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1.
杭州湾北岸水下岸坡微地貌特征及其海床侵蚀指示意义   总被引：1，自引：0，他引：1  
旁侧声纳图像和多波束水下地形测量清晰地揭示了杭州湾北岸水下岸坡4种微地貌形态,分别为冲沟、凹坑、沙波、光滑海底。金山深槽内海底扰动、切割十分强烈,微地貌以冲沟、凹坑为主,局部成沙波片发育。深槽外缘的水下平地微地貌特征主要表现为光滑海底和冲沟交替出现,局部也有沙波分布。旁侧声纳图像和底质综合分析表明杭州湾北岸水下地貌面貌是水动力和泥沙来源共同作用的结果：一方面,冲沟、凹坑和沙波代表的水流方向与涨潮流方向一致,指示了强劲的潮流对海床的侵蚀和改造;另一方面,由于底流水动力较强、底质沉积物粒径较细,冲沟得以普遍发育,而沙波仅在局部的砂质海床中出现。水下岸坡微地貌分布显示了海床侵蚀与地貌格局和水深条件密切相关,表现为主槽内冲刷和改造后再沉积作用较强,主槽外缘的水下平地冲刷作用明显变弱,出现弱能条件下的光滑海底;水下平地中,浅水区冲沟较为发育,深水区则以光滑海底为主。总体而言,杭州湾北岸水下岸坡侵蚀性微地貌广泛分布,海床处于侵蚀状态。  相似文献   

2.
The ridge and swale topography of the Middle Atlantic Bight is best developed on the Delaware-Maryland inner shelf. Here sand ridges can be seen in all stages of formation. Several aspects of the ridge field are pertinent to the problem of ridge genesis. The first is ridge morphology. There is a systematic morphologic change from shoreface ridges through nearshore ridges to offshore ridges, which reflects the changing hydraulic regime. As successively more seaward ridges are examined, maximum side slope decreases, the ratio of maximum seaward slope to maximum landward slope decreases, and the cross-sectional area increases. These changes in ridge morphology with depth and distance from shore appear to be equivalent to the morphologic changes experienced by a single ridge during the course of the Holocene transgression. A second aspect is the change in bottom sediment characteristics that accompanies these large-scale morphologic changes. Megaripples, sand waves and mud lenses appear in the troughs between nearshore and offshore ridges. These changes indicate that the storm flows which maintain ridges are less frequently experienced in the deeper sector, and that the role of high-frequency wave surge becomes less important relative to the role of the mean flow component in shaping the sea-floor. A third aspect is the systematic relationship of grain size to topography. Grain size is 90° out of phase with topography, so that the coarsest sand lies between the axis of the landward trough and the ridge crest, while the finest sand lies between the ridge crest and the axis of the seaward trough. This relationship is characteristic of large-scale bedforms. Finally, flow was measured and transport calculated on the same ridge during a one-month period (November 1976). Threshold was exceeded only during storm events. Mean transport was southerly and a little seaward with respect to both the ridge crest and the shoreline. These flow measurements are in conformity with the pattern of smaller bedforms. A 43-year time series of bathymetric change for this ridge reveals a systematic pattern of landward flank erosion, seaward flank deposition, and seaward crest migration. Sand ridges are considered the consequence of constructive feedback between an initial topography and the resulting distribution of bottom shear stress. The relationship between grain size and topography supports this model, but does not account directly for the oblique angle of the ridge with respect to the coastline. This feature may be due to a more rapid alongshore migration rate of the inshore edge of the ridge than the offshore edge, and the relationship between this migration rate, and the rate of shoreface retreat.  相似文献   

