现代海底热液硫化物的成矿序列和指示意义——以印度洋中脊为例

与快速扩张的洋中脊相比,主要由超慢速-慢速扩张洋脊组成的印度洋中脊具有独特的热液硫化物成矿模式.运用高精度矿相显微镜、XRD、电子探针和ICP-AES/MS等测试手段,对印度洋中脊的热液硫化物矿床样品开展了矿物成分、结构构造、地球化学等各方面分析.结果表明,来自中印度洋脊(CIR)艾德蒙德(Edmond)热液区的硫化物A主要由黄铁矿、白铁矿以及黄铜矿构成,其成矿期次可划分为白铁矿-黄铁矿阶段(Ⅰ)、闪锌矿-黄铜矿阶段(Ⅱ)以及后期石英阶段(Ⅲ),成矿流体温度经历了低-高-低的变化;同样来自于艾德蒙德热液区的硫化物B主要矿物成分为黄铁矿、白铁矿和硬石膏,成矿期次划分为硬石膏-白铁矿-黄铁矿阶段(Ⅰ)和胶状黄铁矿-石英(Ⅱ) 2个阶段,流体温度经历了低-高的变化;与之相比,来自西南印度洋脊(SWIR)龙旂热液区的硫化物C主要由纤铁矿、黄铜矿、黄铁矿和白铁矿组成,成矿期次划分为纤铁矿-白铁矿-黄铁矿阶段(Ⅰ)和闪锌矿-黄铜矿(Ⅱ)阶段,后期闪锌矿、黄铜矿的出现反映热液流体温度发生了升高.地球化学特征表明,印度洋中脊的热液硫化物总体为富Fe型,并相对富集Co和Ni元素,而Zn和Cu元素的含量相对较低.此外,取自艾德蒙德热液区的硫化物与EPR 21°N热液硫化物组成非常相似,而与慢速扩张脊TAG相比,Pb、Zn、Ag和Sr元素含量较高,Cu和Fe元素含量则较低.     

西南印度洋中脊龙旂热液区中硫化物的结构和微量元素特征-——对金赋存形式和沉淀机制的启示

相比于快速和中速扩张洋中脊,慢速和超慢速扩张洋中脊热液区通常含有丰富的金属硫化物资源。近年来的研究表明大洋中脊的扩张速率与矿石中金的品位呈明显的负相关,即超慢速扩张洋中脊热液区矿石中金的含量高。前人对龙旂热液区的构造环境以及硫化物组合进行了详细研究,但是对龙旂热液区硫化物中贵金属金的赋存形式和沉淀机制研究较少。本文对西南印度洋龙旂热液区中的硫化物进行了精细的矿物结构和微量元素分析,并探讨了金的赋存形式和沉淀机制。龙旂热液区的硫化物主要以黄铁矿为主,其次是黄铜矿和闪锌矿,黄铜矿普遍出溶等轴古巴矿,此外还观察到了少量的针钠铁矾和自然金等矿物。根据矿物结构和形态,黄铁矿明显被划分为两期,一期黄铁矿（Py1）自形度低,呈细粒状或胶状,内部多孔洞;二期黄铁矿（Py2）自形度高,呈自形-半自形,且粒径较大。Py1往往存在于Py2内部或以包体的形式被Py2所包裹,Py2则与自形-半自形黄铜矿和闪锌矿等矿物共生。自然金主要存在于Py1的内部孔洞之中,少量存在于Py2以及Py2与其他硫化物之间。相比于Py2,Py1含有更高的Ni、Zn、Pb、Ba、Mn、V、Mg、U、Au、Ag、Cd元素含量,更低的Co...     

快速扩张的东太平洋海隆侧翼年轻深海丘陵的热液释放现象

大洋板块从洋中脊扩张后,经过热传导和热平流,大洋岩石圈冷却下来。据估算,50%的水热损失(5.5×1012W)和流体通量(2.3×1012m3/a)来自于5Ma或者更年轻的海底。来自0.1～5Ma的地壳流体循环的大量矿物沉降,可以解释地震速度的快速增加,上地壳孔隙度和渗透率随年龄增加而降低,以及504B孔岩心中约6.9Ma时的玄武岩蚀变和矿脉层。虽然发现了洋脊侧翼通量增大的证据,但是由于缺少勘探和足够的知识来了解洋脊侧翼的热液如何释放至海底,对于如此大范围的海底热液喷口的直接观察进行地很少。沿着洋中脊顶部已经发现了上百座活动喷口,在这里已经进行…     

