Detrital Zircon U-Pb Geochronology and Its Provenance Implications on Silurian Tarim Basin

Home , Kenorland, Ur (continent)

Journal of Earth Science, Vol. 23, No. 4, p. 455–475, August 2012 ISSN 1674-487X Printed in China DOI: 10.1007/s12583-012-0268-z

Jingyan Liu* (刘景彦) School of Energy Resources, China University of Geosciences, Beijing 100083, China Changsong Lin (林畅松) School of Ocean Sciences, China University of Geosciences, Beijing 100083, China Sitian Li (李思田) Key Laboratory of Tectonics and Petroleum Resources of Ministry of Education, China University of Geosciences, Wuhan 430074, China; School of Energy Resources, China University of Geosciences, Beijing 100083, China Zhenzhong Cai (蔡振忠) Institute of Petroleum Exploration and Exploitation, Tarim Oil Field Company, PetroChina, Korla 841000, China Shiqiang Xia (夏世强), Chao Fu (付超), Yongquan Liu (刘永权) School of Ocean Sciences, China University of Geosciences, Beijing 100083, China

ABSTRACT: As one of the major exploration objects of marine deposit in Tarim basin, Silurian has been paid more attention from oil/gas exploration and geologists. However, due to the widely deposit and later erosion, it is difficult to restore the original basin. The surrounding tectonic activity and provenance systems of Silurian Tarim basin have a lot of controversy. Aid of detrital zircons U-Pb dating data obtained from well drilling of Tabei (塔北) and Tazhong (塔中) areas and Sishichang (四十场 ) and Xiangyangcun (向阳村) outcrop profiles, integrated with other geological and geophysical data, the tectothermal evolution and provenance nature of Silurian deposit have been revealed. Zircons U-Pb dating shows Tarim basin has experienced 5–6 significant tectothermal events: 3 500–3 000 Ma Paleo–Mesoarchean, around 2 500 and 1 800 Ma Paleoproterozoic, around 1 000 and 800 Ma Neopro- terozoic, and 500–400 Ma Eopaleozoic tectothermal events. These tectothermal events reflected the evolution of Tarim microplates and Tarim basin, respectively, corresponded to the forming and spilitting process of Ur supercontinent, Kenorland, Columbia and Rodinia supercontinent. Difference between the samples of Tazhong and Tabei areas This study was supported by the Fundamental Research Funds indicated that North and South Tarim mi- for the Central Universities of China (No. 2010ZD07), the Key croplates were different in Paleo–Mesoarchean, National Natural Science Foundation of China (No. 41130422), and later evolutions were more synchronous the National Natural Science Foundation of China (No. after Paleoproterozoic. Integrated with seismic 40372056) and the State Key Development Program for Basic data and outcrop interpretation, the U-Pb dating Research of China (Nos. 2011CB201103, 2006CB202302). results also revealed that the surrounding tec- *Corresponding author: [email protected] tonic activities were still very active during Silu- © China University of Geosciences and Springer-Verlag Berlin rian, and indicated different regions had differ- Heidelberg 2012 ent source systems. At Tadong (塔东) and Manjiaer (满加尔 ) depressions, major source Manuscript received January 15, 2012. systems came from Ordovician Altyn orogenic belts. Manuscript accepted April 8, 2012. At Tabei area and northwest of Tarim basin, major 456 Jingyan Liu, Changsong Lin, Sitian Li, Zhenzhong Cai, Shiqiang Xia, Chao Fu and Yongquan Liu

source systems came from recycling orogenic zone (the activity of South Tianshan (天山) Mountain) and Precambrian stable basement (local paleo-uplifts at north of Tabei). The Ordovician uplift and orogenic zone at the south of Tarim basin and Precambrian granite basement provided lots of source systems to Tazhong area. KEY WORDS: provenance analysis, zircon U-Pb geochronology, tectonic setting, Silurian, Tarim basin.

INTRODUCTION provenance, depositional systems and favorable Tarim basin, the largest basin in west of China, reservoir distribution are all hot topics worth of developed on pre-Sinian basement and suffered deep discussion. However, due to the widely deposit multi-stages tectonic evolution, is a bearing energy and later erosion, it is difficult to restore the origi- resources and superimposed basin (Jia, 1997). From nal basin. Archaeozoic to Mesozoic and Cenozoic, the basin had In recent years, with the development of ad- experienced long term tectonic reformation and many vanced dating technology, such as zircon LA-ICP-MS, original basins superimposition (Lin et al., 2009; He et SHRIMP U-Pb dating and apatite fission track meth- al., 2005). The long history and complex basin struc- ods, it is possible to provide accurate chronological ture and surrounding tectonic setting made it old basin evidence for basin evolution and provenance systems, with abundant geological significances (Chen et al., and further discuss the surrounding tectonic back- 1996), and attractive to more and more attention of ground. Restoration orogenic events and the research geologists. Meanwhile, Tarim basin is rich in coal, oil on coupling of basin and mountain always are the hot and gas resources (Kang, 2007; Zhou et al., 2007), and theme of the international geological field, and has now it has already become one of the most important made lots of progress (Glorie et al., 2010; Long et al., resource bases of China’s Western Development 2010; Qiu et al., 2010; Li Z et al., 2009; Narelle et al., Strategy. For a long time, the unique geological back- 2009; Li Y P et al., 2007; Cawood and Nemchin, 2000; ground, basin structure and depositional filling, tec- Wysoczanski et al., 1997; Dickinson et al., 1983). In tonic evolution and oil/gas bearing condition of Tarim this article, 4 samples have been carried out for detri- basin have attracted wide interests of geologists and tal zircon U-Pb dating with LA-ICP-MS method. exploration industry (Ren et al., 2011; Cai, 2005; Among them, 3 samples were taken from Silurian Zhang et al., 2002; Kang and Kang, 1996; Li et al., sandstone and 1 sample came from Devonian sand- 1996). Its comparison with other basins of the world stone (sample code: Jm-1). Two samples came from or the relationship with global significant events also well drilling (Jm-1 and Tc-1, taken from Tabei and are research topics with high scientific significances Tazhong, respectively) and 2 were taken from out- (Xu et al., 2011; Jia et al., 2007; Jin and Wang, 2004). crops (SSC-28 and XYC-1, taken from the Sishichang The surrounding tectonic activity and provenance outcrop profile at the northwest of Tarim basin and systems of Silurian Tarim basin have a lot of contro- Xiangyangcun outcrop profile at Kuruktag uplift of versy. Due to the thick deposit (over 10 km in the ba- the east of Tarim basin, respectively). In addition, sin) and deep subsidence during the long geological there is another Devonian sandstone sample taken history, it is more difficult to reveal the old basement from Well Hd14 at Tabei area, which has been fin- and quantify the key tectonic evolution events, which ished debris zircon U-Pb dating (Liu et al., 2012). has made very important influence on the tectonic and Therefore, there are 5 samples, respectively repre- sedimentary evolution in basin, and are worth to deep senting the 5 major parts of Tarim basin, showed the discuss in further research. Silurian, as one of the ma- whole tectothermal events history before Neoprotero- jor exploration objects of marine deposit in Tarim ba- zoic of Tarim basin, and also revealed the difference sin, has been paid more attention from oil/gas explo- of different places. The zircons ages determination in ration and geologists (Kang, 2007; Liu et al., 2004; the Tarim basin provides isotope chronological evi- Song and Wu, 2004; Song et al., 2003). Silurian sur- dence for further exploration the relationship between rounding tectonic background and its basin nature, Tarim microplate and the surrounding supercontinent. Detrital Zircon U-Pb Geochronology and Its Provenance Implications on Silurian Tarim Basin 457

