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Econ. Environ. Geol. 2023; 56(2): 115-123

Published online April 30, 2023

https://doi.org/10.9719/EEG.2023.56.2.115

© THE KOREAN SOCIETY OF ECONOMIC AND ENVIRONMENTAL GEOLOGY

Principle and Application of ‘Image-mapping’ in-situ U-Pb Carbonate Age-dating

Ha Kim1, Seongsik Hong1, Chaewon Park1, Jihye Oh2, Jonguk Kim2, Yungoo Song1,*

1Department of Earth System Sciences, Yonsei University, Seoul 03722, Korea
2Deep-sea and Seabed Mineral Resources Research Center, Korea Institute of Ocean Science and Technology, Busan 49111, Korea

Correspondence to : *yungoo@yonsei.ac.kr

Received: February 14, 2023; Revised: April 26, 2023; Accepted: April 27, 2023

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided original work is properly cited.

Abstract

We introduce a new ‘image-mapping’ in-situ U-Pb dating method using LA-ICP-MS, proposed by Drost et al. (2018), and show the characteristics and usability of this method through several examples of absolute age results determined by first applying it to samples from the Joseon Supergroup of the Early Paleozoic Era in Korea. Unlike the previous in-situ spot analysis, this in-situ U-Pb dating method for carbonate minerals can determine the absolute age with high reliability by applying the 'image-mapping' method of micro-sized domains based on micro-textural observation, as well as determine the absolute age of multiple geological 'events' that occurred after deposition. This was confirmed in the case of determining the syn-depositional age and the multiple post-depositional ages from carbonate minerals of the Makgol and the Daegi Formations. Therefore, if the 'image-mapping' in-situ U-Pb dating method is applied to determine the absolute age of various types of carbonate minerals that exist in various geological environments throughout the geologic era, it will be possible to secure new geological age information.

Keywords image-mapping, in-situ, U-Pb age-dating, carbonate, LA-ICP-MS

‘Image-mapping’ in-situ U-Pb 탄산염광물 연대측정법의 원리 및 적용

김하1 · 홍성식1 · 박채원1 · 오지혜2 · 김종욱2 · 송윤구1,*

1연세대학교 지구시스템과학과
2한국해양과학기술원 심해저광물자원연구센터

요 약

본 연구는 Drost et al. (2018)이 제안한 LA-ICP-MS를 이용한 새로운 ‘image-mapping’ in-situ U-Pb 연대측정법을 소개하고, 국내 전기고생대 조선누층군 시료를 대상으로 처음 적용하여 결정한 절대연대 결과 사례를 통해 이 방법의 특성과 활용성을 알리고자 한다. 탄산염광물을 대상으로 하는 ‘image-mapping’ in-situ U-Pb 연대측정법은 미세조직 관찰을 기초로 미소영역의 ‘image-mapping’ 법을 적용하여, 기존의 점 분석(spot analysis) in-situ 분석법과는 달리, 신뢰성 높은 절대연대를 결정할 수 있을 뿐 아니라, 생성 이후 일어난 복수의 지질학적 ‘사건’ 절대연대도 결정할 수 있다. 막골층과 대기층 탄산염광물로부터 퇴적연대와 함께 복수의 퇴적 이후의 연대를 결정한 적용 사례에서 이를 확인하였다. 따라서 이 같은 ‘image-mapping’ in-situ U-Pb 연대측정법이 전 지질시대에 걸쳐 다양한 지질학적 환경에서 존재하는 다양한 형태의 탄산염광물 절대연대 결정에 적용된다면, 새로운 지질학적 연대정보 확보가 가능할 것이다.

주요어 image-mapping, in-situ, U-Pb 연대측정, 탄산염광물, LA-ICP-MS

Article

Short Note

Econ. Environ. Geol. 2023; 56(2): 115-123

Published online April 30, 2023 https://doi.org/10.9719/EEG.2023.56.2.115

Copyright © THE KOREAN SOCIETY OF ECONOMIC AND ENVIRONMENTAL GEOLOGY.

Principle and Application of ‘Image-mapping’ in-situ U-Pb Carbonate Age-dating

Ha Kim1, Seongsik Hong1, Chaewon Park1, Jihye Oh2, Jonguk Kim2, Yungoo Song1,*

1Department of Earth System Sciences, Yonsei University, Seoul 03722, Korea
2Deep-sea and Seabed Mineral Resources Research Center, Korea Institute of Ocean Science and Technology, Busan 49111, Korea

Correspondence to:*yungoo@yonsei.ac.kr

Received: February 14, 2023; Revised: April 26, 2023; Accepted: April 27, 2023

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided original work is properly cited.

Abstract

We introduce a new ‘image-mapping’ in-situ U-Pb dating method using LA-ICP-MS, proposed by Drost et al. (2018), and show the characteristics and usability of this method through several examples of absolute age results determined by first applying it to samples from the Joseon Supergroup of the Early Paleozoic Era in Korea. Unlike the previous in-situ spot analysis, this in-situ U-Pb dating method for carbonate minerals can determine the absolute age with high reliability by applying the 'image-mapping' method of micro-sized domains based on micro-textural observation, as well as determine the absolute age of multiple geological 'events' that occurred after deposition. This was confirmed in the case of determining the syn-depositional age and the multiple post-depositional ages from carbonate minerals of the Makgol and the Daegi Formations. Therefore, if the 'image-mapping' in-situ U-Pb dating method is applied to determine the absolute age of various types of carbonate minerals that exist in various geological environments throughout the geologic era, it will be possible to secure new geological age information.