3.
A synthesis of high-resolution (Chirp, 2–7 kHz) seismic profiles in the South Korea Plateau reveals that large masses of wavy stratified sediment (≈60–90 m thick) cover broad, gently sloping (<0·5°) ridges in water depths of 1000–2000 m. The wavy stratified sediment (WSS) is characterized by wavy (0·2–5 km in wavelength and <15 m in relief), continuous reflective layers with a basal deformed zone that overlies undeformed, strong reflectors. The WSS exhibits systematic variation in wave dimensions and thickness of internal reflective layers with changes in slope gradient. The troughs of the waves are commonly associated with internal growth faults, and wave amplitude generally increases with subbottom depth. On steep slopes around the ridges, the WSS masses are bounded downslope by slide and slump deposits including slightly translated or rotated WSS blocks. The acoustic and geometric characters, and association with downslope slides and slumps on the steeper slopes, suggest that the WSS masses were most probably formed by slow creep movement before slope failure. In the absence of significant sediment input to the South Korea Plateau, the deep (1000–2000 m in water depth) mass movements were probably triggered by earthquakes that have occurred frequently in this region. Some slightly displaced, intact WSS blocks in the associated slides and slumps downslope reflect a progressive evolution from submarine creep into slide and slump.  相似文献   

4.
The paper presents petrological and geochemical data on mantle peridotite, basalt, and metamorphic rocks sampled in Cruise 36 of the R/V Professor Logachev at the MAR axial zone between 17° and 20° N. These data are interesting not only as providing new information on the inner structure of the oceanic crust in the still-poorly known axial MAR segment but also in the context of the fundamental problem of interaction between magmatic and hydrothermal systems in slow-spreading mid-oceanic ridges. The MAR axial zone between 17° and 20° N was determined to host both weakly and strongly depleted residual peridodites, which suggests that the degree of mantle source melting significantly varied along the ridge axis in this segment. The MAR crest zone comprises slabs of serpentinized peridotite brought to the seafloor surface at various time. The most strongly depleted mantle peridotites likely uplifted later than the mildly and weakly depleted rocks in the same areas. A mantle reservoir beneath the MAR axial zone at 20° N is not isotopically related to the mantle source of the parental MORB melts, and high-Mg metabasites exposed at 17°56- N were derived from a crustal source that was modified near the root zone of a high-temperature hydrothermal system. The studied area seems to display traces of an extinct hydrothermal field and likely an ore occurrence related to it.  相似文献   

5.
The topographic structure of the ocean bottom is investigated at different scales of resolution to answer the question: Can the seafloor be described as a fractal process? Methods from geostatistics, the theory of regionalized variables, are used to analyze the spatial structure of the ocean floor at different scales of resolution. The key to the analysis is the variogram criterion: Self-similarity of a stochastic process implies self-similarity of its variogram. The criterion is derived and proved here: it also is valid for special cases of self-affinity (in a sense adequate for topography). It has been proposed that seafloor topography can be simulated as a fractal (an object of Hausdorff dimension strictly larger than its topological dimension), having scaling properties (self-similarity or self-affinity). The objective of this study is to compare the implications of these concepts with observations of the seafloor. The analyses are based on SEABEAM bathymetric data from the East Pacific Rise at 13°N/104°W and at 9°N/104°W and use tracks that run both across the ridge crest and along the ridge flank. In the geostatistical evaluation, the data are considered as a stochastic process. The spatial continuity of this process is described by variograms that are calculated for different scales and directions. Applications of the variogram criterion to scale-dependent variogram models yields the following results: Although the seafloor may be a fractal in the sense of the definition involving the Hausdorff dimension, it is not self-similar, nor self-affine (in the given sense). Mathematical models of scale-dependent spatial structures are presented, and their relationship to geologic processes such as ridge evolution, crust formation, and sedimentation is discussed.  相似文献   