Based on the tectonic-stratigraphic framework in the original basin with different characteristics at different basin, quantitative research and comprehensive analy- locations resulted in the unique sequence structure of sis of multiple data provides strong evidences and superimposed basin and hydrocarbon accumulation constraint for determining the regional tectonic setting, process in western China. The tectonization and evo- basin evolution and significant tectonic events, un- lution around the basin have deep influences on tran- conformities, and sedimentary filling characteristics sition of palaeotectonics and paleogeography in the responsed to tectothermal events. Silurian detrital zir- basin and generation and accumulation of hydrocar- cons U-Pb dating results also indicate that different bon resources (Liu J Y et al., 2011, 2010; Lin et al., regions have different source systems, which will be 2009; Liu L F et al., 2001). very helpful to analyse the sedimentary development and distribution, and further give a guidance to predict Basin Filling and Tectonic Evolution Sequence favorite reservoir sedimentary systems. In terms of tectonic setting and sedimentary filling evolution of the basin, the Tarim basin has ex- REGIONAL GEOLOGICAL BACKGROUND perienced several important tectonic evolutions and Tectonic Location of the Basin formed multiple unconformities, including (from old 0 Tarim basin is located in the west of China, be- to new) the base of Sinian (T10 ), the base of Siluria 0 0 tween the gigantic Tianshan Mountain and Kunlun (T7 ), the base of Upper Devonian (T6 ), the base of 0 6 Mountain. Its east edge is bound to Altyn fault zone. Triassic (T5 ), the base of Jurassic (T4 ), the base of 2 0 0 Tarim basin, covering 560 000 km , is a large super- Cretaceous (T4 ), the base of Paleogene (T3 ) and 1 imposed basin developed based on pre-Sinian base- Neogene (T2 ). It is possible to work out the 7 primary ment and is sufficient in energy resources (Jia, 1997). tectonic sequences of Sinian–Phanerozoic according The secondary structures units in the basin mainly to the major unconformities of important tectonic consists of uplifts and depressions, such as Tabei up- evolutions, which represents 7 important tectonic de- lift, Tazhong uplift, Bachu uplift, Kuqa depression, velopment and evolution stages and superimposition north depression, Tadong depression, Tanggubazi de- of different original basins (Fig. 2). pression, southwest depression, and so on (Fig. 1). Referred to regional geologic data and previous From Sinian to Paleogene and Neogene period, the research reports, the crystalline basement of Tarim basin has experienced a long geological evolution and formed at pre-Sinian, following the ancient China land multi-stage tectonic reformation history, exhibiting and Rodinia supercontinant. During Sinian, belonged complex structure-strata construction with several to Salayier tectonic cycle, Tarim basin was character- original basins superimposition (Fig. 2). In the global ized with rift valley-aulacogen-continental margin tectonic framework, Tarim basin was located at the slope and terrace. From Cambrian to Early Devonian, edge and foreland of Gondwana land in Neo-Tethyan it belonged to Caledonian tectonic cycle. Tarim basin tectonic domain. Along this belt, a giant global oil-gas was characterized with platform in craton, continental accumulation region has been built, including Persian margin slope and aulacogen during Cambrian to Early Gulf and Middle East. Siberian plate and Kazakhstan and Middle Ordovician. The tectonic setting of the plate located at the north of Tarim basin, and corresponding region was archipelagic ocean envi- Qiangtang-South China plates, Lhasa plate and Indian ronment with the Rodinia ancient land-Asia Ocean plate located at the south of Tarim basin. The geo- cracking and extension. During the Late Ordovician– logical evolutions of the basin since Phanerozoic were Early Devonian, there developed peripheral foreland, closely related to the surrounding plates and blocks craton terrace and craton depression, with the conver- activities, such as extension, cracking, subduction, gent of West Kunlun Ocean, closure of Altyn Ocean, collision and orogeny (Lin et al., 2011; Jin and Wang, closure of South China, North China and Tarim plates. 2004; Jia, 1997; Li et al., 1996). The obvious differen- During the Late Devonian–Permian, it belonged to tiation of basement construction of the basin, Hercynian tectonic cycle. The basin was characterized multi-stage tectonic evolution, superimposition of the with development of rift valley, depressions in or at 458 Jingyan Liu, Changsong Lin, Sitian Li, Zhenzhong Cai, Shiqiang Xia, Chao Fu and Yongquan Liu the edge of craton, with the expansion of ancient Asia Paleo-Ocean. Inland depression and foreland devel- Ocean and Paleo-Tethys Ocean. During Triassic– oped during Cretaceous due to the matching of Gang- Cretaceous, it belonged to Yanshan-Indosinian dise block and Eurasia and closure of Neo-Tethys tectonic cycles. There were inland and foreland de- Ocean. Paleogene–Neogene, it belonged to Himala- pressions during Triassic, corresponding the regional yan tectonic cycle. There were inland and foreland tectonic setting with closure of ancient Asia Ocean basins developed, with the collision between Indian and matching of South China, North China and Sibe- plate and Eurasian plate and uplift of Qinghai-Tibet rian plates. It was inland depression during Jurassic, plateau (Lin et al., 2009; Hao et al., 2003; Guo et al., which was resulted from the expansion of Yaluzangbu 2000; Jia, 1997).

70o 75o 80o 85o 90o 95o E (a) 0 200 km Alamutu 60 No Siberia plate Europe Asia Kazakhstan plate Urumqi

Tarim o

basin B 45 N China Tianshan Mountain o Akeshu Kuqa 30 N Ym2 Kumishi Kashi Sishichang Tabei uplift C1 Korla Hami o India Hd14 30 West Tadong depression Taxinan depressionTarim plate Yh1 Xiangyangcun Africa o o Jm-1 60 90 Mc1 Tazhong uplift Margin of plate Tangc1 Ruoqiang Dunhuang

Kunlun Yumen o Eopaleozoic subduction-suture zone Qieme Altun Mountain Neopaleozoic subduction-suture zone Hetian 40 A East Kunlun Mountain Meso-Cenozoic subduction-suture zone Mountain Thrust fault Qaidam block Samples from well Qiangtang block Samples from outcrop Well location Gemuer A B Location of seismic profile A B 0.6 Angular unconformity (b) 0 1 N T3 Reflection surface on seismic 1.4 T2 0 P Strata T3 E 2.2 0 0 T4 4 T5 5 J 6 T T4 K 3.0 0 P T T6 0 7 C-D3 TWT (s) 3.8 T D-S2

4.6 4 O2+3 T7

1 5.4 Southeast T8 O-13∈ Tanan uplift depression 0 Kuqa 6.2 T9 ∈1-2 depression Thrust fault Tgzbs depression Tazhong uplift Northern depression Tabei uplift Early normal fault Figure 1. Location of plate tectonics (a) and tectonic-sequence framework (b) of Tarim basin.