Keywords image-mapping, in-situ, U-Pb age-dating, carbonate, LA-ICP-MS

‘Image-mapping’ in-situ U-Pb 탄산염광물 연대측정법의 원리 및 적용

김하1 · 홍성식1 · 박채원1 · 오지혜2 · 김종욱2 · 송윤구1,*

1연세대학교 지구시스템과학과
2한국해양과학기술원 심해저광물자원연구센터

Received: February 14, 2023; Revised: April 26, 2023; Accepted: April 27, 2023

요 약

본 연구는 Drost et al. (2018)이 제안한 LA-ICP-MS를 이용한 새로운 ‘image-mapping’ in-situ U-Pb 연대측정법을 소개하고, 국내 전기고생대 조선누층군 시료를 대상으로 처음 적용하여 결정한 절대연대 결과 사례를 통해 이 방법의 특성과 활용성을 알리고자 한다. 탄산염광물을 대상으로 하는 ‘image-mapping’ in-situ U-Pb 연대측정법은 미세조직 관찰을 기초로 미소영역의 ‘image-mapping’ 법을 적용하여, 기존의 점 분석(spot analysis) in-situ 분석법과는 달리, 신뢰성 높은 절대연대를 결정할 수 있을 뿐 아니라, 생성 이후 일어난 복수의 지질학적 ‘사건’ 절대연대도 결정할 수 있다. 막골층과 대기층 탄산염광물로부터 퇴적연대와 함께 복수의 퇴적 이후의 연대를 결정한 적용 사례에서 이를 확인하였다. 따라서 이 같은 ‘image-mapping’ in-situ U-Pb 연대측정법이 전 지질시대에 걸쳐 다양한 지질학적 환경에서 존재하는 다양한 형태의 탄산염광물 절대연대 결정에 적용된다면, 새로운 지질학적 연대정보 확보가 가능할 것이다.

주요어 image-mapping, in-situ, U-Pb 연대측정, 탄산염광물, LA-ICP-MS

    Fig 1.

    Figure 1.Theoretical background of carbonate U-Pb age dating model based on the Tera-Wasserburg concordia diagram of 207Pb/206Pb versus 238U/206Pb isochron plot. Note that carbonate U-Pb age could be interpreted as either syn-depositional age or postdepositional age.
    Economic and Environmental Geology 2023; 56: 115-123https://doi.org/10.9719/EEG.2023.56.2.115

    Fig 2.

    Figure 2.Schematic diagram showing the steps of ‘image-mapping’ in-situ U-Pb carbonate age-dating method. Step 1 is ‘image-mapping’ analysis for selected domain of polished slab. Step 2 is ‘pixel’ analysis based on Iolite software. Step 3 is U-Pb age determination on the Tera-Wasserburg concordia diagram of 207Pb/206Pb versus 238U/206Pb isochron plot using Isoplot (modified from Drost et al., 2018).
    Economic and Environmental Geology 2023; 56: 115-123https://doi.org/10.9719/EEG.2023.56.2.115

    Fig 3.

    Figure 3.‘Image-mapping’ in-situ U-Pb age-dating results of sample SGJ74 from the Maggol Formation (Middle Ordovician). BSE image, element maps (left), and the Tera-Wasserburg concordia of 207Pb/206Pb versus 238U/206Pb isochron plots for age-determination.
    Economic and Environmental Geology 2023; 56: 115-123https://doi.org/10.9719/EEG.2023.56.2.115

    Fig 4.

    Figure 4.‘Image-mapping’ in-situ U-Pb age-dating results of sample SGJ77 from the Maggol Formation (Middle Ordovician). BSE image, element maps (left), and the Tera-Wasserburg concordia of 207Pb/206Pb versus 238U/206Pb isochron plots for age-determination.
    Economic and Environmental Geology 2023; 56: 115-123https://doi.org/10.9719/EEG.2023.56.2.115

    Fig 5.

    Figure 5.‘Image-mapping’ in-situ U-Pb age-dating results of sample SGJ21 from the Daegi Formation (Middle Cambrian). BSE image (A), Mg element-mapping image (B), and the Tera-Wasserburg concordia of 207Pb/206Pb versus 238U/206Pb isochron plots of selected calcite and dolomite domains for two different age-determination (C).
    Economic and Environmental Geology 2023; 56: 115-123https://doi.org/10.9719/EEG.2023.56.2.115

    Table 1 . LA-ICP-MS instrument settings.

    LA-ICP-MS instrument settings
    ICP-MSAgilent 7700
    Laser Ablation SystemNWR193
    Data Reduction S/WIolite
    Energy density (J/cm2)3.75
    Repetition rate (Hz)40
    Scan speed (um/s)10
    Sample depth (um)5
    Beam size (um)80
    Scan methodLine scan
    StandardNIST612
    Carbonate standardWC-1

    Table 2 . ‘Image-mapping’ in-situ U-Pb age-dating results of some carbonate rock samples.

    SampleMineralU-Pb Age (Ma)Upper intercept (207Pb/206Pb)MSWD
    SGJ74Calcite463.615.60.84410.00821.6
    SGJ77Calcite vein92.971.310.81600.01702.8
    SGJ21Calcite63.946.120.64200.01703.6
    SGJ21Dolomite19.066.130.53180.00931.7

    KSEEG
    Apr 30, 2024 Vol.57 No.2, pp. 107~280

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