6.
《China Geology》2021,4(4):571-584
The Philippine Sea is the largest marginal sea in the Western Pacific Ocean and is divided into two parts by the Kyushu-Palau Ridge (KPR). The western part is the West Philippine Basin, and the eastern part consists of the Shikoku and Parece Vela basins. Based on surveyed data of massive high-resolution multibeam bathymetric data and sub-bottom profiles data collected from the southern section of the KPR from 2018 to 2021, this paper analyzes the topographic and geomorphological features, shallow sedimentary features, and tectonic genesis of the southern section of the KPR, obtaining the following conclusions. The southern section of the KPR has complex and rugged topography, with positive and negative topography alternatingly distributed and a maximum height difference of 4086 m. The slope of seamounts in this section generally exceeds 10° and is up to a maximum of 59°. All these contribute noticeably discontinuous topography. There are primarily nine geomorphological types in the southern section of the KPR, including seamounts, ridges, and intermontane valleys, etc. Among them, seven independent seamount groups are divided by five large troughs, forming an overall geomorphological pattern of seven abyssal seamount groups and five troughs. This reflects the geomorphological features of a deep oceanic ridge. Intramontane basins and intermontane valleys in the southern section of the KPR are covered by evenly thick sediments. In contrast, sediments in ridges and seamounts in this section are thin or even missing, with slumps developing locally. Therefore, the sediments are discontinuous and unevenly developed. The KPR formed under the control of tectonism such as volcanic activities and plate movements. In addition, exogenic forces such as underflow scouring and sedimentation also play a certain role in shaping seafloor landforms in the KPR.©2021 China Geology Editorial Office.  相似文献   

7.
Gully erosion is a very serious problem in the black soil region of northeast China. Gully filling is often adopted for controlling gully erosion by local farmers and thus causes more serious soil erosion. In this study an ephemeral gully (EG, 74 m) and a classical gully (CG, 52 m) connected at the gully’s headcut were selected as the study site. Two comparisons were made to explore the effects of gully erosion and the subsequent gully filling on soil depth and soybean yield: (1) soil depth between 81 sample points in the study site and 11 reference points along the same slope with the gully; (2) soybean yield between 81 sample points in the study site and 30 baseline locations near the study site. The results indicated that gully erosion caused the reduction of soil depth and soybean yield. Although filling gullies with soil from adjacent areas seemed to be an expedient way to remediate the gullies, it resulted in substantial soybean yield reduction. Gully erosion reduced the soil depth and soybean yield in 74.4 and 83.9 % of the study site, respectively. The soybean yield reduction ratio was 34.5 % for the whole study site and 2.6 % for the black soil region. Soil depth was the most important soil property indicator to reduce yield. Every 1 cm decrease in soil depth in the areas adjacent to gullies due to infilling activities resulted in a 2 % decrease in yield. More significant was the deposition of sediment from gully erosion, which completely eliminated soybean yield. Currently, effective soil and water conservation measures are not known and adopted by local farmers extensively. In the future, once some measures for preventing soil erosion, in particular gully erosion, were proved effective, these technologies should be disseminated among local farmers.  相似文献   

8.
Gully systems and watersheds are geomorphic units with clear boundaries that are relatively independent of basin landscapes and play an important role in natural geography. In order to explore the morphological characteristics of gully systems and watersheds in the Dry-Hot Valley [South West (SW) China], gullies are interpreted from online Google images with high resolution and watersheds are extracted from digital elevation model at a scale of 1:50,000. The results show that: (1) There are 17,382 gullies (with a total area of 1141.66 km2) and 42 watersheds in the study area. (2) The average gully density of the study area (D) is 4.29 km/km2, gully frequency (F) is 14.39 gullies/km2, the branching ratio (B) is 5.13, the length ratio (L) is 3.12, and the coefficient of the main and tributary gullies (M) is 0.06. The degree of gully erosion is strong to extremely strong, the main development intensity of gully erosion ranges from intense to moderate, and the type of gully system is tributary. (3) The watershed areas (A) are between 0.39 and 96.43 km2, the relief ratio (R) is from 0.10 to 0.19, the circularity ratio (C) is from 0.30 to 0.83, the texture ratio (T) is from 0.82 to 39.35, and the dominant geomorphological texture type is fine. (4) There is a quantitative relationship between F and D:F?=?0.624D2 (R?=0.84) and T is closely related to D, F, M (R2?>?0.7). A, R and C are related to M (R2?>?0.5). The development of gully systems is the result of coupling effects between multiple factors. In this area, the degree of erosion and the condition of the main and tributary gullies can be controlled by the degree of topographic breakage in the watershed, which provides some theoretical basis for the evaluation of gully erosion by the latter. In addition, the scale, relief, and shape have a significant impact on the locations of the main and tributary gullies. For tributary gullies, attention should be paid to the interception and control of runoff and sediment in the small confluence branches in order to prevent gully expansion and head advance. These features can inform the development of targeted measures for the control of soil erosion.  相似文献   

