Tectonic stability since the last interglacial offsets the Glorieuses Islands from the nearby Comoros archipelago
Tectonic stability since the last interglacial offsets the Glorieuses Islands from the nearby Comoros archipelago
复制标题
自上次间冰期以来的构造稳定性使格洛里厄斯群岛与附近的科摩罗群岛相抵消
作者：
M. Guillaume;J. Reyss;P. Pirazzoli;J. H. Bruggemann
Glorieuses群岛的四个化石阶地进行了描述，并提供了新的日期，以解决他们的地层，沉积环境和构造行为。大多数露头由一个单一的沉积单元组成，代表了以Isopora palifera珊瑚为主的广泛礁坪的遗迹。在里斯岛，该单元局部被由Halimeda段组成的倾斜层状床覆盖，暂时解释为风暴过洗。从化石露头中采集的珊瑚样本中获得的可靠U/Th年龄大多在127和123 kyr之间，这表明这些珊瑚礁完全形成于第一个MIS-5e海平面高点，当时海平面达到+3 m。这些阶地的平均海拔为+4.5 m，推测每年上升0.012 ± 0.002 mm。这种相对的构造稳定性与马约特岛的沉降报告形成对比，表明附近的科摩罗和格洛里厄斯群岛的地质环境不同。
The four fossil terraces of the Glorieuses Islands are described, and new dates are provided to resolve their stratigraphy, depositional setting, and tectonic behavior. Most outcrops consist of a single sedimentary unit that represents the remains of an extensive reef flat dominated by Isopora palifera corals. At Lys Island, this unit is locally overlain by dipping layered beds composed of Halimeda segments, tentatively interpreted as storm overwash. Reliable U/Th dates obtained from corals sampled from the fossil outcrops mostly fall between 127 and 123 kyr, suggesting that these reefs formed exclusively during the first MIS-5e sea-level highstand, when sea level reached +3 m. The mean elevation of these terraces being +4.5 m, an uplift of 0.012 ± 0.002 mm year−1 is inferred. This relative tectonic stability contrasts with the subsidence reported from Mayotte Island, suggesting a different geologic setting for the nearby Comoros and Glorieuses archipelagoes.