SAMPLE TEST AND DATA PROCESSING (sample location and lithology description see Fig. 1 The samples for research in this paper are all and Table 1). Except sample Jm-1 comes from the medium-fine sandstones or medium grained sand- Late Devonian Keziertage Formation, the others are stones, weight 2.5–2.8 kg, taken separately from Well all from Silurian Kepingtage Formation. In addition, Juema-1 at the east of Tabei uplift and near Manjiaer there is another Devonian sandstone sample taken depression (sample code: Jm-1), Well Tangcan-1 at the from Well Hd14 at Tabei area, which has been fin- south of Tazhong uplift (sample code: Tc-1), ished debris zircon U-Pb dating and discussed (Liu et Sishichang outcrop profile at Keping-Bachu area of al., 2012). Therefore, there are in fact 5 samples, re- the northwest of Tarim basin (sample code: SSC-28) spectively representing the 5 major parts of Tarim ba- and Xiangyangcun outcrop profile of Kuruktag uplift sin, that is, Tabei area (Hd14), Manjiaer depression at the east of Tarim basin (sample code: XYC-1) (Jm-1), Tazhong area (Tc-1), east of Tarim basin Detrital Zircon U-Pb Geochronology and Its Provenance Implications on Silurian Tarim Basin 459

(XYC-1) and northwest of Tarim basin (SSC-28). The described as Jackson et al. (2004). First, crush the par- geochronology results and character will reflect some ticles into 10 meshes in mechanical mode without information about tectonic movements and different pollution, sieve 40–80 meshes with gradation of provenance areas. 0.45–0.18 mm by standard dry sieving. Second, sepa- Debris zircon U-Pb dating has been performed rate the electromagnetic, nonmagnetic and ferromag- with LA-ICP-MS analytical method, which can be netic heavy minerals through heavy solution, fine

Strata and Age The evolution of Filling sequence Plate tectono reflection prototype basin interface (Ma)

Tectonic cycle

Tectonic sequence

Q India plate and N Eurasian 1 Inland and foreland T2 VII plate collision, depression Tibetan plateau uplift E

0 Himalayan T3 Gandes block and 100 Erosion or loss VI Eurasian continent K Inland depression- matching, Neo-Tethys foreland depression Ocean closure 0 T4

Brahmaputra J Inland depression V River expanded 200 6 T4 Paleo-uplift Inland depression- Paleo-Asia Ocean T IV 0 foreland depression Indosinian-Yanshanian closure South China, T5 North China and Erosion or loss Siberian plates Inland depression matching P 300

4 T5 Paleo-Asia Ocean and Rift-cratonic III Paleo-Tethys Ocean C idnland epression- expanded 7 c T5 ratonic marginal V V depression Hercynian D3 V 0 Paleo-uplift T6 400

32 Peripheral foreland S+D 1 West Kunlun Ocean T6 basin-cratonic II convergent, Altun S1+2 0 V inland depression T7 VV Ocean closure South China, North China and p Carbonate latform and Tarim plates matching O3 deep tubidite 4 T7 V basin 500 V Paleo-uplift O1+2 0 T8 Cratonic inland Rodinia Continent-

Caledonian

∈3 platform-continental Asia Ocean 1 I T8 marginal slope- break apart, pull-apart Aulacogen multi-island and ∈12+ oceans environment 0 T9 V V 600 Rift-aulacogen- Z continental marginal 0 TD slope and platform

Xingkaian AnZ Paleo-Chinese continent and Pro-Sinian crystalized basement VV Rodinia supercontinent formed

Angular unconformity Clastic deposit VV Vocanic rock

Nonangular unconformity Carbonate deposit Deposit interrupt

Figure 2. Tectonic-sedimentary evolution sequence and plate tectonic setting of Tarim basin. 460 Jingyan Liu, Changsong Lin, Sitian Li, Zhenzhong Cai, Shiqiang Xia, Chao Fu and Yongquan Liu

Table 1 Sample location and lithology description

Sample code Formation Strata Location Lithology SSC-28 Upper member of Lower Silurian Sishichang outcrop profile Medium-fine sandstone Kepingtage XYC-1 Upper member of Lower Silurian Xiangyancun outcrop profile Medium-grained sandstone Kepingtage Tc-1 Upper member of Lower Silurian South of Tazhong uplift Medium-grained sandstone Kepingtage Jm-1 Keziertage Upper Devonian East of Tabei uplift Medium-fine sandstone

Hd14 Keziertage Upper DevonianTabei uplift Medium-fine sandstone elutriation separation and electromagnetic separation. content of radioactive Pb and the uncertainties in Then, identify and separate the clastic zircon minerals common lead correction (Sircombe, 1999). The data from the nonmagnetic ones with binocular microscope. processing software is Glitter 4.4, the individual data Select the clean, clear monogenetic zircons with com- point error mean is 1σ, and the weighted mean error is plete crystallization, low metamictization for use. 2σ. Cathodoluminescence (CL) images were obtained from a Cameca electron probe X-ray micro- U-PB GEOCHRONOLOGY OF DETRITAL analyser at Test Center of Chinese Academy of Geo- ZIRCONS logical Sciences, Beijing, so as to determine the inter- Concordia plots of zircon U-Pb ages for all four nal texture of zircon particles and choose potential samples are shown in Fig. 3, and the corresponding target sites for U-Pb dating. The analysis voltage is 50 age-probability plots in Fig. 4. U-Pb geochronologies kV and current 15 nA. Laser ablation ICP-MS zircon of each sample are described as follow. U-Pb analyses were conducted on an Agilent 7500a ICP-MS (Hewlett-Packard, USA) equipped with a 193 Tabei Uplift to Manjiaer Depression (Samples: SS laser, at the Element Geochemistry Lab of Geo- Jm-1 and Hd14) logical Testing Center of China University of Geo- Medium-fine sandstones of sample Jm-1 and sciences (Beijing), China. The working conditions of Hd14 were taken from Keziertage Formation of Late Angilent 7500a ICP-MS are as follows: cooler flows Devonian at east of Tabei uplift and near Manjiaer 15 L/min, auxiliary gas (Ar) flows 1.15 L/min, test depression. Due to their similar dating character and time is 20 ms for U, Th, 204Pb, 206Pb, 207Pb, 208Pb and Hd14 has been discussed (Liu et al., 2012), here just 15 ms for other elements, the diameter of test point refer it to make comparison and more emphasis on beam spot is 36 μm (including microelement). Zircon Jm-1. Based on the principle of looking for uniform 91500 (Wiedenbeck et al., 1995) was used as the location under CL image, avoiding fractures and in- standard and the standard silicate glass NIST was used closure under reflection image and transmitted light to optimize the machine. U, Th and Pb concentrations microscope, a total of 120 zircon grains were selected were calibrated using 29Si as an internal. The and measured from sample Jm-1, with irradiation di- common-Pb correction used the method described by ameter of 30 mm and ablation depth of about 30 mm. Andersen (2002). Raw count rates for 29Si, 204Pb, 206Pb, Among the 120 zircon grains U-Pb dating data, 113 207Pb, 208Pb, 232Th and 238U were collected for age de- ones with unharmonious degree are less than 5% (ac- termination. For zircons older than 1 000 Ma, ages counting for 94.2%) and 7 ones are in 5%–10%, ex- were calculated from their 207Pb/206Pb ratios, whereas hibiting perfect concordia plot (Fig. 3a). According to zircon ages younger than 1 000 Ma were based on number histograms and probability plots for detrital their 206Pb/238U ratios, which provides a more reliable zircon ages of Jm-1 (Fig. 4a), the valid U-Pb dating age estimate for these younger grains due to the low data mainly distributes in 5 intervals: around 400–500, Detrital Zircon U-Pb Geochronology and Its Provenance Implications on Silurian Tarim Basin 461

800, 1 800–2 000, 2 500 and 3 500 Ma. U-Pb ages of teen samples ages (11.7%) range of 1 579–2 200 Ma, 48 detrital zircons (40%) range from 406 to 472 Ma, with prominent peak of 1 800 Ma. Ten samples ages with prominent peak of 423.53 Ma. Most zircons are (8.3%) range of 2 300–2 600 Ma, with prominent peak characterized by high Th/U ratios (0.43–2.57) and of 2 500 Ma. The oldest zircon U-Pb age is 3 525 Ma, oscillatory zones in CL images (Fig. 5), indicative of a indicating the Paleoarchean. These zircon grains magmatic origin. The ages of 41 zircons (34.2%) mostly show faint zoning in CL images, suggestive of range from 583 to 1 166 Ma, with prominent peak of a metamorphic origin. 805.88 Ma. Among them, most are typical magmatic zircons (i.e., sample No. 27, Fig. 5), showing com- South of Tazhong Uplift (Sample: Tc-1) pletely short prismatic, square pyramid, automorphic Sixty zircon grains were random selected and 51 or hypautomorphic crystal, with clearly magmatic effective U-Pb dates were obtained from sample Tc-1. crystallization oscillation girdle, which formed during Medium-grained sandstone was from upper member magmatic exhalation due to different Th/U content. of Kepingtage Formation of Early Silurian. U-Pb ages There are also some metamorphic origin zircons as range widely from 752 to 2 827 Ma. Most ages can be suggested by the lower Th/U ratio (0.06) and cloudy divided into three groups: 752–900 Ma (24 grains, internal character, with gray or gray-white solid re- 47%, with prominent peak of 800 Ma), 1 000– crystallization and irregular cedar leaf structure at CL 1 401 Ma (8 grains, 16%, with prominent peak of image (i.e., sample No. 22, Fig. 5). There are lots of 1 000 Ma), 1 481–2 200 Ma (14 grains, 27%, with Archean–Paleoproterozoic zircon ages, suggesting prominent peak of 1 800 Ma) and 2 524–2 827 Ma (5 relatively determinate tectonic-thermal events. Four- grains, 9.8%, with prominent peak of 2 500 Ma) (Fig.