9.
2020年3月30日,西昌市经久乡发生森林大火,响水沟流域植被被林火大面积烧毁,同年雨季,响水沟流域内多条沟道暴发泥石流,其中1#、2#、3#沟毗邻居民房屋和耕地,影响较为严重。通过野外调查、遥感解译和室外试验,以响水沟1#、2#、3#沟为研究对象,分析了不同林火烈度下,渗透特征、坡面侵蚀和沟道侵蚀的差异,从而揭示响水沟火后泥石流的成灾机理。结果表明,林火是泥石流暴发的重要诱因,火后泥石流的降雨阈值会明显降低。林火干扰导致坡面土壤的渗透系数表现出不同程度的降低,林火烈度越严重的区域,渗透系数越小,降雨更大比例地转化为坡面径流参与到坡面侵蚀。随降雨次数的增多,轻度、中度、重度火烧区域的坡面土壤侵蚀深度均增加;中度、重度林火烈度的侵蚀深度差异不大,且明显高于轻度区域,说明当林火烈度达到中度时,坡面土壤便会受到较大程度的侵蚀。地形条件相似的沟道,林火烈度越严重,泥石流侵蚀能力越强,最终体现于沟道两岸崩滑体数量越多,沟道宽度和深度越大。  相似文献   

10.
Episodic seafloor spreading, ridge topography, and fault movement at ridges find (more extreme) analogs in the arc and back-arc setting where the volcanogenic massive sulfide (VMS) deposits that we mine today were formed. The factors affecting sulfide accumulation efficiency and the extent to which sulfides are concentrated spatially are the same in both settings, however. The processes occurring at mid-ocean ridges therefore provide a useful insight into those producing VMS deposits in arcs and back-arcs. The critical observation investigated here is that all the heat introduced by seafloor spreading at mid-ocean ridges is carried out of the crust within a few hundred meters of the ridge axis by ??350°C hydrothermal fluids. The high-temperature ridge hydrothermal systems are tied to the presence of magma at the ridge axis and greatly reduce the size and control the shape of axial magma intrusions. The amount of heat introduced to each square kilometer of ocean crust during its formation can be calculated, and its removal by high-temperature convection allows calculation of the total base metal endowment of the ocean basins. Using reasonable metal deposition efficiencies, we conclude that the ocean floor is a giant VMS district with metal resources >600 times the total known VMS reserves on land and a copper resource which would last >6,000?years at current production rates.  相似文献   

11.
A comprehensive model for the activity of the elementary accretion segment at fast‐spreading ridges relies on integration of structural data from the Oman ophiolite and geophysical results from the East Pacific Rise (EPR) around 9°N, which are of comparable size and spreading rates. The axial melt lens at shallow crustal level provides a link between Deval segmentation at the seafloor and a lower melt sill at Moho level, imaged at the EPR as a crustal melt zone (CMZ) and mapped in Oman as the Moho transition zone (MTZ). Both are attached to a mantle upwelling at the EPR, and to a frozen diapir in Oman. The physical link between diapiric mantle uprising at the Moho and Devals segmentation at the seafloor is the melt being injected from the mantle into the lower MTZ, ponding there, and then being released by powerful injections into the upper melt lens. The magma chamber covers the diapir at a distance of 5 km from the ridge axis.  相似文献   