西南印度洋脊龙旂热液场金属硫化物的矿物学组成及指示意义

西南印度洋脊(SWIR)是当前洋底超慢速扩张洋脊的典型代表,具有独特的热液硫化物矿床形成机理,对位于该洋脊的龙旂热液场硫化物样品进行了系统的矿物学分析,结果表明:该区硫化物为高温热液喷溢活动所形成的富Fe型硫化物,目前已经历了一定程度的氧化蚀变;硫化物矿物组合以磁黄铁矿、黄铁矿为主,其次是少量黄铜矿、白铁矿和(铁)闪锌矿;黄铜矿出溶等轴古巴矿现象普遍,部分样品中可见自然金颗粒。经综合分析,该区热液成矿作用可划分为3个成矿阶段和1个后期海底风化阶段:(1)高温的黄铁矿+黄铜矿(等轴古巴矿)+磁黄铁矿阶段,(2)中高温的黄铁矿+闪锌矿阶段,(3)低温的胶状或莓球状黄铁矿+白铁矿+自然金阶段,(4)后期硫化物海底氧化性蚀变阶段主要是形成Fe的氧/羟化物。在整个成矿期间,流体温度有不同程度的波动,主要硫化物矿物形成时端元流体的温度应在335℃以上,瞬间(短时)或局部热液的最高温度推测超过400℃。本区的磁黄铁矿属于富钴型磁黄铁矿亚类,经历了六方磁黄铁矿+黄铁矿→单斜磁黄铁矿+黄铁矿的变化,表明该区热液流体发生了快速降温的演化过程。     

慢速扩张洋中脊热液成矿的典型实例——青藏高原北部德尔尼铜矿地质对比研究

青海德尔尼铜矿是发育在青藏高原北部的块状硫化物矿床,其赋矿围岩为阿尼玛卿蛇绿岩套中的超基性岩,代表了古特提斯洋的残骸。通过对德尔尼铜矿的详细地质解剖,认为其保留了大量海底热液喷流的地质记录,包括:矿体上部普遍发育的薄层喷流岩;多孔状硫化物中保留下来的胶状结构、草莓结构和角砾结构;矿石的主要矿物组成;与黄铁矿碎屑同期形成的方解石、长英质胶结物;与大西洋Rainbow、TAG热液硫化物矿床相似的矿体分带性。根据洋脊玄武岩中TiO2全岩含量估算德尔尼蛇绿岩所代表的这一段古特提斯洋洋中脊为慢速-超慢速扩张洋中脊,半扩张速率为1.1~2.5cm/a。类比现今洋中脊热液硫化物成矿过程,认为德尔尼铜矿经历了海底喷流、冷却保存和俯冲侵位等3个阶段,其中海底喷流阶段可能与洋底核杂岩具有成因联系,俯冲侵位过程中的矿体和超基性岩、玄武岩受逆冲断层控制。与世界上其他陆地上保存的类似矿床相比,德尔尼铜矿时代年轻(石炭纪),矿床结构和构造及其围岩蚀变特征保存完整,是慢速-超慢速洋脊超基性围岩热液成矿作用的典型实例,可以称之为德尔尼型成矿作用,研究其成矿过程,对研究和理解现今洋中脊超基性岩系统热液成矿作用(尤其是深部成矿作用)具有重要的意义。     

西南印度洋中脊龙旂热液区(49°39′E)的地震波各向异性研究进展与展望

龙旂热液区(49°39′E)是超慢速扩张西南印度洋中脊(SWIR)上发现的首个活动热液喷口,也是我国开展海底多金属硫化物资源勘探和走向深海大洋的重点研究区域。前期三维层析成像研究成功地揭示了该区的深部结构特征,但仅仅是提供了静态信息,相比之下,地震波各向异性研究是揭示其深部动力学机制的有效手段之一。本文简要介绍了龙旂热液区开展的主动源和被动源海底地震仪(OBS)探测实验,并初步分析了前期三维层析成像的走时残差数据,发现其与方位角之间存在显著的余弦函数关系,表明该区速度结构存在各向异性,但其各向异性来源尚不明确。探索各向异性来源将有望揭示该区的热液循环机制,为认识超慢速扩张SWIR热液区形成的动力学演化过程提供科学依据。因此,本文拟在前期研究基础上,利用主动源和被动源OBS地震数据,通过纵波方位各向异性和横波分裂联合分析的方法,重点研究地壳和地幔各向异性特征,并结合三维速度模型与区域地质背景资料,对获得的快波方向和快、慢波到时差参数进行深入分析,阐明地壳内裂隙分布、应力场变化和地幔流动特征,从而揭示龙旂热液区的热液循环机制、岩石圈形变和深部动力学过程等科学问题。     

