Dates of Holocene environmental changes in Lake Bafa: A hierarchical Bayesian analysis of change points

Yıl 2023, , 23 - 36, 30.06.2023

Zeki Bora Ön

https://doi.org/10.17211/tcd.1283443

Öz

The timing of the separation of Lake Bafa from the Aegean Sea and its subsequent transition to a
lake remains a topic of debate, with considerable uncertainties associated with the proposed dates
for these transitions. This study introduces a novel approach, hierarchical Bayesian change point
analysis (HBCPA), to identify tipping points in paleoenvironmental time series. The objective is to
offer more precise and objectively selected results concerning the previously uncertain transition
dates of Lake Bafa’s geological evolution in the Holocene. The method presented in this study is
applied to analyze stable oxygen and carbon isotope data from foraminifer and ostracod shells,
as well as total organic carbon (TOC) data, obtained from the BAFA09P02 sediment core. Results
indicate that the transition from a marine to an isolated lagoon environment occurred around
2060 years BP, with an 89% uncertainty interval ranging from 2250 to 1870 years BP. Additionally,
the transition from an isolated lagoon to a brackish lake environment is estimated to have occurred
around 595 years BP, with an 89% uncertainty interval ranging from 780 to 425 years BP. The
results of this study illustrate that the suggested HBCPA approach holds the capability to identify
tipping points in environmental data while quantifying their intrinsic uncertainties.

Anahtar Kelimeler

Büyük Menderes Valley, Gibbs sampling, Maiandros River, MCMC, Miletos

Holosen’de Bafa Gölü’ndeki ortamsal değişikliklerin tarihleri: Hiyerarşik Bayes değişim noktası analizi

Öz

Bafa Gölü’nün Ege Denizi’nden ayrılmasının ve ardından tatlısu gölüne geçişinin zamanlaması
tartışmalıdır ve bu değişimler için önerilmiş olan tarihlerin belirsizlik aralıkları oldukça
geniştir. Bu çalışmada, paleoçevre verilerinin analizinde kullanılmak üzere yeni bir yaklaşım
olarak “hiyerarşik Bayes değişim noktası analizi” (HBCPA) önerilmektedir ve sonuç olarak
Bafa Gölü’nün Holosen’de ortamsal değişim tarihleri için önerilmiş geniş belirsizlik aralıklarını
daraltma amacını taşımaktadır. Önerilen yöntem, BAFA09P02 çökel karotu foraminifer ve
ostrakod kavkılarından elde edilen duraylı oksijen ve karbon izotop verileri ile toplam organik
karbon (TOC) verileri üzerinde uygulanmıştır. Sonuçlar, denizel ortamdan kapalı lagünel ortama
geçişin yaklaşık GÖ 2060 yıl civarında gerçekleştiğini ve %89 belirsizlik aralığının GÖ 2250 ila
1870 yılları aralığında olduğunu göstermektedir. Kapalı bir lagünden acısu göl ortamına geçişin
ise yaklaşık GÖ 595 yıl civarında gerçekleştiği ve %89 belirsizlik aralığının GÖ 780 ila 425 yıllarını
kapsadığı bulunmuştur. Bu çalışmanın sonuçları, önerilen HBCPA yönteminin jeolojik verilerde
çevresel değişim noktalarını, sahip oldukları belirsizlikleri ile ölçme potansiyeline sahip olduğunu
göstermektedir.

