Tectonic Controls on the Pleistocene–Holocene Wudalianchi Volcanic field (Northeastern China)
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http://www.paper.edu.cn Journal of Asian Earth Sciences 24 (2005) 419–431 Tectonic controls on the Pleistocene–Holocene Wudalianchi volcanic field (northeastern China) Yu Wanga,*, Hongzhou Chenb aGeologic Laboratories Center and Department of Geology, China University of Geosciences, Beijing 100083, China bSeismological Bureau of Heilongjiang Province, Harbin 150036, China Received 28 May 2002; revised 19 November 2003; accepted 12 December 2003 Abstract The Wudalianchi volcanic field developed during the Pleistocene–Holocene but is dormant at present. Its latest eruption occurred in 1719–1721 AD. The volcanic rocks are high-potassium alkaline basalts derived from the upper mantle (c. 100–120 km depth) as indicated by geochemical data. The field is located in an old tectonic transition zone surrounded by four regional normal faults. The volcanic craters are aligned along NE–NNE-striking fractures and faults, although a NNW-striking sub-surface fracture zone probably controlled the eruptions beginning at 1.33 ^ 0.08 Ma. Beneath the volcanic field, the Moho interface lies at a depth of 33.5–35 km. Eruptions evolved from fissure type to central type eruptions. The field is characterized by an intraplate tectonic setting in a non-orogenic compressional regime which resulted from the subduction of the West Pacific plate beneath the eastern Asian continental margin starting 3–2 Ma ago. q 2004 Elsevier Ltd. All rights reserved. Keywords: Volcanic field; Young alkaline basalts; Northeastern China; Intraplate setting; Compressional tectonic regime; Tectonic control 1. Introduction To the north and south of the Wudalianchi volcanic field, there are other Quaternary volcanoes and volcanic The Wudalianchi volcanic field is located in north- fields, namely the Xiaogulihe (Genghe) Volcano, the eastern China, at 488350 –488510N latitude, 1258570 – Keluo volcanic field, and the Erkeshan Volcano (Fig. 2), 1268310E longitude (Fig. 1), near the NNE-trending with volcanic rocks of similar composition and similar geological age. These volcanoes are distributed along Dahinggan Mountain belt. It is far from the subduction a NNW-trending belt comprising the 320 km long zone of the West Pacific plate. On the southern side of the Wudalianchi volcanic zone. This paper covers mainly Wudalianchi volcanic field, there is the Songliao Basin the Wudalianchi volcanic field. (Fig. 2), a middle Jurassic–early Cenozoic intracontinental Two theories have been put forward to explain the rift-depression which evolved from the middle Jurassic to tectonic setting of the Wudalianchi volcanic field: it occurs early Cenozoic (Heilongjiang Bureau of Geology and (1) in a continental rift environment (Ding, 1988; Qiu et al., Mineral Resources, 1993; Zhang et al., 1997; Wang et al., 1991; Chen and Ren, 1997) and (2) in a hot-spot setting 1999). On the northern side is the Xiaohinggan Mountain formed by intraplate mantle upwelling (Wang, 1997; Gong, belt with a WNW-trending uplift which has evolved since 1997b). Although Cenozoic basalt has been extruded in the late Mesozoic. On the eastern side lies the Songwu intracontinental rift settings in many places in northeastern Graben with NNE–NE-striking normal faults and fractures; China (Whitford-Stark, 1987; Jilin Bureau of Geology and it was formed during the early Cretaceous–middle Mineral Resources, 1988; Chen and Ren, 1997), the Cenozoic (Heilongjiang Bureau of Geology and Mineral tectonic evolution in the Mesozoic and Cenozoic does Resources, 1993). not support the explanation that the eruptions of the Wudalianchi volcanic field have occurred in a continental * Corresponding author. Tel.: þ86-10-8232-1028; fax: þ86-10-8232- rift setting. In fact, the tectonic stress was not extensional 1983. during the eruptions of the Wudalianchi volcanic field E-mail address: [email protected] (Y. Wang). (Wang et al., 1999). 1367-9120/$ - see front matter q 2004 Elsevier Ltd. All rights reserved. doi:10.1016/j.jseaes.2003.12.010 转载 中国科技论文在线 http://www.paper.edu.cn 420 Y. Wang, H. Chen / Journal of Asian Earth Sciences 24 (2005) 419–431 Fig. 1. Location of the Wudalianchi Volcanic Field (NE China). Abbreviations are as follows: W. V.—Wudalianchi volcanic field, C. V.