Precise timing of MIS 7 substages from the Austrian Alps

Wendt, Kathleen A.; Li, Xianglei; Edwards, R. Lawrence; Cheng, Hai; Spötl, Christoph

doi:https://doi.org/10.5194/cp-17-1443-2021

Articles | Volume 17, issue 4

https://doi.org/10.5194/cp-17-1443-2021

© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/cp-17-1443-2021

© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 17, issue 4

Research article

|

09 Jul 2021

Research article |

| 09 Jul 2021

Precise timing of MIS 7 substages from the Austrian Alps

Kathleen A. Wendt, Xianglei Li, R. Lawrence Edwards, Hai Cheng, and Christoph Spötl

Download

Final revised paper (published on 09 Jul 2021)
Supplement to the final revised paper
Preprint (discussion started on 20 Nov 2020)
Supplement to the preprint

Interactive discussion

Status: closed

AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment

- Printer-friendly version

- Supplement

RC1: 'Comments on "Precise timing of MIS 7 sub-stages from the Austrian Alps" by Wendt et al.', Anonymous Referee #1, 03 Dec 2020
- AC1: 'Reply to RC1', Kathleen Wendt, 05 Mar 2021
RC2: 'Wendt et al.', Anonymous Referee #2, 16 Dec 2020
- AC2: 'Reply on RC2', Kathleen Wendt, 05 Mar 2021

Peer-review completion

AR: Author's response | RR: Referee report | ED: Editor decision

ED: Reconsider after major revisions (06 Mar 2021) by Amaelle Landais

AR by Kathleen Wendt on behalf of the Authors (29 Apr 2021) Author's response Author's tracked changes Manuscript

ED: Referee Nomination & Report Request started (30 Apr 2021) by Amaelle Landais

RR by Anonymous Referee #2 (03 May 2021)

Suggestions for revision or reasons for rejection

I am largely satisfied with the revisions. A few additional points:

1. The Hendy test plots are incorrect (I am going off the Supp A and B figure versions reproduced in the “author response” file): the C and O axis labels should be swapped.

2. The conclusion that there is no correlation between C and O for the Hendy tests is not convincing. Many look well correlated (e.g. H1 to H3 of Supp B, and H1 to H6 in Supp A - it is hard to tell because the axis ranges on the right square plot of each plot pair are too wide, and conceal the upward trend - please reduce the range of axis values). So I would not be so dogmatic with statements about lack of isotopic equilibrium. Fortunately, the signal in these speleothems is so large, a modest amount of kinetic fractionation is not a big issue.

3. Some of the drill hole positions for the Hendy traverses for Supp B are either poorly aligned on the image or do not represent coeval calcite (I certainly hope it is the former). For the sake of future readers, it would be helpful to have this corrected / made more accurate, as it does not set a good example for those speleothemists new to the game.

4. I remain adamant that the speleothem does not capture all of TIII because the older H-event (S8.2) is part of the termination, as correctly inferred in both Cheng et al. 2009 and Pérez-Mejías et al. 2017. The speleothem clearly started growing after S8.2, between S8.2 and S81, so it captures most of TIII but not all of it.

5. The time series from Columbu et al. (2019) is actually from Crovassa Azzurra Cave in Sardinia (Figure 5).

6. Re contribution from the summit of Hintertux glacier: based on the oblique-angle image of Figure 1, it seems that during glacier advances, ice formed at or near the summit of the massif could flow under gravity over the surface above the cave and its meltwaters could infiltrate the cave - so meltwater from a higher altitude could reach the cave, unless my sense of 3D is letting me down.

7. Line 49: should be TIIIa, not TIIa.

8. Line 161: ‘long and short timescales’: please be more specific, e.g. orbital vs millennial (or centennial).

9. Line 234: To the best of my knowledge, the process of PCP cannot directly affect d18O unless evaporative enrichment occurs. Please provide a reference supporting this point. I would have thought differences in the recharge altitude of individual drip points (not out of the question for a deep cave set in mountainous terrain) could comfortably explain small d18O offsets.

10. Throughout the Discussion, references to your figures are needed.

Hide

RR by Anonymous Referee #1 (19 May 2021)

ED: Publish subject to minor revisions (review by editor) (20 May 2021) by Amaelle Landais

AR by Kathleen Wendt on behalf of the Authors (27 May 2021) Author's response Author's tracked changes Manuscript

ED: Publish subject to technical corrections (02 Jun 2021) by Amaelle Landais

AR by Kathleen Wendt on behalf of the Authors (03 Jun 2021) Author's response Manuscript

Short summary

In this study, we tested the upper limits of U–Th dating precision by analyzing three stalagmites from the Austrian Alps that have high U concentrations. The composite record spans the penultimate interglacial (MIS 7) with an average 2σ age uncertainty of 400 years. This unprecedented age control allows us to constrain the timing of temperature shifts in the Alps during MIS 7 while offering new insight into millennial-scale changes in the North Atlantic leading up to Terminations III and IIIa.