现代海底超镁铁质岩系热液系统与地质意义

现代海底热液循环与洋中脊地质过程一直是国际洋中脊计划研究的热点.海底热液系统多数都与海底玄武岩及其水-岩反应直接相关,而一类与深海橄榄岩的产出及其蛇纹石化作用有关的海底热液系统——超镁铁质岩系热液系统,以具有高浓度H2和CH4异常而低SiO2浓度为显著特征,主要分布在慢速扩张大西洋中脊和超慢速扩张北冰洋Gakkel洋脊和西南印度洋中脊.超镁铁质岩系热液系统在流体组成、构造背景和硫化物成矿方面与玄武岩热液系统有很大差异,主要表现在地幔来源超镁铁质岩石的普遍出露、喷口流体高的H2和CH4异常以及硫化物中高Co/Ni比值.超镁铁质岩系热液系统的发现丰富了全球洋中脊热液系统的研究内容,对洋中脊地质过程、海底热液活动及其成矿作用研究具有重要意义.     

西南印度洋中脊岩石地球化学特征及其岩浆作用研究

作为超慢速扩张脊的代表,西南印度洋中脊(SWIR)因其独一无二的地形地貌特征、洋壳结构、洋壳增生机制、岩浆和热液活动以及深部动力学过程,近30年来成为国内外研究的热点区域。基于近年来对SWIR玄武岩、辉长岩及橄榄岩的岩石学和地球化学研究成果总结,重点探讨了沿SWIR轴向(大尺度)以及单个洋脊分段(小尺度)的岩石地球化学变化特征及其影响因素,阐述了SWIR的岩浆供应及洋壳增生模式。其中,在9°～16°E斜向扩张脊,以构造作用为主的洋脊扩张模式导致了更宽的洋壳增生带和显著的地球化学异常;而在50°～51°E脊段,发育了强烈的火山活动,其成因机制包括克洛泽热点与洋中脊相互作用、微热点、古老熔融事件的残留地幔再熔融等几种观点。此外,西南印度洋中脊龙旂热液区(～49.7°E)的最新研究表明,其热液循环路径与拆离断层的发育密不可分,热液流体循环最深可达莫霍面以下6 km。因此,在今后的一段时间,应进一步加强SWIR不同空间尺度地幔源区性质、洋中脊构造与岩浆作用过程、热点-洋中脊相互作用和岩浆-热液活动与成矿等主要科学问题的研究。     

海洋核杂岩形成机制及其热液硫化物成矿意义

海洋核杂岩是近年来新提出的洋底构造样式,其主要产出于慢速-超慢速扩张洋中脊轴两侧,目前在中大西洋脊、西南印度洋脊、中印度洋脊以及东南印度洋脊均发现海洋核杂岩。海洋核杂岩以其表面梳状构造为主要的探测特征,其构造要素还包括平行于洋脊轴的拆离断层、上盘后期正断层等;其岩石组合以出露于洋底的地幔岩石为主。海洋核杂岩的发育与慢速-超慢速洋脊的扩张速率、岩浆补给和拆离断层的发育有关:慢速-超慢速扩张洋脊的岩浆补给不足以平衡洋脊扩张所带来的空间应变量,从而以在薄弱带发育拆离断层来弥补,并继而使拆离断层下盘的地幔岩石出露洋底表面,形成海洋核杂岩。海洋核杂岩的发育经历了发育初期、发展期、成熟期和衰亡期等周期。海洋核杂岩为洋底热液硫化物矿床的发育提供了物质来源、热液通道等有利条件,或将是热液硫化物矿床发育的有利构造条件,是一种新的远离洋脊轴的热液系统。     

