54th CCOP Annual Session & 71st Steering Committee Meeting October 28 ~ November 03, 2018 Busan, Republic of Korea
BUSAN NATIONAL GEOPARK FIELD GUIDEBOOK
November 01 2018 54th CCOP Annual Session & 71st Steering Committee Meeting
CONTENTS
Excursion Schedule 1 Location 2
01 Introduction 3
02 Geological background of Busan 5 2.1 Gyeongsang Basin 7 2.2 Yangsan Fault System 8 2.3 Geology of Busan 10 2.4 Dadaepo Basin located between 11 the Yangsan and Dongnae faults
03 Busan National Geopark 12
04 Geosites of the Busan National Geopark 15 4.1 Nakdonggang estuary 16 4.2 Morundae 17 4.3 Dusong peninsula 18 4.4 Songdo peninsula and Dudo island 18 4.5 Taejongdae 19 4.6 Oryukdo and Igidae 20 4.7 Jangsan 20 4.8 Geumjeongsan 21 4.9 Orbicular gabbro 22 4.10 Baekyangsan 22
05 Songdo Peninsula Geosite 24
06 Haedong Yonggungsa (Temple) 30
07 Reference 32 Busan National Geopark Field Guidebook
Excursion Schedule
Time Schedule
09:00~10:00 Hotel → Busan Air Cruse (Cable Car)
10:00~11:00 Cable Car Tour
Songdo Peninsula Geosite 11:00~12:30 (Busan National Geopark)
12:30~13:00 Songdo → Restaurant
Lunch 13:00~14:00 (Mokjangweon)
14:00~15:00 Restaurant → Yonggungsa
15:00~16:30 Haedong Yonggungsa (Temple)
16:30~17:00 Yonggungsa → Hotel
01 54th CCOP Annual Session & 71st Steering Committee Meeting
Location
Yonggungsa
Grand Hotel
Arrival
Waypoint 1
SongdoSongdo Waypoint 2
RestaurantRestaurant
02 01INTRODUCTION 54th CCOP Annual Session & 71st Steering Committee Meeting
01 INTRODUCTION Welcome to Busan! Busan, a bustling city of approximately 3.6 million residents, is located on the southeastern tip of the Korean Peninsula (Fig. 1). The size of Busan is 768.408 km² which is 0.8% of the whole land of the Korean Peninsula. The natural environment of Busan is a perfect example of harmony among mountains, rivers, and sea. Its geography includes a coastline with superb beaches and scenic cli s, mountains which provide excellent hiking and extraordinary views, and hot springs scattered throughout the city. You can enjoy four distinct and beautiful seasons in Busan. Many tourists visit Busan all year round because of the nice weather and beautiful scenery.
Fig. 1. Location of Busan and photographs showing major tourist attractions.
Busan is the second largest city in Korea. Its deep harbor and gentle tides have allowed it to grow into the largest container handling port in the country and the fth largest port in the world. As for its geopolitical location, the city comes at the southern tip of a strip that connects Asia, Siberia, and Europe. It also serves as a main gateway to the Paci c Ocean. This location places the city at the center of international sea transportation. The city's natural endowments and rich history have resulted in Busan's increasing reputation as a world class city of tourism and culture, and it is also becoming renowned as an international conventions (from http://english.busan.go.kr). A geopark is a uni ed area with geological heritages of international signi cance. Busan became a national geopark of Korea in November 2013. Three Korean islands (Dok-do, Ulleung-do, Jeju-do) were also certi ed as national geoparks in December 2012. Busan is, however, the rst geopark located inland in Korea. The geopark initiative was launched by UNESCO in response to the perceived need for an international initiative that recognizes sites representing an earth science interest. In this eld excursion, we can review the geology of Busan and tour the Busan National Geopark.
04 02 GEOLOGICAL BACKGROUND OF BUSAN 54th CCOP Annual Session & 71st Steering Committee Meeting
02 GEOLOGICAL BACKGROUND OF BUSAN The Korean Peninsula, located on the eastern Eurasian continental margin, is an important tectonic link between eastern China and the Japanese Island Arc (Fig. 2A). Busan is located in the southeasternmost part of the Cretaceous Gyeongsang Basin wherein several NNE-trending major faults, such as Yangsan, Dongnae, and Ilgwang faults belonging to the Yangsan Fault System, are developed. Detailed explanations are as follows.
Fig. 2. (A) Tectonic outline of the eastern Eurasian margin (modi ed after Xu et al., 1987; Ren et al., 2002; Itoh et al., 2006), (B) Distribution of Cretaceous sedimentary basins (greenish areas) in the Korean peninsula (after Chough and Sohn, 2000). (C) Simpli ed geological map (modi ed from Hwang et al., 1996; Kim et al., 1998; Choi et al., 2002) and key beds (modi ed from Jeong et al., 2005; Jeon and Sohn, 2008; Hwang and Woo, 2009) of the Gyeongsang Basin.