—Changbaishan Tianchi Volcano, QL-DB—Qinling-Dabie, DMT—Dahinggan Mountain Belt, XMT—Xiaohinggan Mountain Belt, YL-YTF—Yilan-Yitong Fault, MS- DHF—Mishan-Dunhua Fault. The area covered by ocean is shown by broken lines. Fig. 2 is shown. Based on geologic mapping of the Wudalianchi volcanic the field are aligned NE (Fig. 3). These craters are of small field and its surroundings, we analyzed structural styles scale and were formed by flowing basaltic lava. The conical formed in the Cenozoic sediments. Using magnetotelluric craters consist of two parts: the lower part is a shield of sounding results, sequences of volcanic eruptions, seismic- basaltic lava and the upper part is formed by pyroclastic reflection profiles, and seismic focal mechanisms, the crustal rocks. Each volcanic eruption was controlled by basement structure and faulting patterns around and beneath the faults or fissures; the eruptions involved mainly flowing lava Wudalianchi volcanic field were assessed. We also and were either central or fissure type of eruptions. reconstructed the tectonic setting of the Wudalianchi The magma was derived from a depth c. 100–120 km at volcanic eruption centers in order to understand the a source temperature of c. 1068–1100 8C according to relationship between intraplate volcanoes and tectonic stress estimates from mantle source inclusions of websterite and as well as the tectonic control on the passage of magma from clinopyroxenite (Qiu et al., 1991; Gong, 1997a). Radio- the upper mantle to the surface in an intraplate setting. metric (K–Ar) dating of the volcanic products yielded the following age values (Fig. 4): a middle Pleistocene eruption period ,1.33 ^ 0.08–1.27 ^ 0.09 Ma (Miu et al., 1983; 2. Eruption sequences and characteristics Liu, 1987), late Pleistocene eruptions ,0.8 ^ 0.22, of volcanic rocks 0.57 ^ 0.05, 0.52 ^ 0.14 and 0.30–0.65 Ma (Miu et al., 1983; Gong, 1997a,b), and a Holocene eruption—1719– The basaltic lavas from the Wudalianchi volcanic field 1721 AD (mainly from the Laoheishan and Huoshaoshan cover more than 800 km2. The 14 conical volcanic craters of craters). Recently, Li et al. (1999) dated many basaltic rocks 中国科技论文在线 http://www.paper.edu.cn Y. Wang, H. Chen / Journal of Asian Earth Sciences 24 (2005) 419–431 421 Fig. 2. Regional geologic characteristics of the Wudalianchi volcanic field and adjacent areas. Abbreviations are as follows: W. V.—Wudalianchi volcanic field, K. V.—Keluo volcanic field, X. V.—Xiaogulihe Volcano, E. V.—Erkeshan Volcano, DMFF—Dahinggan Mountain Front Fault, NF—Nenjiang Fault, NMF—Nuomoer Fault, CFSB—Central Fault of the Songliao Basin, X-WFZ—Xiaogulihe-Wudalianchi Fault or Fracture Zone (The level of the Moho discontinuity is inferred from mean Bouguer gravity anomaly data on 1 £ 18 grid squares; there is a lack of data near the NW corner of the figure). Figs. 3 and 6 are shown. using the K–Ar method and demonstrated a similar Hughes, 1982), making it a high-potassium alkali-basalt. sequence. The historic and thermoluminescent dates yielded A special characteristic is that there is no plagioclase, but an age of 278–283 a (Ji and Li, 1998) for the latest eruption, alkali feldspar is found in the basalt (Gong and Xu, 1997). indicating that this is presently a dormant volcano. The lavas are rich in LREE, Ti, Rb, Cs, Sr, Ba and Ta. The K2O content in the Wudalianchi volcanic rocks is The Y/Nb ratio is less than 1 (Gong and Xu, 1997); Sr is 4.28–5.91% with an average of 5.28% (Xu, 1997); it is 1221–1702 ppm, Ba is 1296–2120 ppm, (La/Nb)N is higher than the normal average of 3.65% (Sorensen, 1974; 63.4–45.2, and (Sm/Nd)N is 0.517–0.560 (Wang, 1997). 中国科技论文在线 http://www.paper.edu.cn 422 Y. Wang, H. Chen / Journal of Asian Earth Sciences 24 (2005) 419–431 Fig. 3. Distribution, alignment, and age of craters across the Wudalianchi volcanic field. Abbreviation of litho-stratigraphic units are as follows: Q—Quaternary sediments, N—Tertiary sediments, K—Cretaceous strata. The isotopic data are from Miu et al. (1983), Liu (1987), Gong (1997a,b) and Li et al. (1999). Unit of isotopic data is Ma. The petrological evidence, major and trace element Rocks from the other nearby Quaternary volcanoes, such composition, and Sr–Nd–Pb isotopes suggest that the as the Keluo volcanic field and the Xiaogulihe Volcano on K-rich volcanic rocks may have been derived from a the eastern side of the Dahinggan Mountain belt and the metasomatic EMI mantle (Fan et al., 1999), and that no Erkeshan Volcano to the south–southeast, have geochem- partial melts of crustal material were added to the magma ical and petrologic characteristics similar to the high- (Zhang et al., 1995; Fan et al., 1999). potassium alkali-basalt from the Wudalianchi volcanic field, Fig. 4. Spectrum of geochronological data from the Wudalianchi, the Keluo, and Erkeshan volcanoes. The data are from Miu et al. (1983), Liu (1987), Gong (1997a,b), and Li et al. (1999). 中国科技论文在线 http://www.paper.edu.cn Y. Wang, H. Chen / Journal of Asian Earth Sciences 24 (2005) 419–431 423 including leucotephrite and many leucitic minerals (Table 1 and Fig. 4). Together they comprise the NNW-trending Quaternary basalt zone (see Fig. 2), known as the . Wudalianchi volcanic zone. Pattern and type of eruption Conical and shield Central, Conical 3. Geophysical evidence Several Cenozoic uplifts and depressions occur around the Wudalianchi volcanic field. The Wudalianchi volcanic field is located in a triangular area bounded by different tectonic belts (Fig. 2). These are: (1) the WNW-trending Xiaohinggan Mountain belt, (2) the NNE-trending Dahing- gan Mountain belt, (3) the NE–NNE-trending Songliao rift- depression basin, and (4) the NE–NNE-trending Songwu on the surface Controlled structures ? NE-striking faults or fissureNE-striking faults or Central, fissure Conical Central–fissure, Graben.