Late Pliocene–Recent Tectonic Setting for the Tianchi Volcanic Zone, Changbai Mountains, Northeast China

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Journal of Asian Earth Sciences 21 (2003) 1159–1170

Late Pliocene–recent tectonic setting for the Tianchi volcanic zone, Changbai Mountains, northeast China

Yu Wanga,*, Chunfeng Lib, Haiquan Weic, Xinjian Shanc aGeologic Laboratories Center and Department of Geology, China University of Geosciences, Xueyan Road 29, Haidian District, Beijing 100083, People’s Republic of China bSeismological Bureau of Jilin Province, Changchun 130022, People’s Republic of China cInstitute of Geology, China Seismological Bureau, Beijing 100029, People’s Republic of China

Received 22 January 2002; revised 10 September 2002; accepted 3 December 2002

Abstract Mafic volcanic rocks have erupted in the Tianchi volcanic zone, Changbai Mountains, northeast China, since late Pliocene time. The zone formed in an extensional environment during early-middle Cenozoic time, and in a compressional environment during late Cenozoic. Crustal thickness (about 40 km) in the Changbai Mountains is larger than the regional average of 34–36 km to the northwest and southeast. The conduit for magma upwelling was not coincident with the NE-striking regional faults, but seem to be confined to a deep-seated NW–WNW- striking fault zone. Since the late Pliocene, the Tianchi volcanic zone was subjected to crustal uplift within an intracontinental, weakly compressional environment (with minor WNW–ESE shearing) related to the westward subduction of the West Pacific plate. The nature of this volcanism is not typical of active, subduction-related continental margin volcanism. The magmatic evolutionary process evolved from trachybasalt through basaltic trachyandesite, trachyte, and pantellerite. q 2003 Elsevier Ltd. All rights reserved.

Keywords: Tianchi volcanic zone; Tectonic setting; Fault zone; Volcanic eruption; Late Pliocene–Recent

1. Introduction eruption of 1199 AD (based on 14C dating, Liu et al., 1992a, b, 1998), there have been numerous eruptions of various The Tianchi volcanic zone of the Changbai Mountains is sizes during last 900 years (Jin and Cui, 1999). located in the eastern part of the northeastern China Situated on the eastern margin of the Eurasian plate, the continent, at 408400 –428400N latitude and 1278000 – Tianchi volcanic zone, as well as Nanbaotai Volcano in 1298000E longitude, and bounded by Korea (Fig. 1). This Korea (Cao et al., 1998; Liu et al., 1998), is part of the volcanic zone has been active since Cenozoic time (Liu, western Pacific volcanic belt. This belt separates the 1987; Jilin Bureau of Geology and Mineral Resources, Japanese back-arc extensional region from the West Pacific 1988; Ding, 1988; Liu et al., 1992a,b). The Tianchi Volcano plate. During the Cenozoic, the northeastern China (this volcano was called Baitoushan Volcano in Chinese or continent was in an extensional environment. During the Paektusan Volcano in Korean, 10 years ago) had one of the Miocene, the opening of the Sea of Japan resulted in largest global eruptions in the last 2000 years (Machida intraplate extension in northeastern China (Liu, 1987; Ding, et al., 1990; Liu et al., 1998) and is still a high-risk volcano 1988; Liu et al., 1992a,b; Jin and Zhang, 1994; Chen, 1997). (Liu et al., 1992a,b, 1998). The Tianchi Volcano represents Many researchers have different viewpoints on the genesis a centered zone for the eruption of basaltic magma in the of the volcanoes in the Tianchi volcanic zone, including a region since late Cenozoic time. The volume of erupted rift environment, intracontinental or intraplate volcanism products is estimated to be about 9000 km2. Since the great related to the subduction of the West Pacific plate, etc. (Liu, 1987; Whitford-Stark, 1987; Ding, 1988; Xu, 1988; Jilin * Corresponding author. Bureau of Geology and Mineral Resources, 1988; Liu et al., E-mail address: [email protected] (Y. Wang). 1989a,b; Jin and Zhang, 1994; Liu et al., 1998).

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Fig. 1. Geotectonic position of the Tianchi volcanic zone of the Changbai Mountains. Abbreviations are as follows: F1—Siping-Changchun Fault, F2—Yilan- Yitong Fault, F3—Mishan-Dunhua Fault. Figs. 2 and 3 are shown. The Changbai Mountains are illustrated by inclined lines and water area is shown by dotted lines.

Studies on the structures and geological history of the predominantly Mesozoic granite (200–130 Ma) (Jilin Tianchi volcanic zone have raised a number of important Bureau of Geology and Mineral Resources, 1988)(Fig. 2). questions: (1) Is volcanism related to rifting or other Normal faults and some basins were formed in the early- tectonic processes? (2) Was the eruption of pantellerite in middle Cenozoic. The Paleocene system is mainly dis- the Tianchi volcanic zone of the Changbai Mountains and tributed in several NE-trending fault depression-basins, adjacent area in Korea controlled by the NW–WNW- where extensive basaltic volcanic activity erupted mainly striking faults that formed in response to WSW–ENE- basalts and trachytes. Since middle-late Pliocene to trending compression? (3) What is the relationship between Pleistocene time, crustal uplift occurred in the Changbai the eruptive history of the Tianchi volcanic zone and the Mountains. The Tianchi volcanic zone includes several NE-striking fault zones developed in northeastern China? large volcanoes such as Tianchi, Wangtian’e, Xitudingzi, Based on our results from structural studies, timing of Nanbaotai and others (see Fig. 2). fault activity, interpretation of satellite images, deep MT sounding, inversion and analysis of seismic sources, dating of volcanic activity, and petrological and geochemical 3. Petrochemical characteristics of different phases studies, we conclude the following: volcanic activity in the of volcanic rocks Tianchi volcanic zone was associated with an intracontinental, weakly compressional environment related to Basalts of different early-middle Cenozoic periods in the westward subduction of the West Paciﬁc plate, but was Tianchi volcanic zone of the Changbai Mountains and not typical of subduction-related continental margin adjacent areas exhibit the volcanic character of an volcanism. intracontinental environment (Liu, 1987; Jilin Bureau of Geology and Mineral Resources, 1988; Jin and Zhang, 1994). The composition and petrological characteristics of 2. Summary of the regional geology middle-late Cenozoic (31–5.2 Ma) volcanic rocks vary from alkali olivine basalt-latite, primarily exposed in the The basement of the Tianchi volcanic zone and western part, and latite in the eastern part. These volcanic surrounding area consists of Archean to middle-late rocks contain upper-mantle inclusions and are generally Proterozoic metamorphic rocks, Paleozoic strata, and characteristic of alkaline rocks. The late Cenozoic (since 中国科技论文在线 http://www.paper.edu.cn