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02.1GYEONGSANG BASIN In the Cretaceous, the Korean Peninsula was located behind the volcanic arc, induced by oblique subduction of the proto-Paci c (Izanagi/Kula) plate (Chough et al., 2000; Chough and Sohn, 2010). A large nonmarine sedimentary basin named the Gyeongsang Basin formed in the southeastern part of the peninsula, whereas a number of small basins formed in the southwestern part (Fig. 2B). These small basins are interpreted to have formed by sinistral, brittle shearing at the releasing fault bends and stepovers along several strike–slip faults and then terminated in the Late Cretaceous when the Izanagi plate changed in the direction of motion, resulting in orthogonal subduction against the Asian continent (Chun and Chough, 1992; Ryang and Chough, 1997; Lee, 1999; Lee and Chough, 1999; Chough et al., 2000; Kim et al., 2003, 2009; Chough and Sohn, 2010). The extension mode of the Gyeongsang Basin, however, is still uncertain, although it is interpret- ed as a backarc basin produced by oblique subduction of the proto-Paci c plate underneath the Eurasia plate (Chough et al., 2000; Chough and Sohn, 2010). The Gyeongsang Basin comprises three subbasins: Yeongyang, Uiseong, and Miryang subbasins from north to south (Chang, 1975; Fig. 2C). The Yeongyang subbasin is demarcated from the Uiseong subbasin by the Andong Fault System (Won et al., 1978) or Cheongsong Ridge (Chang, 1975; Kang and Lee, 2008), and Uiseong and Miryang subbasins are bounded by the Palgongsan Fault (Chang, 1977; Chang and Park, 1997; Fig. 2C). The basin was lled by alluvial, uvial, and lacustrine deposits with subduction-re- lated magmatic rocks. They are subdivided into (1) the non-volcanic sedimentary strata of the Sindong Group, (2) the partly volcanic strata of the Hayang Group, (3) dominantly volcanic strata of the Yucheon Group, and (4) the Bulguksa intrusive rocks in ascending order, according to their occurrence and the amounts of volcanic materials (Chang, 1975; Choi, 1986; Chang et al., 2003; Fig. 2C). Recently, Chough and Sohn (2010) suggested that the volcanic and plutonic rocks constitut- ed a volcanic arc platform (Gyeongsang Volcanic Arc) and that sedimentary rocks located in the west of the arc are backarc strata (Gyeongsang Backarc Basin).
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Fig. 3. Geologic map of Busan area, with the Yangsan Fault System.
02.2 YANGSAN FAULT SYSTEM NNE or NE-trending tectonic lines distributed in the eastern part of the Eurasia plate, such as the Tan-Lu Fault in China and Median Tectonic Line in Japan, can give important clues to understand tectonic regime and to reveal the volcanic activities and crustal deformations in the East Asia during the Cretaceous to Neogene. Especially, the NNE-trending Yangsan Fault System (abbreviated as YFS), located in the eastern part of the Gyeongsang Basin, appears to have played a signi cant role in crustal deformation and sedimentation in the Gyeongsang Basin during the late Cretaceous and Paleogene. The YFS is composed of the Jain, Miryang, Moryang, Yangsan, Dongnae, and Ilgwang faults, from west to east (Fig. 2C). Among them, the Yangsan Fault is the most conspicuous strand of the YFS and is traced for more 200 km with a few km-thick fractured zone. Many studies, such as structural, geophysical, petrological, and magnetic anisotro- py researches, reported that the YFS underwent the multiple deformations in the Cretaceous to Quaternary (Chang et al., 1990; Kim, 1992; Chang, 2002; Chang and Chang, 1998; Hwang et al., 2004, 2007a,b, 2008a,b, 2012; Cho et al., 2007, Choi et al., 2009; Kang and Ryoo, 2009; etc.) due to the change of the movement directions
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and subduction angles of the proto-Paci c plate (Xu et al., 1987; Maruyama et al., 1997; Zhang et al., 2003; Chough and Sohn, 2010). The magnetic fabric study of the granite rocks adjacent to the Yangsan Fault documented that the granitic rocks were emplaced within the NW-trending extensional ssures produced secondarily by the sinistral movement of the Yangsan Fault during 70 to 60 Ma (Cho et al., 2007). Meanwhile, the dextral movement of the Yangsan Fault, showing ca. 21 km horizontal o set, was produced by a NE-SW compressional stress according to fault slip data (Chang and Chang, 1998) after ca. 48 Ma based on the laterally separated granitic body (Hwang et al., 2004, 2007a). In addition, K-Ar ages of the Dongnae Fault gouges are 57.5 to 40.4 Ma (Choo and Chang, 2000). Several studies also reported that some segments of the YFS recently reacted as reverse faults under the current E-W compressional stress regime (Kyung et al., 1999; Kim and Jin, 2006; etc.).
Fig. 4. Geological map of the Dadaepo Basin (modi ed after Chang et al., 1983).
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Fig. 5. (A) Schematic representation of the extensional features and stress- eld associated with the sinistral movement of the NNE trending strike-slip faults. (B) A pull-apart basin model originat- ed by NNE-trending sinistral simple shear. (C) Movement of structural lines and plate tectonic setting of the eastern Eurasian margin in the late Cretaceous (after Kim, 1992). TF: Tan-Lu Fault, YF: Yangsan Fault, MTL: Median Tectonic Line, AF: Amur Fault (Central Sikhote-Alin Fault), KMR: Gilju-Myeongcheon Rift Valley, KYT: Kita-Yamato Trough, CR: Chugaryeong Rift Valley, YFS: Yangsan Fault System, EKF: East Korea Fault, OF: Oki Fault, NTL: Nagato Tectonic Line, ISTL: Itoigawa-Shizuoka Tectonic Line, SM: Sieria seamount, YR: Yamato rise, KP: Korea plateau, UP: Ulleung plateau, OB: Oki bank, OR: Oki ridge.
