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1.
The paper reports the results of a geochemical study of volcanogenic rocks from the southern part of the Kyushu–Palau Ridge. Volcanic structures, such as plateaulike rises, mountain massifs, and single volcanoes, are the major relief-forming elements of the southern part of the Kyushu–Palau Ridge. They are divided into three types according to the features of the relief and geological structure: shield, cone-shaped, and dome-shaped volcanoes. The ridge was formed on oceanic crust in the Late Mesozoic and underwent several stages of evolution with different significance and application of forces (tension and compression). Change in the geodynamic conditions during the geological evolution of the ridge mostly determined the composition of volcanic rocks of deep-mantle nature. Most of the ridge was formed by the Early Paleogene under geodynamic conditions close to the formation of oceanic islands (shield volcanoes) under tension. The island arc formed on the oceanic basement in the compression mode in the Late Eocene–Early Oligocene. Dome-shaped volcanic edifices composed of alkaline volcanic rocks were formed in the Late Oligocene–Early Miocene under tension. Based on the new geochemical data, detailed characteristics of volcanic rocks making up the shield, cone-shape, and dome-shape stratovolcanoes resulting in the features of these volcanic edifices are given for the first time. Continuous volcanism (with an age from the Cretaceous to the Late Miocene and composition from oceanic tholeiite to calc-alkaline volcanites of the island arc type) resulting in growth of the Earth’s crust beneath the Kyushu–Palau Ridge was the major factor in the formation this ridge. 相似文献
2.
A. Geisslinger H. B. Hirschleber M. Schnaubelt J. J. Dañobeitia J. Gallart 《Geo-Marine Letters》1996,16(2):57-64
During the Volcanic Island Clastic Apron Project (VICAP), south of the Canary Islands, a total of 700 line-km multichannel seismic profiles were acquired. Two prominent reflectors (A and C) were observed alternately: A is the top of the volcanic apron. C, at a depth of about 5.8 s (two way traveltime twt), can be correlated to reflector R7, a marker dated mid-Miocene (16 Ma) at the DSDP site 397. The deepest reflection (E) in the basin was observed at 8 s (twt), which is an atypical oceanic basement. 相似文献
3.
A number of samples have been dredged from the upper parts of Amanay and El Banquete Seamounts, yet volcanic materials have been collected only on Amanay Seamount. Based on textural features and the presence or absence of kaersutite, two main types of olivine pyroxene basaltic rocks have been identified. The rocks are basanites with high enrichment in the most incompatible elements, similar to that displayed by Ocean Island Basalts. Samples from Amanay Seamount formed due to a low degree of melting of an enriched mantle, very similar to that which probably caused the Miocene volcanic activity of Fuerteventura. The age of Amanay volcanic rocks, 15.3 ± 0.4 and 13.1 ± 0.3 Ma, is similar to those of the older volcanic units exposed in the nearby islands (Gran Canaria, Fuerteventura and Lanzarote). This proves the formation of a separate submarine volcanic edifice coeval with the other edifices of the Eastern Canarian Volcanic Ridge. Volcanic activity on the submarine edifice is thought to have ceased at about 13 Ma, simultaneous with the adjacent main volcanic construction. 相似文献
4.