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Fig. 2. Regional geologic characteristics of the Tianchi volcanic zone and its surroundings. Abbreviations are as follows: YL-YT Fault—Yilan-Yitong Fault, MS-DH Fault—Mishan-Dunhua Fault, N-Q—Tertiary–Quaternary sediments, LG V.—Longgang Volcano. Circled area by dashed line represents distribution of pantellerite. Numbers are K–Ar, Ar–Ar and U–Pb data. Age data in the Figure are cited from Jilin Bureau of Geology and Mineral Resources (1988).

2.77 Ma) volcanic rocks are mainly distributed in the tendencies of REE distribution patterns are similar for Tianchi volcanic zone and its surroundings and are conﬁned trachyteandbasalt.Sr–Nd–Pb isotopic data from the Tianchi to a NW–WNW-trending zone (Fig. 3). Rocks of the volcanic rocks plot in an area between MORB and enriched Tianchi Volcano represent three phases of activity, basalt mantle end member components (Liu et al., 1998). 87Sr/86Sr shield (2.77–1.59 Ma), alkali trachytic cone (1.00– and 143Nd/144Nd ratios (0.7051–0.7054 and ,0.5125, 0.04 Ma) and pantelleritic volcanic debris erupted during respectively) range from corresponding primitive mantle to the Holocene. The magmatic evolution of the Tianchi an enriched mantle end member (Fan et al., 1999a,b). Based volcanic zone evolved from trachybasalt, through basaltic on isotopic and geochemical data, Basu et al. (1991); Chen trachyandesite, trachyte, and pantellerite. (1997); Fan et al. (1999a,b) deduced that the pantellerite was Petrochemical and geochemical studies show that the derived by crystallization–differentiation of the basalt with- Tianchi volcanic zone, from its shield-building to the out addition of the crustal materials. It is interesting to note Holocene eruption of volcanic detritus, indicates character- that the Nd–Sr–Pb isotopic signatures (Basu et al., 1991)of istics of co-magmatic evolution (Basu et al., 1991; Xie and theTianchivolcanicrocksaresimilar tooceanicislandbasalts Wang, 1988; Chen, 1997; Liu et al., 1998; Fan et al., 1999a,b). having enriched mantle characteristics (Zindler and Hart, The magma was derived from the upper mantle, and there was 1986). no hybridization of the crustal materials (Basu et al., 1991; Fan et al., 1999a,b). The chondrite-normalized REE distribution pattern for the Tianchi volcanic rocks indicate that the 4. Regional geophysical characteristics REE values in trachyte are commonly higher than those in basalt, with the exception of Eu (Basu et al., 1991; Liu et al., Bouguer gravity anomaly contours over the Tianchi 1998). Eu exhibits a clearly positive anomaly in the basalt but volcanic zone are elliptical and vary stepwise. The ahighnegativeanomalyintrachyte. Nevertheless,thegeneral anomalies show large gradients, with a step down of about 中国科技论文在线 http://www.paper.edu.cn

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Fig. 3. Distribution and isotopic data for Cenozoic volcanic rocks in the Changbai Mountains and adjacent areas. Abbreviations are as follows: SP-CC— Siping-Changchun, YL-YT—Yilan-Yitong, MS-DH—Mishan-Dunhua. Area circled by dashed line is the Tianchi volcanic zone while the rectangular area outlined by dashed lines is the inferred potential eruption zone. Isotopic data are in unit of Ma. Numbers in circled areas are as follows: 1—Xitudingzi Volcano, 2—Tianchi Volcano, 3—Wangtian’e Volcano, 4—Nanbaotai Volcano in Korea and 5—Longgang volcanic area. Numbers refer to K–Ar data from Liu (1987), Liu et al. (1992a,b), Jin and Zhang (1994), and Jilin Bureau of Geology and Mineral Resources (1988).

1 km per 10 km. The anomaly corresponds to the volcanic The satellite images indicate that WNW-striking faults cut geomorphology of the Tianchi volcanic zone. Depth to the across NE- and nearly E–W-striking faults (Fig. 4). MT Moho is 40 km or more and only 34–36 km on average to sounding data show a northwest-trending low-density body the southeast and northwest. The northwestern side of the at a depth of 50 km through the Tianchi volcanic zone (Tang Changbai Mountains represents a fault depression-basin et al., 1999). Obviously, the crustal structure is inconsistent formed during the early-middle Cenozoic, with a crustal with most of the northeast China region (Jilin Bureau of thickness of 32–37 km. The southeastern side thins east- Geology and Mineral Resources, 1988; Ma, 1989; Dong, ward to the Sea of Japan. The mantle depression zone is 1993). In general, the crustal structure in the Tianchi centered at the Changbai Mountains and extends in a volcanic zone is fairly complicated. northeast direction. The studied area shows a maximum Bouguer gravity anomaly. The anomaly value reaches as 2100 mgl or more. 5. Characteristics of regional seismicity and tectonic An interpretation of filtered (D 0.10 km) gravity field over stress field the Changbai Mountains area (Jin and Zhang, 1994) indicates that a negative anomaly exists south of the A comprehensive analysis of Ms . 3 earthquakes from Tianchi volcanic zone, while the anomaly on top of the 500 AD to present indicates that shallow earthquakes in the Tianchi Volcano reaches þ80 (10 £ 1022 mgl/km) (Fig. 4). Changbai Mountains area are mostly of Ms , 4. The Values are highest to the north and lowest to the southeast. frequency of earthquakes is lower toward the continental 中国科技论文在线 http://www.paper.edu.cn

