the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 01 Jul 2025
Continental shelf glaciations off Northeast Greenland since the late Miocene
Abstract. Amplified Arctic warming is triggering dramatic changes to the Greenland Ice Sheet (GrIS). Studying past warm periods can provide process insights valuable to predictions of future ice sheet response. Miocene (23.03 – 5.33 Ma) and Pliocene (5.33 – 2.58 Ma) global climatic records include periods of warmer than present temperatures thought to represent analogues to near-future scenarios. Despite this, the details of the long-term glacial history of the eastern and northeastern sectors of Greenland are still largely unresolved. Here, we use seismic reflection and borehole data to describe the late Cenozoic glacial architectural development of the Northeast Greenland continental margin and thereby reconstruct long-term ice sheet evolution. We identify three key unconformable seismic surfaces that define three mega units of predominantly glacial origin. Two of the surfaces are for the first time correlated across the entire outer Northeast Greenland margin and tied to both Ocean Drilling Program Sites 909 and 913. We show that the late Miocene onset of shelf progradation occurs around 6.4 Ma, marking the first recorded advance of grounded ice masses across the NE Greenland shelf, forming depocentres (trough mouth fans) beyond the palaeo-shelf edge. Subsequently during the late Miocene and early Pliocene, the GrIS expands multiple times across the shelf, extending the continental shelf seawards. Based on the development of more extensive and thicker depocentres along the entire outer shelf and upper slope, we suggest an intensification of shelf glaciations after ~4.1 Ma, possibly coinciding with the intensification of the Northern Hemisphere glaciations (3.6 – 2.7 Ma).
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The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
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Journal article(s) based on this preprint
Interactive discussion
Status: closed
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RC1: 'Comment on egusphere-2025-2906', Renata Giulia Lucchi, 30 Jul 2025
- AC1: 'Reply on RC1', Frank W. Jakobsen, 16 Oct 2025
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RC2: 'Comment on egusphere-2025-2906', Wolfram Geissler, 15 Sep 2025
Dear authors,
thank you very much for your study about the continental shelf glaciation off Northeast Greenland. Your study is an important contribution to understand the late Neogene-Quaternary evolution of the Greenland Ice Sheet despite the fact that drilling records are still too sparse in the study region. Especially impressive is that you are now able to map the development of individual glacial trough systems and related trough mouth fans throughout the studied time period. In comparison to an earlier study by Berger and Jokat (2009) using only sparse academic data, your study can build on an extensive combined seismic data set acquired by academic institutions and industry. This brings me already to my major points of criticism: (1) you do not consider the study of Berger & Jokat (2009) which was the first study about the late Neogene-Quaternary glaciations in NE Greenland based on marine seismic reflection data. Though referenced here and there throughout the manuscript mainly for data, it is even missing in the reference list. And (2), the seismic reflection data acquired by the Alfred Wegener Institute should be clearly referenced (e.g., Berger and Jokat, 2009; additional remark: maybe DOIs will be very soon available for the AWI data sets) and it should be documented in the section Data availability that the data is courtesy of the Alfred Wegener Institute and request should be directed to the institute and not TGS. A more technical point related to the various data sources, you should clearly mark the seismic profile names on the images.
I do not have any major criticism on the overall approach, results and interpretations. It is clearly documented that your seismic correlations are tied to only two (three) regional boreholes drilled by ODP and the KANUMAS consortium. In some cases, you mention that not all discussed horizons can be clearly tied to a lithological age in these boreholes; in that case you should further present and discuss these boundaries with their larger uncertainties (e.g., reflector NEG-3).
Some of the figures would benefit from minor revisions to make lines and individual features clearer. The size of some figures could be enlarged (to full page size). You should add profile names as mentioned before, and it would be great if SHOT/CDP numbers could be added. For the conversion to depth/thickness and vertical resolution, you use a seismic velocity of only 1500 m/s. For a glacially overprinted shelf I suggest to use higher seismic velocities as documented by various seismic refraction data. At least you could indicate a range using a minimum and maximum velocity. I would suggest that you actually try to estimate true thicknesses in meters instead of only discussing difference in two-way travel times between reflectors. Are there any data on seismic velocities available from TGS or KANUMAS?
