The giant Mauritanian cold-water coral mound province: Oxygen control on coral mound formation
The giant Mauritanian cold-water coral mound province: Oxygen control on coral mound formation
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DOI：
10.1016/j.quascirev.2018.02.012
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发表时间：
2018-04
影响因子：
4
通讯作者：
C. Wienberg;J. Titschack;A. Freiwald;N. Frank;T. Lundälv;M. Taviani;L. Beuck;A. Schröder‐Ritzrau;T. Krengel;D. Hebbeln
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作者：
C. Wienberg;J. Titschack;A. Freiwald;N. Frank;T. Lundälv;M. Taviani;L. Beuck;A. Schröder‐Ritzrau;T. Krengel;D. Hebbeln
大西洋最大的连贯冷水珊瑚（CWC）丘省位于毛里塔尼亚边缘，那里高达100 米高的丘延伸到距离约400 公里，排列在两个斜坡平行链中，水深400 - 550 米。此外，cwc存在于许多海底峡谷中，在一些峡谷两侧正在形成孤立的珊瑚丘。对77个铀系列珊瑚年龄进行了评估，以阐明在过去~ 12万年中沿毛里塔尼亚边缘的CWC定殖和珊瑚丘发育的时间。结果表明，在末次间冰期，珊瑚丘上存在ccs，但数量较少，对应于珊瑚丘的沉积速率为16 cm kyr−1。最后一次冰期和去冰期是CWC生长最丰富的时期，导致丘积增强（>1000 cm kyr−1），然后随着全新世的开始，整个边缘的丘积停止形成。直到今天，毛里塔尼亚的土丘都处于休眠状态，只有少量的化学武器生长。至少从晚全新世开始，峡谷中就有丰富的活cwc。因此，这些峡谷可能成为CWCs的避难所，有可能在沿开阔斜坡的土丘上观察到适度的重新殖民脉冲。全新世前珊瑚丘沉积的时间和速率以及珊瑚丘停止形成的时间在各个珊瑚丘之间有所不同，这可能是水体结构垂直/侧向变化的结果，这些变化分别使珊瑚丘靠近或远离缺氧水域。
The largest coherent cold-water coral (CWC) mound province in the Atlantic Ocean exists along the Mauritanian margin, where up to 100 m high mounds extend over a distance of ∼400 km, arranged in two slope-parallel chains in 400–550 m water depth. Additionally, CWCs are present in the numerous submarine canyons with isolated coral mounds being developed on some canyon flanks. Seventy-seven Uranium-series coral ages were assessed to elucidate the timing of CWC colonisation and coral mound development along the Mauritanian margin for the last ∼120,000 years. Our results show that CWCs were present on the mounds during the Last Interglacial, though in low numbers corresponding to coral mound aggradation rates of 16 cm kyr−1. Most prolific periods for CWC growth are identified for the last glacial and deglaciation, resulting in enhanced mound aggradation (>1000 cm kyr−1), before mound formation stagnated along the entire margin with the onset of the Holocene. Until today, the Mauritanian mounds are in a dormant state with only scarce CWC growth. In the canyons, live CWCs are abundant since the Late Holocene at least. Thus, the canyons may serve as a refuge to CWCs potentially enabling the observed modest re-colonisation pulse on the mounds along the open slope. The timing and rate of the pre-Holocene coral mound aggradation, and the cessation of mound formation varied between the individual mounds, which was likely the consequence of vertical/lateral changes in water mass structure that placed the mounds near or out of oxygen-depleted waters, respectively.