Figure 3. Concordia plots for detrital zircon ages of Jm-1 samples. 462 Jingyan Liu, Changsong Lin, Sitian Li, Zhenzhong Cai, Shiqiang Xia, Chao Fu and Yongquan Liu

Figure 4. Number histograms and probability plots for detrital zircon ages of different samples.

4). Most zircons that yield dates in the ranges of (Figs. 3 and 4). The group of 592–949 Ma are mostly 752–1 401 Ma are characterized by high Th/U rations attributed to a magmatic origin due to higher Th/U (0.43–2.75) and show distinct oscillatory zones, rations (0.85–2.6) and well-zoned crystal textures in indicative of a magmatic origin. The other two groups CL images. The other three groups mostly show faint have notable characteristics of low Th/U rations internal zoning, probably indicative of metamorphic (0.03–0.67) and display faint zoning in CL images, genesis. suggestive of a metamorphic origin. Northwest of Tarim Bain (Sample: SSC-28) Northeast of Tarim Bain (Sample: XYC-1) Sandstone sample (sample code: SSC-28) taken Sandstone sample (sample code: XYC-1) taken from upper member of Kepingtage Formation of Early from upper member of Kepingtage Formation of Early Silurian at Sishichang outcrop profile of Bachu Silurian at Xiangyangcun outcrop profile of Kuruktag County, near of northwest margin of Tarim basin. uplift, near of northeast margin of Tarim basin. Sixty Sixty zircon grains were random selected and 56 ef- zircon grains were random selected and 58 effective fective U-Pb dates were obtained. U-Pb ages mostly U-Pb dates were obtained. U-Pb ages mostly range range from 528 to 3 021 Ma, mainly distributed into 4 from 627 to 2 719 Ma, mainly distributed into 4 in- intervals: 528–1 400 (26 grains, 46.4%, prominent tervals: 592–949 Ma (15 grains, 25.8%, prominent peak of around 800 Ma), 1 500–2 300 (19 grains, peak of around 800 Ma), 969–1 300 Ma (10 grains, 33.9%, prominent peak of around 1 800 Ma), 2 400– 17.2%, prominent peak of around 1 000 Ma), 1 400– 2 800 (10 grains, 17.8%, prominent peak of around 2 200 Ma (17 grains, 29.3%, prominent peak of 2 600 Ma) and 3 000 Ma (1 grain, 3 021 Ma) (Figs. 3 around 1 800 Ma) and 2 300–2 800 Ma (14 grains, and 4). 24.1%, prominent peak of around 2 500–2 600 Ma) Detrital Zircon U-Pb Geochronology and Its Provenance Implications on Silurian Tarim Basin 463

Figure 5. Typical CL images for detrital zircons of Jm-1 samples. In-situ measure spots (circles), numbers (referred to Table 1) and U-Pb apparent ages are marked in each images.

DISCUSSION Hd14 and SSC-28, there are 3–4 ancient metamorphic Detrital Zircon Geochronological Implications for zircons of Archaean, which reflect the Archaeozoic Tectothermal Events basement of more than 3 billion years. The 3 000– According to the zircon U-Pb dating distribution 3 500 Ma basement metamorphism tectothermal density (age spectrum) reflected by the test results and events, is accordance with the Ur supercontinent characters in CL images, it indicates that the sources forming time. The oldest age (3 525 and 3 502 Ma) of zircons include both recycled sedimentary rocks, appeared at Tabei area (Jm-1 and Hd14), the second magmatic rocks and metamorphic rock zircons with old one is northwest of Tarim basin (SSC-28, about age of Archean–Paleoproterozoic (3 500–3 000, 3 000 Ma), then is the south of Tazhong area (Tc-1, 2 600–2 500 and 2 000–1 800 Ma), Mesoproterozoic around 2 800 Ma) and finally is the east of Tarim ba- and Neoproterozoic (1 000–800 Ma), Eopaleozoic sin (XYC-1, about 2 600 Ma, which is coincide with (475–440, 436–412 Ma). These tectothermal events the Sm-Nd and Rb-Sr isochrones age of amphibolite will be discussed below, respectively. at Altyn and Kuruktag area (Guo et al., 2003, 2000), though Hu and Rogers (1992) has ever got 3 263± (1) Meso-Archean to paleopro-terozoic basement 129 Ma Sm-Nd isochrones age measured from the metamorphism tectothermal events dark gray amphibolite of Tuogelabulake Group at the Dating ages of 3 500–3 000, 2 600–2 500 and south of Xinger Village in Kuruktag area, which has 2 000–1 800 Ma represent the basement metamor- been considered as the oldest basement age of Tarim phism tectothermal events occurred during period basin. The results can be compared with the fission from Meso-Archean to Paleoproterozoic of Tarim ba- track result of Precambrian blueschist apatite of Aksu sin. According to the test results of sample Jm-1, area by Zhang et al. (2009), and apatite fission-track 464 Jingyan Liu, Changsong Lin, Sitian Li, Zhenzhong Cai, Shiqiang Xia, Chao Fu and Yongquan Liu of Precambrian basement rocks at Kuruktag uplift by cially at the north and east of Tarim basin (samples: Zhu et al. (2010), and U-Pb zircon dating of Silurian Jm-1 and XYC-1), becoming one of the main prove- sandstone at Tazhong area by Qian et al. (2007). The nance events of Silurian deposit. Since it was so oldest ages’ distribution indicates the north of Tarim prominent at all samples, if it is possible to indicate basin has older basement than that of south of Tarim that Tarim basin has a uniform basement since this basin, which may confirmed by geophysical data of movement? Or since that, the whole basin’s evolutions magnetic anomaly characteristics of Tarim basin were more synchronous. It is different opinion from basement (Fig. 6). The magnetic anomaly map of the previous research reports and need more evidences basin shows magnetic anomaly is obviously different and further discussion later. The study of Paleopro- between the north and south of Tarim basin. Magnetic terozoic tectonic evolution of the North China craton anomaly is relatively weak in the north and there are also suggests that the eastern and western blocks col- several NE direction strong—weak interval zones in lided at 2.5 Ga during an arc/continent collision the south, which is explained to be a matching belt of (Kusky and Li, 2003). two ancient blocks. There may be a large amount of The age of 1 800 Ma is about the Columbia su- ancient magmatic rocks distributed along the belt (Jia percontinent forming period, which also has very ob- and Wei, 2002). The existence of 3 000–3 500 Ma vious response on all samples, indicating Tarim basin Paleo–Mesoarchean basement metamorphism tecto- was a part of Columbia supercontinent. According to thermal events possibly revealed parts of Tarim basin pyroxenite gneiss, 1 800–2 000 Ma also represents the has ever been a part of the Ur supercontinent. Three second accretion event of Proterozoic (the first accre- thousand and 3 500 Ma reflect the oldest crust form- tion occurred around 2 000–2 200 Ma according to ing (magmatic activity) and continental cratonization granite gneiss) (Wu et al., 2009). process (He et al., 2002). The age of 2 600–2 500 Ma is about the Kenor- (2) Neoproterozoic tectothermal events land supercontinent forming period, which has very The age of 1 000–800 Ma, is about the intraplate obvious response on all samples of Tarim basin, espe- cracking magmatic activity, which was relevant to