12.
Ma  J. Y.  Li  Z. B.  Ma  B. 《Natural Hazards》2020,104(1):51-72

Gully slope is one of the most active areas of soil erosion in small watershed of the Chinese Loess hilly–gully region. Although its soil erosion has been effectively controlled with the implementation of the “Grain-for-Green Program” in this region, the soil water storage and distribution have been also impacted. In particular, unreasonable revegetation model has aggravated the water shortage, which may in turn threaten the health of ecosystems. However, yet little is known about the effect mechanism of vegetation on soil water in the gully slope. In this study, we examined the relationship between two revegetation modes, including afforestation (i.e. black locust forest) and natural revegetation (i.e. the grassland), and soil water in a depth of 0–120 cm of the gully slope, during the rainy season. The results showed that the effect of the vegetation to the soil water was smaller than that of the precipitation. Furthermore, the response of soil water to the environmental factors was higher in afforestation vegetation due to its lower soil water content, resulting in higher space dependence for soil water, compared to the natural revegetation. The lower soil water content of the black locust forest was mainly caused by its higher recession rate, not its supply. The soil water was deficient for a long time, caused by afforestation, with a shallower formation depth of the dried soil layer and stronger desiccation degree. However, this deficient could not be effectively relieved until in wet year. In comparison with the ridge slope, the effect of vegetation to soil water in gully slope was stronger, with greater water consumption in afforestation vegetation and the higher water storage in natural revegetation. From the aspect of water resources conservation on the water scale, the natural revegetation was the optimal revegetation mode in the gully slope of the loess hilly region.

  相似文献   

13.
Soil moisture variability and controls are little known in large gullies of the Loess Plateau which represent complex topography with steep slopes. This study analyzed spatial–temporal variability of soil moisture at the 0–20, 20–40, 40–60, and 60–80 cm depths in a large gully of the Loess Plateau based on root-zone soil moisture measurements for 3 years (2009–2011). The result showed that mean soil moisture, standard deviation (SD), and coefficient of variation, were highly dependent on depth; the highest mean value was observed at the 20–40 cm depth, while the lowest one was at the 0–20 cm depth. The SD increased with mean soil moisture for various depths as soil moisture was relatively wet; however, a transition that SD decreased with mean soil moisture occurred when soil moisture was relatively dry. Positive correlations exist between moisture contents over different depths, and that the relationships of the neighboring layers are relatively high with R 2 from 0.70 to 0.76. Correlation analysis, principle component analysis, and stepwise multiple regression analysis showed that soil particle size distribution and topography (slope and elevation) were the main environmental factors controlling soil moisture variability in the large gully.  相似文献   

14.
现代海底热液活动区的分布与构造环境分析   总被引：8，自引：2，他引：6  
对全球490多个热液活动区的三维空间分布和构造背景进行了研究,对发育热液活动的构造环境进行了分类,并对各种构造环境发育热液活动的频度进行了统计分析。根据已有的统计数据指出了现代海底热液活动的三维空间分布规律,并对此进行了理论分析。指出现代海底热液活动区主要沿大洋中脊、弧后盆地和板内火山分布,并主要限于40°N和40°S中、低纬度带之间,水深集中在 1300～3700 m之间。出现热液活动概率最高的水深为 2600 m,其次为 1700 m、1900 m、 2200 m、3000 m和 3700 m,平均水深为 2532 m。扩张轴的中轴谷、海底火山口及不发 育中轴谷的扩张脊是发育热液活动的主要构造背景。并提出,现代海底热液活动总是出现在构造活动的部位,但并不是构造活跃的部位就发育热液活动。热液活动的发育和构造并不直接相关但却和岩浆发育密切相关。热液活动的发育在位置上受控于岩浆活动,在时间上,它发生在岩浆活动结束后,是强烈的热膨胀、热冷缩后的释热形式。  相似文献   

