Spatial distribution of (sub-)outcropping methane-derived authigenic carbonate structures at the outer Aquitaine Shelf

The present database is composed of a polygon shape file (.shp) dedicated to GIS applications. This seafloor surface represents the area within which (sub-)outcropping methane derived authigenic carbonates were identified based on ship-borne multibeam bathymetry and seafloor backscatter data; as displayed in Figs. 4 and S1a of Dupré et al. 2020 (Dupré S, Loubrieu B, Pierre C, Scalabrin C, Guérin C, Ehrhold A, Ogor A, Gautier E, Ruffine L, Biville R, Saout J, Breton C, Floodpage J, Lescanne M (2020) The Aquitaine Shelf Edge (Bay of Biscay): A Primary Outlet for Microbial Methane Release. Geophysical Research Letters 47 (7):e2019GL084561. doi:10.1029/2019gl084561). The presence of (sub-)outcropping methane-derived authigenic carbonates at the seafloor was confirmed by remotely-operated-vehicle dives during the GAZCOGNE2 marine expedition.
The acoustic data were acquired in 2013 on board the R/V Le Suroît during the GAZCOGNE1 expedition with two ship-borne multibeam echosounders, the Kongsberg EM302 and EM2040, with transmission frequency of 30 and 200 kHz, respectively. Details on multibeam data acquisition, processing and interpretation of sub-outcropping methane-derived authigenic carbonate structures are presented in Dupré et al 2020 (including a Supporting Information section).
Cited from Dupré et al 2020: “The carbonates are exclusively located along the shelf edge with the majority (98%) between 140 and 220 m water depths. The (sub-)outcropping carbonates are spread over a 375 km2 area that extends over a distance of 80 km between the Cap Ferret and Capbreton canyons. The western spatial limit of the methane-derived authigenic carbonates coincides with the shelf break.”

本数据库由面向地理信息系统（GIS）应用的多边形形状文件（.shp）构成。该海底表面覆盖的区域内，基于船载多波束测深与海底背散射数据，已识别出（次）出露的甲烷成因自生碳酸盐岩（methane-derived authigenic carbonates），相关区域详见Dupré等人2020年发表文献的图4与补充材料图S1a（Dupré S, Loubrieu B, Pierre C, Scalabrin C, Guérin C, Ehrhold A, Ogor A, Gautier E, Ruffine L, Biville R, Saout J, Breton C, Floodpage J, Lescanne M (2020) The Aquitaine Shelf Edge (Bay of Biscay): A Primary Outlet for Microbial Methane Release. Geophysical Research Letters 47 (7):e2019GL084561. doi:10.1029/2019gl084561）。GAZCOGNE2海洋科考航次期间的遥控无人潜器（remotely-operated vehicle, ROV）下潜作业，证实了该海底存在（次）出露的甲烷成因自生碳酸盐岩。

该声学数据采集于2013年，由GAZCOGNE1科考航次期间搭载于“勒苏瓦”号（R/V Le Suroît）科考船的两台船载多波束测深仪（multibeam echosounders）完成，分别为Kongsberg EM302与EM2040，其发射频率依次为30 kHz与200 kHz。关于多波束数据采集、处理以及（次）出露甲烷成因自生碳酸盐岩构造的解译细节，已在Dupré等人2020年的研究（含补充信息章节）中予以阐述。

引自Dupré等人2020年的研究："该类碳酸盐岩仅分布于陆架边缘区域，其中98%位于水深140~220 m的区间内。（次）出露碳酸盐岩分布面积达375 km²，延伸范围跨越费雷角（Cap Ferret）与卡布雷顿（Capbreton）峡谷之间的80 km海域。甲烷成因自生碳酸盐岩的西部空间边界与陆架坡折带重合。"