02.3 GEOLOGY OF BUSAN The geology of Busan area is composed of (1) the dacitic and andesitic volcanic rocks of the Yucheon Group intercalated with (2) the tu aceous sedimentary rocks of the Dadaepo and Taejongdae formations, (3) the rhyolitic rocks of the Yucheon Group, (4) the Bulguksa Granitic Rocks intruding into the earlier rocks, and (5）the Quaternary alluvium, in ascending order (Fig. 3). The Dadaepo Basin, located in the southeastern part of Busan, is interpreted as an intraarc pull-apart basin produced by sinistral movement of the Yangsan and Dongnae faults (Chough and Sohn, 2010; Cho et al., 2011). Detailed explanations of the Dadaepo Basin are as follows (Section 2.4).
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02.4 DADAEPO BASIN LOCATED BETWEEN THE YANGSAN AND DONGNAE FAULTS
The Dadaepo Basin was isolatedly extended between the NNE-trending Yangsan and Dongnae faults (Fig. 4). The basin ll, named the Dadaepo Formation, comprises channelized conglomerates and sandstones that are intercalated in dominantly purple mudstones in the lower part. The upper part of the formation is dominated by ne- to coarse-grained tu aceous sandstones and olive to dark gray mudstones with abundant volcanic interbeds. The formation unconformably overlies dacitic rocks of about 94 Ma and is overlain by basaltic andesite of about 69 Ma (Ar-Ar age). The overall con guration of the strata of the Dadaepo Forma- tion indicates a syn-depositional tilting of the basin oor toward north-northeast. A number of outcrop-scale faults are observed in the basin ll, of which the majori- ty is normal faults including syn-depositional growth faults, trending northwest. Orientations of ma c (magmatic) and clastic dikes, interpreted to be approximate- ly contemporaneous with the accumulation of the Dadaepo Formation, are also nearly parallel to the strikes of the outcrop-scale normal faults. All these extension- al structures, therefore, consistently indicating the NE-SW extension of the basin, are obliquely intersected at an angle of 40°-60° with the bounding Yangsan and Dongnae faults of the basin. It is, thus, concluded that the Dadaepo Formation was deposited in a pull apart basin that was subsided by the NNE-trending sinistral strike–slip faulting in the southeastern part of the Korean Peninsula during the Campanian of the late Cretaceous, due to the north-northwestward oblique subduction of the proto-Paci c (Izanagi/Kula) or Paci c plate under the eastern margin of the Eurasian plate (Fig. 5).
11 03 BUSAN NATIONAL GEOPARK Busan National Geopark Field Guidebook
03 BUSAN NATIONAL GEOPARK Geopark is a new system for development of local economy through conserva- tion, education, and tourism and has scienti c importance for the earth sciences and outstanding scenic values. The Busan National Geopark was certi cated by the Minister of Environment of Korea in November 2013. Certi ed 12 geosites, located in coast, mountain, and estuary, are as follows (Fig. 6). The Nakdonggang estuary geosite, the largest present delta in Korea, has diverse estuary landforms and sedimentary structures. The Morundae, Dusong peninsula, Songdo penin- sula, and Dudo island geosites, located in the Dadaepo Basin, provide a basis for the interpretation of tectonic setting, deformation history, sedimentary environ- ment of the SE Korea during the Late Cretaceous. The Taejongdae geosite has a variety of coastal erosion features and uplift landforms. The Oryukdo and Igidae geosites have various geoheritages related to the Yucheon volcanism in the Late Cretaceous with later coastal erosion landforms. The Jangsan geosite shows also a variety of geoheritages concerning the late Cretaceous rhyolitic volcanism. The Geumjeongsan geosite located in mountain area has gorgeous granite weather- ing landforms. The Orbicular gabbro geosite is the 267th Natural Monument of Korea. The Baekyangsan include geoheritages associated with Cretaceous lake deposits. All the geosites in Busan show the geodiversities, and have been posted on previous researches or used in academic purposes, so that their academic values have been demonstrated. The Busan National Geopark also has a signi cant advantage of urban geopark in accessibility to the geosites through public transportation, well-equipped education system, and tourism infrastructures in Busan metropolitan city. The inhabitants can thus develop the local economy by preserving the geoheritages and nature resources and participating in the geopark operation. Consequently, the geopark will play a leading role in satisfying diverse demands of recent tourism as a successful urban geopark (Kang et al., 2014).
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Fig. 6. Overview map with distribution and characteristics of geosites and their ge oheritages in the Busan National Geopark.
14 04 GEOSITES OF THE BUSAN NATIONAL GEOPARK 54th CCOP Annual Session & 71st Steering Committee Meeting
04 GEOSITES OF THE BUSAN NATIONAL GEOPARK The Busan National Geopark is divided into 4 districts, and is composed of a total of 12 geosites (Fig. 7).
Fig. 7. The range and location of the Busan National Geopark.
04.1 NAKDONGGANG ESTUARY Nakdonggang estuary is the largest modern delta in Korea, where Nakdong River meets the South Sea. Well-formed small and large sized deltas have been good habitats for migratory birds. It was thus designated as the Precious National Treasure No. 179. Various estuary landforms and sedimentary features such as o shore bars, beaches, dunes, wetlands are scattered all over the Nakdonggang estuary geosite. Education and tourism infrastructures such as the Nakdonggang Estuary Eco Center and Amisan Observatory are also well-established.
