보고서 정보
주관연구기관 |
한국지질자원연구원 Korea Institute of Geoscience and Mineral Resources |
연구책임자 |
송교영
|
참여연구자 |
김성원
,
고경태
,
김복철
|
보고서유형 | 최종보고서 |
발행국가 | 대한민국 |
언어 |
한국어
|
발행년월 | 2013-12 |
주관부처 |
미래창조과학부 KA |
사업 관리 기관 |
한국지질자원연구원 Korea Institute of Geoscience and Mineral Resources |
등록번호 |
TRKO201400005800 |
DB 구축일자 |
2014-06-07
|
초록
▼
1. 서 언
1:50,000 축척의 정읍도폭 지질조사 사업은 2012년부터 시작하여 2013년까지 2년간에 걸쳐 미래창조과학부 출연과제로 수행되었다.
정읍도폭은 국토지리정보원에서 발간한 축척 1:50,000의 정읍 도엽(도엽번호 NJ 52-1-11)의 남쪽 2/3에 속하는 지역으로서 Bessel TM 좌표체계로 경도 126O 45' 00" ~ 127O 00' 00", 북위 35O 30' 00" ~ 35O 40' 00" 내에 위치한다. 행정구역상
1. 서 언
1:50,000 축척의 정읍도폭 지질조사 사업은 2012년부터 시작하여 2013년까지 2년간에 걸쳐 미래창조과학부 출연과제로 수행되었다.
정읍도폭은 국토지리정보원에서 발간한 축척 1:50,000의 정읍 도엽(도엽번호 NJ 52-1-11)의 남쪽 2/3에 속하는 지역으로서 Bessel TM 좌표체계로 경도 126O 45' 00" ~ 127O 00' 00", 북위 35O 30' 00" ~ 35O 40' 00" 내에 위치한다. 행정구역상으로 조사지역의 중심부에 전라북도 정읍시가 위치하고 정읍시를 중심으로 정읍시의 남서부부터 정읍시 입암면, 소성면, 덕천면, 영원면, 이평면, 정우면, 태인면, 옹동면, 북면, 칠보면, 산내면이 시계 방향으로 위치하고 있으며, 도폭지역 의 남서부에 고창군 성내면이 도폭지역의 남동부에 순창군 쌍치면이 위치하고 있다.
Abstract
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1. INTRODUCTION
The geological map of the Jeongeup sheet was mapped on a 1:50,000 scale as one of the fundamental projects of the Korea Institute of Geoscience and Mineral Resources (KIGAM) during 2010∼2011, funded by the Ministry of Science, ICT and Future Planning of Korea. The quadrangle, whic
1. INTRODUCTION
The geological map of the Jeongeup sheet was mapped on a 1:50,000 scale as one of the fundamental projects of the Korea Institute of Geoscience and Mineral Resources (KIGAM) during 2010∼2011, funded by the Ministry of Science, ICT and Future Planning of Korea. The quadrangle, which lies in the south-western part of the Korean peninsula, is bounded by the coordinates of longitude 126°45'00"~127°00'00" East and latitude 35°30'00"~35°40'00" North. The survey area is located in the northern part of the Naejangsan National Park area, so it is some difficult to access and investigation. Method of the geological investigation was wholly dependent on the reconnaissance, and during the fieldwork 1:25,000 scale topographic maps were used. The administrative district of the survey area includes most of the Jeongeup city, a part of the Gochang-gun and the Sunchang-gun of the JeollaNamdo province.
The topography of the Jeongeup quadrangle is characterized by a mountain range in the southeastern part of the quadrangle, a broad plains in the north and northwestern part. A NNE trend big lineament divides the Jeongeup quadrangle to two blocks geological distribution and topographically. And NE and NNW trend lineaments are located in the southwestern part of the Jeongeup quadrangle. A drainage pattern is NNE and NNW trend which flows from south to north, which make large depositional plains along the rivers.
This topography is closely related to the geology and geological structure of the quadrangle.
2. GENERAL GEOLOGY
The Jeongeup sheet area consists of the Paleozoic schist, the Triassic granite, the Jurassic granites, the Cretaceous volcanics and sediments and the Quaternary sedimentary rocks. The geological successions of the Jeongeup sheet are presented in Table 1.
2.1. Paleozoic Schist
The Paleozoic schist which belong to the Okcheon Belt as a metamorphic sediments, is quartz mica schist including a thin bedded quartzite or metasandstone and limestone.
