Journal of Asian Earth Sciences 46 (2012) 1–19 Contents lists available at SciVerse ScienceDirect Journal of Asian Earth Sciences journal homepage: www.elsevier.com/locate/jseaes Distribution and erosion of the Paleozoic tectonic unconformities in the Tarim Basin, Northwest China: Significance for the evolution of paleo-uplifts and tectonic geography during deformation ⇑ Changsong Lin a, , Haijun Yang b, Jingyan Liu c, Zhifeng Rui c, Zhenzhong Cai b, Yongfeng Zhu b a School of Ocean Sciences and Resources, China University of Geosciences, Beijing 100083, China b Petroleum Exploration & Production Institute, PetroChina Company Limited, Beijing 100083, China c School of Energy Resources, China University of Geosciences, Beijing 100083, China article info abstract Article history: The distribution and erosional features of the Paleozoic major tectonic unconformities in the Tarim Basin, Received 4 March 2011 and their genetic relation to the development of paleo-uplifts as well as the evolution of geodynamic set- Received in revised form 20 September tings, are documented in this paper based on the integral analysis of seismic, drilling, and outcrop data. 2011 During the Paleozoic, the Tarim Basin underwent three major tectonic deformation stages, which resulted Accepted 11 October 2011 in three angular unconformities and in significant changes in basin geomorphology and paleogeography. Available online 23 November 2011 The tectonic deformation at the end of the Middle Ordovician was characterized by development of the southern central paleo-uplift, the northern depression, and the southeastern Tangguzibasi depression in Keywords: the basin. The thickest denudation belts of the unconformity (T ) are distributed mainly along the Unconformities g5-2 Paleo-uplifts thrust structural highs. A stronger deformation event took place at the end of the Late Ordovician and Tectonic setting formed a huge uplift along the southwestern and southeastern basin margins and the western part of Tectonogeography the Tabei uplift along the northern basin margin, producing an extensive angular unconformity (Tg5) with Paleozoic Tarim Basin maximum erosion thickness of 1500–2000 m. This tectonic event resulted in an abrupt change in overall geography of the basin, from a deepwater marine environment at the late stages of the Late Ordovician to a littoral and neritic basin in the Early Silurian. The deformation that occurred at the end of the Middle Devonian was the strongest in the Paleozoic. It generated the most widespread angular unconformity (Tg3) within the basin and led to extensive erosion, with maximum denudation thickness of 3000– 5000 m in the northern and northeastern parts of the basin. The topography of the basin during the late Devonian was characterized by a high in the northeast and a low in the southwest, forming an embay- ment basin opening to the southwest during the Early Devonian to Carboniferous. The transgression in general from southwest to northeast deposited extensive coastal sandstones onlapping the erosion-lev- eled unconformity (Tg3). Comparative analysis of uplifting in the basin with the regional tectonic setting shows that deformation that took place during the three periods was related to the evolution of the paleo-oceanic plates and the orogenesis around the basin. The closure of the North Kunlun Ocean and subsequent collision is suggested to be the main cause for the development of the central paleo-uplift at the end of the Middle Ordovician and the strong uplift and erosion of the southwestern and southeast- ern basin margin at the end of the Late Ordovician. The large-scale uplift and denudation of the northern part of the basin, including the Tabei–Kongquehe uplift belt, as well as the folding and hinging of the Manjiaer depression, was coeval with, and more related to, the subduction and collision of the South Tianshan orogenic belt and the Altyn trench-arc-basin system at the end of the Middle Devonian. Ó 2011 Elsevier Ltd. All rights reserved. 1. Introduction development of a series of large-scale paleo-uplifts and tectonic unconformities. The deformation stages indicated by extensive The Tarim Basin, located in western China, is a large superim- angular unconformities resulted in significant changes in tectonic posed basin that underwent multiple phases of tectonic deforma- geomorphology and geography of the basin. An investigation of tion from the Sinian to Cenozoic (Li et al., 1996; Jia, 1997). The the development of the unconformities and paleo-uplifts is impor- basin architecture is complicated, and is characterized by the tant in unraveling the geodynamic setting of the basin’s evolution. Petroleum exploration in the basin has shown that most of the ⇑ Corresponding author. hydrocarbon accumulation was closely related to development of E-mail address: [email protected] (C. Lin). the paleo-uplifts and distribution of the unconformities. Thus, 1367-9120/$ - see front matter Ó 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.jseaes.2011.10.004 2 C. Lin et al. / Journal of Asian Earth Sciences 46 (2012) 1–19 research on the evolution of paleo-uplifts and the tectonogeogra- et al., 2009), but in this paper we aim to investigate the evolution phy of the Tarim Basin has greatly intensified over the past two of the Paleozoic tectonogeography of the basin during critical decades (Xu et al., 2005; Li et al., 1996; Jia, 2002; Jin and Wang, deformation stages. 