Anahtar Kelimeler

Büyük Menderes Vadisi, Gibbs örneklemesi, Maiandros Nehri, Milet, MZMC

Kaynakça

• Akçer-Ön, S., Greaves, A. M., Manning, S. W., Ön, Z. B., Çağatay, M. N., Sakınç, M., Oflaz A., Tunoğlu, C., & Salihoğlu, R. (2020). Redating the formation of Lake Bafa, western Turkey: Integrative geoarchaeological methods and new environmental and dating evidence. Geoarchaeology 35(5), 659–677. https://doi. org/10.1002/gea.21791
• Aksu, A. E., Piper D. J. W., & Konuk T. (1987). Quaternary growth patterns of Büyük Menderes and Küçük Menderes deltas, western Turkey. Sedimentary Geology 52(3), 227–250. https:// doi.org/10.1016/0037-0738(87)90063-7
• Brückner, H., Herda, A., Kerschner, M., Müllenhoff, M., & Stock, F. (2017). Life cycle of estuarine islands — From the formation to the landlocking of former islands in the environs of Miletos and Ephesos in western Asia Minor (Turkey). Journal of Archaeological Science: Reports 12, 876–894. https://doi. org/10.1016/j.jasrep.2016.11.024
• Cahill, N., Rahmstorf, S., & Parnell, A. C. (2015). Change points of global temperature. Environmental Research Letters 10(8), 084002. https://iopscience.iop.org/ article/10.1088/1748-9326/10/8/084002
• Denwood, M. J. (2016). runjags: An R package providing interface utilities, model templates, parallel computing methods and additional distributions for MCMC models in JAGS. Journal of Statistical Software 71(9), 1–25. https://doi.org/10.18637/jss. v071.i09
• Flint, R. F., & Deevey, E. S. (1962). Editorial statement. Radiocarbon 4, i–ii.
• Gallagher, K., Bodin, T., Sambridge, M., Weiss, D., Kylander, M., & Large, D. (2011). Inference of abrupt changes in noisy geochemical records using transdimensional changepoint models. Earth and Planetary Science Letters 311(1), 182–194. https://doi.org/10.1016/j.epsl.2011.09.015
• Knipping, M., Müllenhoff, M., & Brückner, H. (2008). Human induced landscape changes around Bafa Gölü (western Turkey). Vegetation History and Archaeobotany 17(4), 365–380. https:// doi.org/10.1007/s00334-007-0132-8
• Kruschke, J. K. (2015). Doing Bayesian Data Analysis. (2nd ed.). Academic Press. https://www.sciencedirect.com/ book/9780124058880/doing-bayesian-data-analysis?via=ihub= Lindeløv, J. K. (2020). mcp: An R package for regression with multiple change points. OSF Preprints. https://doi.org/10.31219/osf.io/ fzqxv
• Mozafari, N., Sümer, Ö., Tikhomirov, D., Ivy-Ochs, S., Alfimov, V., Vockenhuber, C., İnci, U., Sözbilir, H., & Akcar, N. (2019). Holocene seismic activity of the Priene-Sazlı Fault revealed by cosmogenic 36Cl, western Anatolia, Turkey. Turkish Journal of Earth Sciences 28(3), 410–437. https://doi.org/10.3906/yer-1810-6
• Müllenhoff, M., Handl, M., Knipping, M., & Brückner, H. (2004). The evolution of Lake Bafa (Western Turkey): Sedimentological, microfaunal and palynological results. Coastline Reports 1(2004), 55–66.
• Ön, Z. B. (2023). A Bayesian change point analysis re-examines the 4.2 ka BP event in southeast Europe and southwest Asia. Quaternary Science Reviews. 312, 108163. https://doi. org/10.1016/j.quascirev.2023.108163
• Ön, Z. B., Greaves, A. M., Akçer-Ön, S., & Özeren M. S. (2021). A Bayesian test for the 4.2 ka BP abrupt climatic change event in southeast Europe and southwest Asia using structural time series analysis of paleoclimate data. Climatic Change 165(7), 1–19. https://doi.org/10.1007/s10584-021-03010-6
• Ön, Z. B., Macdonald, N., Akçer-Ön, S., & Greaves, A.M. (2023). A novel Bayesian multilevel regression approach to the reconstruction of an eastern Mediterranean temperature record for the last 10,000 years. The Holocene 33(7), 807–815. https:// doi.org/10.1177/09596836231163508
• Plummer, M. (2003, March 20-22). JAGS: A program for analysis of Bayesian graphical models using Gibbs sampling [Conference presentation abstract]. Proceedings of the 3rd international workshop on distributed statistical computing, Vienna, Austria. https://www.r-project.org/conferences/DSC-2003/ Proceedings/Plummer.pdf
• R Core Team (2023). : A Language and Environment for Statistical Computing. R Foundation for Statistical Computing, Vienna, Austria. https://www. R-project.org/
• Salihoğlu, R. & Akçer-Ön, S. (2020, November 15-20). Holocene environmental changes at Bafa Lake (SW Anatolia) according to ostracod and benthic foraminifer distribution [Conference presentation abstract]. 21th Paleontology-Stratigraphy Workshop Pandemia special, Turkey, pp. 52–53.