卡罗琳M4平顶海山区地貌特征与地质过程研究

GEOMORPHOLOGICAL CHARACTERISTICS AND GEOLOGICAL PROCESSES OF CAROLINE M4 GUYOT

卡罗琳M4平顶海山位于卡罗琳海脊与马里亚纳海沟交界处,对其地貌与地质过程的研究有利于深入理解地球动力及环境背景与该地区海山演化的关系。基于“科学”号实测的全覆盖多波束水深数据与“发现”号遥控无人潜水器(remote operated vehicle, ROV)多次下潜获取的近海底影像资料,描述了卡罗琳M4平顶海山及附近区域的地形地貌特征,并对影响海山演化的主要地质过程进行了分析。线性喷发中心等火山地貌指示了研究区内沿线性喷口的裂隙式喷发活动。“C”字型的弯曲形态与陡崖说明山顶平台边缘经历过多次崩塌与破坏,滑坡痕与沉积块体/碎屑组成了块体搬运体系,并在中下段斜坡转变为浊流形成冲沟与水道。M4海山顶部还发育有较为完整的残留环礁地貌,其被淹没的机制可能是由于上升流输入的丰富营养物质影响了底栖环境的光照,从而抑制了珊瑚生长。

The Caroline M4 guyot lies on the junction of the Caroline Ridge and the Mariana Trench.It is an isolated and submerged carbonate platform in minimum water depth of only 28 m below sea surface.Using high-resolution multi-beam bathymetric data collected by R/V“Kexue”,and near-bottom observation video data obtained by ROV“Faxian”,the topographic and geomorphological features of the Caroline M4 guyot were described and the main geological processes affecting the evolution of the guyot were analyzed.Volcanic landforms such as linear eruption centers indicate fissure eruption activities along linear vents occurred in the study area.The C-shaped curvature forms and slump scarps indicate collapse of the margin atop the guyot.The mass transport complexes(MTCs)composed of failure scars and fallen blocks or debris transformed into turbidity currents and formed gullies and channels in the middle-lower slope.The guyot top displays a relatively complete morphology of an atoll.The mechanism of its inundation may be that the rich nutrients input by the upwelling affect the illumination of the benthic environment and inhibit the growth of corals.