西南印度洋中脊51°E(#26洋脊段)地质特征及其对海底热液活动的指示

在海底多金属硫化物调查过程中，对于已知热液区需要精细地质填图工作，而这种填图往往存在覆盖面积较小、所包含的地质要素较少以及与区域构造作用和岩浆活动联系不足等问题。基于历年大洋航次在西南印度洋中脊#26洋脊段（51°E区域）所获得的深海光学拖曳系统的资料，结合高精度多波束水深数据，提出一种系统的底质热液异常划分原则，识别出热液蚀变岩石或角砾、疑似热液沉积物、热液生物及其遗骸富集和胶结碳酸盐4种底质热液异常类型。高分辨率海底地质填图结果表明，本区存在4处热液活动的异常区。#26洋脊段热液活动频率值为2～10，至少是全球海底热液活动频率经验公式的1.8倍以上。我们认为在超慢速扩张脊局部熔融异常或者发育非转换不连续带的洋脊段，可能存在更多的海底热液活动，也具有形成大型多金属硫化物矿床的潜力。     

Newly discovered hydrothermal fields along the ultraslow-spreading Southwest Indian Ridge around 63°E

The ultraslow-spreading Southwest Indian Ridge(SWIR) to the east of the Melville fracture zone is characterized by very low melt supply and intensive tectonic activity. Due to its weak thermal budget and extremely slow spreading rate, the easternmost SWIR was considered to be devoid of hydrothermal activity until the discovery of the inactive Mt. Jourdanne hydrothermal field(27°51′S, 63°56′E) in 1998. During the COMRA DY115-20 cruise in2009, two additional hydrothermal fields(i.e., the Tiancheng(27°51′S, 63°55′E) and Tianzuo(27°57′S, 63°32′E)fields) were discovered. Further detailed investigations of these two hydrothermal sites were conducted by Chinese manned submersible Jiaolong in 2014–2015. The Tiancheng filed can be characterized as a lowtemperature(up to 13.2°C) diffuse flow hydrothermal field, and is hosted by fractured basalts with hydrothermal fauna widespread on the seafloor. The Tianzuo hydrothermal field is an inactive sulfide field, which is hosted by ultramafic rocks and controlled by detachment fault. The discovery of the three hydrothermal fields around Segment #11 which receives more melt than the regional average, provided evidence for local enhanced magmatism providing heat source to drive hydrothermal circulation. We further imply that hydrothermal activity and sulfide deposits may be rather promising along the easternmost SWIR.     

Two-stage influences of hydrothermal fluids on pumice near the Iheya North hydrothermal field,Okinawa Trough

Hydrothermal precipitates and hydrothermal alteration products could record important information about temporal variations of seafloor hydrothermal systems. Geochemistry, mineralogy, and microscopic features of three pumice samples (T3-1, T3-2, and T3-3) near the Iheya North hydrothermal field were analyzed in this article. The results show that T3-3 sample has undergone at least two-stage influences by hydrothermal fluids. In the first stage, pure amorphous silica from hydrothermal fluid precipitated in the vesicles of all three T3 samples as a result of conductive cooling and fluid–seawater mixing. The precipitation temperatures according to oxygen isotope thermometer are approximately 13–21°C. In the second stage, T3-3 pumice underwent low-temperature hydrothermal alteration, during which the amorphous silica precipitates were redissolved, together resulting in losses of FeO and SiO₂ and gains of MgO, Pb, Zn, and Cu. Furthermore, ferruginous filamentous silica, which might be related to activities of Fe-oxidizing bacteria, was formed in the altered pumice. The transformation from pure amorphous silica precipitation to redissolution of the silica in T3-3 pumice might indicate a rise of temperature and/or decrease in silica concentrations in hydrothermal fluids, implying a changing hydrothermal environment.     

A data processing method for MAPR hydrothermal plume turbidity data and its application in the Precious Stone Mountain hydrothermal field

Hydrothermal plume is an important constituent of seabed hydrothermal circulation and is also one of the characteristics of active hydrothermal vents. Portable Miniature Autonomous Plume Recorders （MAPR） attached to a towed deep-sea instrument was used to search for hydrothermal plumes and hydrothermal vents. We introduced the basic principle of MAPR based on deep towing technology to detect plumes, then analyzed the factors affecting the quality of the MAPR data and presented a data correction method for MAPR, including instrument location correction, noise reduction processing, system error elimination and seawater background reduction. Finally we applied the method to analyze MAPR data obtained during the Chinese DY115-21 cruise on R/VDayang Iin the “Precious Stone Mountain” hydrothermal field on the Gala-pagos Microplate. The results provided a better understanding of the distribution of the hydrothermal activ-ity in this field, indicating the presence of a new hydrothermal vent.     