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Fig. 8. (A) Nakdonggang Estuary Eco Center. The center provides various informations of geology, topography, and ecology of the estuary to visitors. (B) Bird observatory installed in the center. (C) Electric cart for visitors served from the center. (D) Amisan Observatory exhibits geology, estuary, and history of the estuary. (E) O shore bars seen from the Amisan Observatory.
04.2 MORUNDAE The Morundae geosite is a land-tied island (tombolo) that is connected to land only by a spit of beach materials. The geology of the area comprises sedimentary rocks of the Dadaepo Formation such as conglomerate, sandstone, siltstone, and mudstone and the Quaternary terrace deposits. We can also observe typical geological features, such as syn-depositional normal fault, clastic dike, ower structure in strike-slip fault zone, en echelon calcite veins, sand pipes by seismic shock (liquefaction), conglomerates and chert clast, and comb structure. In addition, there are various attractions such as Dadaepo beach, Dadaepo Sunset Fountain of Dream, Dadaepo shell mound, and Dadaepo Gaeksa.
Fig. 9. (A) Quaternary terrace deposit between alluvium and the lower Dadaepo Formation. (B) Neptunian type clastic dikes. (C) NW-trending normal faults showing horst type. (D) Chert clasts in conglomerates. (E) NW-trending syn-depositional normal faults showing half-graben type.
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04.3 DUSONG PENINSULA In the Dusong peninsula geosite, we can see distinctive geoheritages such as andesitic sill, conjugate normal fault, compound calcrete deposit, reduction spot, petri ed wood fragment, clastic dike, paleo-seismic structure, and dinosaur egg fossil along a developed geotrail. In particular, clastic dikes show intriguing inject- ed structures such as root zone, branched system, and bridged segment.
Fig. 10. (A) Andesitic sill intruding the lower Dadaepo Formation and xenolith (insert in right-top). (B) Graben type-conjugate normal faults. (C) Outcrop photographs of clastic dikes showing cross-cutting relationship (left). They also show branched system (right). (D) Compound calcrete deposits and reduction spot (insert in right-bottom) in the lower Dadaepo Formation. (E) Paleo-seismic structures showing sandy ball-and-pillow type and pillar structure (insert in right-top). (F) Dinosaur egg fossil in the lower Dadaepo Formation.
04.4 SONGDO PENINSULA AND DUDO ISLAND The Songdo peninsula and Dudo geosites provide a basis for the interpretation of evolution history of the Dadaepo Basin. In these sites, we can observe a lot of typical geological features, such as cross-bedding, cut and ll structure, ripple mark, reduction spot, syn-depositional fault, clastic dike, magmatic dike and sill, dinosaur egg fossil, and so on. They have high scienti c and educational values. There are also various tourist sites such as Songdo Beach and Amnam Park near to these geosites.
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Fig. 11. (A) Deck facilities built in geotrail course. (B) Outdoor exhibition of rocks and minerals. (C) The upper Dadaepo Formation and overlying basaltic andesite (lava ows). (D) Cross-strati ed tu aceous sandstone with volcanogenic clasts. (E) Angular calcrete nodules in purple mudstone. (F) Fossils of dinosaur egg nest in purple sandstones. (G) Dudo island geosite. (H) The Lower Dadaepo Formation unconformably overlying the volcanic basements of the basin. (I) Tu breccia (the volcanic basement).
04.5 TAEJONGDAE The Taejongdae geosite, designated as the national cultural heritage scenic spot No. 17, is located at the southern end of the Yeongdo Island. The geosite shows a typical uplift landform and associated coastal erosion features and has a high scienti c value about the Quaternary crustal uplift in the Korean Peninsula. Furthermore, fascinative geological features are observed in this site, such as negative ower structure produced by sinistral strike-slip faulting, orbicular hornfels, slump structure within tu aceous sedimentary rocks, and composite (felsic and ma c) magmatic dikes. Various tourist sites such as National Maritime Museum, Dongsam-dong Shell Midden Museum, and Jagalchi market are also located near to the site.
Fig. 12. (A) Panoramic view of the Taejongdae geosite with the Yeongdo Lighthouse. (B) Close-up of orbicular hornfels. (C) Slump structure in the tu aceous sediments (Taejongdae Formation). (D) Uplifted notch (arrow) formed by undercutting due to wave erosion. (E) Wave-cut platforms (terraces) showing the Quaternary crustal uplift of SE Korean Peninsula during the Quaternary, SE Korea.
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04.6 ORYUKDO AND IGIDAE The Oryukdo, designated as the national cultural heritage scenic spot No. 24, and Igidae geosites have various geoheritages associated with the Yucheon volcanism during the Late Cretaceous and later coastal erosion landforms. In these geosites, we can observe tu aceous sedimentary rocks, andesitic volcanic breccia, copper mine produced along fault damage zone, marine potholes, sea cave, sea cli s along the geotrail. These sites are the most famous geosites because of the easy accessibility and outstanding scenery.
Fig. 13. (A) Panoramic view of the Oryukdo (from left to right Deungdaeseom, Gulseom, Songgot- seom, Suriseom, Solseom and Bangpaeseom). (B) Oryukdo Skywalk. (C) Marine potholes on a wave-cut platform. (D) Sea cave formed by erosion due to wave and current. (E) Intermediate dike bearing hornblende megacrysts intruding volcanic breccia. Close-up of the hornblende phenocrysts in upper right conner. (F) Tu aceous sedimentary rocks observed along sea cli .