80o 85o E Kuqa 0 200 km Xinghuo1 Tashen1 Korla Aksu

Kashgar

Ruoqiang

Qiemo

Outline of Tarim basin 0 abnormality isoline NW basement teconotic line Positive abnormality isoline Negative abnormality isoline NE basement teconotic line

Figure 6. Magnetic anomaly characteristics of Tarim basin basement and well location where metamorphic basement encountered (modified from Jia, 1997). Detrital Zircon U-Pb Geochronology and Its Provenance Implications on Silurian Tarim Basin 465 the Rodinia supercontinent teconoism (the subduction mantle superplume events (Li et al., 2003), which led occurred at 1 000–800 Ma) (Hao and Zhai, 2004; to the breakup of Rodinia supercontinent. Zhang et al., 2004a). In recent years, the research on The mantle superplume splitting and intensive Rodinia supercontinent is a common concern all over magmatic activities also made Tarim basin into re- the world. The configuration of Rodinia superconti- gional extension tectonic setting, forming deep great nent and the locations of main blocks of China, such valley and basite-hyperbasite rocks. Then the snow- as South China block and Tarim block, became the ball event started and entered stable continental envi- key issues of geological discussion. According to the ronment around 750 Ma and thus formed continental regional analysis, the ancient supercontinent Rodinia basalt. From Sinian to Early and Middle Ordovician, converged around 950 Ma and formed granite base- there were rift valley or aulacogen, marginal slope and ment. It started to breakup in Sinian with the mantle carbonate platform in craton developed under the plume expansion around 820 Ma. All samples of this extension tectonic environment (Lin et al., 2009; Jia, research are very obvious correspond to this tectonic 1997). The basin was surrounded by archipelago movement (prominent at around 800 Ma), indicating oceans, such as Kunlun Ocean, South Tianshan Ocean Tarim basin was a part of Rodinia supercontinent. and northern paleo-ocean, and there is extension fault South China microplate, Qaidam massif and Tarim developed in the basin (Lin et al., 2009). The base- block were involved and overthrusted into the both ment of basin was obvious segmentation and tectonic sides of Qinling-Qilian-Kunlun orogenic belts (Su et activities. This movement formed the broadest range al., 2004). Besides similar Neoproterozoic sedimen- of clastic source for later deposit of Tarim basin (Wu tary construction, there also developed a large amount et al., 2009). The sample (XYC-1) taken from of various Neoproterozoic igneous rocks, which Xiangyangcun outcrop of Kuruktag uplift at the east diagenetic ages reach an obvious peak between 820 of Tarim basin shows anomaly prominent at around and 750 Ma (Fig. 7). It indicates that the middle and 1 000 Ma, and becoming the most important tecto- west of China have actively responded to 830–740 Ma thermal events.

Figure 7. Age spectrum comparision of Precambrian tectothermal events of Tarim basin and South China (according to Su et al., 2004).

(3) Eopaleozoic tectothermal events cian (470–475 Ma), the end of Middle Ordovician Eopaleozoic magmatic tectothermal events in- (456–464 Ma) and the end of Ordovician (around 440 clude 475–440 Ma Ordovician and 436–412 Ma Silu- Ma). The Ordovician tectothermal events and the rian tectothermal events. strongly uplifts were mainly related to the collision The 475–440 Ma Ordovican tectothermal and invasion of West Kunlun and west section of East events Ordovican intensive magma activities con- Kunlun at the south and southeast margin of Tarim centrated on 3 periods, i.e., Early and Middle Ordovi- basin. From Early and Middle Ordovician, the tectonic 466 Jingyan Liu, Changsong Lin, Sitian Li, Zhenzhong Cai, Shiqiang Xia, Chao Fu and Yongquan Liu environment from extension was transforming to north. There was fluvial delta system developed in compress environment. The tectothermal events re- Keping area at the north edge of basin, Yingmaili, sulted in widely distributed unconformities and partial Caohu and Hade areas. There are large scale 4 2 0 erosion in the basin (named T7 , T7 and T7 interfaces north-to-south progradational structures on the seismic on seismic profiles) (Lin et al., 2009). profiles (Fig. 9). It indirectly indicates that there were According to regional study data, from Sinian– strong uplift and erosion in the northern orogenic belt, Cambrian to Ordovician–Silurian, the south margin of which provided material sources to the basin. The ex- Tarim basin was changed from extension mechanism trusion in the south and southeast of the basin was still into extrusion mechanism (He et al., 2011; Lin et al., very strong. There are proximal coarse clastic alluvial 2009). The surrounding paleo-oceans, such as North fan and fluvial systems found in wells Yingnan-2, Kunlun Ocean, North Tianshan Ocean and Altyn Kongque-1 and Tangcan-1. Ocean, have transformed from expansion to extrusion In summary, the tectothermal events of Tarim ba- during Early Ordovician and early Middle Ordovician. sin reflected by U-Pb dating in this research are ac- Along West Kunlun Mountain Wuyitage-Kudi- cordance with the previous research reports (Chen et Aqikekule Lake-Xiangride suture zone, there devel- al., 2009). The ancient Tarim land core formed during oped large amount of Eopaleozoic island-arc type in- paleo-Archean magmatism about 3.6–3.2 billion years termediate acidity intrusive rocks and volcanic rocks, ago, and further consolidation in the magmatism with 449–494 Ma isotope ages (Zhang et al., 2004b; process about 2.8 billion years, formed a hot core with Hao et al., 2003; Jia et al., 2003). It indicates that the granulite-amphibolite high metamorphic grade. About subduction occured at Early Ordovician and reached 1.8 billion years ago, the Tarim land core thoroughly the peak in Middle Ordovician. These tectonic move- cooled down and formed stable Tarim platform. ments induced large scale volcanism and incursion, Around 9 billion years ago, the south edge of Tarim and deposited widely volcanic ash and pyroclast in the platform cracked and formed a spreading ridge and Middle Ordovician strata of Tarim basin. With the ocean. The Early Palaeozoic Altyn Ocean and extinction of North Kunlun Ocean and Altyn trench-arc-basin system started to subduct and collide trench-arc-basin system, tectonic extrusion further orogeny at the Early Ordovician, and up to the maxi- resulted in folded uplift of the north edge of Altyn and mum at the end of Ordovician (peak age for 443 Ma) Luobupo areas, where became main provenance areas with island arc magmatism developed. of Upper Ordovician–Silurian in Manjiaer depression and Tazhong area. Potential Provenances Change and Silurian Basin The 436–412 Ma Silurian tectothermal events Character There are already a lot of evidences of large scale ex- (1) Silurian provenance analysis trusion at the south edge of basin. However, it is con- The surrounding tectonic activity and provenance troversial whether there were intensive tectonic activi- systems of Silurian Tarim basin have been a lot of ties at the north edge (Gao et al., 2006; Chen et al., controversy, and different regions has different source 1999). According to the dating results of Devonian systems. Silurian major source systems came from the sandstones from Tabei area: Jm-1 and Hd14 (Fig. 8), surrounding orogenic belts and paleo-uplifts in basin, the Early and Middle Silurian (428–436 Ma) are the and parent rocks are granite (Zhang and Zhang, 2006). peak periods of magmatic activities, and the Middle Sedimentary system distribution built with integrated Silurian is the most intensive period (424–426 Ma). seismic data, drilling wells and outcrop data (Fig. 10) There were obvious magmatic activities at the end of revealed possible source direction of Silurian Tarim Silurian (412–415 Ma). It indicates that the surround- basin. In summary, the major source systems mainly ing tectonic activities during the whole Silurian were came from recycling orogenic belts and stable base- very active. Besides the continuous extrusion from ment (local paleo-uplifts). West Kunlun and Altyn orogenic belts, there were ob- There occurred mass volcanic activities along the vious activities in South Tianshan Mountain in the Altyn fault belts during Ordovician, around 487–414 Detrital Zircon U-Pb Geochronology and Its Provenance Implications on Silurian Tarim Basin 467

Figure 8. Age spectrum comparison of Silurian tectothermal events of Jm-1 (a) and Hd14 (b).

