Consideration for Historical Application of Augen Gneiss and Petrographic Characteristics for Rock Properties of Donghachong Tomb from Royal Tombs of Neungsanri in Buyeo, Korea

부여 능산리고분군 동하총 석재의 암석기재적 특성과 안구상편마암의 역사적 활용성 고찰

Abstract

The Donghachong tomb from Royal Tombs at Neungsanri is composed of 15 sides including the floor, and the most highly proportion of rock, two-mica granite, are used on the 7 sides (46.6%). Also, augen gneiss consist with another 3 sides (20.0%), and each of the remaining 3 sides (6.7%) are made up of granodiorite, gneissous granite and leucocratic granite, all of which were used to comprise the tabural stone. Meanwhile, the two floors of the burial chamber and the front chamber, are made up of brick-shaped amphibole schist (13.3%). These rocks are occurred in the Buyeo area and their provenance sites are located at the side of Guemgang river. The Memorial Stone for Liu Renyuen in Tang China is a typical augen gneiss showing distinct schistosity and augen texture. This rock has the same petrographic characteristics with the rocks used to build the Donghachong tomb, Sanjikri dolmens and Setapri pagoda in Buyeo. This augen gneiss is distributed from the Jeungsanri in Buyeo to Dukjiri in Gongju as a large scaled rock body, and where currently are the quarries to produce stone aggregates, garden and landscape rocks. Thus, it is highly probable that the site around Buyeo was the source area of augen gneisses since the Bronze Age. However, while augen gneiss is easier to form into shapes it should have disadvantages when it comes to painting on the tomb wall because of their petrographic characteristics of low strength and dark color. Therefore, it is very intriguing to investigate which transportation method the people of Baekje chose with consideration of the distance and terrain, efficiency and convenience.

능산리고분군 동하총은 바닥을 포함하여 15면으로 이루어졌으며, 가장 많이 사용한 암석은 복운모화강암으로 7면(46.6%)에 활용하였다. 또한 안구상편마암 3면(20.0%), 화강섬록암, 편마상화강암 및 우백질화강암을 각각 1면(6.7%)으로, 모두 판석으로 구성하였다. 현실과 전실 바닥의 각섬석편암(13.3%)은 모전석으로 사용하였다. 이 암석들은 모두 부여 일대에서 산출되며 주로 금강변에 산지가 분포한다. 당유인원기공비는 뚜렷한 편리와 안구상조직을 갖는 전형적인 안구상편마암이다. 이 암석은 동하총, 산직리 고인돌 및 세탑리 오층석탑의 일부 석재에 활용한 안구상편마암과 같은 종류이다. 이 안구상편마암은 부여 증산리에서 공주 덕지리로 연장되는 대규모 암체로 분포하며, 현재 정원석과 조경석 및 골재용 채석장이 있는 것으로 보아, 부여일대에서는 청동기시대부터 안구상편마암을 활용하기 위한 공급지가 있었을 개연성은 충분하다. 이는 암질이 약해 가공에 수월성은 있으나, 어두운 색을 띠어 벽화의 바탕과 각자에는 단점도 있었을 것이다. 따라서 백제인들이 거리와 지형 및 효율성과 수월성을 두고 어떤 운송체계를 선택했을지 매우 흥미로운 일이다.

Fig. 1. Geological map around the Royal Tombs in Neungsanri and Buyeo area.

Fig. 2. The present state of Donghachong tomb from Royal Tombs in Neungsanri. (A) Southern entrance of the tomb. (B)Inside stones of tumulus painted four side guardians. (C) Lotus and cloud patterns painted in inside of the roof stone.

Fig. 3. Occurrences and present state of the Monument for Liu Renyuan of Tang China. (A) The Monument for Liu Renyuan discovered from Busosan mountain. (B) Rock fragments carving the Chinese letter of the Monument for Liu Renyuan. (C) The present state of the Monument for Liu Renyuan conserved in Buyeo National Museum. (A and B referred from National Museum of Korea, 2010).

Fig. 4. Lithological maps for rock properties in four side of Donghachong tomb from Royal Tombs in Neungsanri.

Fig. 5. Lithological and petrographic images of two-mica granite (A, D), augen gneiss (B, E) and amphibole schist (C, F),respectively.

Fig. 6. Lithological and petrographic images of granodiorite (A, D), gneissous granite (B, E) and leucocratic granite (C, F),respectively.

Fig. 7. Microphotographs showing the two-mica granite (A), augen gneiss (B) and amphibole schist (C), respectively. Am;amphibole, Bt; biotite, Ch; chlorite, Pl; plagioclase, Q; quartz.

Fig. 8. X-ray powder diffraction patterns of two-micagranite (A) and amphibole schist (B), respectively. M;mica group minerals, Pl; plagioclase, Q; quartz, K; alkali feldspar, Ch; chlorite, Am; amphibole.

Fig. 9. Diagrams showing the magnetic susceptibilities of rock properties from the Donghachong tomb and presumed source rocks near the Buyeo area.

Fig. 10. Schematic distributions of various rocks along the Geumgang river in Buyeo area (modified after Lee et al., 2015).

Fig. 11. Field occurrences of porphyritic granodiorite (A), and ancient cutting traces (B and C) from Okyeobong in Ganggyeong (modified after Lee et al., 2007).

Fig. 12. Monument for Liu Renyuan of Tang China (A), typical texture of augen in gneiss (B) and stereoscopic view on augen gneiss of the monument (C).

Fig. 13. Field occurrences of Sangikri dolmens (A), ancient cutting traces on rocks of dolmen surface ( B) and typical texture of augen in gneiss (C) of the dolmens.

Fig. 14. Field occurrences of Setapri stone pagoda (A), augen gneiss used in basement rocks (B) and typical texture of augen in gneiss (C) of rock property.

Fig. 15. Quarry showing augen gneiss for garden, landscape and aggregate stones from Deokjiri of Tancheon in Gongju (A,B) and typical texture of augen in gneiss (C) from the quarry.

Fig. 16. Microphotographs showing the augen gneiss (A to C) and X-ray powder diffraction patterns of augen gneiss (D) of the Deokjiri quarry. Bt; biotite, M; mica group minerals, Pl; plagioclase, Q; quartz, K; alkali feldspar.

Fig. 17. Diagrams showing the magnetic susceptibilities of augen gneiss from various cultural properties near the Buyeo and presumed source rocks of the augen gneiss in the Deokjiri quarry.