04.7 JANGSAN The Jangsan (634 m) geosite is close to the Haeundae Beach that is the Busan's No. 1 beach. The Jangsan mountain is interpreted as a volcanic cauldron which is a relict structure of the late Cretaceous volcanic activities. A variety of geoheritages and landforms are also discovered in the mountain, such as block stream, Yangun falls, and spherulitic rhyolites known as ‘ ower stone’.
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Fig. 14. (A) Spherulitic rhyolite. (B) Rhyolite showing ow structure. (C) Block stream formed by an accumulation of boulder and angular blocks. (D) Yangun falls.
04.8 GEUMJEONGSAN Geumjeongsan (801.5 m), considered as a representative mountain in Busan, has gorgeous granite weathering landforms and geological structures such as tor, inselberg, and block stream. These structures are located along the Geumjeong- sanseong Fortress, the largest fortress in Korea. Various tourist sites such as Beomeosa Temple, Geumjeongsanseong Fortress, Geumgang Park, and Dongnae Spa are also located near to the site.
Fig. 15. (A) Panoramic view of inselbergs and tors developed along the Geumjeongsansung Fortress. (B) Geumsaem (gnamma) formed by long-term weathering on granite rock. (C) Tor formed by intense weathering related to vertical and sheeting joints. (D) Wonhyobong composed of group of pinnacle tors. (E) Block stream formed by an accumulation of boulder and angular blocks.
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04.9 ORBICULAR GABBRO The orbicular gabbro, designated as the Natural Monument No. 267, is the sole orbicular gabbro in South Korea. Because the orbicular gabbro is only reported less than 10 sites in the world, it has very high geological value and capability of tourism resources. This site thus will be a leading site of the Busan National Geopark through the proper protection system and trail course. The orbicules in the site are classi ed into four types such as proto-orbicules, single-shell orbicules, multi-shelled orbicules, and complex orbicules, according to the state of growth and the number of shells. The orbicules have cores of chie y plagioclase and olivine which are surrounded by alternating plagioclase-rich and olivine- or augite-rich shells.
Fig. 16. (A) Panoramic view of orbicular gabbro. (B) Proto-core. (C) Single-shelled orbs. (D) Multi-shelled orbs.
04.10 BAEKYANGSAN The Baekyangsan (642 m) geosite, composed of the Cretaceous sedimentary rocks (Icheonri Formation), andesitic lava, andesitic pyroclastic rocks, tu aceous sedimentary rocks, rhyolitic pyroclastic rocks, intrusive rocks. Especially, limestone caves and calcic paleosols, lying at hillside of the mountain, are observed in the lacustrine sedimentary strata. In addition, there are several experience centers in this geosite, providing various natural and ecology experience activities such as wetland and forest experiences.
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Fig. 17. (A) Limestone cave in the lacustrine sedimentary strata. (B) Calcrete deposits in the tu aceous sediments. (C) Tu aceous sediments. (D) Sungjigok falls.
23 05 SONGDO PENINSULA GEOSITE (BUSAN NATIONAL GEOPARK) Busan National Geopark Field Guidebook
05 SONGDO PENINSULA GEOSITE (BUSAN NATIONAL GEOPARK) At this stop, we will observe the Late Cretaceous Dadaepo Formatio in the Dadaepo Basin. This stop is located on the southern coast of Busan City. STOP-1. Lower Dadaepo Formation
Fig. 18. Outcrop photographs of Stop-1. (a) Lower Dadaepo Formation. (b) Conglomerate layers. (c) Chert clasts in the conglomerates. (d) Reduction spots observed in reddish siltstone.
About 70-80 million years ago, the Songdo Peninsula area started pulling apart to create the bowl-shaped Dadaepo Basin, and sediments deposited to form the Dadaepo Formation. The beginnings of this formation were made by repeated river ooding. As the basin deepened it became a lake, and the Upper Dadaepo Formation was deposited. The Lower Dadaepo Formation is easy to observe near the coastal cli s of the Songdo peninsular geotrail. The Lower Dadaepo Formation is comprised of channelized conglomerates and sandstones that are intercalated in dominantly purple mudstones, indicating repeated ooding. Unlike the Upper Dadaepo Formation, only a small amount of volcanic materials can be found in the Lower Dadaepo Formation. Various structures like reduction spots, bioturbation, and calcretes can be seen in red beds, with chert clasts, cross-bedding, scour-and- ll structures in the conglomerate. White to light greenish grey circular structures called reduction spots can be observed in the red sandstone and siltstone of the Lower Dadaepo Formation. These spots usually are elliptical, with a nuclear in the middle that originated from the outside. Although the beds were originally red, the burial migration of ground- water has caused the reduction of ferric oxide to ferrous oxide, which is slightly soluble. The resulting color change is caused by the leaching of reduced iron. Thick conglomerates of the Lower Dadaepo Formation can be well observed at this site. In this area, there are six to eight conglomerate layers formed by channel ooding. These conglomerates are composed of many kinds of clasts, including chert, having various sizes and shapes.
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Characteristically, there are many chert clasts in conglomerate. Chert is formed by either, deposits of dead silicate skeletals of organisms, or precipitation of silicate components. Chert clasts in conglomerates are usually translucent brick colored, including white, grey, and brown clasts from time to time. Very small radiolarian fossils can be observed under the microscope.