The Paleozoic schists are a basement of the Jeongeup sheet, and occur in the south-central part of the quadrangle as scattered small xenolith body in the Jurassic granite and in the western part as a NE trend belt type.
Schistosity foliation of schists are usually regular as N24-40OE/18-40ONW in the south-central part of the quadrangle.
This has been classified as age unknown metasediments, so we are trying to find out the age of this rock using the SHRIMP U-Pb zircon dating. The SHRIMP U-Pb detrital zircon dating of metasandstone yielded a weighted mean 206Pb/238U age of ca. 335 Ma, indicative of the upper limit Paleozoic Carboniferous sedimentation. And the SHRIMP U-Pb zircon dating of granodiorite which had intruded into metasandstone is a weighted mean 206Pb/238U age of 219±3 Ma, indicative of the Late Triassic intrusion. Thus, we can infer geological age of this rock as the late Paleozoic Era.
2.2. Triassic Foliated Biotite Granite
The Triassic foliated biotite granite which belonging to the Songrim granites occurs in the northeastern part of the Jeongeup sheet and extends to the Gimje sheet. This is intruded by the Jurassic two mica granite. The total alkali versus silica composition of this granite shows granite to granodiorite in composition.
This granite shows well foliations which are usually regular as N40-70OE/60-70OUNW and large variation in composition across foliation.
It shows gray or light gray color and has a medium-grained equi-granular texture. Mineral assemblage of foliated biotite granite is represented by quartz, alkali feldspar, plagioclase and biotite together with minor amount of apatite, zircon, allanite and opaque minerals. Many alkali feldspars show carlsbad twining and are decomposed into perthite. Biotite is often replaced by chlorite and sericite.
The SHRIMP U-Pb zircon dating of this granite is a weighted mean 206Pb/238U age of 228±3 Ma, indicative of the Late Triassic intrusion.
2.3. Jurassic Granites
The Jurassic granites, which belong to so-called the Daebo Granite, are foliated hornblende-biotite granite, biotite granite, two mica granite, porphyritic granodiorite and muscovite-biotite granite in the Jeongeup sheet.
Foliated hornblende-biotite granite occurs in south part of the Jeongeup sheet as a NE trend belt type and extends to the Galdam sheet. This is intruded by the Jurassic two mica granite and is covered by the Cretaceous volcanics in unconformity. The total alkali versus silica composition of this granite shows granodiorite in composition.
Foliated hornblende-biotite granite shows well-developed foliations which are N32-55OE/28-55ONW and N70-72OE/28-43OSE according to the locality.
It shows dark gray or greenish gray color and has a medium to coarse grained equi-granular texture. This granite is characterized by subhedral to anhedral alkali feldspar phenocrysts ranging 1~2cm and commonly occurs as foliated granite although some parts are massive. Mineral assemblage of foliated hornblende-biotite granite is represented by quartz, alkali feldspar, plagioclase, biotite and hornblende with minor amount of titanite, zircon, allanite and opaque minerals. Many alkali feldspars show carlsbad twining and are decomposed into perthite. Biotite is often replaced by chlorite and sericite.
The SHRIMP U-Pb zircon dating of foliated hornblende-biotite granite is a a weighted mean 206Pb/238U age of 174±2 Ma, indicative of the Middle Jurassic intrusion.
Biotite granite occurs in the southwestern part of the Jeongeup sheet and is intruded by the Jurassic two mica granite and muscovite-biotite granite. It shows light gray color, a medium to coarse-grained equi-granular texture. This granite contains subhedral to anhedral alkali feldspar phenocrysts ranging 1~3cm and occurs commonly as porphyritic granite although some parts are massive without feldspar phenocryst. Many alkali feldspars show carlsbad twining and are decomposed into perthite.
Biotite granite contains a fine-grained mafic microgranular enclave. It is a granite to granodiorite in composion according to total alkali versus silica composition. Mineral assemblage comprises quartz, alkali feldspar, plagioclase and biotite with minor amount of titanite, zircon, allanite and opaque mineral.
Biotite is often replaced by chlorite and sericite.
The SHRIMP U-Pb zircon dating of biotite granite is a weighted mean 206Pb/238U age of 171±3 Ma, indicative of the Middle Jurassic intrusion.