J. Acosta E. Uchupi A. Muñoz P. Herranz C. Palomo M. Ballesteros 《Marine Geophysical Researches》2003,24(1-2):1-40
In this paper we discuss the results of a swath bathymetric investigation of the Canary archipelago offshore area. These new
data indicate that volcanism is pervasive throughout the seafloor in the region, much more that would be suggested by the
islands. We have mapped tens of volcanic edifices between Fuerteventura and Gran Canaria and offshore Tenerife, La Gomera,
El Hierro and La Palma. Volcanic flows are present between Tenerife and La Gomera and salic necks dominate the eastern insular
slope of La Gomera. This bathymetry also supports land geologic studies that indicate that the oceanic archipelago has acquired
its present morphology in part by mass wasting, a consequence of the collapse of the volcanic edifices. In the younger islands,
Tenerife, La Palma and El Hierro, the Quaternary (1.2 to 0.15 Ma) debris avalanches are readily recognizable and can be traced
offshore for distances measured in tens of km. Off the older islands, Lanzarote, Fuerteventura, Gran Canaria and La Gomera
(<20 to 3.5 Ma), the avalanches have been obscured by subsequent turbidity current deposition and erosion as well as hemipelagic
processes. The failure offshore western Lanzarote is in the form of a ramp at the base of the insular slope bound on the seaward
side by a scarp. Its size and the lack of evidence of rotation along its landwards side precludes the possibility that it
is a slump. It probably represents a slide whose outer scarp is caused by break-up of the slide. Mounds on the ramp’s surface
may represent post-displacement volcanic structures or exotic blocks transported to their present locations by the slide.
The failures offshore Fuerteventura are so large that, although they occurred in the Miocene-Pliocene, exotic blocks displaced
from upslope are still recognizable in the insular margin morphology. The Canary Island insular margin appears to be a creation
of Miocene-Pliocene mass wasting and more recent turbidity current deposition and erosion, and hemilepagic deposition. Failures
offshore La Gomera are due to debris flows and/or turbidity currents. These events have obscured earlier mass wasting events.
An erratum to this article is available at . 相似文献
5.
The Kane Transform offsets spreading-center segments of the Mid-Atlantic Ridge by about 150 km at 24° N latitude. In terms of its first-order morphological, geological, and geophysical characteristics it appears to be typical of long-offset (>100 km), slow-slipping (2 cm yr-1) ridge-ridge transform faults. High-resolution geological observations were made from deep-towed ANGUS photographs and the manned submersible ALVIN at the ridge-transform intersections and indicate similar relationships in these two regions. These data indicate that over a distance of about 20 km as the spreading axes approach the fracture zone, the two flanks of each ridge axis behave in very different ways. Along the flanks that intersect the active transform zone the rift valley floor deepens and the surface expression of volcanism becomes increasingly narrow and eventually absent at the intersection where only a sediment-covered ‘nodal basin’ exists. The adjacent median valley walls have structural trends that are oblique to both the ridge and the transform and have as much as 4 km of relief. These are tectonically active regions that have only a thin (<200 m), highly fractured, and discontinuous carapace of volcanic rocks overlying a variably deformed and metamorphosed assemblage of gabbroic rocks. Overprinting relationships reveal a complex history of crustal extension and rapid vertical uplift. In contrast, the opposing flanks of the ridge axes, that intersect the non-transform zones appear to be similar in many respects to those examined elsewhere along slow-spreading ridges. In general, a near-axial horst and graben terrain floored by relatively young volcanics passes laterally into median valley walls with a simple block-faulted character where only volcanic rocks have been found. Along strike toward the fracture zone, the youngest volcanics form linear constructional volcanic ridges that transect the entire width of the fracture zone valley. These volcanics are continuous with the older-looking, slightly faulted volcanic terrain that floors the non-transform fracture zone valleys. These observations document the asymmetric nature of seafloor spreading near ridge-transform intersections. An important implication is that the crust and lithosphere across different portions of the fracture zone will have different geological characteristics. Across the active transform zone two lithosphere plate edges formed at ridge-transform corners are faulted against one another. In the non-transform zones a relatively younger section of lithosphere that formed at a ridge-non-transform corner is welded to an older, deformed section that initially formed at a ridge-transform corner. 相似文献
6.