15.
为保护黄河流域矿区生态环境,以府谷县庙哈孤矿区安山煤矿125203工作面为背景,采用数值模拟实验、相似材料模拟实验和理论分析相结合的手段,基于工作面过双沟地形开采时地表裂缝发育位置、发育形态等参数,总结出开采诱发地表裂缝发育规律。通过理论分析,建立了浅埋煤层过双沟地形开采地表裂缝发育相对位置函数T及其判别条件,讨论了双沟地形沟谷参数与地表裂缝发育相对位置之间的关系。研究表明,工作面过支沟G1时,共发育地表裂缝4条,最大裂缝宽度23 cm,最大错台11 cm,裂缝发育超前于工作面推进;过主沟G2时共发育地表裂缝7条,最大裂缝宽度79 cm,最大错台45 cm,裂缝发育滞后于工作面推进。裂缝发育相对位置受地质条件、沟深、坡度和沟谷跨度等因素共同影响。地表裂缝发育相对位置函数与裂缝超前(滞后)距离、裂缝宽度和错台以及单沟裂缝总条数密切相关。双沟相互影响程度与工作面推进方向有关。研究结果可为浅埋煤层沟谷下开采地表裂缝发育研究提供一定的理论依据。   相似文献   

16.
Seaward of the Bosphorus Strait, the south‐west Black Sea shelf is dominated by the world's largest channel network maintained by a quasi‐continuous saline (ca 35 → 31 psu) underflow. Calculations indicate that >85% of the initial discharge of ca 104 m3s?1 spills overbank before the shelf edge. This paper documents interaction of the overspill with sea bed topography using multibeam bathymetry, echo‐sounder images of the water column, conductivity–temperature–depth profiles and sediment cores. Overbank spill is widespread, particularly through crevasse channels and on the middle shelf where confinement by channel banks is negligible. Towards the outer shelf, the wind‐driven Rim Current advects mud along the shelf, contributing to levée successions and deposition on stoss sides of elongate transverse ridges. Echo‐sounder profiles reveal metre‐scale eddies over megaflutes, and breaking lee waves and internal hydraulic jumps over ridges. Megaflutes reach 600 m long and 7 m deep, yet form where the underflow, outside the flute, is no thicker than ca 2 to 5 m. Two types of elongate seaward‐facing ridges are recognized. Type 1 ridges, 2 to 5 m high, consist of bivalve‐rich muddy sand in low‐angle (3·5° to 6°) cross‐sets created by the underflow. Type 2 ridges, ca 5 m high, have crests up to 2 km long and a buried wedge‐shaped foundation (the ‘ridge‐core’) comprised of facies similar to Type 1 ridges. These ridge‐cores are blanketed on the landward side by stratified muds, and are capped by obliquely oriented ribs supporting a diverse benthic community. This facies distribution is interpreted to result from stoss‐side and lee‐side velocity and turbulence fluctuations induced by internal hydraulic jumps and breaking lee waves in overspilling portions of the underflow. Experimental results published by W.H. Snyder and co‐workers effectively explain ridge evolution and flow across the ridges, and therefore can be applied with confidence to less easily studied deep‐marine settings swept by turbidity currents.  相似文献   

17.
Comprehensive analysis of detailed bathymetric data obtained during legs 24–27 of the R/V Akademik Nikolai Strakhov has been carried out on the Knipovich Ridge. The revealed variations of magmatic activity along the axis supplement the available information on segmentation of this ridge [7, 19, 33]. The new statistical data characterize seismic activity under settings of ultraslow oblique extension. As follows from the seismic data, the Knipovich Ridge belongs to structural units with intermediate geodynamics between the spreading ridge and transform fault. Magmatic and amagmatic segments of the Arctic ultraslow Knipovich and Gakkel mid-ocean ridges are compared.  相似文献   