When you refer to ODP drill sites 909 and 913, make it clear that especially the deep hole at site ODP913 suffered from limited time towards the end of the expedition. Therefore, the upper part of the hole was not cored with the exception of short intervals. That does not mean that it is a poor recovery, it was sparse coring due to time constraints.
Please be correct in using terms, e.g., reflections define boundaries of intervals, not the intervals (e.g., line 251). And do not mix “reflections” and “unconformities”, e.g, lines 273 & 274; both terms have different meanings, but reflectors could be interpreted as unconformities.
If you use geographical names, please make clear if they were defined earlier by others (e.g., IT-A/B/C inter-trough areas by Arndt et al. 2015). Maybe add bank features as documented in the Marine Gazetteer (e.g, Belgica Bank).
The manuscript would benefit if you try to separate better between observations, interpretations and discussion. Sometimes, it is still a bit too much intermixed, in my opinion.
The Discussion section would need a bit more elaboration. Especially, compare your results with the previous study of Berger and Jokat (2009) with respect to the overall timing of the NE Greenland shelf glaciations. Also, make clear how you measure/interpret the intensification of the glaciations. What could be the role of erosion? Why there is non-deposition (or reduced deposition) in some areas in specific time intervals? Check the duration of deposition for your mega-unit MU-1? Is it an interval or only a singular short-term event at about 6.4 Ma? What is about the interval from mid to late Miocene, might there be glaciations in East Greenland as proposed by others before? What is known about the sedimentary/basement structure beneath the IT areas? How this could influence the glacial evolution of these areas?
Please check the reference list for completeness. A few more relevant references are indicated in the annotated manuscript.
Some additional minor comments and suggestions you will find also in the annotated manuscript.
I hope, my comments will help you to improve your manuscript and increase its future impact.
With best regards, Wolfram Geissler
- AC2: 'Reply on RC2', Frank W. Jakobsen, 16 Oct 2025
Interactive discussion
Status: closed
-
RC1: 'Comment on egusphere-2025-2906', Renata Giulia Lucchi, 30 Jul 2025
Title: Continental shelf glaciations off Northeast Greenland since the late Miocene
Authors: Frank W. Jakobsen, Monica Winsborrow, Tove Nielsen, Jan Sverre Laberg, Andreia Plaza-Faverola, Christoph Böttner, Adrián López-Quirós, Sverre Planke, Benjamin Bellwald
This manuscript investigates the long-term glacial history of the Northeast Greenland Ice Sheet by analyzing a large seismic dataset and sedimentary information from three boreholes on the continental margin. The manuscript reconstructs the ice sheet evolution since ~6.4 Ma corresponding with the first recorded advance of grounded ice masses across the NE Greenland shelf, and the intensification of the shelf glaciation after ~4.1 Ma, potentially linked to Northern Hemisphere glaciation onset.
The manuscript is very well written, and the discussion is nicely developed. I made only minor edit suggestions through the text and some comments to be considered (see attached pdf).
Some highlights:
Paragraph 4.2 Seismic Units: When presenting the seismic mega units, please provide through the text an approximation of the thickness in meters next to the s (TWT)
Pag 18, line 479: What is the time frame here, 7.0–6.4 Ma? Does "multiple glaciations" imply alternating warm periods between glacial events, or were the ice streams continuously present during an overall cold period with alternating periods of ice streams' still stand and reactivation?
Pag 24, line 662: in support to the statement here, you can consider to add the preliminary report of IODP Exp-403 that documented the presence of IRD through the Pliocene record at sites U1619 and U1620 or, alternatively, the Scientific Proceedings that will be released end of January 2026 (i.e. Lucchi, R.G., St. John, K.E.K., Ronge, T., and the Expedition 403 Scientists, in press 2026. Initial Report: Eastern Fram Strait Palaeo-Archive. Proceedings of the International Ocean Discovery Program)
Pag 24, line 684: within the oceanographic factors facilitating the onset of glaciation on the eastern Greenland margin, it is worthy to acknowledge also the cooling influence of the cold Eastern Greenland Current, activated by the opening of the Fram Strait which still contributes to sustaining the eastern Greenland Ice Sheet despite of the ongoing warming trend.
The last paragraph (5.3) of the discussion is more speculative. Nevertheless, the discussion is very well developed and linked to previous studies, providing a series of possible forcing mechanisms to consider for the establishment of the Greenland ice sheet.
TABLE 1 write TGS and GXT in full in the captions.