The 85°E Ridge, located in the Bay of Bengal of the northeastern Indian Ocean is an enigmatic geological feature as it possesses unusual geophysical signatures. The ridge's internal structure and mode of eruptions are unknown due to lack of deep seismic reflection and borehole data control. Here, we analyze 10 km of long-streamer seismic reflection data to unravel the ridge's internal structure, and thereby to enhance the understanding of how the ridge was originated and grew over a geologic time. Seismic facies analysis reveals the ridge structure consisting of volcanic vent and several stratigraphic units including packs of prograding clinoforms. The clinoform sequences are interpreted as volcanic successions, and led to the formation of lava-delta fronts. Interpreted features of lava-fed deltas and intervening erosional surfaces, and mass flows along ridge flanks suggest that the 85°E Ridge is a volcanic construct, and was built by both subaqueous and multiphase sub-marine volcanism during the Late Cretaceous (approximately from 85 to 80 Ma). At later time, from Oligocene-Miocene (∼23 Ma) onwards the ridge was buried under the thick sediments of the Bengal Fan system. 相似文献
7.
8.
Rick A. Hagen Nancy A. Baker David F. Naar R. N. Hey 《Marine Geophysical Researches》1990,12(4):297-315
SeaMARC II side-scan sonar data reveal that a large area of seafloor north and west of Easter Island has been disrupted by
recent submarine volcanism. A large volcanic area begins approximately 60 km WNW of the island and extends for over 130 km
to the west. The volcanic field is characterized by high backscatter intensity in the side-scan sonar records and is elevated
400–1000 m above the N-S seafloor fabric that surrounds it. This field, the Abu Volcanic Field, covers at least 2500 km2 and appears to consist of recent lava flows and small volcanoes. Backscatter intensity of the Abu Volcanic Field is similar
to that of the adjacent ridge flank which is less than 0.4 Ma, suggesting a similar age for its formation.
Two additional areas of high backscatter immediately north of Easter Island cover a combined area of over 300 km2. The sidescan sonar records show that these features are clearly of volcanic origin and are not debris flows from the nearby
island. The flows are nearly 300 m thick and are morphologically similar to subaerial pahoehoe lava shields. Their high backscatter
indicates that they are also the products of relatively recent submarine volcanic activity.
The presence of these large areas of recent volcanism in the vicinity of Easter Island has important implications for the
various models that have been proposed to explain the origin of the Easter Seamount Chain. In addition, the similar ages of
Easter Island and the Easter Microplate suggest that the presence of a hotspot near or beneath this fast-spreading portion
of the East Pacific Rise about 4.5 m.y. ago may have initiated the large-scale rift propagation that created the microplate. 相似文献
9.
文章采用GPS-RTK技术进行2016年金山三岛滩涂水下地形测量,绘制金山三岛滩涂水下地形云图,并与2014年和2015年滩涂水下地形测量结果进行对比,得出以下结论:金山三岛连线左右1km之内的地形起伏变化大,小金山岛南北侧各有一条深坑,大小金山岛之间有一条贯穿东西向的深槽,它的形成与涨落潮流不一致以及人为活动有关,大金山岛与浮山岛之间有一类似山脊样的地形,浮山岛南侧也有一深坑存在。近3年金山三岛滩涂水下地形变化不大,局部小范围内有淤积和冲刷。定期对三岛滩涂水下地形进行测量可以掌握其变化规律,为管理部门提供管理基础资料。 相似文献
10.
In the equatorial Atlantic the Ceará and Sierra Leone rises lie on opposing sides of the mid-ocean ridge and are equidistant from its axis. The northern and southern boundaries respectively, of the two rises are formed by the same fracture zones. The area of shallowest acoustic basement under the Ceará Rise coincides with the presence of a 1–2 km thick seismic layer (velocity: 3.5 km/sec) lying over the oceanic layer 2. This 3.5 km/sec layer is interpreted as a sequence of volcanics which began erupting about 80 m.y. ago when the sites of the two rises lay at the ridge axis. As the “abnormal” volcanic activity ceased, the breakup of this volcanic pile into two pieces has formed the Ceará and Sierra Leone rises.