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Fig. 4. Filtering (D 0.10 km) and interpretation of the gravity ﬁeld for faults in the Tianchi volcanic zone of the Changbai Mountains and surrounding area (Simpliﬁed after Jin and Zhang, 1994) F1—Cuocaodingzi-Houchuan Fault, F2—Tianchi-Sunshan Fault, F3—Manjiang-Baitoushan Fault, F4—Liudaogou- Tianchi-Zhenfengshan Fault.

margin (Fig. 5). Most of these earthquakes occurred in an areas, and composite fault plane solutions of small area that contains a dense network of NE–NNE-striking earthquakes in the central and eastern parts of Jilin faults, especially at fault intersections (there is little data on Province and part of Korea (Table 1). Our statistical structures in Korea). Deep-source earthquakes occurred analyses indicate that ruptures occur on nearly vertical, mostly in the sea or continental margin zone, whereas strike–slip faults with a nearly horizontal slip direction. shallow earthquakes rarely occurred. The focal depth The average orientation of the P axis for these gradually increases from the Japan Trench (up to 600 km earthquakes is sub-latitudinal. The major and minor maximum depth) to the northeastern China continent (such principal compressive stress axes of the tectonic stress as in the Hunchun area, Fig. 5). The locations of deep- field are horizontal. The average orientation of the source earthquakes define a SE–NW trending pattern. This regional major principal compressive stress is ESE– phenomenon may reflect a gradually increasing depth of WNW. Because the P-axis orientation for earthquakes subduction of the West Pacific plate with the subduction can reflect the major principal compressive stress front reaching beneath the China continent (in the Hunchun orientation for regional tectonic stress field, we interpret area). Based on these data, Zhang and Tang (1983) the average major principal compressive stress orientation suggested a 238 subduction angle for the West Pacific as ESE–WNW in the study area. This is parallel to the plate. The nearest epicenter of the earthquake swarm is orientation and the nature of tectonic stress in north- 120 km from the Tianchi Volcano. Accordingly, Liu et al. eastern China (Ding, 1988; Gao, 1988; Fu, 1996; Meng (1998) suggested that the Tianchi Volcano must be located et al. 1996). in front of the subduction plate. Focal mechanism solutions The principal compressive stress axis of deep-source of earthquakes in the Sea of Japan and northeastern China earthquakes in the Sea of Japan and the northeastern indicate ENE–WSW (sub-latitudinal) compression (Zhao, China continent is parallel to the direction of plate 1991). subduction, but the principal extensional stress axis is We analyzed focal mechanism solutions of moderate vertical to it (Zhang and Tang, 1983; Zhang 1988; Zhao, and strong earthquakes occurring in northeastern China 1991). The focal mechanism of deep-source earthquakes (mainly around the Changbai Mountains) and its adjacent is consistent with the features reflected by shallow 中国科技论文在线 http://www.paper.edu.cn

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Fig. 5. Distribution of deep-shallow-source seismic epicenters in the Changbai Mountains and adjacent areas.

earthquakes. The characteristics of the regional stress 6. Characteristics of regional faults in the Tianchi ﬁeld and layering of the shallow crust in the Changbai volcanic zone Mountains and its adjacent areas indicate a state of crustal uplift, rather than crustal faulting and subsidence, Several large-scale faults, mainly striking NE-, NW- and caused by the mantle upheaval. The distribution of CO2 NNE, in the Tianchi volcanic zone and its adjacent areas gas at depth and deep-layer mantle compression is constitute the general structural framework of the area oriented NW–SE (Zhang and Hu, 1999). during the Cenozoic. The early-middle Cenozoic structures

Table 1 Part of the parameters of focal mechanism solutions of individual earthquakes in the study area and adjacent areas

Time (year) Location Depth (km) Magni. (Ms) Nodal plane A Nodal plane B P-axis T-axis

Strike Dip Dip angle Strike Dip Dip angle Orient. Dip angle Orient. Dip angle

1960 1268540,448240 8 5.7 55.38 325.38 828 1398 2298 498 285.58 348 1808 21.58 1966 1258060,438480 24 5.2 428 3128 648 142.58 528 698 2718 38 3.58 34.58 1966 1258070,438500 Crust 5.2 2228 648 3238 698 928 38 1848 348 1990 1268060,448570 Crust 3.9 428 NW 708 1468 NE 558 988 108 3598 418 1980 Korea Crust 5.7 1598 SW 778 658 SE 788 1138 18 2038 208 1978–1983 Korea Crust Small 3258 NE 708 288 NW 828 758 58 3458 208 1974 1278120,428200 Crust 4.8 988 NE 408 348 SE 708 848 528 3308 188 1940 1308300,448280 570 7.3 938 58 808 308 NW 208 3498 338 2038 518 1957 1318120,448010 590 7.0 348 1248 158 198 2898 758 1128 318 中国科技论文在线 http://www.paper.edu.cn