Geological characteristics of the Qiaoyue Seamount and associated ultramafic-hosted seafloor hydrothermal system (～52.1°E,Southwest Indian Ridge)

Hydrothermal vent incidence was once thought to be proportional to the spreading rate of the mid-ocean ridges (MORs). However, more and more studies have shown that the ultraslow-spreading ridges (e.g., Southwest Indian Ridge (SWIR)) have a relatively higher incidence of hydrothermal venting fields. The Qiaoyue Seamount (52.1°E) is located at the southern side of segment #25 of the SWIR, to the west of the Gallieni transform fault. The Chinese Dayang cruises conducted eight preliminary deep-towed surveys of hydrothermal activity in the area during 2009 and 2018. Here, through comprehensive analyses of the video and photos obtained by the deep-towed platforms, rock samples, and water column turbidity anomalies, a high-temperature, ultramafic-hosted hydrothermal system is predicted on the northern flank of the Qiaoyue Seamount. We propose that this hydrothermal system is most likely to be driven by gabboric intrusions. Efficient hydrothermal circulation channels appear against a backdrop of high rock permeability related to the detachment fault.     

Distal axis sulfide mineralization on the ultraslow-spreading Southwest Indian Ridge: an LA-ICP-MS study of pyrite from the East Longjing-2 hydrothermal field

The newly discovered East Longjing-2 hydrothermal field (ELHF-2) is located on the Dragon Horn oceanic core complex of the ultraslow-spreading Southwest Indian Ridge, approximately 12 km from the ridge axis. This study measured the chemical compositions of pyrite from ELHF-2 using a laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) to investigate the genesis of the field. Three generations of pyrite were classified, and found that: Py1 and Py2, rich in V, Mn, U, and Se, occur in altered basalt debris and the silica alteration matrix, respectively. Py3 was mainly intergrown with chalcopyrite in quartz veins and had higher Cu, In, Ag, Sb, and Au contents than Py1 and Py2. Some elements, such as Au, Se, and Pb, are likely presented as direct substitution with Fe2+ in pyrite, while Cu, Zn, Co, Ni, and Ag probably occur both as direct substitution with Fe and as distributed micro- to nanoparticle-sized sulfides. Meanwhile, the occurrence of V, Mn, and U is likely presented as oxide inclusions. Trace element geochemistry suggested that the pyrite was formed under high-temperature conditions, and the ore forming elements were likely derived from ultramafic rocks. In addition, Py1 and Py2 were formed under higher water/rock ratio and higher temperature conditions, with more seawater involvement compared with Py3. The formation of ELHF-2 was probably driven by exothermic serpentinization reactions with an additional magmatic heat. This study shows that high-temperature hydrothermal circulation driven by magmatic activity can be developed on distal rift flank areas of magma-starved ultraslow-spreading ridges.     

西南印度洋脊“断桥”热液区深部地质构造研究

Polymetalic sulfide is the main product of sea-floor hydrothermal venting, and has become an important sea-floor mineral resources for its rich in many kinds of precious metal elements. Since 2007, a number of investigations have been carried out by the China Ocean Mineral Resources Research and Development Association(COMRA)cruises(CCCs) along the Southwest Indian Ridge(SWIR). In 2011, the COMRA signed an exploration contract of sea-floor polymetallic sulfides of 10 000 km2 on the SWIR with the International Seabed Authority. Based on the multibeam data and shipborne gravity data obtained in 2010 by the R/V Dayang Yihao during the leg 6 of CCCs21, together with the global satellite surveys, the characteristics of gravity anomalies are analyzed in the Duanqiao hydrothermal field(37°39′S, 50°24′E). The "subarea calibration" terrain-correcting method is employed to calculate the Bouguer gravity anomaly, and the ocean bottom seismometer(OBS) profile is used to constrain the two-dimensional gravity anomaly simulation. The absent Moho in a previous seismic model is also calculated.The results show that the crustal thickness varies between 3 and 10 km along the profile, and the maximum crustal thickness reaches up to 10 km in the Duanqiao hydrothermal field with an average of 7.5 km. It is by far the most thicker crust discovered along the SWIR. The calculated crust thickness at the Longqi hydrothermal field is approximately 3 km, 1 km less than that indicated by seismic models, possibly due to the outcome of an oceanic core complex(OCC).     