Two mica granite occurs in the central part to northeastern part of the Jeongeup sheet and is intruded by the Jurassic muscovite-biotite granite. This is the major rock in sheet. It shows light gray color, a medium to coarse-grained equi-granular texture. This granite contains subhedral to anhedral alkali feldspar phenocrysts ranging 1~3cm according to the place, and commonly occurs as massive granite. A alkali feldspars show carlsbad twining usually.
It is a granite to granodiorite in composion according to total alkali versus silica composition. Mineral assemblage comprises quartz, alkali feldspar, plagioclase and biotite together with minor amount of apatite, zircon, allanite and opaque mineral.
Two mica granite is characterized by low magnetic susceptibility with 0.024∼0.061 mSI, while muscovite-biotite granite, biotite granite and foliated hornblende-biotite granite is 1.63∼14.4, 1.66∼10.9 and 3.59∼13.5 mSI each rock.
The SHRIMP U-Pb zircon dating of two mica granite is a weighted mean 206Pb/238U age of 170±3 Ma, indicative of the Middle Jurassic intrusion.
Porphyritic granodiorite occurs in the northwestern part of the Jeongeup sheet as a small scale and extends to the Gimje sheet. This is intruded by the
Jurassic muscovite-biotite granite. It shows gray color, a medium to coarse-grained equi-granular texture. This granite contains subhedral to anhedral alkali feldspar phenocrysts ranging 2~4cm according to the place. A alkali feldspars show carlsbad twining and are decomposed into perthite. Major mineral assemblage comprises quartz, microcline, perthite, plagioclase and biotite, minor mineral composition is secondary muscovite, magnetite, apatite and epidote. Magnetic susceptibility is high, 13.1∼18.9 mSI, SHRIMP zircon U-Pb age is 170.0±2.6 Ma(Kim et. al., 2012).
Muscovite-biotite granite occurs in the northwestern part of the Jeongeup sheet. It shows light gray color and has a medium to coarse-grained equi-granular texture. This granite contains subhedral to anhedral alkali feldspar phenocrysts ranging 1~3cm and commonly occurs as porphyritic granite though some parts are massive.
This granite contains a fine-grained mafic microgranular enclave sometimes. It is a granite to granodiorite in composion according to total alkali versus silica composition. Mineral assemblage comprises quartz, alkali feldspar, plagioclase and biotite with minor amount of muscovite, titanite, zircon, allanite and opaque mineral. Biotite is often replaced by chlorite and sericite. This granite is characterized by muscovite which comprise primary ones and secondary ones all together. For the rest, it is almost same with biotite granite.
The SHRIMP U-Pb zircon dating of this granite is a weighted mean 206Pb/238U age of 166±2∼168±2 Ma, indicative of the Middle Jurassic intrusion.
2.4. Cretaceous Volcanic Rocks
The Cretaceous volcanic rocks occupy mainly the southeastern part of the Jeongeup sheet and extend to the Galdam sheet, the Sunchang sheet and the Shinheung sheet. They consist of the Baegyangsa volcanics which contains sediments and the Naejangsa volcanics.
The Baegyangsa volcanics occurs in the southeastern part of the Jeongeup sheet and cover over the Jurassic foliated hornblende-biotite granite and two mica granite in unconformity. They consist of andesitic lapilli tuff, tuff breccia, basaltic lava and sediments. The total alkali versus silica composition of the Baegyangsa volcanics shows a series of differentiation well and large variation from trachytic andesite, andesite to andesitic basalt. So these volcanic rocks can be classified to volcanic complex. Bedding of tuff developed well as N165OW/36ONE according to the locality. Basaltic lava often intercalated in andesitic lapilli tuff with 3∼4m thickness. Mineral assemblage comprises quartz, plagioclase, pyroxene, hornblende and biotite with minor amount of olivine and opaque mineral.
Sediments are intercalated in andesitic tuff in conformity. They are syn-depositional sediments with andesitic tuff. They consist of gravelly sandstone, coarse or medium-grained sandstone and mudstone. This sediments shows well bedding which are usually regular as N30-35OE/52-66OSE and large variation in composition across bedding.
The SHRIMP U-Pb detrital zircon dating of sandstone is a weighted mean 206Pb/238U age of 93 Ma, indicating the upper limit sedimentation of the Late Cretaceous. The SHRIMP U-Pb zircon dating of andesitic basalt which had extruded out on andesitic tuff is a weighted mean 206Pb/238U age of 75 Ma, indicative of the Late Cretaceous extrusion.