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were developed and distributed along NE–ENE-striking Pleistocene. The ‘X-shaped’ shear joints cutting through tectonic zones (Fig. 3). Formation of a series of NE-striking the pantellerite and basalt shield in the Tianchi volcanic fault basins and eruption of basalt during the middle-early zone and surrounding area are at an acute angle to the Cenozoic provide information on the nature of the extension easterly direction. This indicates that they were affected by and the characteristics of volcanism within an intraconti- sub-latitudinal compression, but locally by WNW–ESE- nental rift environment (Liu, 1987; Jilin Bureau of Geology shearing, since the Pleistocene. and Mineral Resources, 1988; Zhao, 1988, 1990; Jin and Since the late Pliocene to Pleistocene, the region from Zhang, 1994; Wang et al., 1999). Korea to northeastern China was in a state of crustal compression. During that time, it underwent extensive 6.1. Liudaogou-tianchi-zhenfengshan fault regional crustal uplift at a rate of up to 2.71 mm/a on the eastern margin of Korea. The crustal uplift rate decreases The NE-striking, NW-dipping (60–808) Liudaogou- from east to west (Lee, 1991). An integrated investigation of Tianchi-Zhenfengshan fault cuts across the Tianchi Vol- river terraces and uplifted sediments since the Quaternary cano, as shown in the filtered D0.10 km diagram (Fig. 4). indicates a crustal uplift rate of 0.21–0.33 mm/a on average The fault exhibits a strike–slip character on the surface. in the Changbai Mountains and surrounding area since the Field studies of Quaternary sediments, which are 22–60 m Pleistocene, and less than 0.2 mm/a to the west. The thick, show that the fault does not cut these deposits. available data indicate that the vertical deformation rate of the Changbai Mountains body reached about 1 mm/a since 6.2. Tumenjiang river fault the Pleistocene. The crustal uplift rate gradually decreases from east to west and is consistent with east-west The NE-striking, NW-dipping (60–808) Tumenjiang compression in northeastern China. River fault cuts late Tertiary sediments. Dikes have been emplaced along the Tumenjiang River Fault and cut across 2.77 Ma basalt. This is consistent with shear features in the 7. Space–time distribution of late Cenozoic volcanic shallow layer formed by sub-latitudinal compression since eruptions 3 Ma and the dike may have formed locally during shearing. 7.1. Space–time distribution of volcanic activity 6.3. NW–WNW- and W–E-striking fault zones The early–middle Cenozoic volcanic activity is dis- In addition to the described WNW-, NW-faults and fault tributed along NE-striking faults, such as the Liudaogou- zones, almost all E–W-striking fault zones can be mapped Tianchi-Zhenfengshan and Tumenjiang River faults (Fig. through the Tianchi volcanic zone and surrounding area. At 3). Since the late Cenozoic, especially the late Pliocene– least five faults (two of them passibly deep faults) are seen Pleistocene, the volcanic activity was not distributed along in satellite images. In Fig. 4, the main WNW–ESE-striking these faults but rather confined to limited areas, mainly at faults are: (1) Cuocaodingzi-Houchuan Fault, (2) Manjiang- the Tianchi volcanic zone, such as in Wangtian’e, Baitoushan Fault, and (3) Tianchi-Sunshan Fault. In satellite Xitudingzi, Nanbaotai Mount in Korea, and along the images, the WNW-striking (280–3008) Manjiang-Bai- WNW-NW-striking tectonic zones or in NNW-striking toushan and Tianchi-Sunshan faults show an extensional local zones (Figs. 3 and 6). Volcanic rocks in the Tianchi ‘zigzag-shape’ character. These WNW-striking deep-seated Volcano are up to 1300 m thick (300 m on average) in the faults are distributed on both the northern and southern sides center and thin toward its periphery. This indicates that the of the Tianchi Volcano and are consistent with the Tianchi volcanic zone represents a central region for distribution of volcanoes formed since the late Pliocene. eruption of basaltic and trachytic magma since late Near the Tianchi Volcano, the E-W-striking faults do not cut Cenozoic time. Quaternary sediments. Chronological evidence for fault activity during the 7.2. Time sequence of volcanic activity in the Tianchi Quaternary indicates that most of the NE- and NW-striking volcanic zone since the late Pliocene (,3 Ma) faults have not been significantly activated since 100 ka BP. The age of NE-striking faults on the northern side of the Along the periphery of the Tianchi volcanic zone, Tianchi Volcano was determined by using TL (thermo- volcanoes locally trend NW–WNW from the eastern luminescence dating) and yielded an age of 156 ^ 7.8 ka. coast of Korea to Wangtian’e, Xitudingzi, etc. west of the Based on TL dating, the Tumenjiang River Fault last moved Tianchi volcanic zone (Fig. 6). Their common features are between 100 and 400 ka and the Mishan-Dunhua Fault last basalt in the lower part and trachyte and pantellerite in the moved between 200 and 300 ka. In combination with aerial upper part. The Tianchi Volcano has undergone early photographs and satellite imaging data, it follows that shield-building (2.77–1.51 Ma), middle cone-building shallow and surficial faults were not significantly activated (1.00–0.04 Ma), and late volcanic debris-formed sheet on the northeastern China continent since the late stages (Holocene). 中国科技论文在线 http://www.paper.edu.cn

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Fig. 6. Interpretation of satellite images for fault structures and volcanic distribution in the Tianchi volcanic zone of the Changbai Mountains and surrounding area. The Tianchi Volcano is near the site at 428000N and 1288050E.