STOP-2. Calcic paleosol (calcrete) and normal fault Following the Songdo Peninsula trail, there are nodules in sedimentary rocks that are either white or light pink. These are pedogenic calcretes (calcic palesols). Calcrete generally forms in arid or semi-arid climate when minerals leach from the upper layer of the soil and accumulate in the next layer. The form of calcrete di ers by the maturity, which can be either nodular or bedding-like. If the maturity is low, calcrete nodules are usually small, and it becomes bigger in size or forms a layer with increasing maturity. Calcretes are important indicators of the past climate. Commonly found calcretes in red beds of Dadaepo Formation indicate that the climate was arid during that time.
Fig. 19. Outcrop photographs of Stop-2. (a) Normal fault and calcic paleosol layer. (b) Intra-clast type calcrete.
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Red sandstone with siltstone, grey conglomerate, and calcic paleosol are piled in order until they suddenly lose consistency at this site due to a fault. This fault has a hanging wall below the footwall, displaying a good example of a normal fault. Near the main fault, smaller faults can be seen. Because the Dadaepo Formation is interpreted to have formed in a pull-apart basin that was opened by NNE trending strike-slip faults, many normal faults that have formed due to tension can be observed in the Dadaepo Formation. They can provide important information about the tectonic environment and formation mechanism of the Dadaepo Basin.
STOP-3. Dinosaur egg nest fossils and rhylotic dyke swarms
Fig. 20. Outcrop photographs of Stop-3. (a, b) Dinosaur egg fossils in the lower Dadaepo Formation. (c, d) Rhyolitic dike swarms.
The Songdo Peninsula was a paradise for dinosaurs when the Lower Dadaepo Formation was under deposition during the late Cretaceous (ca. 70 Ma). Dinosaurs roamed the land and the area surrounding the lake to nd nesting grounds. This evidence is well preserved in the Lower Dadaepo Formation in the form of footprints, eggs, and bone fossils. Recently, attention has been drawn to the area as dinosaur eggs in the red siltstone and sandstone have been discovered. The size of the eggs are about 10 cm, 10 of which were found in nearly perfect condition. Following the Songdo Peninsula trail, yellowish rocks that cut through the wood- en-panel-like parallel bedding can be observed. These bright rocks are rhyolitic dykes. Three dykes are tilted to the same direction, and this kind of multiple dykes are called a dyke swarm. Because rhyolitic dykes are stronger than the surrounding sedimentary rocks, exotic and beautiful landforms were formed by di erential erosion.
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STOP-4. Ignimbrite (dacitic tuff) and Upper Dadaepo Formation
At this stop, the red beds changes to dark grey tu aceous sediment. So we can de ne this site as a boundary between the Lower and Upper Dadaepo formations. Such a dramatic change is thought to have been caused by environmental chang- es from a river to a lake. An unusual red bed containing a lot of white feldspar crystals can be found in the transition zone from the Lower to the Upper Dadaepo formations. This is the ignimbrite that owed into the lake during an explosive volcanic eruption. This ignimbrite is a keystone that tells us that there was active volcanism during the deposition of the Upper Dadaepo Formation, and the environmental change to a deep lake was related to this volcanic activity. The Upper Dadaepo Formation is dominated by tu aceous sediments derived from volcanic activity, and bedding plane, crossbedding, ripple marks, and scour-and- ll structures are well preserved. Volcanic rock fragments derived from volcanic activity that occurred near the lake margins are common in this forma- tion. The transition from the Lower to Upper Dadaepo formation is demarcated by an intercalation of a silicic ignimbrite.
Fig. 21. Outcrop photograph of Stop-4. (a) An exposure showing the sharp contacts between the massive purple mudstone of the lower Dadaepo Formation, a few meter-thick and massive dacitic ignimbrite layer in the middle, and the well-bedded sandstone/gray mudstone succession of the upper Dadaepo Formation. (b) Close-up of the dacitic crystal-rich and pumice-free ignimbrite. (c) Cross-strati ed tu aceous sandstones with volcanogenic clasts. (d) Volcanogenic clasts in the tu aceous sandstones and conglomerates.
28 Busan National Geopark Field Guidebook
STOP-5. Basaltic lava overlying the upper Dadaepo Formation There was a big lake called the Dadaepo Basin in the Songdo area during the late Cretaceous Period, and sediments were deposited at lake margins to form the Dadaepo Formation. One day, a volcano erupted near this area to create a geologi- cal site such as this, with lava owing into the lake to cover the Dadaepo Forma- tion, which existed before. The radiometric age of the basalt here is estimated to be about 70 million years old. The boundary between basalt and the Dadaepo Formation is irregular, with the basalt showing typical characteristics of lava, such as porphyritic and vesicular textures, and auto brecciation. Dark gray lavas rest on cross-strati ed tu aceous sandstones of the Dadaepo Formation on the Songdo Peninsula, and are in turn overlain by thick volcanic breccias. The contact between the lavas and tu aceous sandstones is irregular. Load structures, formed by sinking of the overlying lavas, and ame structures produced by squeezing upward of sediments into the overlying lavas are frequently observed along the contact. The feldspar phenocrysts in the lavas are aligned nearly parallel to the bedding of the underlying sandstone beds. Auto-brecciated fragments and stretched vesicles are also observed in the lavas.
Fig. 22. Outcrop photograph of Stop-5. (a) Panoramic view of the upper Dadaepo Formation, composed of greenish/gray cross-strati ed tu aceous sandstone and arkosic sandstone, and the overlying basaltic andesite (lava ow). (b) Close-up of irregular loaded scoured contact between the basaltic andesite and the underlying tu aceous sandstone and overlying captured in the underlying sandstone. (c-e) Close-up of the basaltic andesite showing auto-brecciated lava fragments and stretched vesicles and feldspar phenocrysts.