2004; Lin et al., 2004; Pang et al., 2006; Kang, 2007; Liu et al., The study in this paper has shown that the contact feature and 2008; Lin et al., 2008, 2009). erosion distribution of a tectonic unconformity can provide very The development of unconformities, particularly their erosion useful information for reconstruction of paleo-uplifts and tectono- and origin within the basin’s dynamic setting, has been one of geography, and that the formation of paleo-uplifts and angular the imperative and long-term controversies in basin analysis. The unconformities within the basin was closely related to the coeval formation of stratigraphic unconformities can be attributed to tec- subduction of the surrounding paleo-ocean and the collision of tonics, eustasy, or climatic change (Huuse and Clausen, 2001; orogenic belts. We address these issues by integrating the analysis Dickinson et al., 2002; Jaimes and de De Freitas, 2006; Otonicar, of seismic profiles, well logs and outcrop data, with a focus on the 2007; Baranoski et al., 2009). However, angular unconformities comprehensive interpretation and correlation of long seismic pro- with underlying deformed strata are usually generated by tectonic files across the basin. This study may serve as a foundation for fur- events or uplifting (e.g., Coakley et al., 1991; Paola and Domenico, ther research on the dynamic evolution of the basin and the 1995; Mindszenty et al., 1995; Yu and Chou, 2001; Rafini et al., prediction of reservoir distribution within it. 2002; Li et al., 2004; Ghiglione and Ramos, 2005). In the Tarim Ba- sin, many previous works have identified a number of major angu- lar unconformities with tectonic origin within the Paleozoic (e.g., 2. Geologic setting and tectonostratigraphy He, 1995; Zhang et al., 1996,; Jia, 1997; Chen et al., 2007; Lin et al., 2008; Liu et al., 2008 2007). Erosional amounts of some ma- The Tarim Basin lies between the Chinese Tianshan Mountains jor unconformities in parts of the basin were estimated through to the north and the western Kunlun Mountains to the south, strata correlation or quantitative modeling (Zhang et al., 2000,; and is confined by the Altyn Fault Belt to the southeast. The basin Zhou et al., 2006; Wang et al., 2010, 2007). In particular, there have is diamond shaped in plane view, and covers an area of about been many investigations concerning the significance of the 560,000 km2, with an east–west length of more than 1000 km unconformities in petroleum accumulation in the uplift belts in and a south–north length of over 800 km. The Tarim basin can be the basin (e.g., He, 2002; Deng et al., 2008; Xiao et al., 2009). How- tectonically divided into several units, including the Kuqa depres- ever, most of these studies focused on parts of the basin based on sion, the Tabei uplift belt, the North depression belt (the Manjiaer local data and less attention has been paid to the variation and dis- and the Awati depressions), the Central uplift belt, the Southeast- tribution of the unconformities and their erosion in basin scale. ern uplift belt, and the Taxinan marginal depression (Fig. 1, modi- Generally the formation of the angular unconformities is regarded fied from Jia (1997)). as the product of tectonism, but their genetic relation to the devel- The basement of the Tarim Basin consists of Pre-Sinian conti- opment of uplifts and the evolution of geodynamic setting of the nental crust (Jia, 2002). The continent was formed in a subduction basin, particularly the evolution of the surrounding paleo-oceanic setting during the Early Neoproterozoic (Nakajima et al., 1990; plates or orogenesis have been less studied. There are also many Wang et al., 1990; Xiao et al., 1992; Che et al., 1994; Chen et al., investigations concerning the reconstruction of the paleogeogra- 2000), which is suggested to be the result of the collision between phy of the Tarim Basin (Feng et al., 2006; Wang et al., 2006; Zhao the North and South Tarim Blocks (Wu et al., 2010). The breakup of Fig. 1. Schematic tectonic map of the Tarim Basin, showing the distribution of tectonic units within the basin (modified after Lin et al. (2009)). C. Lin et al. / Journal of Asian Earth Sciences 46 (2012) 1–19 3 the continent might have taken place in the Nanhua period during rienced a compressive inversion during the Late Paleozoic. The the separation from the Rodinia supercontinent (Gao et al., 2009; Tadong uplift that flanks the present northeastern margin of the Wu et al., 2010).