FIGURES are generally of good quality. I added some comments on the attached PDF to improve the visibility of the text.
Figure 2, the patterns used to indicate the presence of silty clay/clayey silt, sandy clay, and dropstones/IRD are too similar. Please follow my suggestion to improve the logs
Figure 3 and 4, please change some of the white text to black text including the letters labeling the dashed boxes, the scale, and the border of the colored arrows (or avoid the border and use a sharper color for the arrows).
Figure 6, add “NEG= Northeast Greenland unconformity (-1, 2, 3)” in the caption.
Figure 7, use red dots to indicate the boreholes. Also please add the location of the main throughs and banks described through the text (WT, NT, SKT, IT-A, etc.)
More details in the attached PDF
Best regards, Renata G. Lucchi
- AC1: 'Reply on RC1', Frank W. Jakobsen, 16 Oct 2025
-
RC2: 'Comment on egusphere-2025-2906', Wolfram Geissler, 15 Sep 2025
Dear authors,
thank you very much for your study about the continental shelf glaciation off Northeast Greenland. Your study is an important contribution to understand the late Neogene-Quaternary evolution of the Greenland Ice Sheet despite the fact that drilling records are still too sparse in the study region. Especially impressive is that you are now able to map the development of individual glacial trough systems and related trough mouth fans throughout the studied time period. In comparison to an earlier study by Berger and Jokat (2009) using only sparse academic data, your study can build on an extensive combined seismic data set acquired by academic institutions and industry. This brings me already to my major points of criticism: (1) you do not consider the study of Berger & Jokat (2009) which was the first study about the late Neogene-Quaternary glaciations in NE Greenland based on marine seismic reflection data. Though referenced here and there throughout the manuscript mainly for data, it is even missing in the reference list. And (2), the seismic reflection data acquired by the Alfred Wegener Institute should be clearly referenced (e.g., Berger and Jokat, 2009; additional remark: maybe DOIs will be very soon available for the AWI data sets) and it should be documented in the section Data availability that the data is courtesy of the Alfred Wegener Institute and request should be directed to the institute and not TGS. A more technical point related to the various data sources, you should clearly mark the seismic profile names on the images.
I do not have any major criticism on the overall approach, results and interpretations. It is clearly documented that your seismic correlations are tied to only two (three) regional boreholes drilled by ODP and the KANUMAS consortium. In some cases, you mention that not all discussed horizons can be clearly tied to a lithological age in these boreholes; in that case you should further present and discuss these boundaries with their larger uncertainties (e.g., reflector NEG-3).
Some of the figures would benefit from minor revisions to make lines and individual features clearer. The size of some figures could be enlarged (to full page size). You should add profile names as mentioned before, and it would be great if SHOT/CDP numbers could be added. For the conversion to depth/thickness and vertical resolution, you use a seismic velocity of only 1500 m/s. For a glacially overprinted shelf I suggest to use higher seismic velocities as documented by various seismic refraction data. At least you could indicate a range using a minimum and maximum velocity. I would suggest that you actually try to estimate true thicknesses in meters instead of only discussing difference in two-way travel times between reflectors. Are there any data on seismic velocities available from TGS or KANUMAS?
When you refer to ODP drill sites 909 and 913, make it clear that especially the deep hole at site ODP913 suffered from limited time towards the end of the expedition. Therefore, the upper part of the hole was not cored with the exception of short intervals. That does not mean that it is a poor recovery, it was sparse coring due to time constraints.
Please be correct in using terms, e.g., reflections define boundaries of intervals, not the intervals (e.g., line 251). And do not mix “reflections” and “unconformities”, e.g, lines 273 & 274; both terms have different meanings, but reflectors could be interpreted as unconformities.
If you use geographical names, please make clear if they were defined earlier by others (e.g., IT-A/B/C inter-trough areas by Arndt et al. 2015). Maybe add bank features as documented in the Marine Gazetteer (e.g, Belgica Bank).
The manuscript would benefit if you try to separate better between observations, interpretations and discussion. Sometimes, it is still a bit too much intermixed, in my opinion.