Figure 9. Large scale north-to-south progradation configuration on seismic profile (Line CN917) at the northeast of Tarim basin.

Ma (Liu et al., 2003), which became the main prove- (Figs. 11a–11c) and Dawangou outcrop of Keping area nance of Silurian deposit. According to the U-Pb ages, (Figs. 11d–11f, location of outcrop see Fig. 1). Delta 400–500 Ma Ordovician as the important provenances front mouth bar shows reverse cycling sequence con- appeared at sample Jm-1 of the east of Tabei area, re- struction (Figs. 11a, 11d) and large scale subdistributary flecting the deposit of east of Tabei area (Manjiaer channel shows blocky construction medium sandstone depression) mainly came from Altyn orogenic zone. (Figs. 11b, 11c) and lots of tabular or trough At the east of Tarim basin, Xiangyangcun outcrop of cross-bedding, with pyrite nodule (Figs. 11e, 11f). Kuruktag uplift (XYC-1), the major provenances are As to Tabei area, the provenance is more com- Neoproterozoic (1 000, 800 Ma), where is lack of Or- plex. Heavy mineral type and content of several sand- dovician volcanic deposit and relative U-Pb ages, with stones of Silurian Kepingtage Formation from Tabei lots of Paleoproterozoic isotopic ages (Guo et al., area revealed there were both recycling orogenic zone 2003; Hu et al., 2001), means the major provenance provenance and stable basement provenance (Liu et was Paleoproterozoic basement. At Keping-Bachu al., 2011). There are some signs about the orogenic area, the northwest of Tarim basin (SSC-28), the ma- activities of part of South Tianshan Mountain at the jor provenances are Neoproterozoic (800 Ma) and north edge of the basin. Large-scale fluvial delta pro- Paleoproterozoic (1 800 Ma), reflected the deposit gradation constructure from north to south on seismic mainly came from Precambrian basement. This area profiles and heavy mineral showing recycled orogenic has been considered as stable continental craton at provenance character indicate that part of South Tian- Silurian, and source systems came from mature conti- shan Mountain possibly provide clastic source for Si- nental area (Li et al., 1999). Local delta systems de- lurian deposit at Tabei area. According to the seismic veloped at Xiangyangcun outcrop of Kuruktag uplift and drilling data of Tabei area, there existed local 468 Jingyan Liu, Changsong Lin, Sitian Li, Zhenzhong Cai, Shiqiang Xia, Chao Fu and Yongquan Liu

Kuruktag uplift N o 0 125 km 42 00'N Kuqa Korla Kn1 Yingmailai Caohu Wushi Ln17 Cao1 Tianshan Mountain Yd2 Xiang3 Qk1 Xiangyangcun Ym17 Jn4 Akesu Ym2 Jm1 Sl1 Yn2 Yw2 Sishichang Hd14 Yn1 Hd7 YingN2 YingD2

o Acan4 Keping Shun8 Tn1 Dawangou Am1 Yh1 40 00' Keping uplift Mc1 Md1 An1 Qiao1 Am2 Pi1 Shun2 Mx1 Mx2 Ruoqiang Shun1 Td1 Fang1 He4 Tz49Tz39 Bachu Tz33 Tz32 Kashi Td2 Z13 Tz12 Ls1 Tz37 He3 Bad2 Tz61 Tz22 Tz28 He2 Tz4 Gd1 Tz29 Altun Mountain Ma4 Tz26

o Tangc1 Qieme Mac1

38 00' Subtidal-intertidal sand bar Intertial mixed flat Fan/braided delta Hetian West Kunlun Mountain Minfeng Shallow marine East Kunlun Mountain Proximal delta front Bathyal region Coastal debris system Uplift/erosion area

o Far delta front-lower shoreface Major source direction

36 00' 76o 00' 80o 00' 84o 00' 88o 00'E

Figure 10. Sedimentary system distribution and possible source direction of Silurian Tarim basin. paleo-uplift before Silurian deposit along Lunnan, lots of source systems. Yingmaili and Wensu uplifts, where Precambrian Over 500 samples’ statistical analysis of rock basement exposured. Most zircons ages of Tabei area composition from drilling wells of Tazhong and Tabei are Precambrian (Wu et al., 2009). Therefore, local areas also reveals the different characteristics of sedi- paleo-uplifts at the north of Tarim basin were the main mentary system and provenance (Table 2). The major provenance of Silurian deposit at Tabei area. rock types are quartz sandstone and lithical quartz At the south of Tazhong area (Tc-1), the major sandstone. The content of lithic at fluvial delta deposit provenances are Neoproterozoic (800 Ma) and Paleo- area is significant higher, general over 40%, such as proterozoic (1 800, 2 500 Ma), where are lack of wells Cao1, Hd13, Hd18, Hd21, and so on, which Paleo–Mesoarchean provenance, obvious different reflected the character and influence of recycling from Tabei area. The sources of zircons in the Silurian provenance. While at the region where developed sandstones in Tazhong are different from each other foreshore or shoreface depositional systems, the con- largely (Qian et al., 2007). Besides recycling sedi- tent of quartz is absolute predominance (over 85%, mentary rocks and magmatic rocks, the metamorphic quartz sandstone), such as Well Bs1, also reflecting rock zircons are also the major sources, with ages of the character and influence of local paleo-uplifts. Archean–Paleoproterozoic (1.8, 2.2 and 2.6 Ga). Re- Lithical quartz sandstone dominated at Tazhong area, gional tectonic setting study shows, at the end of Or- generally over 40%, such as wells Tz166, Tz70, and dovician, the south of Tazhong area uplift largely so on, reflecting the character and influence of recy- due to the strong compression from the closure of cling provenance. ancient Kunlun Ocean and Altyn Ocean, where became major provenance of Silurian deposit of (2) Silurian basin character Tazhong area. Proximal coarse clastic fluvial and As well as the surrounding tectonic activities, it delta sedimentary can be found at wells Yingnan 2, is controversial and inconspicuous on the properties of Kongque 1 and Tangshan 1. The Neoproterozoic Silurian Tarim basin. Someone think that it is inland and Paleoproterozoic old land crust granite provided craton depression, while the others think that it is relic Detrital Zircon U-Pb Geochronology and Its Provenance Implications on Silurian Tarim Basin 469 backarc basin. In this research, the major elements of tablished by Bhatia (1983) through dominate elements sandstones of Silurian Kepingtage Formation and Ta- of sandstone, the sandstone tectonic setting and source taaiertage Formation of major wells in Tazhong and characteristics are discussed. From SiO2/20—K2O+

Tabei areas have been measured. According to the Na2O—TiO2+Fe2O3+MgO graphic of Fig. 12, most of tectonic background diagram of provenance area es- the dominate elements and ratios of sandstone

Figure 11. Local Silurian delta systems developed at Xiangyangcun outcrop of Kuruktag uplift (a)–(c) and Dawangou outcrop of Keping area ((d)–(f), location of outcrop see Fig. 1). (a), (d) Delta front mouth bar showing reverse cycling construction on both of outcrops; (b)–(c) large scale subdistributary channel medium sandstone showing blocky construction of Xiangyangcun outcrop; subdistributary channel with lots of tabular or trough cross-bedding and pyrite nodule on Dawangou outcrop. 470 Jingyan Liu, Changsong Lin, Sitian Li, Zhenzhong Cai, Shiqiang Xia, Chao Fu and Yongquan Liu

