海洋地质与环境重点实验室知识库

海山被认为是岩石圈、水圈与生物圈相互作用的关键交叉点，蕴藏有丰富的渔业和矿产资源。西太平洋分布有全球最密集、复杂的海山系统，然而高分辨率测深资料的缺失限制了海山研究的广泛开展。雅浦-卡罗琳海区地处菲律宾海板块、太平洋板块与卡罗琳板块三大板块的汇聚处，海底地貌特征复杂并发育了数量众多的海山。基于多个航次中“科学”号实测的全覆盖多波束水深数据与“发现”号ROV下潜获取的近海底影像资料，本研究首先描述了雅浦-卡罗琳海区的水深地形特征，并对多座海山的具体形态及底质环境进行了分析，讨论了各种地质过程对海山地貌塑造的影响，以期为雅浦-卡罗琳海区的海山演化研究提供参考。研究结果也可以为西太平洋与雅浦-卡罗琳海区的海洋科学研究与资源调查提供基础地质信息支撑。

根据各区相对位置关系，本研究将雅浦-卡罗琳海区划分为帕里西维拉海盆地貌体系、雅浦俯冲带地貌体系与卡罗琳海脊地貌体系，并依据板块构造地貌分类方法划分了四级地貌类型。通过对研究区精细地貌的研究，发现帕里西维拉海盆内脊-槽地貌具有不同走向，雅浦海沟不同坡面形态存在差异，索罗尔海槽内可识别线状排列的海山与深海洼地。研究结果表明，这些地貌形态不同程度上受到了弧后扩张方向改变、俯冲侵蚀作用与海槽扩张活动等构造环境的影响。

八座位于雅浦-卡罗琳海区的海山得到了专项调查并采集了高分辨率的水深地形数据，它们分别是位于马里亚纳海沟北侧的M1和M2海山，位于雅浦海沟西侧的Y3海山，以及位于卡罗琳海脊上的M4～M8海山。其中，M2和M4海山规模较大，为被淹没的孤立碳酸盐台地，山顶平坦且接近海平面，边坡随水深增大坡度变小。Y3海山为雅浦岛弧海山链的一部分，呈细长条带状，靠近海沟一侧边坡陡峭。M5～M7海山位置靠近，规模较小。M8海山为一大型火山锥，与M4海山之间有山脊相连。总体而言，所有海山的大部分表面都被碳酸盐沉积物覆盖，火山构造和玄武岩露头少见。同时，在多数海山上部，都能采集到礁灰岩或珊瑚碎石，指示了地质历史时期的热带浅水沉积环境。

在雅浦-卡罗琳海区的海山上，识别出了火山脊/锥、断层崖、滑坡壁、冲沟等地貌特征，可以与岩浆、构造、侵蚀沉积等地质过程相联系。线性喷发中心等火山地貌指示了卡罗琳海脊上的裂隙式喷发活动。雅浦-马里亚纳海沟的俯冲通过俯冲侵蚀与挠曲断裂两种形式分别对上覆板块与下沉板块的海山边坡造成影响。M2与M4海山顶部的喀斯特坑洞可能触发崩塌破坏，并在山顶平台边缘残留“C”字型的弯曲形态。滑坡壁与沉积块体/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。此外，彗星痕迹底形与边缘等深流凹陷说明研究区存在强烈的底流作用。

Seamounts are key intersection points among the lithosphere, hydrosphere, and biosphere, containing rich fisheries and mineral resources. The western Pacific Ocean features the densest and most complex seamount system worldwide. However, a lack of field survey data makes for inconsistent research of this system. The Yap-Caroline Sea area is located at the junction of the Philippine Sea Plate, Pacific Plate, and Caroline Plate. The seafloor geomorphological features are complex and numerous seamounts have developed. Here, based on bathymetric data collected by shipborne multibeam echosounder system and in-situ exploration data acquired by a remote-operated vehicle (ROV) in different cruises, the topographic characteristics of the Yap-Caroline Sea area were described. In addition, the bathymetric details and bottom environment of serial seamounts in the study area are analyzed, and the different geological processes shaping the seamounts are discussed. The research results can provide a reference for the study of seamount evolution in the Yap-Caroline Sea area, and can also provide basic geological information support for marine scientific research and resource surveys in the Western Pacific and Yap-Caroline Sea area.

