Reef growth history at intermediate to mesophotic depths since the end of the Last Glacial period along the Great Barrier Reef shelf edge

M. Humblet, J. Webster, Y. Yokoyama, J. Braga, K. Fujita, Y. Iryu, S. Fallon, W. Thompson
{"title":"Reef growth history at intermediate to mesophotic depths since the end of the Last Glacial period along the Great Barrier Reef shelf edge","authors":"M. Humblet, J. Webster, Y. Yokoyama, J. Braga, K. Fujita, Y. Iryu, S. Fallon, W. Thompson","doi":"10.54780/iassp49/07","DOIUrl":null,"url":null,"abstract":"Reef communities at intermediate (10 to 30 m) and mesophotic (~ 30 to 150 m) depths occupy large areas of sea floor but little is known about their potential to accrete vertically, their response to sea-level change and other environmental perturbations. In this study, the authors have examined cores from two holes, M0040A and M0041A, drilled by the International Ocean Drilling Program Expedition 325 along the shelf edge of the modern GBR at 131 m water depth. The objective was to investigate reef growth history at palaeo-water depths > 20 m over a time period spanning 30,000 years, from the end of the Last Glacial period through the last deglaciation. Based on changes in lithologies and biotic components, and a robust chronostratigraphic framework supported by 47 radiometric ages, the authors have identified two episodes of reef growth, one during Marine Isotope Stage (MIS) 2 and the other at the onset of the deglaciation, both characterised by abundant microbialite crusts and distinct coral assemblages. Palaeo-water depths range from 30 to 60 m and from 20 to 30 m for the MIS 2 and early deglacial reef sections, respectively. The first episode of reef growth documented in the cores initiated at 27 to 25 ka, possibly in response to increased light availability and change in sedimentation resulting from falling sea-level between 32 and 29 ka from MIS 3 and also to low atmospheric pCO2 at the end of the Last Glacial period. Reef accretion was reduced or ceased sometime between 24 and 19 ka, coinciding with the rapid 20 m sea-level fall of the peak Last Glacial Maximum and minima of SSTs. Reef growth resumed at 19.5 to 18.5 ka, influenced by a period of moderate sea-level rise and increasing sea surface temperatures at the onset of the deglaciation. Reef growth termination at ca. 17 ka correlates with a major episode of reef demise previously identified in adjacent mid and outer terrace cores and linked to reduced water quality combined with rapid deglacial sea-level rise. Vertical accretion (VA) rates were calculated based on two methods: linear visual fitting and Bayesian modelling. The findings show that the highest VA rates are associated with microbialite boundstone. Reef ecosystems dominated by microbialite and corals developed at intermediate and mesophotic depths, and grew vertically at maximum rates of 2 to 5 mm yr-1 depending on the method used, over a period of rapid environmental change during the transition from MIS 3 to MIS 1. Further study needs to explore the potential of modern-type deep coralgal communities to cope with higher rates of sea-level rise predicted this century.","PeriodicalId":297740,"journal":{"name":"Coral Reefs and Sea-Level Change: Quaternary Records and Modelling","volume":"1 1","pages":"0"},"PeriodicalIF":0.0000,"publicationDate":"2022-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Coral Reefs and Sea-Level Change: Quaternary Records and Modelling","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.54780/iassp49/07","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
引用次数: 0