In the South Atlantic, the northern and southern boundaries of the Rio Grande Rise are also formed by fracture zones and an approximately 1 km thick layer with a velocity of 3.5 km/sec exists also under this rise. The same fracture zones appear to bound the Walvis Ridge. Drilling data suggests that both the Rio Grande Rise and Walvis Ridge have subsided continuously since their creation. The igneous rocks recovered from both rises consist of alkalic basaltic suites typical of oceanic volcanic islands. The existing data favor a model in which “excessive” volcanism along the same segment of the Mid-Atlantic Ridge created both the South Atlantic aseismic rises between 100 and 80 m.y. ago. In both the examples, the northern and southern boundaries of the rises are formed by the same fracture zones which originally bounded the abnormally active segment of the ridge axis. 相似文献
11.
D. Franke U. BarckhausenN. Baristeas M. EngelsS. Ladage R. LutzJ. Montano N. PellejeraE.G. Ramos M. Schnabel 《Marine and Petroleum Geology》2011,28(6):1187-1204
The South China Sea formed by magma-poor, or intermediate volcanic rifting in the Paleogene. We investigate the structure of the continent-ocean transition (COT) at its southern margin, off NW Palawan between the continental blocks of Reed Bank and the islands of Palawan and Calamian. Several surveys, recorded by the BGR from 1979 to 2008, established a comprehensive database of regional seismic lines, accompanied with magnetic and gravity profiles.We interpret two major rifted basins, extending in the NE direction across the shelf and slope, separated by a structural high of non volcanic origin.The continent-ocean transition is interpreted at the seaward limit of the continental crust, when magnetic spreading anomalies terminate some 80-100 km farther north. The area in between displays extensive volcanism - as manifest by extrusions that occasionally reach and cut the seafloor, by dykes, and by presumed basaltic lava flows - occurring after break-up.The COT is highly variable along the NW Palawan slope: One type shows a distinct outer ridge at the COT with a steep modern seafloor relief. The other type is characterised by rotated fault blocks, bounded by listric normal faults ramping down to a common detachment surface. Half-grabens developed above a strongly eroded pre-rift basement. The seafloor relief is smooth across this other type of COT.We suggest the pre-rift lithospheric configuration had major influence on the formation of the COT, besides transfer zones. Volcanic domains, confined to the north of competent crustal blocks correlate with the style of the COT.Gravity modelling revealed an extremely thinned crust across the shelf. We propose a depth-dependent extension model with crust being decoupled from mantle lithosphere, explaining the discrepancy of subsidence observed across the South China Sea region. 相似文献
12.
This paper presents the results of geological studies carried out during the two marine expeditions of the R/V Akademik M.A. Lavrent’ev (cruises 37 and 41) in 2005 and 2006 at the underwater Vityaz Ridge. Dredging has yielded various rocks from the basement
and sedimentary cover of the ridge within the limits of three polygons. On the basis of the radioisotope age determinations,
petrochemical, and paleontological data, all the rocks have been subdivided into the following complexes: the volcanic ones
include the Paleocene, Eocene, Late Oligocene, Middle Miocene, and Pliocene-Pleistocene; the volcanogenic-sedimentary ones
include the Late Cretaceous-Early Paleocene, Paleogene undifferentiated, Oligocene-Early Miocene, and Pliocene-Pleistocene.
The determination of the age and chemical composition of the rocks has enabled us to specify the formation conditions of the
extracted complexes and to trace the geological evolution of the Vityaz Ridge. The presence of young Pliocene-Pleistocene
volcanites allows one to come to a conclusion about the modern tectono-magmatic activity of the central part of the Pacific
slope of the Kuril Islands. 相似文献
13.