Table 2 Lithologic composition statistic and comparison from major wells of Tazhong and Tabei areas

Area Well Number of Quartz content Feldspar content Lithic content Muddy Cement samples (%) (%) (%) content content (%) (%) Range Average Range Average Range Average Range Average Tazhong TZ32 20 49–70 57.5 3–8 5 26–49 37 5 6 TZ18 2 80–88 84 0–1 0.8 12–20 16.2 3.5 6.8 TZ4-7–38 9 51–63 55.3 3–7 4.8 32–39 33.6 15 3.2 TZ408 6 45–80 72.5 2–20 6 15–26 21 2 8.9 TZ166 14 38–64 47 2–4 3 34–57 48.5 13 2.1 TZ122 13 44–64 49.5 6–21 18.8 26–35 32 1.4 13 TZ117 59 57–64 61 7–15 11 25–33 28 3 14 TZ112 17 57–70 61 2–8 4.6 27–39 34 2.5 10.6 TZ111 9 62–72 67 7–11 8.8 20–27 23.8 3 7 TZ70 11 34–50 39 10–15 12 33–54 48 4 9 TZ69 21 50–68 60 3–10 7.5 26–48 33 4.5 6.8 TZ68 15 40–52 48.2 13–17 15 35–44 36 6 6.2 TZ63 11 58–70 63.5 7–14 10 17–30 27 7.2 6 TZ47 10 63–72 66 3–8 5.6 22–32 28 2.5 13 Tabei Bs1 2 83–87 85 2 2 11–15 13 2 2.6 Cao1 45 30–57 39 11–23 17 33–50 42 3.6 3 Dh27 10 78–88 83 0–1 0.5 12–22 17 3.3 8 Ha1 5 34–82 70 7–17 9.6 11–50 20.4 1.4 1 Ha4 3 45–47 46 15–17 16 37–41 39 0.7 8.5 Hd13 4 50–55 52.3 3–6 4.5 40–45 43.3 1 4.7 Hd18 20 33–78 49.2 1–9 4 21–90 48 1.8 13.4 Hd18c 13 55–75 63 2–3 2.2 23–43 34.5 0.6 9.3 Hd21 35 30–85 57 1–8 3 13–65 39.7 2.2 7.5 Jn1 67 42–74 58 2–9 5.9 22–51 31.1 8 3 Ym11 10 42–95 72 1–9 2.8 4–49 25.7 3.3 4 Ym35 11 75–90 84.2 0.3–1 0.6 10–25 15.7 1.7 2.8 Yn2 70 48–90 68.8 1–5 2 9–51 29.3 3.4 2.2 samples in Kepingtage Formation lies in areas be- land arc in Tabei area. It is related to the strong sub- tween the oceanic island arc and continental island arc, duction and closure of North Kunlun Ocean and Altyn especially that the samples from Tabei area (Xiaotang Ocean in the south during Silurian. With the extrusion 1, Hade 17, Lunnan 60) are distributed more concen- stress transfered from south to north, the basin setting trated and regularity. The samples taken from transi- transfered from oceanic island arc to continental is- tional zone between Tabei and Tazhong area (such as land arc. Besides, the sandstone samples obtained wells Yihe 4 and Shun 1) mainly indicate the charac- from Tataaiertage Formation also reflected obviously teristic of oceanic island arc sources. The differences that the differences of Tazhong and Tabei areas. The of Tazhong and Tabei samples indicate that the source samples from Tabei (Hade 17) are characteristics with area of Tazhong is nearer to oceanic island arc than continental island arc and near active continental mar- that of Tabei, and gradually transit to continental is- gin, while those from Tazhong area (Shun 1) are with Detrital Zircon U-Pb Geochronology and Its Provenance Implications on Silurian Tarim Basin 471 oceanic island arc characteristics. orogenic belt. Besides a large amount of clastic mate- According to the graphic relationship between rials of volcanic arc orogenic belt, there were clastic plate-tectonics and geochemical composition of sand- materials from the uplift in craton. Silurian sandstones stones built by Dickinson et al. (1983), most of Silu- analysis further confirmed the provenance mainly rian sandstones in Tazhong and Tabei areas lie in re- came from Ordovician compression and uplift of cycling orogenic zone (Fig. 13), indicating the mate- Altyn orogenic belts, Precambrian old basement and rial sources of Silurian mainly came from recycling local uplifts in basin.

Figure 12. Interactive graphics of major elements of sandstone determination source properties. (a) Sand- stones of Kepingtage Formation; (b) sandstones of Tataaiertage Formation. The average data of typical sandstones in oceanic island arc, continental island arc, active continental margin and passive continental margin is quoted from Bhatia (1983).

CONCLUSIONS 3 500–3 000 Ma Paleo–Mesoarchean, around 2 500 With LA-ICP-MS method, 3 Silurian and 2 De- and 1 800 Ma Paleoproterozoic, around 1 000 and vonian sandstone samples taken respectively from 800 Ma Neoproterozoic, and 500–400 Ma Eopaleo- Tabei area (Jm-1 and Hd14), Tazhong area (Tc-1), zoic tectothermal events. Each tectothermal event re- Sishichang outcrop at northwest of Tarim basin spectively represented relevant response on the form- (SSC-28) and Xiangyangcun outcrop at east of Tarim ing and spilitting process of Ur supercontinent, basin (XYC-1) have been carried out for zircon U-Pb Kenorland, Columbia and Rodinia supercontinent, dating. The dating results revealed the whole tecto indicating Tarim microplate or Tarim basin has in- thermal events history before Neoproterozoic of Tarim volved the whole evolution of supercontinent. The basin, and provenance systems of Silurian. zircons ages determination in the Tarim basin provides (1) Zircons U-Pb dating shows Tarim basin has isotope chronological evidence for further exploration experienced 5–6 significant tectothermal events: the relationship between Tarim block and the sur- 472 Jingyan Liu, Changsong Lin, Sitian Li, Zhenzhong Cai, Shiqiang Xia, Chao Fu and Yongquan Liu rounding supercontinents. basin, reflecting the old basement of north and south (2) The dating results’ difference indicated dif- of Tarim were not the same block, which may be con- ferent parts of Tarim have suffered different tecto- firmed by magnetic anomaly data. Since Paleopro- thermal events. The oldest ages’ distribution indicates terozoic, the whole basin’s evolutions were more the north and northwest of Tarim basin has older synchronous. basement than that of south and northeast of Tarim

Tabei area Tabei area Q Q Quarts sandstone (apogrit) 90 10 Lithic quarts 90 10 Bs1 Bs1 Feldspathic Ym35 sandstone Ym35 80 20 20 quarts sandstone Dh27 (apogrit) Intermediate 80 Dh27 Ym11 Ym11 (apogrit) 70 30 continent 30 Ha1 Yn2 Feldspathic lithic 70 Ha1 Yn2 Hd18c quarts sandstone Hd18c 60 Jn1 40 60 Jn1 40 Hd21 (apogrit) Hd21 50 Hd13 50 Hd13 50 50 Hd18 Ha4 Hd18 Ha4 Lithic sandstone Re-orogenic 40 Cao1 60 Uplifted 40 Cao1 60 Feldspathic lithic zone sandstone base (apogrit) Dissected arc 30 70 30 70 (apogrit)

20 80 20 80 (apogrit) Intermediate arc (apogrit) 90 90 10 Feldspathic sandstone 10 Undissected

Lithic feldspathic sandstone arc F 90 80 70 60 50 40 30 20 10 R FR90 80 70 60 50 40 30 20 10