29 06HAEDONG YONGGUNGSA (TEMPLE) Busan National Geopark Field Guidebook
06 HAEDONG YONGGUNGSA (TEMPLE) Haedong Yonggungsa Temple is situated on the coast of the north-eastern portion of Busan. This superb attraction o ers visitors the rare nd of a temple along the shore line; most temples in Korea are located in the mountains. Haedong Yonggungsa Temple was rst built in 1376 by the great Buddhist teach- er known as Naong during the Goryeo Dynasty. Haesu Gwaneum Daebul (Seawa- ter Great Goddess Buddha), Daeungjeon Main Sanctuary, Yongwangdang Shrine, Gulbeop Buddhist Sanctum (enclosed in a cave), and a three-story pagoda with four lions can all be seen looking out over the ocean.
Fig. 23. Photographs of the Haedong Yonggungsa.
The main sanctuary of the temple was reconstructed in 1970 with careful attention paid to the colors that were traditionally used in such structures. On the right-hand side, inside the a cave, is a uniquely designed Buddhist sanctum, while situated just in front of the main sanctuary is a three-story pagoda with four lions. The four lions are symbolizing joy, anger, sadness, and happiness. Other special sites at the temple are the 108 stairs and stone lanterns lining the rocky landscape. After going down the 108 steps, one will be delighted with the beauty of the temple. Midway down the 108 steps one can stop and enjoy the calming sounds of the waves, and view the majestic sunrise.
Many people often come to this spot on New Year's Day to make a wish for the new year as they watch the sun come up. April is an especially beautiful time of year with cherry blossoms in full bloom. The birth of Buddha is also celebrated in the fourth month of the lunar calendar and o ers a spectacular night view as the temple area is aglow with lit lanterns (from http://english.visitkorea.or.kr/).
31 07 REFERENCES Busan National Geopark Field Guidebook
07 REFERENCES
Chang, C.J., Chang, T.W., 1998. Movement History of the Yangsan Fault based on Paleos- tress Analysis. The Journal of Engineer Geology of Korea 8, 35-49 (in Korean with English abstract).
Chang, K.H., 1975. Cretaceous stratigraphy of southeast Korea. Journal of the Geological Society of Korea 11, 1–23.
Chang, K.H., Park, S.O., 1997. Aspects of tectonics and volcanism recorded in Cretaceous medial Kyongsang Basin, SE Korea. Economic and Environmental Geology 30, 143–151 (in Korean with English abstract).
Chang, K.-H., Suzukib, K., Parka, S.-O., Ishida, K., Uno, K., 2003, Recent advances in the Cretaceous stratigraphy of Korea. Journal of Asian Earth Sciences 21, 937-948.
Chang, K.H., Woo, B.G., Lee, J.H., Park, S.O., ,Yao, A., 1990, Cretaceous and Early Cenozoic stratigraphy and history of eastern Kyongsang Basin, S. Korea. Journal of the Geological Society of Korea 26, 471-487.
Cho, H., Son, M., Kim, I.-S., 2007. Anisotropy of magnetic susceptibility (AMS) of the granitic rocks in the Eastern Region of the Yangsan Fault. Economic and Environmental Geology 40, 171-189 (in Korean with English abstract).
Choi, H.I., 1986. Sedimentation and evolution of the Cretaceous Gyeongsang Basin, southeastern Korea. Journal of the Geological Society of London 143, 29–40.
Choi, J.-H., Yang, S.-J., Kim, Y.-S., 2009, Fault zone classi cation and structural characteris- tics of the southern Yangsan fault in the Sangcheon-ri area, SE Korea. Journal of the Geological Society of Korea 45, 9-28 (in Korean with English abstract).
Choo, C.O., Chang, T.W., 2000. Characteristics of clay minerals in gouges of the Dongrae fault, southeastern Korea, and implications for fault activity. Clays and Clay Minerals 48, 204-212.
Chough, S.K., Kwon, S.-T., Ree, J.-H., Choi, D.K., 2000, Tectonic and sedimentary evolution of the Korean peninsula: a review and new view. Earth-Science Reviews 52, 175-235.
Chough, S.K., Sohn,, Y.K., 2010, Tectonic and sedimentary evolution of a Cretaceous continental arc–backarc system in the Korean peninsula: New view. Earth-Science Reviews 101, 225-249. Chun, S.S., Chough, S.K., 1992. Tectonic history of Cretaceous sedimentary basins in the southwestern Korean Peninsula and Yellow Sea. In: Chough, S.K. (Ed.), Sedimentary Basins in the Korean Peninsula and Adjacent Seas. Korean Sedimentology Research Group, Special Publication. Hanlimwon Publishers, Seoul, pp. 60–76.
Hwang, B.H., Ernst, W.G., McWilliams, M., Yang, K., 2008, Geometric model of conjugate faulting in the Gyeongsang Basin, southeast Korea. Tectonics, 27, TC6015.
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Hwang, B.H., Lee, J.D., Yang, K., McWilliams, M., 2007a, Cenozoic strike-slip displacement along the Yangsan fault, southeast Korean Peninsula: International Geology Review 49, 768–775.
Hwang, B.H., McWilliams, M., Son, M., Yang, K., 2007b, Tectonic implication of A-type granites across the Yangsan fault, Gigye and Gyeongju areas, southeast Korean Peninsu- la. International Geology Review 49, 1094–1102.
