TY - JOUR
T1 - How is sea level change encoded in carbonate stratigraphy?
AU - Geyman, Emily C.
AU - Maloof, Adam C.
AU - Dyer, Blake
N1 - Funding Information:
Thank you to Jeff Birch at Small Hope Bay Lodge and the Bahamas Environment, Science & Technology Commission for making work possible on Andros Island. Also thank you to Alex Cartwright, Rudolph ‘Timer’ Coakley, Niki Hinsey, Tano Humes, Anastasia Mackey, Alvin Marshall, Sonny ‘Abba’ Martin, Bhruna Neymor, Garnet Thompson, Linda Whyms, and local customs and immigration. Chris Allen at Air Flight Charters and Dawn Reading at Princeton provided logistical support. Thank you to Sujith Ravi for generous access to his laser diffraction particle size analyzer. Thank you to Liam O'Connor and Tano Humes for assistance in the field, to James Bishop for help planning our work in Arrow Canyon, and to Frederik Simons and Akshay Mehra for helpful feedback and advice. Finally, thank you to Bruce Wilkinson and Peter Burgess for detailed reviews. This material is based upon work supported by NSF Division of Earth Sciences Grant 1410317 and by the Princeton Environmental Institute through the Smith-Newton Scholars Program. This work also was supported by the GSA Northeastern Section Stephen G. Pollock Undergraduate Student Research Grant, The Evolving Earth Foundation , the High Meadows Foundation , and the Sigma Xi Research Society . Planet provided the RapidEye satellite imagery through the Planet Research Ambassadors Program (Planet Team, 2017). The Bahamas grain size measurements and the facies and bathymetry maps ( Fig. 1 ) are provided on the data repository Princeton DataSpace ( https://doi.org/10.34770/27zb-m284 ).
Funding Information:
Thank you to Jeff Birch at Small Hope Bay Lodge and the Bahamas Environment, Science & Technology Commission for making work possible on Andros Island. Also thank you to Alex Cartwright, Rudolph ?Timer? Coakley, Niki Hinsey, Tano Humes, Anastasia Mackey, Alvin Marshall, Sonny ?Abba? Martin, Bhruna Neymor, Garnet Thompson, Linda Whyms, and local customs and immigration. Chris Allen at Air Flight Charters and Dawn Reading at Princeton provided logistical support. Thank you to Sujith Ravi for generous access to his laser diffraction particle size analyzer. Thank you to Liam O'Connor and Tano Humes for assistance in the field, to James Bishop for help planning our work in Arrow Canyon, and to Frederik Simons and Akshay Mehra for helpful feedback and advice. Finally, thank you to Bruce Wilkinson and Peter Burgess for detailed reviews. This material is based upon work supported by NSF Division of Earth Sciences Grant 1410317 and by the Princeton Environmental Institute through the Smith-Newton Scholars Program. This work also was supported by the GSA Northeastern Section Stephen G. Pollock Undergraduate Student Research Grant, The Evolving Earth Foundation, the High Meadows Foundation, and the Sigma Xi Research Society. Planet provided the RapidEye satellite imagery through the Planet Research Ambassadors Program (Planet Team, 2017). The Bahamas grain size measurements and the facies and bathymetry maps (Fig. 1) are provided on the data repository Princeton DataSpace (https://doi.org/10.34770/27zb-m284).
Publisher Copyright:
© 2021 Elsevier B.V.
PY - 2021/4/15
Y1 - 2021/4/15
N2 - The history of organismal evolution, seawater chemistry, and paleoclimate is recorded in layers of carbonate sedimentary rock. Meter-scale cyclic stacking patterns in these carbonates often are interpreted as representing sea level change. A reliable sedimentary proxy for eustasy would be profoundly useful for reconstructing paleoclimate, since sea level responds to changes in temperature and ice volume. However, the translation from water depth to carbonate layering has proven difficult, with recent surveys of modern shallow water platforms revealing little correlation between carbonate facies (i.e., grain size, sedimentary bed forms, ecology) and water depth. We train a convolutional neural network with satellite imagery and new field observations from a 3,000 km2 region northwest of Andros Island (Bahamas) to generate a facies map with 5 m resolution. Leveraging a newly-published bathymetry for the same region, we test the hypothesis that one can extract a signal of water depth change, not simply from individual facies, but from sequences of facies transitions analogous to vertically stacked carbonate strata. Our Hidden Markov Model (HMM) can distinguish relative sea level fall from random variability with ∼90% accuracy. Finally, since shallowing-upward patterns can result from local (autogenic) processes in addition to forced mechanisms such as eustasy, we search for statistical tools to diagnose the presence or absence of external forcings on relative sea level. With a new data-driven forward model that simulates how modern facies mosaics evolve to stack strata, we show how different sea level forcings generate characteristic patterns of cycle thicknesses in shallow carbonates, providing a new tool for quantitative reconstruction of ancient sea level conditions from the geologic record.
AB - The history of organismal evolution, seawater chemistry, and paleoclimate is recorded in layers of carbonate sedimentary rock. Meter-scale cyclic stacking patterns in these carbonates often are interpreted as representing sea level change. A reliable sedimentary proxy for eustasy would be profoundly useful for reconstructing paleoclimate, since sea level responds to changes in temperature and ice volume. However, the translation from water depth to carbonate layering has proven difficult, with recent surveys of modern shallow water platforms revealing little correlation between carbonate facies (i.e., grain size, sedimentary bed forms, ecology) and water depth. We train a convolutional neural network with satellite imagery and new field observations from a 3,000 km2 region northwest of Andros Island (Bahamas) to generate a facies map with 5 m resolution. Leveraging a newly-published bathymetry for the same region, we test the hypothesis that one can extract a signal of water depth change, not simply from individual facies, but from sequences of facies transitions analogous to vertically stacked carbonate strata. Our Hidden Markov Model (HMM) can distinguish relative sea level fall from random variability with ∼90% accuracy. Finally, since shallowing-upward patterns can result from local (autogenic) processes in addition to forced mechanisms such as eustasy, we search for statistical tools to diagnose the presence or absence of external forcings on relative sea level. With a new data-driven forward model that simulates how modern facies mosaics evolve to stack strata, we show how different sea level forcings generate characteristic patterns of cycle thicknesses in shallow carbonates, providing a new tool for quantitative reconstruction of ancient sea level conditions from the geologic record.
KW - Bahamas
KW - carbonates
KW - cycles
KW - sedimentary facies
KW - stratigraphy
UR - http://www.scopus.com/inward/record.url?scp=85100401626&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85100401626&partnerID=8YFLogxK
U2 - 10.1016/j.epsl.2021.116790
DO - 10.1016/j.epsl.2021.116790
M3 - Article
AN - SCOPUS:85100401626
SN - 0012-821X
VL - 560
JO - Earth and Planetary Science Letters
JF - Earth and Planetary Science Letters
M1 - 116790
ER -