Tazhong area Tazhong area Q Q Quarts sandstone (apogrit) Lithic quarts 10 90 10 sandstone 90 Feldspathic (apogrit) 20 80 Tz18 20 80 Tz18 quarts sandstone Feldspathic lithic Intermediate Tz408 (apogrit) Tz408 30 Tz111 30 70 quarts sandstone continent 70 Tz47 Tz111 Tz63 Tz63 Tz47 (apogrit) Tz4-38 Tz4-38 40 60 Tz117 40 60 Tz117 Tz69 Tz112 Tz69 Tz112 Tz32 Tz32 50 50 50 Tz122 50 Tz122 Tz68 Tz68 Tz166 Tz166 Re-orogenic Lithic sandstone60 40 60 40 Feldspathic lithic Uplifted Tz70 Tz70 zone sandstone base Dissected arc 70 30 70 30 (apogrit) (apogrit)

20 80 20 80 (apogrit) Intermediate arc 90 10 90 10 Undissected sandstone Feldspathic sandstone (apogrit) Lithic feldspathic arc FR90 80 70 60 50 40 30 20 10 FR90 80 70 60 50 40 30 20 10

Figure 13. Sandstone types and its indicating on plate tectonic setting of Silurian in Tabei area (upper) and Tazhong area (below). The graphic relationship between plate-tectonics and geochemical composition of sandstones according to Dickinson et al. (1983).

(3) Integrated with seismic data and outcrop in- paleo-uplifts at north of Tabei). The Ordovician uplift terpretation, the U-Pb dating results also revealed that and orogenic zone at the south of Tarim basin and the surrounding tectonic activities were still very ac- Precambrian granite basement provided lots of source tive during Silurian, and indicated different regions systems to Tazhong area. had different source systems. At Tadong and Manjiaer depression, major source systems came from Ordovi- ACKNOWLEDGMENTS cian Altyn orogenic belts. At Tabei area and northwest This study was supported by the Fundamental of Tarim basin, major source systems came from recy- Research Funds for the Central Universities of China cling orogenic zone (the activity of South Tianshan (No. 2010ZD07), the Key National Natural Science Mountain) and Precambrian stable basement (local Foundation of China (No. 41130422), the National Detrital Zircon U-Pb Geochronology and Its Provenance Implications on Silurian Tarim Basin 473

Natural Science Foundation of China (No. 40372056) Guo, Z. J., Zhang, Z. C., Jia, C. Z., et al., 2000. The Structural and the State Key Development Program for Basic Framework of Precambrian Basement of Tarim Craton. Research of China (Nos. 2011CB201103, Sci. China (Ser. D), 30(6): 568–575 2006CB202302). We thank geo-researcher Li Su of Guo, Z. J., Zhang, Z. C., Liu, S. W., et al., 2003. U-Pb Geo- the LA-ICP-MS Laboratory of Geosciences (Beijing) chronological Evidence for the Early Precambrian Com- for helping the zircon dating; thanks go to the guide in plex of Tarim Craton, NW China. Acta Petrologica Sinica, provenance analysis from Senior Researcher Zhong Li 19(3): 537–542 (in Chinese with English Abstract) of Institute of Geology and Geophysics of CAS. Hao, J., Liu, X. H., Sang, H. Q., 2003. Geochemical Characte- riatics and 40Ar/39Ar Age of the Ayak Adamellite and Its REFERENCES CITED Tectonic Significance in the East Kunlun, Xinjiang. Acta Andersen, T., 2002. Correction of Common Lead in U-Pb Petrologica Sinica, 19(3): 517–522 (in Chinese with Eng- Analyses that do not Report 204Pb. Chemical Geology, 192: lish Abstract) 59–79 Hao, J., Zhai, M. G., 2004. Jinning Movement and Sinian Bhatia, M. R., 1983. Plate-Tectonics and Geochemical Compo- System in China: Their Relationship with Rodinia sition of Sandstones. Journal of Geology, 91(6): 611–627 Supercontinent. Chinese Journal of Geology, 39(1): Cai, X. Y., 2005. Reservoiring Conditions and Exploration 139–152 (in Chinese with English Abstract) Targets in Tarim Basin. Oil & Gas Geology, 26(5): He, D. F., Jia, C. Z., Li, D. S., et al., 2005. Formation and Evo- 590–597 (in Chinese with English Abstract) lution of Polycyclic Superimposed Tarim Basin. Oil & Cawood, P. A., Nemchin, A. A., 2000. Provenance Record of a Gas Geology, 26(1): 64–77 (in Chinese with English Rift Basin: U/Pb Ages of Detrital Zircons from the Perth Abstract) Basin, Western Australia. Sedimentary Geology, 134(3–4): He, D. F., Yuan, H., Li, D., et al., 2011. Chronology, 209–234 Geochemistry and Tectonic Setting of Granites at the Core Chen, C., Lu, F., Jia, D., et al., 1999. Closing History of the of Tugerming Anticline, Tarim Basin: Indications of Southern Tianshan Occanic Basin, Western China: An Paleozoic Extensional and Compressional Cycle at the Oblique Collsional Orogeny. Tectonophysics, 302: 23–40 Northern Margin of Tarim Continental Block. Acta Chen, F. J., Wang, X. W., Zhang, G. Y., et al., 1996. The Petrologica Sinica, 27(1): 133–146 (in Chinese with Eng- Tectonic Evolution and Its Relationship with Oil/Gas in lish Abstract) the North of Tarim Basin in Xinjiang. Geological He, G. Q., Li, M. S., Zhou, H., 2002. The Stage of Cratoniza- Publishing House, Beijing. 34–156 (in Chinese with tion in the Formation of Continental Lithosphere. Earth English Abstract) Science Frontiers, 9(4): 217–224 (in Chinese with English Chen, X. H., Yin, A., Gehrels, G. E., et al., 2009. Geothermo- Abstract) chronology and Tectonic Evolution of Eastern Altyn Tagh Hu, A. Q., Rogers, G., 1992. The First Found of 3.3 Ga Rocks Mountains, Northwestern China. Earth Science Frontiers, on the North Margin of Taim, Xingjiang, China. Chinese 16(3): 207–219 Science Bulletin, 37: 627–630 Dickinson, W. R., Beard, L. S., Brakenridge, G. R., et al., 1983. Hu, A. Q., Zhang, G. X., Chen, Y. B., et al., 2001. A Model of Provenance of North American Phanerozoic Sandstones in Division of the Continental Crust Basement and the Time Relation to Tectonic Setting. Geol. Soc. Am. Bull., 94(2): Scales of the Major Geological Events in the 222–235 Xinjiang—Based on Studies of Isotopic Geochronology Gao, J., Long, L. L., Qian, Q., et al., 2006. South Tianshan: A and Geochemistry. Xinjiang Geology, 19(1): 12–19 (in Late Paleozoic or a Triassic Orogen? Acta Petrologica Chinese with English Abstract) Sinica, 22: 1049–1061 (in Chinese with English Abstract) Jackson, S. E., Pearson, N. J., Griffin, W. L., et al., 2004. The Glorie, S., De Grave, J., Buslov, M. M., et al., 2010. Application of Laser Ablation-Inductively Coupled Multi-Method Chronometric Constraints on the Evolution Plasma-Mass Spectrometry to in Situ U-Pb Zircon Geo- of the Northern Kyrgyz Tien Shan Granitoids (Central chronology. Chemical Geology, 211: 47–69 Asian Orogenic Belt): From Emplacement to Exhumation. Jia, C. Z., 1997. The Structure Character and Petroleum of the Journal of Asian Earth Sciences, 38(3–4): 131–146 Tarim Basin, Northwest China. Petroleum Industry Press, 474 Jingyan Liu, Changsong Lin, Sitian Li, Zhenzhong Cai, Shiqiang Xia, Chao Fu and Yongquan Liu

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