The Naejangsa volcanics occurs in the southeastern part and southern part of the Jeongeup sheet. It cover over the Jurassic foliated hornblende -biotite granite and the Baegyangsa volcanics in unconformity, and intrude to two mica granite. They consist of rhyolitic lapilli tuff, welded tuff and rhyolite.
The total alkali versus silica composition of the Naejangsa volcanics shows a series of differentiation well and large variation from dacite, rhyo-dacite to rhyolite. Strike and dip of rhyoritic flowage are very irregular, so there are no uniform trend in stratification of rhyolitic tuff. Rhyolite rock fragments which size is 2∼3cm are comprised in lapilli tuff according to the locality. Mineral assemblage comprises quartz, plagioclase, and biotite with minor amount of opaque mineral.
2.5. Quaternary deposits
Quaternary sedimentary deposits are widely distributed along the present river courses and on the plain of land. The old river sediments can be observed in the track of the quaternary diluvium. Alluvium consists of unconsolidated sand, beach sand, gravel and mud, and faint stratification can be recognized although sorting is very poor.
3. GEOLOGICAL STRUCTURE
Geological structures of the Jeongeup sheet are represented inferred brittle fault and four phase ductile deformation including regional foliation, mylonitized foliation and folding.
Lineaments analyzed from digital elevation model shows predominant orientation of NNE-SSW, NE-SW and NW-SE directions around the Jeongeup sheet.
There are only one inferred fault in quadrangle which is NNE-SSW direction from south to north area. This fault shows clear and big lineament which is extend from the Gimje sheet. There are no fault outcrop and displacement of distributed rocks in the quadrangle, so we can just infer the presence of fault with distribution of the Jurassic granites.
Four main deformational phases (D1, D2, D3 and D4) are recognized in the Jeongeup quadrangle, which is the ductile deformations including regional foliation, mylonitized foliation and folding. Most of pre-D1 structures were erased by subsequent intense and extensive D1 and D2 events and it is very difficult to establish pre-D1 events in this quadrangle.
The D1 is represented by regional schistose foliation in the Paleozoic schist, and is related to the NE-SW directed compression. The D2 is represented by strong foliation, and is related to the NE-SW directed compression which is recognized in the Late Triassic foliated biotite granite.
The D3 is represented by strong mylonitized foliation with NE-SW directed compression which is recognized in the Middle Jurassic foliated hornblende-biotite granite. This foliation shows a sinistral strike-slip sense.
The D4 is represented by folding with NE-SW trend folding plain, and is related to the NW-SE directed compression which is recognized in the Middle Jurassic foliated hornblende-biotite granite.
목차 Contents
- 표 지 ... 1
- 목 차 ... 7
- 1. 서 언 ... 9
- 2. 지 형 ... 11
- 3. 지질배경 및 층서 ... 13
- 4. 지질 각론 ... 17
- 가. 고생대 편암 ... 17
- 나. 트라이아스기 엽리상 흑운모화강암 ... 19
- 다. 쥬라기 화강암류 ... 21
- (1) 엽리상 각섬석-흑운모화강암 ... 22
- (2) 흑운모화강암 ... 24
- (3) 복운모화강암 ... 27
- (4) 반상 화강섬록암 ... 29
- (5) 백운모-흑운모화강암 ... 30
- 라. 백악기 화산암 ... 32
- (1) 백양사화산암류 ... 33
- (2) 내장사화산암류 ... 37
- 마. 제4기 충적층 ... 40
- 5. 지질연대 및 지화학 분석 ... 41
- 가. 고생대 편암 ... 41
- 나. 트라이아스기 엽리상 흑운모화강암 ... 42
- 다. 쥬라기 화강암류 ... 44
- (1) 엽리상 각섬석-흑운모 화강암 ... 44
- (2) 흑운모화강암 ... 46
- (3) 복운모화강암 ... 48
- (4) 백운모-흑운모화강암 ... 50
- 라. 백악기 화산암류 ... 52
- (1) 백양사화산암류 ... 52
- 6. 지질 구조 ... 56
- 가. 단층 ... 57
- 나. 엽리 구조 ... 58
- 참고 문헌 ... 61
- SUMMARY ... 63
- 끝페이지 ... 78
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