From the late Pliocene to early Pleistocene, olivine- During the Holocene, two great eruptions of the Tianchi basaltic magma erupted from the Tianchi Volcano and tens Volcano occurred at 4105 a BP and 1199 AD (Machida of volcanic vents along its periphery, flooded radially et al., 1990; Liu et al., 1998), and produced pyroclastic outward, and formed a volcanic shield that became a base of cumulates and pumice flow. The 1199 AD eruption the Tianchi Volcano. The shield-building stage occurred represents a large-scale Plinian-type eruption of volcanic during eruption of olivine basalt at 2.77–2.12 Ma, overlain debris. by basalt at 1.66–1.59 Ma, which in turn are overlain by basaltic lavas (primarily olivine pyroxenite, pyroxene 7.3. Distribution of pantellerite basalt, olivine basalt, and basalt) at 1.48–0.10 Ma (Liu, 1987; Jin and Zhang, 1994; Liu et al., 1998; Cao et al., 1998; Pantellerite is distributed within a limited NW–WNW- Fan et al., 1999a,b). striking zone constrained by granite and deep-metamorphic During the middle–late Pleistocene, a large volume of rocks. The pantellerite formed in the Tianchi, Wangtian’e, alkali trachytic lava centered at the Tianchi Volcano Xitudingzi volcanoes, and Nanbaotai Volcano on the Korea accumulated around the Tianchi volcanic vent. It covered side. These volcanoes define a NW–WNW-striking zone the 2.77–2.12 Ma basalt lavas and formed a Tianchi (Fig. 6) from the continent of China to the Korean margin, volcanic cone. In the late Pleistocene, the Tianchi volcanic but are not found on the western side of the circled area in cone erupted trachytic magma and formed a sub-volcano of Figs. 2 and 3. basaltic lava-scoria that accumulated on the slope of Tianchi The rocks in Wangtian’e are alkalic rhyolite rich in volcanic cone. The eruptions during the cone-building stage K2O þ Na2O(.9%) (Fan et al., 1999a,b). Geochemical occurred between 0.10 and 0.04 Ma as several eruptive data show that the Wangtian’e Volcano and Tianchi cycles. Volcano are similar in composition and are composed of 中国科技论文在线 http://www.paper.edu.cn

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bimodal volcanic rocks that lack mid-acidic andesite and The volcanic eruptions in the Tianchi volcanic zone of the trachyandesite (Cao et al., 1998; Fan et al., 1999a,b). The Changbai Mountains and surrounding area were affected by Wangtian’e Volcano also experienced shield-forming and the deeply buried NW–WNW-striking faults. The volcanic cone-forming stages. A similar process also occurred in the products formed on the surface are characterized by mantle Nanbaotai Volcano of Korea (Jin and Zhang, 1994; Cao diaper and non-fissure volcanic eruptions. Since the late et al., 1998; Fan et al., 1999a,b). Pliocene–Pleistocene, the eruption of magma in the Tianchi volcanic zone of the Changbai Mountains may not have been related to the existence of surface faults. The NE- 8. Tectonic setting for volcanic activity in the Tianchi striking faults did not serve as the conduit for the magma volcanic zone upwelling. Surface fissures affected the upwelling of volcanic material during the early phases of eruption and During Cenozoic time, in addition to large-scale hence the fissure-type volcanic eruptions occurred in the extension in the early-middle Cenozoic and weak sub- Tianchi volcanic zone. In the late phase, the volcanic latitudinal compression since Pleistocene time, there was eruptions were in a state of weak compression and affected also compression in northeastern China during the transition by WNW–NW-striking deep faults. between extension and compression (Gao, 1988; Wang Since 3–2 Ma, the West Pacific plate subducted et al., 1999; Wang and Chen, unpublished data). In general, westward. The northeastern China continent entered a the extension led to formation of fault depressions, compressional stage, when seismicity significantly corresponding to basinal sedimentation, and volcanic occurred. Deep-source earthquakes with focal depths of activity (Gao, 1988; Jin and Zhang, 1994; Wang, 1998; 580–600 km occurred in an area 120–100 km northeast Wang et al., 1999). of the Tianchi Volcano. Focal mechanisms of intermedi- During the early-middle Cenozoic (Paleocene–middle ate-deep earthquakes on the continental margin of Miocene?), NW–SE extension in northeastern China led to northeastern China and in the Sea of Japan show that extensive basaltic eruption (Liu, 1987; Liu et al., 1989a,b; earthquakes occurred on west-dipping thrust fault planes. Liu et al., 1992a,b; Jin and Zhang, 1994; Wang, 1998; Wang Intermediate-shallow earthquakes occurred on strike–slip et al., 1999; Peng and Yin, 1999). Eruption products are faults. At the same time, the sub-latitudinal dikes formed distributed along NE-striking faults, such as the Mishan- on the Tumenjiang River Fault east of the Tianchi Dunhua and Liudaogou-Tianchi-Zhenfengshan faults. Tec- Volcano. These are indicators for magma upwelling tonic activity in northeastern China is also consistent with during shearing (Cas and Wright, 1988), indicating that subduction of the West Pacific plate (Maruyama and Seno, the E-W compression was a principal stress for the 1986; Ding, 1988; Ma, 1989; Tokyo Institute of Technol- seismicity in the region, but there was shear stress in ogy, 1989; Basu et al., 1991). During Cenozoic time, local areas. Analysis of focal mechanism solutions of extension of the Sea of Japan was consistent with Cenozoic shallow earthquakes yielded an average ENE–WSW extensional subsidence in northeast China (Uyeda and major principal stress direction. That is to say, the Miyashiro, 1974; Lallemand and Jolivet, 1986; Tokyo volcanic activity in the Tianchi volcanic zone of the Institute of Technology, 1989; Otofuji et al., 1994). Changbai Mountains occurred in an intracontinental, non- Since the late Pliocene–Pleistocene, the northeastern orogenic compressional tectonic environment rather than China continent experienced sub-latitudinal east-west in an extensional tectonic environment. compression. Sub-latitudinal compression resulted in seis- The subduction front of the West Pacific plate or micity and crustal uplift in the region. It corresponds to subduction of the Kula-Pacific Ridge (Uyeda and Miya- closure of the Sea of Japan and continued westward shiro, 1974) possibly reached beneath the China continent subduction of the West Pacific plate beneath the Eurasian (in the Hunchun area) and affected northeastern China and plate (Tokyo Institute of Technology, 1989). Crustal uplift the mantle beneath it. Geochemical analysis of rocks gradually diminished from east to west and appeared to be a indicates that the trend of magma evolution for the volcanic non-uniform. It did not lead to mountain building typical of products in the Changbai Mountains area during different a compressional environment, but only reflects weak time periods is approximately similar; the magma may have intracontinental compression with no large-scale thrusting. been derived from partial melting of mantle sources with The characteristics of the tectonic stress field and the characteristics of a MORB-like end-member and a sub- distribution and characteristics of ‘X-shaped’ shear joints continental enriched mantle (EM I) (Basu et al., 1991). The also show sub-latitudinal compressional or compression- upwelling of magma in the subcontinental asthenosphere shearing deformation rather than extension. Although may have been affected by the subducted slab of the West earlier NE-striking faults and graben were formed, they Pacific plate or submergence of the Kula-Pacific Ridge did not affect the volcanic activity along the NW–WNW- beneath the Asiatic plate since the late Cretaceous as striking deep faults or deep-seated fault zones and the proposed by Uyeda and Miyashiro (1974). The available upwelling of magma along these fault zones. The volcanic petro-geochemical data cannot explain the consistence of activity was mainly distributed in a NW–WNW direction. volcanic products with volcanic material on the continental 中国科技论文在线 http://www.paper.edu.cn