Based on the topographic characteristics, the study area was divided into the Yap Back-arc Basin Geomorphic System, the Yap Subduction Zone Geomorphic System and the Caroline Ridge Geomorphic System. According to the classification standard of the plate tectonic, four geomorphological units were classified. Through detailed geomorphologic analysis, it is found that the ridge-trough landforms in the Parece Vela Basin have different strike directions, and slopes on both sides of the Yap Trench display different morphologic features. The linear arrangement patterns of seamounts and deep-sea depressions can be identified in the Solor Trough. The research results show that the tectonic activities, such as the collision of the Yap Trench and the Caroline Ridge, subduction erosion, and trough expansion, play roles in shaping the landforms of the study area.

Eight seamounts located in the Yap-Caroline Sea area have been specially surveyed and high-resolution bathymetric topographic data have been collected. M1 and M2 seamounts are located on the north side of the Mariana Trench, Y3 seamount is located on the west side of the Yap Trench, and M4~M8 seamounts were located on the Caroline Ridge, respectively. Among them, M2 and M4 seamounts are large in scale and are identified as submerged isolated carbonate platforms. The tops of the mountains are flat and close to sea level, and the gradient of the slopes decrease with increasing water depth. The Y3 seamount is part of the Yap Arc seamount chain. It is in the banded shape with a steep slope close to the trench. Seamounts M5, M6 and M7 are closely located and are small in scale. The M8 seamount is a large volcanic cone connected to the M4 seamount by a ridge topography. Overall, all seamounts were covered by carbonate deposits over most of their surfaces, with fewer volcanic formations and basalt outcrops. On the upper parts of most seamounts, reef limestone or coral rubbles can be found, indicating a tropical shallow-water sedimentary environment experienced in the past.

On the seamounts in the Yap-Caroline Sea area, geomorphic features such as volcanic cones, fault scarps, landslide scars, gullies have been recognized and linked to magmatic, tectonic and erosion-depositional processes. Subduction processes along the Yap-Mariana Trench affects the morphological characteristics of the seamounts on the overriding and downgoing plates through subduction erosion and bending-faulting processes, respectively. Margin collapse might be triggered by karst holes on the summit platform edge of seamounts, forming arcuate, bight-like structures on the edges. The mass transport complexes (MTCs) composed of failure scars and fallen blocks or debris transform into turbidity currents and form gullies and channels in the middle and lower slope. In addition, marginal contourite depressions and bedforms of the comet marks indicate strong bottom currents in the study area.

第1章 绪论  1

1.1 研究目的及意义  1

1.2 研究现状  2

1.2.1 雅浦-卡罗琳海区研究现状  2

1.2.2 海山国内研究现状  3

1.2.3 海山国外研究现状  5

1.3 本文的主要工作  8

第2章 研究区概况与研究方法  9

2.1 研究区概况  9

2.2 研究方法  11

第3章 雅浦-卡罗琳海区地形地貌特征  15

3.1 帕里西维拉海盆地貌体系  16

3.2 雅浦俯冲带地貌体系  18

3.3 卡罗琳海脊地貌体系  20

3.4 雅浦-卡罗琳海区地貌分类  22

第4章 雅浦-卡罗琳海区海山地貌特征  25

4.1 M1与M2海山  26

4.2 Y3海山  29

4.3 M4与M8海山  32

4.4 M5, M6与M7海山  37

第5章 雅浦-卡罗琳海区海山地质过程分析  41

5.1 雅浦-卡罗琳海区内火山作用的模式  41

5.2 俯冲活动对海山形态的影响  42

5.3 边缘崩塌与斜坡重力过程  42

5.4 底流作用的地貌表征  43

5.5 生物礁的生长与消亡  44

第6章 结论与展望  47

6.1 结论  47

6.2 不足与展望  47

参考文献  49

致  谢  61

作者简历及攻读学位期间发表的学术论文与其他相关学术成果  63