西南印度洋龙方斤热液区羽流信号的检测与通量估算

热液流体在物理化学特征方面与周围海水存在较大差异,探测温度异常和浊度异常是寻找热液羽状流信号的重要手段。本文采用“大洋一号”科考船第20航次的拖曳CTD数据和浊度数据,以及21航次的定点CTD数据,研究了西南印度洋龙方斤热液区的温度异常和浊度异常现象。研究表明热液区中性浮力层在水深2 550~2 650 m间,厚度约为100 m,温度异常达0.01 ℃;水深 2 750~2 800 m间亦有温度异常,最大可达0.08 ℃;温度异常水深处存在相应的浊度异常。深层背景海水位温和位密间存在简单线性关系。此外,经初步估计,热液活动区初始浮力通量为8.78×10^-4 m⁴/s³;通过中性浮力层估算热液热通量,约为130±43 MW。     

海底热液活动的环境与产物

近23年的调查研究,使我们认识到分布于洋中脊、弧后盆地、岛弧和热点等环境的海底热液活动发育在多种围岩类型之上,包括超基性岩石、基性岩石、中性岩石、酸性岩石和沉积物。海底热液活动经历了岩浆去气作用、流体-岩石/沉积物相互作用和流体-海水混合,获取了岩浆、岩石、海水和沉积物的物质,构成了热液循环,产生了高温、低氧、高或低pH值、富含Fe、Mn、Cu、Zn、Pb、Hg、As等元素以及气体组分（甲烷、氢等）的喷口流体,影响了海水、沉积、岩石和生物环境,形成了热液柱、硫化物、含金属沉积物和蚀变岩石等热液产物,组成了海底热液系统。未来,促进海底热液活动探测技术和热液产物测试方法的发展,对海底热液区的岩石、喷口流体、热液柱、硫化物、含金属沉积物以及热液循环、生物活动的持续观测与研究,无疑将为人类探知海底地质过程及生命活动、保护海底热液环境和合理开发利用海底资源提供有力的工作支撑。     

西南印度洋脊49.6°E热液区热液产物和玄武岩地球化学特征

利用X射线荧光法和ICP-MS等方法对取自超慢速扩张的西南印度洋脊(SWIR) 49.6°E热液区的热液产物和玄武岩样品进行元素地球化学特征分析研究,结果表明:(1)与亏损型洋中脊玄武岩(N-MORB)相比,研究区玄武岩样品的主量元素组成显示其偏碱性,而微量元素对比表明该区玄武岩明显富集Pb元素;(2)对热液产物的综合分析表明这些样品多为Fe-Si-Mn氧羟化物且都为热液来源;(3)热液产物的∑REE含量介于玄武岩和海水之间,经球粒陨石标准化的稀土元素(REE)分布模式均表现出Eu正异常和轻稀土(LREE)富集的特征。另外,本研究还表明,利用玄武岩和热液产物地球化学指标不仅能够模拟出以热液喷口为中心的元素地球化学晕,而且能反映出热液活动的影响范围。     

Control of the stress field on shallow seafloor hydrothermal paths: A case study of the TAG hydrothermal field

The stress state and rock mechanical properties govern the growth of faults and fractures, which constitute shallow hydrothermal pathways and control the distribution of seafloor massive sulfide (SMS) mounds in the seafloor hydrothermal field. The stress field has an important influence on the formation and persistence of hydrothermal pathways. Based on multibeam bathymetric data from the Trans-Atlantic Geotraverse (TAG) field, we establish two three-dimensional geological models with different scales to simulate the stress field, which investigate the characteristics of hydrothermal pathways and associated SMS mounds. The simulation results show that oblique faults and fissures form in the tensile stress zone and that mounds, including active and inactive hydrothermal mounds form in the compressive stress zone. Fault activity, which is related to the stress field, affects the opening and closing of hydrothermal channels and changes the permeability structure of subseafloor wall rock. Therefore, the stress field controls the development and persistence of shallow hydrothermal pathways. The features of shallow hydrothermal pathways in the stress field can provide geomechanical information that is useful for identifying favorable zone for SMS deposit formation.