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margin formed by deeply subducting plate motion (i.e. the evolutionary process of the Tianchi Volcano, from trachy- magma for the volcanic activity was not derived directly basalt through basaltic trachyandesite-trachyte and from a volcanic arc generated by plate subduction). The pantellerite. formation of pantellerite is related to the deep crustal The rise of magma to the surface is dependent on the structure along the periphery of the Tianchi volcanic zone, existence of vertical or subvertical fractures, or pathways in and not to the addition of deeply subducted material. This the crust (Cas and Wright, 1988). During rifting or other conclusion differs from that of addition of subducted tectonic processes, the eruption of acidic magma together oceanic crustal material to the mantle (Peacock et al., with basaltic magma may occur from a crustal magmatic 1994), as no andesitic series was developed on the active reservoir, and bimodal volcanic rocks would result (Hil- continental margin or in an orogenic belt (Thorpe, 1982). In dreth, 1981). The basaltic magma would enter the upper fact, the subducted West Pacific plate materials may not be mantle-crust magmatic reservoir where crystallization– carried into the lower part of the Tianchi volcanic zone. The differentiation might then proceed. At the same time, the eruption of the Tianchi volcanic rocks is characteristic of specific middle-upper crust structure on the northern and intracontinental volcanic activity rather than continental western sides of the Tianchi volcanic zone can facilitate the margin or intraplate volcanic activity. It may be related to transfer of basaltic magma from east to west. This explains continental rifting (Bailey, 1974) and deep-source seismi- why basalt was erupted on the western side of the Tianchi city. The volcano is in a transition zone inboard of the active volcanic zone. For example, the basaltic lavas on the continental margin and outboard of the continental interior. Longgang Volcano, 160 km away from the Tianchi Volcano, were derived from a magma chamber located at the top of the upper mantle at a depth of 35–50 km (Shi 9. Discussion et al., 1999). Therefore in the Tianchi volcanic zone, the basalt, trachyte and pantellerite were erupted together. 9.1. Dynamic analysis of formation of pantellerite and Petrological and petro-geochemical characteristics and relative volcanic rocks space-time distribution of the volcanic products in the zone indicate that since middle-late Pliocene–Pleistocene time, From analysis of deep-source (.400 km) earthquakes, volcanic activity was closely related to the crustal structure. and the more than 1100 km distance between the volcanic When the upper-mantle magma migrated or crept westward, belt and West Pacific-Eurasian plate boundary, geologists the crust in the zone obstructed its progressive movement, and geophysicists suggested that the West Pacific plate has resulting in pooling of magma. Thus, crystallization and subducted into the upper mantle at 400–500 km depth differentiation of the magma took place in local areas and (Zhang and Tang, 1983; Zhao, 1990). According to Uyeda hence formed different products, ranging from basalt to and Miyashiro (1974), submergence of the Kula-Pacific pantellerite. This may be the main cause for the distribution Ridge beneath the Asiatic plate during the late Cretaceous of pantellerite in a NW–WNW-trending local zone. The resulted in thinning and breaking of the continental magma erupted in other areas, however, did not form similar lithospheric plate in eastern Asia. pantellerite. The Tianchi Volcano represents a central zone for the eruption of basaltic magma and the volume of eruption products is estimated to be about 9000 km2. Liu et al. (1998) 10. Conclusions suggested that such a large volume of volcanic products formed in a relatively small area requires needed one or A series ofvolcaniceruptionsinthe Tianchivolcaniczone, more magma chambers beneath it. The heating of the from a basalt-constructed shield, trachyte cone, to Holocene subducted West Pacific plate resulted in partial melting of pantellerite, occurred since 2.77 Ma. A single parental the subcontinental mantle. Through crystallization–differ- magma evolved through cogenetic magmatic processes. entiation, a portion of subcontinental mantle melt may have The basalt, trachyte and pantellerite formed since 3 Ma are upwelled into a crustal-level magmatic chamber. The distributed in a NW–WNW-striking zone, from Tianchi, magmatic activity observed may reflect a dynamic model Wangtian’e, and Xitudingzi volcanoes to Nanbaotai Volcano for a ‘multiple chamber magmatic system’ in the upper in Korea. The westward subduction of the West Pacific plate mantle. The existence of a multiple chamber system in the since ,3 Ma has significantly affected the volcanic activity crust and upper mantle beneath the Tianchi Volcano of the Tianchi volcanic zone. The volcanic activity in the zone therefore formed a unified magmatic system. during late Cenozoic time did not result from back-arc From major, minor, and rare element data, the volcanic extension or subduction of the Kula-Pacific Ridge and does rocks in the Tianchi volcanic zone were principally derived not have the characteristics of volcanic activity occurring from crystallization–differentiation of consanguineous along an active continental margin. magma. The trachyte is derived from crystallization– The eruption of volcanoes in the Tianchi volcanic zone differentiation of basaltic magma and pantellerite from and surrounding area since late Pliocene time was not trachytic magma. This is consistent with the magmatic affected by the NE- and NNE-trending structures, but was 中国科技论文在线 http://www.paper.edu.cn

