Volumetric budget calculation of sediment and carbon storage and export for a late Holocene mid-shelf mudbelt system (NW Iberia)

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• 作者：Ferdinand K.J. Oberle ; ^{foberle@marum.de" class="auth_mail} ; Till J.J. Hanebuth ; Benjamin Baasch ; Tilmann Schwenk
• 关键词：Continental shelves ; Mud depocenter ; Holocene sediment budget ; Shelf sediment transport ; Carbon cycle ; Iberia
• 刊名：Continental Shelf Research
• 出版年：15 March, 2014
• 年：2014
• 卷：76
• 期：Complete
• 页码：12-24
• 全文大小：3829 K

文摘

Confined fine-grained depoenters (mudbelts) on continental shelves play an important role as common and major fluviogenic submarine depocenters along the source-to-sink pathway and in global sedimentary and carbon cycles. This study provides a complete high-resolution isopach-based budget analysis using closely-spaced, high-resolution seismic-reflection data of an exemplary mid-shelf mudbelt system located on the open and narrow continental shelf of NW Iberia.

The budget analysis reveals that 3.957-4.227 km³ of sediments [i.e., 4073 to 4351 Mt (dry)] are stored in this depocenter. In conjunction with river-discharge estimates, we calculate that, over the past 5300 yr, approximately 34% to 36% of total fluvial sediments supplied to the ocean remain in the shelfal mud depocenter and the balance bypasses the shelf. Total accumulation values for TOC and CaCO₃ amount to 40.31 to 43.46 t and 174.73 to 186.68 Mt, respectively. High-resolution isopach analysis shows high regional morphodynamic variability of the main sediment transit routes, an aspect easily overlooked by core-based or low-resolution profiling studies. The budget analysis reveals persistent low accumulation over the past 5300 yr and thus clarifies that a uniformitarian view of applying modern accumulation rates to the late Holocene can significantly underestimate effective sediment off-shelf transport.