Gravity and multichannel seismic reflection constraints on the lithospheric structure of the Canary Swell 总被引：1，自引：0，他引：1
Deep penetrating multichannel seismic reflection and gravity data have been used to study the lithospheric structure of the Canary Swell. The seismic reflection data show the transition from undisturbed Jurassic oceanic crust, away from the Canary Islands, to an area of ocean crust strongly modified by the Canary volcanism (ACV). Outside the ACV the seismic records image a well layered sedimentary cover, underlined by a bright reflection from the top of the igneous basement and also relatively continuous reflections from the base of the crust. In the ACV the definition of the boundary between sedimentary cover and igneous basement and the crust-mantle boundary remains very loose. Two-dimensional gravity modelling in the area outside the influence of the Canary volcanism, where the reflection data constrain the structure of the ocean crust, suggests a thinning of the lithosphere. The base of the lithosphere rises from 100 km, about 400 km west of the ACV, to 80 km at the outer limit of the ACV. In addition, depth conversion of the seismic reflection data and unloading of the sediments indicate the presence of a regional depth anomaly of an extension similar to the lithospheric thinning inferred from gravity modelling. The depth anomaly associated with the swell, after correction for sediment weight, is about 500 m. We interpret the lithospheric thinning as an indication of reheating of old Mesozoic lithosphere beneath the Canary Basin and along with the depth anomaly as indicating a thermal rejuvenation of the lithosphere. We suggest that the most likely origin for the Canary Islands is a hot spot. 相似文献
14.
The breakup of western margin of Australia from Greater India started around 155 Ma and progressed southwards. After the separation, the interceding intraplate region experienced large volumes of submarine volcanism, extending over 100 Myrs. The Christmas Island Seamount Province (CHRISP, as it has been dubbed) lies south of the Java-Sunda Trench, and contains numerous submerged volcanic seamounts, and two sub-aerially exposed island groups—Cocos (Keeling) Islands, and Christmas Island. While recent geochronological investigations have shed light on the diverse eruption ages of the volcanics of this region, some islands/seamounts have demonstrated protracted volcanic histories, and it is not clear how the volcanic loading, tectonic subsidence, and subsequent emergence history of the islands relates to these discrete volcanic episodes. This study utilises a number of geophysical techniques to determine the crustal structure, loading and subsidence history, and last sub-aerial exposure age for the CHRISP. The study shows that flexural and subsidence modelling are reliable techniques in constraining the age of the seamounts when geochronological techniques are not possible. Utilising regional gravity signatures, we model the crustal structure underneath the Cocos (Keeling) Island, and constrain the thickness of the limestone cover between 900 and 2,100 m. Using age-depth subsidence curves for oceanic lithosphere the time since these seamounts were exposed above sea-level was determined, and a trend in exposure ages that youngs towards the west is observed. Two episodes of volcanism have been recorded at Christmas Island and they are of different origin. The younger phase in the Pliocene is a manifestation of flexure induced cracks produced in the lithosphere as it rides the subduction fore-bulge, whereas a low velocity seismic zone rising from the lower mantle, and tectonic reorganization, may be associated with the older Eocene volcanic phase, as well as much of the rest of the province. Our modelling also supports the existence of an older, undated volcanic core to Christmas Island, based on the loading ages from flexural modelling. 相似文献
15.
Detailed morphological data collected from the submarine flanks of the Canary Islands have revealed numerous submarine canyons down to water depths of >3,000 m. These canyons are interpreted to have formed by submarine erosion. We postulate formation of proto-canyons by downslope-eroding mass flows which originate on land, enter the sea, and continue below sea level for several tens of kilometers. Once proto-canyons have been formed, they become deepened by further erosion and failures of the canyon walls and/or floor. Large amounts of sediments, funnelled through the canyons from the islands into the adjacent deep-ocean sedimentary basins, play an important role in the evolution of volcanic aprons surrounding ocean islands. Some major canyon systems appear to have persisted for at least 14 million years. 相似文献
16.
