Burial and Heat Flux Modelling along a Southern Vøring Basin Transect: Implications for the Petroleum Systems and Thermal Regimes in the Deep Mid-Norwegian Sea

Round 1

Reviewer 1 Report

This manuscript presents burial and heat flux modelling along a southern Vøring Basin transect, then discusses the petroleum systems and thermal regimes in the deep Mid-Norwegian Sea. This manuscript is well-written and presents qualified data analysis and interpretation. I have a few suggestions/comments to improve its contents.

1. I suggest to make a section of “Geologic Background” with a figure of basin evolution history to help readers’ better understanding for the study area. The first three paragraphs of “Introduction” can move to the “Geologic background”.
2. Line 104 and other parts: I recommend a recent reference published at this journal; Kim et al. (2020) Numerical Modelling to Evaluate Sedimentation Effects on Heat Flow and Subsidence during Continental Rifting. Geosciences 10, 451.
3. Line 135. Throughout the manuscript, some units are not easy to recognize... cmyr^-1...
4. Line 144. How about provide an arrow with “Figure 2” in Figure 1 for the profile location.
5. “Section 2. Materials and methods” provides good descriptions, but too long. Please shorten or subdivide more. And some parts seem better for “Results”.
6. Both sections 3.1 and 3.2 are titled as Heat Flux History.
7. Current ‘Discussion’ section is a mix of new results and discussion. Some parts such as ‘4.1. Hot and Cold Models’ should move to “Results”.
8. Line 616-617. Bracket ( was used twice.
9. Line 828. A similar case from field study was introduced in a recent work. The subsidence anomaly, hydrothermal alteration, and thermal buoyancy by adjacent mantle plume during the post-rift was discussed in Lee et al (2020) Early Cretaceous subsidence of the Naturaliste Plateau defined by a new record of volcaniclastic-rich sequence at IODP Site U1513. Gondwana Research 82, 1–11.
10. Some texts in figures are too small/unclear to read... Re-arranging and –sizing are required for readability.

Author Response

Please see attachement

 

Author Response File: Author Response.docx

Reviewer 2 Report

Authors have constructed thermo-tectono-stratigraphic model across the southern Vøring Basin, which accounts for the main rifting events that shaped the margin and continental break-up. In the distal margin, the temperature and maturity data from boreholes located along the Vigrid Syncline and the Gjallar Ridge suggest a progressive increase of the geothermal gradients oceanward, which is inconsistent with the low heat flux measured at the surface. Two scenarios are put forward which attempt to reconcile the borehole temperature and maturity data with the measured surface heat flux in the distal margin. A high regional thermal gradient throughout the Cenozoic associated with mantle dynamics effects (edge-driven convection and/or the Icelandic Plume) is supported by lithosphere-scale, gravity-topography models and explains the borehole temperature and maturity data. Such model predicts heat flux values within the higher range of the observed in the distal and intermediate sectors of the margin, and lacks a rift model rational to explain the prolonged high temperature gradients (and possibly also associated subsidence anomalies) following continental break-up. Alternatively, an increased geothermal gradient within the pre-Cenozoic sediments caused by pervasive hydrothermal circulation during the Plio-Pleistocene, or intermittently throughout the Cenozoic, is supported by the widespread evidence of hydrothermal vent complexes in the deep margin, some of which acting as fluid conduits to present-day, and may explain both the temperature and maturity data at well locations, and the seafloor heat flux measurements.

Authors offer fundamental integrated analyse of basin thermal history giving substantial new information. Article is well written and nicely illustrated. I recommend it for publication in its present form. 

Author Response

Dear reviewer,

Thank you for revising our manuscript and the encouragement for publication. I hope you found the topic interesting, and that the reading was pleasent and informative.

kind regards

tiago