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significantly controlled by NW–WNW-striking, deeply Dong, B.Z., 1993. Depth of the upper mantle and its deep tectonic buried faults. In the process of volcanic eruption, the crust characteristics in northeastern China. Northeastern Seismological was under an east-west compressional stress. The driving Research 9, 25–35.in Chinese with English abstract. Fan, Q.C., Liu, R.X., Li, D.M., Li, Q., 1999a. Significance of K–Ar age of force came from the westward subduction of the West bimodal volcanic rocks at Wangtian’e Volcano, Changbaishan area. Pacific plate since ,3 Ma. The stress was sub-latitudinal Chinese Science Bulletin 44, 660–663. compression and locally shearing rather than extension. Fan, Q.C., Liu, R.X., Wei, H.Q., Sui, J.L., Li, N., 1999b. Petrogeochemical During volcanic eruptions and at present, the crust in the characteristics of Holocene eruption of the Tianchi Volcano, Changbai Mountains. Geological Review 45 (Suppl), 263–271.in Chinese with zone has been uplifted. English abstract. The geotectonic background for the volcanic activity was Fu, W.Z., 1996. Deep earthquakes in northeastern China and their tectonic indirectly restricted by the subduction of the West Pacific significance. Journal of Changchun University of Earth Sciences 26, plate, during which time no orogenic andesites or island-arc 316–321.in Chinese with English abstract. volcanics formed. The formation of pantellerite is related to Gao, M.X., 1988. Late Cenozoic taphrogenesis, shallow and deep earthquakes, and volcanism in northeastern China. Northeastern the deep crustal structure along the periphery of the Tianchi Seismological Research 4, 17–28.in Chinese with English volcanic zone and not to the addition of deep subduction abstract. material. The pantellerite formed by crystallization and Hildreth, W., 1981. Gradients in silicic magma chambers: implications for differentiation of magma from a trachyte chamber, whereas lithospheric magmatism. Journal of Geophysical Research 86, trachytic magma was most likely derived from a basaltic 10153–10192. Jilin Bureau of Geology and Mineral Resources, 1988. Regional Geology of chamber. The volcanic eruption in the Tianchi volcanic Jilin, Geological Publishing House, pp. 505–602, in Chinese. zone is intracontinental rather than active continental Jin, D.C., Cui, Z.X., 1999. A study of volcanic eruptions in Tianchi Volcano, margin or intraplate. Changbai Mountains recorded in historical documents. Geological Review 45 (Suppl), 304–307.in Chinese with English abstract. Jin, B.L., Zhang, X.Y., 1994. Researching Volcanic Geology in Changbai Acknowledgements Mountains, Northeast Korea Nation Education Press, Changchun, China, pp. 1–223, in Chinese. This study was supported by the China Seismological Lallemand, S., Jolivet, L., 1986. Japan Sea: a pull-apart basin? Earth and Bureau. We are indebted to Profs Liu, R.X. and Fan, Q.C. Planetary Science Letters 76, 375–389. Lee, C.N., 1991. Neotectonic movements and the formation of present (Institute of Geology, China Seismological Bureau) for their topography in northern Korea and its vicinity. Jilin Geology, 1–12.in constructive comments and Dr Jeffrey Lee (Central Chinese with English abstract. Washington University, USA) for improvements to the Liu, J.Q., 1987. Study on geochronology of the Cenozoic volcanic rocks in English. Associate Profs. Yang, Q.F. and Li, Z.T. northeastern China. Acta Petrologica 4, 21–31.in Chinese with English (Seismological Bureau of Jilin Province) referred much abstract. Liu, X., Xiang, T.Y., Wang, X.K., 1989a. Period division of Cenozoic isotopic data and regional geological and geophysical volcanic activity in Changbaishan area. Jilin Geology, 31–41.in information. The manuscript benefited greatly from com- Chinese. ments by Dr A.R. Basu and an anonymous reviewer. Liu, Y.Z., Liang, H.Q., Liu, J.Z., 1989b. Stress field change in time and space and seismological activity in northeastern China. Northeastern Seismological Research 5, 17–24.in Chinese with English abstract. Liu, R.X., Chen, W.J., Sun, J.Z., Li, D.M., 1992a. K–Ar chronology and tectonic settings of Cenozoic volcanic rocks in China. In: Liu, R.X., (Ed.), Chronology and Geochemistry of Cenozoic Volcanic Rocks in China, Seismological Press, Beijing, pp. 1–43, in Chinese. Liu, R.X., Li, J.T., Wei, H.Q., Xu, D.M., Yang, Q.F., 1992b. Changbaishan References Tianchi Volcano—A recent dormant volcano for potential dangerous eruptions. Acta Geophysica 35, 661–664.in Chinese with English Bailey, D.K., 1974. Continental rifting and alkaline magmatism. In: abstract. Sorensen, H., (Ed.), The Alkaline Rocks, Wiley, New york, pp. Liu, R.X., Wei, H.Q., Li, J.T., 1998. Recent eruptions of the Changbaishan 148–159. Tianchi Volcano, Scientific Press, pp. 1–159, in Chinese. Basu, A.R., Wang, J.W., Huang, W.K., 1991. Major element, REE, and Pb, Ma, X.Y., 1989. Lithospheric Dynamics Atlas of China, China Carto- Nd and Sr isotopic geochemistry of Cenozoic volcanic rocks of eastern graphic Publishing House, pp. 1–68, in Chinese. China: implications for their origin from suboceanic-type mantle Machida, H., Morwaki, H., Zhao, D.C., 1990. The recent major eruption of reservoirs. Earth and Planetary Science Letters 105, 149–169. Changbai Volcano and its environmental effects. Geographical reports Cao, L., Jin, B.L., Zhu, D., 1998. Comparison of Cenozoic volcanic rocks at of Tokyo Metropolitan University 25, 1–20. the Sino-Korean boundary. Journal of Changchun University of Science Maruyama, S., Seno, T., 1986. Orogeny and relative plate motions: and Technology 28, 127–134.in Chinese with English abstract. example of the Japanese islands. Tectonophysics 127, 305–329. Cas, R.A.F., Wright, J.V., 1988. Volcanic Successions—Modern and Meng, X.S., Zhu, J.C., Sun, W.B., Xu, X.L., Li, D.H., 1996. Shallow Ancient, pp. 445–467, London, Sydney. moderate and deep-source earthquakes in northeastern China and the Chen, Z.F., 1997. Volcanic rocks in the Tianchi area of Changbaishan, West Pacific Plate subduction. Northeastern Seismological Research northeastern China. Master degree thesis, Taiwan University, pp. 3–87, 12, 12–23.in Chinese with English abstract. in Chinese. Otofuji, Y., Kambara, A., Matsuda, T., Nohda, S., 1994. Counterclockwise Ding, G.Y., 1988. Neotectonic environment for volcanism and deep-seated rotation of northeast Japan: paleomagnetic evidence for regional extent earthquakes in northeastern China. Northeastern Seismological and timing of rotation. Earth and Planetary Science Letters 121, Research 4, 3–9.in Chinese with English abstract. 503–518. 中国科技论文在线 http://www.paper.edu.cn