The Discussion section would need a bit more elaboration. Especially, compare your results with the previous study of Berger and Jokat (2009) with respect to the overall timing of the NE Greenland shelf glaciations. Also, make clear how you measure/interpret the intensification of the glaciations. What could be the role of erosion? Why there is non-deposition (or reduced deposition) in some areas in specific time intervals? Check the duration of deposition for your mega-unit MU-1? Is it an interval or only a singular short-term event at about 6.4 Ma? What is about the interval from mid to late Miocene, might there be glaciations in East Greenland as proposed by others before? What is known about the sedimentary/basement structure beneath the IT areas? How this could influence the glacial evolution of these areas?
Please check the reference list for completeness. A few more relevant references are indicated in the annotated manuscript.
Some additional minor comments and suggestions you will find also in the annotated manuscript.
I hope, my comments will help you to improve your manuscript and increase its future impact.
With best regards, Wolfram Geissler
- AC2: 'Reply on RC2', Frank W. Jakobsen, 16 Oct 2025
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Frank Werner Jakobsen
Monica Winsborrow
Tove Nielsen
Jan Sverre Laberg
Andreia Plaza-Faverola
Christoph Böttner
Adrian López-Quirós
Sverre Planke
Benjamin Bellwald
The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
- Preprint
(3820 KB) - Metadata XML
-
Supplement
(1106 KB) - BibTeX
- EndNote
- Final revised paper
Title: Continental shelf glaciations off Northeast Greenland since the late Miocene
Authors: Frank W. Jakobsen, Monica Winsborrow, Tove Nielsen, Jan Sverre Laberg, Andreia Plaza-Faverola, Christoph Böttner, Adrián López-Quirós, Sverre Planke, Benjamin Bellwald
This manuscript investigates the long-term glacial history of the Northeast Greenland Ice Sheet by analyzing a large seismic dataset and sedimentary information from three boreholes on the continental margin. The manuscript reconstructs the ice sheet evolution since ~6.4 Ma corresponding with the first recorded advance of grounded ice masses across the NE Greenland shelf, and the intensification of the shelf glaciation after ~4.1 Ma, potentially linked to Northern Hemisphere glaciation onset.
The manuscript is very well written, and the discussion is nicely developed. I made only minor edit suggestions through the text and some comments to be considered (see attached pdf).
Some highlights:
Paragraph 4.2 Seismic Units: When presenting the seismic mega units, please provide through the text an approximation of the thickness in meters next to the s (TWT)
Pag 18, line 479: What is the time frame here, 7.0–6.4 Ma? Does "multiple glaciations" imply alternating warm periods between glacial events, or were the ice streams continuously present during an overall cold period with alternating periods of ice streams' still stand and reactivation?
Pag 24, line 662: in support to the statement here, you can consider to add the preliminary report of IODP Exp-403 that documented the presence of IRD through the Pliocene record at sites U1619 and U1620 or, alternatively, the Scientific Proceedings that will be released end of January 2026 (i.e. Lucchi, R.G., St. John, K.E.K., Ronge, T., and the Expedition 403 Scientists, in press 2026. Initial Report: Eastern Fram Strait Palaeo-Archive. Proceedings of the International Ocean Discovery Program)
Pag 24, line 684: within the oceanographic factors facilitating the onset of glaciation on the eastern Greenland margin, it is worthy to acknowledge also the cooling influence of the cold Eastern Greenland Current, activated by the opening of the Fram Strait which still contributes to sustaining the eastern Greenland Ice Sheet despite of the ongoing warming trend.
The last paragraph (5.3) of the discussion is more speculative. Nevertheless, the discussion is very well developed and linked to previous studies, providing a series of possible forcing mechanisms to consider for the establishment of the Greenland ice sheet.
TABLE 1 write TGS and GXT in full in the captions.
FIGURES are generally of good quality. I added some comments on the attached PDF to improve the visibility of the text.
Figure 2, the patterns used to indicate the presence of silty clay/clayey silt, sandy clay, and dropstones/IRD are too similar. Please follow my suggestion to improve the logs
Figure 3 and 4, please change some of the white text to black text including the letters labeling the dashed boxes, the scale, and the border of the colored arrows (or avoid the border and use a sharper color for the arrows).
Figure 6, add “NEG= Northeast Greenland unconformity (-1, 2, 3)” in the caption.
Figure 7, use red dots to indicate the boreholes. Also please add the location of the main throughs and banks described through the text (WT, NT, SKT, IT-A, etc.)
More details in the attached PDF
Best regards, Renata G. Lucchi