Abstract

Reef communities at intermediate (10 to 30 m) and mesophotic (~ 30 to 150 m) depths occupy large areas of sea floor but little is known about their potential to accrete vertically, their response to sea-level change and other environmental perturbations. In this study, the authors have examined cores from two holes, M0040A and M0041A, drilled by the International Ocean Drilling Program Expedition 325 along the shelf edge of the modern GBR at 131 m water depth. The objective was to investigate reef growth history at palaeo-water depths > 20 m over a time period spanning 30,000 years, from the end of the Last Glacial period through the last deglaciation. Based on changes in lithologies and biotic components, and a robust chronostratigraphic framework supported by 47 radiometric ages, the authors have identified two episodes of reef growth, one during Marine Isotope Stage (MIS) 2 and the other at the onset of the deglaciation, both characterised by abundant microbialite crusts and distinct coral assemblages. Palaeo-water depths range from 30 to 60 m and from 20 to 30 m for the MIS 2 and early deglacial reef sections, respectively. The first episode of reef growth documented in the cores initiated at 27 to 25 ka, possibly in response to increased light availability and change in sedimentation resulting from falling sea-level between 32 and 29 ka from MIS 3 and also to low atmospheric pCO2 at the end of the Last Glacial period. Reef accretion was reduced or ceased sometime between 24 and 19 ka, coinciding with the rapid 20 m sea-level fall of the peak Last Glacial Maximum and minima of SSTs. Reef growth resumed at 19.5 to 18.5 ka, influenced by a period of moderate sea-level rise and increasing sea surface temperatures at the onset of the deglaciation. Reef growth termination at ca. 17 ka correlates with a major episode of reef demise previously identified in adjacent mid and outer terrace cores and linked to reduced water quality combined with rapid deglacial sea-level rise. Vertical accretion (VA) rates were calculated based on two methods: linear visual fitting and Bayesian modelling. The findings show that the highest VA rates are associated with microbialite boundstone. Reef ecosystems dominated by microbialite and corals developed at intermediate and mesophotic depths, and grew vertically at maximum rates of 2 to 5 mm yr-1 depending on the method used, over a period of rapid environmental change during the transition from MIS 3 to MIS 1. Further study needs to explore the potential of modern-type deep coralgal communities to cope with higher rates of sea-level rise predicted this century.
末次冰期末以来大堡礁陆架边缘中至中深水的珊瑚礁生长历史
中等深度(10 ~ 30米)和中水深(~ 30 ~ 150米)的珊瑚礁群落占据了大面积的海底,但人们对它们垂直积聚的潜力、它们对海平面变化和其他环境扰动的响应知之甚少。在这项研究中,作者检查了两个孔M0040A和M0041A的岩心,这两个孔是由国际海洋钻探计划远征325队沿着现代GBR的陆架边缘在131米水深处钻探的。目的是调查从末次冰期结束到末次冰消期的3万年中,古水深约20米的珊瑚礁生长历史。基于岩性和生物成分的变化,以及由47个放射性年龄支持的可靠的年代地层框架,作者确定了两个时期的珊瑚礁生长,一个是在海洋同位素阶段(MIS) 2,另一个是在冰川消退的开始,两者都以丰富的微生物岩壳和独特的珊瑚组合为特征。MIS 2段和早期冰礁段的古水深分别为30 ~ 60 m和20 ~ 30 m。岩心中记录的第一次珊瑚礁生长始于27至25 ka,可能是对从MIS 3开始的32至29 ka之间海平面下降导致的光可用性增加和沉积变化的反应,也是对末次冰期末期大气二氧化碳分压降低的反应。礁体增生在24 ~ 19 ka之间的某个时间减少或停止,与末次冰期海温最大值和最小值的峰值海平面快速下降20 m一致。受消冰期开始时海平面适度上升和海面温度升高的影响,珊瑚礁在19.5 ~ 18.5 ka恢复生长。大约17 ka的珊瑚礁生长终止与先前在邻近的中部和外部阶地岩心中发现的一个主要的珊瑚礁消亡事件有关,并与水质下降和冰川消融海平面迅速上升有关。采用线性视觉拟合和贝叶斯建模两种方法计算垂直吸积率。研究结果表明,最高的VA率与微生物结合石有关。在从MIS 3向MIS 1过渡的一段快速环境变化期间,以微生物岩和珊瑚为主的珊瑚礁生态系统在中深水和中深水发育,垂直生长的最大速率为2至5毫米/年,具体取决于所使用的方法。进一步的研究需要探索现代型深海珊瑚群落的潜力,以应对本世纪预测的更高的海平面上升速度。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
求助全文
约1分钟内获得全文 求助全文
来源期刊
自引率
0.00%
发文量
0
×
引用
GB/T 7714-2015
复制
MLA
复制
APA
复制
导出至
BibTeX EndNote RefMan NoteFirst NoteExpress
×
提示
您的信息不完整,为了账户安全,请先补充。
现在去补充
×
提示
您因"违规操作"
具体请查看互助需知
我知道了
×
提示
确定
请完成安全验证×
copy
已复制链接
快去分享给好友吧!
我知道了
右上角分享
点击右上角分享
0
联系我们:info@booksci.cn Book学术提供免费学术资源搜索服务,方便国内外学者检索中英文文献。致力于提供最便捷和优质的服务体验。 Copyright © 2023 布克学术 All rights reserved.
京ICP备2023020795号-1
ghs 京公网安备 11010802042870号
Book学术文献互助
Book学术文献互助群
群 号:481959085
Book学术官方微信