1170 Y. Wang et al. / Journal of Asian Earth Sciences 21 (2003) 1159–1170

Peacock, S.M., Rushmer, T., Thompson, A.B., 1994. Partial melting of Whitford-Stark, J.L., 1987. A survey of Cenozoic volcanism on subducting oceanic crust. Earth and Planetary Science Letters 121, Mainland Asia. The Geological Society of America, Special Paper 227–244. 213, 1–74. Peng, Y.J., Yin, C.J., 1999. Tertiary volcanic rock chronohorizon and Xie, G.H., Wang, J.W., 1988. Study on petrochemistry and Sr–Nd–Pb tectonic setting in Jilin Province. Geological Review 45 (Suppl), isotopic geochemistry of Cenozoic volcanic rocks in Changbai Mts. 204–214.in Chinese with English abstract. area. Acta Petrologica 4, 1–13.in Chinese. Shi, L.B., Lin, C.Y., Han, X.L., Chen, X.D., 1999. Principal features of Xu, D.M., 1988. Structures of the volcanic activity in Changbai Mts. area. mantle xenoliths in Jinlongdingzi volcanics, Longgang Volcano Northeastern Seismological Research 4, 53–63.in Chinese. Cluster, Jilin Province and their geological implications. Geological Zhang, Z.Q., 1988. Studying on deep-source earthquakes. Northeastern Review 45 (Suppl), 308–318. Seismological Research 4, 65–73.in Chinese.

Tang, J., Jin, G.W., Zhao, G.Z., 1999. Induction arrow and its application in Zhang, J.G., Hu, H.T., 1999. A discussion on the genesis of CO2 out gassed Tianchi Volcano, Changbai Mountains. Geological Review 45 (Suppl), in geothermal processes around the Tianchi Lake, Changbai Mountains. 294–303.in Chinese with English abstract. Geological Review 45, 231–235. Thorpe, R.S., 1982. Andesites—Orogenic Andesites and Related Rocks, Zhang, L.M., Tang, X.M., 1983. Subduction of the West Paciﬁc Plate and Wiley, New York, pp. 1–724. deep-source seismic zone in Northeast China. Acta Geophysica 26, Tokyo Institute of Technology, 1989. Japanese National Committee for the 331–340.in Chinese. Dynamics and Evolution of the Lithosphere Project (DELP): Deep Zhao, W.F., 1988. Geological background of Hunchun deep earthquakes in Structure of the Japanese Islands, 21. Oceanic Press, pp. 1–116, in the northeastern China continent and in correlation with seismic Japanese with English titles. activities in inland. Northeastern Seismological Research 4, 37–43.in Uyeda, S., Miyashiro, A., 1974. Plate tectonics and the Japanese islands: a Chinese. synthesis. Geological Society of American Bulletin 85, 1159–1170. Zhao, W.F., 1990. Correlative activity of volcanoes, deep and shallow Wang, Y., 1998. Evolutionary Processes and Dynamics of the Orogenic earthquakes in the continental margin of China. Northeastern Belts and Basins in North China in the Mesozoic and Cenozoic, Seismological Research 6, 83–94.in Chinese. Geological Publishing House, pp. 1–91, in Chinese with English Zhao, Z., 1991. Characteristics of intermediate and deep earthquakes in and summary. near Japan Sea. Northeastern Seismological Research 7, 1–16.in Wang, Y., Li, C.F., Chen, H.Z., 1999. Tectonic settings of Cenozoic Chinese. volcanism in northeastern China. Geological Review 45 (Suppl), Zindler, A., Hart, S.R., 1986. Chemical geodynamics. Annual Review of 180–189.in Chinese with English abstract. Earth Science 14, 463–471.