A. P. Sedov G. I. Kazakevich V. V. Matveenkov L. P. Volokitina S. V. Luk’yanov V. A. Rashidov 《Oceanology》2008,48(4):578-587
A possible mechanism of the formation of chains of intraplate seamounts and islands alternative to the “hot spot” hypothesis is considered. It is related to the appearance of additional stresses in the lithospheric plate when it ascends over a mantle inhomogeneity and descends from it. The magnitude of these stresses (～600 bar) is sufficient for formation of deep fracture zones. In the paper, schemes of formation of volcanic chains are described. The formation of the “faults-volcanoes-volcanic chains” sequence may follow two different ways. The first is controlled by the fracture zones formed along the direction of the plate movement. In this case, feeding channels are localized along the boundary of the rise. If the chain is gradually formed simultaneously with the plate motion, the age of the volcanoes along the chain may change in a more or less regular way. The second type is formed by fractures orthogonal to the movement direction. They may be formed when the plate ascends over a mantle inhomogeneity and/or descends from it. In this case, adjacent volcanoes may have similar ages. A combination of these two variants may also be encountered. The mechanism posed allowed us to explain selected facts referring to the volcanic chains of French Polynesia and may be applied to other regions of the Pacific Ocean. 相似文献
17.
白垩纪以来太平洋上地幔组成和温度变化 总被引：1，自引：0，他引：1
张国良 《海洋学报(英文版)》2016,35(4):19-25
The geological evolution of the Earth during the mid-Cretaceous were shown to be anomalous, e.g., the pause of the geomagnetic field, the global sea level rise, and increased intra-plate volcanic activities, which could be attributed to deep mantle processes. As the anomalous volcanic activities occurred mainly in the Cretaceous Pacific, here we use basalt chemical compositions from the oceanic drilling(DSDP/ODP/IODP) sites to investigate their mantle sources and melting conditions. Based on locations relative to the Pacific plateaus, we classified these sites as oceanic plateau basalts, normal mid-ocean ridge basalts, and near-plateau seafloor basalts. This study shows that those normal mid-ocean ridge basalts formed during mid-Cretaceous are broadly similar in average Na8, La/Sm and Sm/Yb ratios and Sr-Nd isotopic compositions to modern Pacific spreading ridge(the East Pacific Rise). The Ontong Java plateau(125–90 Ma) basalts have distinctly lower Na8 and143Nd/144 Nd, and higher La/Sm and 87Sr/86 Sr than normal seafloor basalts, whereas those for the near-plateau seafloor basalts are similar to the plateau basalts, indicating influences from the Ontong Java mantle source. The super mantle plume activity that might have formed the Ontong Java plateau influenced the mantle source of the simultaneously formed large areas of seafloor basalts. Based on the chemical data from normal seafloor basalts, I propose that the mantle compositions and melting conditions of the normal mid-ocean ridges during the Cretaceous are similar to the fast spreading East Pacific Rise. Slight variations of mid-Cretaceous normal seafloor basalts in melting conditions could be related to the local mantle source and spreading rate. 相似文献
18.
经过对"探宝号"调查船在2001年8月在南海东北部陆坡及台湾南部恒春海脊海域采集的多道地震剖面资料进行的地震反射波数据分析、研究和解释,结果表明:(1)南海东北部陆坡段区域和台湾南部恒春海脊海域地震剖面上均显示有被作为天然气水合物存在标志的BSR,但两区域构造成因、形式和相关地质环境的不同造成了此两处的天然气水合物成因及过程的不同.(2)南海东北部陆坡区域的水合物形成与该区广泛发育的断裂带、滑塌构造体及其所形成的压力场屏蔽环境有关,而台湾南部恒春海脊海域的天然气水合物的形成则与马尼拉海沟俯冲带相关的逆冲推覆构造、增生楔等及其所对应的海底流体疏导体系有关.(3)南海陆缘区域广泛发育有各种断裂带、滑塌构造体、泥底辟、俯冲带、增生楔等,且温压环境合适,是天然气水合物矿藏极有可能广泛分布的区域. 相似文献
19.