Hwang, B.H., Son, M., Kim, J.-S., Yang, K., Kim, J.-S., 2012, Cenozoic wrench tectonics and oroclinal bending in SE Korea. International Geology Review 54, 642-653.
Hwang, B.H., Son, M., Yang, K., Yoon, J., Ernst, W.G., 2008b, Tectonic evolution of the Gyeongsang Basin, southeastern Korea from 140 Ma to the present, based on a strike-slip and block-rotation tectonic model. International Geology Review 50, 343–363.
Hwang, S.K., Woo, B.G., 2009, Role of the Cheongryangsan Conglomerate and the Osipbong Basalt in Classifying Stratigraphy of the Hayang Group, Yeongyang Subbasin. Journal of Petrological Society of Korea 18, 181-194 (in Korean with English abstract).
Jeon, Y.M., Sohn, Y.K., 2008. Characteristics, emplacement processes, and stratigraphic implications of the basalts intercalated in the Hayang Group, Cretaceous Gyeongsang Basin, SE Korea. Journal of the Geological Society of Korea 44, 707–727 (in Korean with English abstract).
Jeong, J.O., Jeon, Y.M., Sohn, Y.K., 2005. Petrography and modal compositional variations of the Cretaceous Kusandong Tu , Korea. Journal of the Geological Society of Korea 41, 73–90 (in Korean with English abstract).
Kang, H.-C., Paik, I.S., 2013, Review on the geological ages of the formations in the Gyeongsang Basin, Korea. Journal of the Geological Society of Korea 49, 17-29 (in Korean with English abstract).
Kang, K., Cho, H., Kim, H.J., Kim, S., Son, M., Kim, J.-S. and Paik, I.S., 2014, The value of the Busan National Geopark's geosites and geoheritages: a case study focused on geotrail. Journal of the Geological Society of Korea 50, 21-41 (in Korean with English abstract).
Kang, J.-H., Lee, D.-S., 2008, Geological structure around Andong fault system, Pungcheon-myeon, Andong, Korea. Journal of Petrological Society of Korea 17, 83–94 (in Korean with English abstract).
Kang, J.-H., Ryoo, C.-R., 2009, The movement history of the southern part of the Yangsan Fault Zone interpreted from the geometric and kinematic characteristics of the Sinheung Fault, Eonyang, Gyeongsang Basin, Korea. Journal of the Petrological Society of Korea 1, 19-30 (in Korean with English abstract).
Kim, I.-S., 1992. Origin of tectonic evolution of the East Sea (Sea of Japan) and the Yangsan Fault System: a new synthetic interpretation. Journal of the Geological Society of Korea 28, 84-109 (in Korean with English abstract).
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Kim, S.B., Chough, S.K., Chun, S.S., 2003. Tectonic controls on spatio-temporal develop- ment of depositional systems and generation of ning-upward basin lls in a strike-slip setting: Kyokpori Formation (Cretaceous), south-west Korea. Sedimentology 50, 639–665.
Kim, S.B., Kim, Y.-G., Jo, H.R., Jeong,K.S., Chough, S.K., 2009. Depositional facies, architecture and environments of the Sihwa Formation (Lower Cretaceous), mid-west Korea with special reference to dinosaur eggs. Cretaceous Research 30, 100–126.
Kim, Y.-S., Jin, K., 2006, Estimated earthquake magnitude from the Yugye Fault displace- ment on a trench section in Pohang, SE Korea. Journal of the Geological Society of Korea. 42, 79-94 (in Korean with English abstract).
Kyung, J.B., Lee, K., Okada, A., 1999, A Paleoseismological Study of the Yangsan Fault- Analysis of Deformed Topography and Trench Survey. Journal of the Korean Geophysical Society 2, 155-168 (in Korean with English abstract).
Lee, D.W., 1999. Strike-slip fault tectonics and basin formation during the Cretaceous in the Korean Peninsula. Island Arc 8, 218–231.
Lee, S.H., Chough, S.K., 1999. Progressive changes in sedimentary facies and stratal patterns along the strike-slip margin, northeastern Jinan Basin (Cretaceous), southwest Korea: implications for di erential subsidence. Sedimentary Geology 123, 81–102.
Maruyama, S., Isozaki, Y., Kimura, G., Terabayashi, M., 1997. Paleogeographic maps of the Japanese Islands: Plate tectonic synthesis from 750 Ma to the present. The Island Arc 6, 121-142.
Ryang, W.H., Chough, S.K., 1997. Sequential development of alluvial/lacustrine system: Southeastern Eumsung Basin (Cretaceous), Korea. Journal of Sedimentary Research 67, 274–285.
Won, C.K., Kang, P.C., Lee, S.H., 1978. Study on the tectonic interpretation and igneous pluton in the Gyeongsang Basin. Journal of the Geological Society of Korea 14, 79–92 (in Korean with English abstract).
Xu, J.W., Zhu, G., Tong, W.X., Cui, K.R., Lin, Q., 1987. Formation and evolution of the Tancheong-Lujiang wrench fault system: A major shear system to the northwest of the Paci c Ocean. Tectonophysics 134, 273-310.
Zhang, Y.Q., Dong, S., Shi, W., 2003, Cretaceous deformation history of the middle Tan-Lu fault zone in Shangdong Province, eastern China. Tectonophysics 363, 243-258.
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NATIONAL GEOPARK FIELD GUIDEBOOK