order to map crustal heterogeneity indicators of continental processes, which are then preserved in the and to see where the modern river derives its sediment. We use this sedimentary record within basins supplied by those rivers. The major knowledge to interpret Eocene fluvio-deltaic sedimentary rocks col- rivers of Southeast Asia have been the subject of significant speculation lected by coring within the South China Sea to determine how the about their development, as a result of their proposed interaction with Eocene Pearl River compares with the modern. This then allows us to ⁎ Corresponding author at: Department of Geology and Geophysics, Louisiana State University, Baton Rouge 70803, USA. E-mail addresses: [email protected], [email protected] (P.D. Clift). http://dx.doi.org/10.1016/j.margeo.2017.07.011 Received 18 June 2016; Received in revised form 11 July 2017; Accepted 16 July 2017 0025-3227/ © 2017 Elsevier B.V. All rights reserved. Please cite this article as: Liu, C., Marine Geology (2017), http://dx.doi.org/10.1016/j.margeo.2017.07.011 C. Liu et al. Marine Geology xxx (xxxx) xxx–xxx 110˚E 115˚E 120˚E Bei A 25˚ B 50 km C Yangtze Block N Taiwan Pearl B P4 Dong Cathaysia X28 L18 P1 Indochina Hainan L13 L21 20˚ R11 705 ODP 1148 N South China Sea IODP U1435 C Beipan River B 26˚ Hongshui River Liu River 501 25˚ 105 005 102 Gui River Nanpan River 003 He River 24˚ Bei River ong River D 206 P7 P4 P1 906 304 N 23˚ 705 903 Yu River R11 Pearl River mouth 22˚ 0 200 km 105˚ 110˚ 115˚ Fig. 1. A) Map showing the Pearl River area in a regional context, as well as the location of IODP Site U1435, ODP Site 1148 and industrial wells. B) Close-up image of the distributary system in the Pearl River Mouth area. C) Map showing the distribution of the Pearl River tributaries, as well as the sampling locations. understand how the river has developed to its present state. River is one of the major sediment sources to the northern part of the The modern Pearl River Drainage (PRD) covers 8600 km2 and flows South China Sea, although flux from Taiwan's many smaller rivers has across the South China tectonic block, composed of both the Yangtze been significantly greater in the recent geologic past (Milliman and Craton and the Cathaysia Block (Yao et al., 2013)(Fig. 2). The Pearl Meade, 1983). The climate of the PRD is dominated by the East Asian Fig. 2. Map showing the major tectonic blocks 27˚N within the Pearl River catchment, as well as the Hongshui River sample locations. Cathaysia block covers the SE area from which most of our samples are derived. 26˚N The Yangtze block includes only three of the samples in the NE of catchment. The boundary between these two blocks is modified after He Liu River 501 25˚N et al. (2014). Subdivisions within these blocks 105 He River are defined based on the results of the analysis 005 Gui River River 102 presented here. 003 Bei 24˚N ng River o 206 D P7 P4 P1 906 304 23˚N 903 705 Yu River R11 22˚N 0 200 km 105˚E 110˚E 115˚E Yangtze Craton ~400 Ma - Caledonian influence Cathaysia ~800 Ma - Yangtze Craton influence ~100 Ma - Cretaceous arc influence ~1000 Ma - Cathaysia influence ~250 Ma - Indosinian influence ~1800 Ma - Luliangian influence 2 Download English Version: https://daneshyari.com/en/article/8912069 Download Persian Version: https://daneshyari.com/article/8912069 Daneshyari.com.