Large‐scale connectivity of Grapsus grapsus (Decapoda) in the Southwestern Atlantic oceanic islands: integrating genetic and morphometric data 
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下载免费PDF全文 Mariana M. Teschima Patrícia R. Strӧher Carina R. Firkowski Marcio R. Pie Andrea S. Freire 《Marine Ecology》2016,37(6):1360-1372
The degree of connectivity among island populations can influence their demography and affect their level of genetic differentiation. In this study we investigated genetic and morphometric differences among four populations of Grapsus grapsus (Linnaeus 1758), in Saint Peter and Saint Paul Archipelago (0°55′ N, 29°20′ W), Fernando de Noronha Archipelago (3°50′ S, 32°24′ W), Rocas Atoll (3°50′ S, 33°49′ W) and Trindade Island (20°30′ S, 29°20′ W) from 2003 to 2011. Morphometric results indicated the existence of two distinct groups based on the morphology of their chelae (Trindade Island/Saint Peter and Saint Paul Archipelago versus Fernando de Noronha/Rocas Atoll). In addition, genetic variation in a fragment of the mitochondrial control region revealed substantial differentiation between Trindade and the other islands, with Trindade Island showing only exclusive haplotypes. The congruence of the genetic and morphologic analyses suggests the occurrence of a divergent population in Trindade Island as well as high connectivity among the three remaining equatorial islands. This is the first study to assess the level of morphologic differentiation and genetic connectivity of a species among all four Southwestern Atlantic oceanic islands. Our results provide valuable insight into understanding connectivity through surface ocean currents and suggest that the unstable current system of this area could be responsible for different dispersal patterns. We also suggest that the design of Brazilian marine protected areas should be adjusted to provide stronger protection for Trindade Island as it harbors unique genetic and morphologic variation in G. grapsus. 相似文献
20.
洋中脊和弧后盆地热液区热液流体B同位素组成的系统性差异 总被引：1，自引：0，他引：1
硼(B)是流体迁移元素，趋向于在热液流体中富集而成为常量元素。不同来源的B其同位素组成有着明显的区别。因此，B的含量及其同位素组成可标识热液流体(元素)的物质来源、水–岩反应程度及沉积物(元素)混入等重要过程，对海底热液活动及其成矿作用过程具有重要的示踪意义。迄今，对全球主要热液活动区热液流体中B的含量及同位素组成特征已做了大量的测试分析及研究工作，积累了丰富的资料和重要研究成果。但是，对不同地质背景(构造环境)条件下热液流体中B的含量及同位素组成特征尚缺乏系统性的对比分析，进而对造成不同环境热液流体中元素及其同位素组成的系统性差异的原因或机制尚缺乏深入的认识。本文在获取了洋中脊和弧后盆地主要热液活动区热液端元流体中B的含量及其同位素组成数据的基础上，定量估算了热液流体中B的主要来源，并对洋中脊和弧后盆地热液端元流体中B同位素组成的系统性差异进行了分析及成因探讨。结果表明，不同热液活动区热液端元流体的δ11B值都具有较大的变化范围，水–岩反应过程中不同来源B的混合是热液流体B同位素组成变化的主要原因。无沉积物覆盖的洋中脊和弧后盆地热液区热液流体中的B主要为海水与基底岩石来源B的混合，弧后盆地岩浆挥发性组分对热液系统的直接贡献及两种不同地质背景下基底岩石地球化学组成与水–岩反应程度的差异是其热液端元流体B同位素组成差异的主要原因。在有沉积物覆盖的弧后盆地热液区，热液流体中B的同位素组成与前两者之间存在显著差异，具有异常低的δ11B值，水–岩反应过程中沉积物来源B的加入是导致热液流体中δ11B值系统性降低的主要原因，沉积物的吸附作用也在一定程度上影响了热液流体的B同位素组成。有沉积物覆盖的洋中脊热液区热液流体同样受到了沉积物来源B加入的影响，具有较低的δ11B值，且相对于冲绳海槽受到了更强烈的沉积物吸附作用的影响。基于以上分析，并结合热液流体的Sr同位素组成特征，本文提出了洋中脊和弧后盆地这两大构造环境中热液流体B同位素组成系统性差异的成因模式。 相似文献