18.
In Zimbabwe four contrasting gully locations and associated gully patterns are present, reflecting spatial variations in precipitation, bedrock, soil type and landuse. Deep dendritic gullies, associated with landslip activity and subsurface piping, characterise the wet Eastern Highlands and areas with sodic soils. Shallow discontinuous gully systems characterise bornhardt terrain in the Communal Lands. Dambo gullies tend to form a continuation of the fluvial system. The pattern and temporal variation of gullies was studied in three areas of Communal Land (Mhondoro-Ngesi, Mangewende, Mutema) with particular reference to the influence of average slope and landuse on gully development. In areas of sodic soils the gullies appear to be largely the product of natural processes and their development has only partly been influenced by landuse changes. In contrast the shallow gullies developed on granitic/gneissic terrain tend to occur on cultivated or recently cultivated land. The case studies indicate that a full assessment of gully development can only be achieved if a temporal perspective is also considered.  相似文献   

19.
A dry debris avalanche will produce different volumes of colluviums or depositions (loose materials), which can have a significant impact on mountainous rivers or gullies. The loose material supply process caused by a debris avalanche is an important issue for understanding secondary disasters that form via the coupling of water flow and loose materials. Two flumes were designed for laboratory tests of the loose materials supply process to rivers/gullies, and the related impact factors were analyzed. Experimental results show that the supply of loose materials is a continuous process that directly relates to the avalanche’s mass movement processes. The sliding masses with smaller particle sizes are more sensitive to the flume slope and exhibited a longer supply time. The time-consuming for the debris avalanche travel in the flume decreased with the increasing particle size (such as flume B, time-consuming is decreased 0.2 s when the particle size increased from <1.0 to 20–60 mm), landslide volume and flume slope (flume A, consuming 1.6–2.1 s when flume slope is 29° decreased to consuming 1.3–1.5 s when flume slope is 41°), which means the increasing mobility of loose materials. The total supply time increased with the increasing landslide volume or decreasing particle size and flume slope. An empirical model for the process is presented based on numerous laboratory tests and numerical simulations, which can successfully describe the supply process for loose materials to a river/gully. The supply process of loose materials to mountainous gully from a dry debris avalanche is controlled by the material compositions of sliding masses, topographical conditions, landslide volume and bed friction, where large-volume debris avalanches that occur in mountainous river regions are more likely to obstruct the river flow and form a landslide-dammed lake.  相似文献   

20.
Fracture-fissure systems found at mid-ocean ridges are dominating conduits for the circulation of metallogenic fluid. Ascertaining the distribution area of active faults on both sides of mid-ocean ridges will provide a useful tool in the search for potential hydrothermal vents, thus guiding the exploration of modern seafloor sulfides. Considering the Mid-Atlantic Ridge 20°N–24°N (NMAR) and North Chile Rise (NCR) as examples, fault elements such as Fault Spacing (?S) and Fault Heave (?X) can be identified and quantitatively measured. The methods used include Fourier filtering of the multi-beam bathymetry data, in combination with measurements of the topographic slope, curvature, and slope aspect patterns. According to the Sequential Faulting Model of mid-ocean ridges, the maximal migration distance of an active fault on either side of mid-ocean ridges—that is, the distribution range of active faults—can be measured. Results show that the maximal migration distance of active faults at the NMAR is 0.76–1.01 km (the distance is larger at the center than at the ends of this segment), and at the NCR, the distribution range of active faults is 0.38–1.6 km. The migration distance of active faults on the two study areas is positively related to the axial variation of magma supply. In the NCR study area, where there is an abundant magma input, the number of faults within a certain distance is mainly affected by the variation of lithospheric thickness. Here a large range of faulting clearly corresponds to a high proportion of magmatism to seafloor spreading near mid-ocean ridges (M) value, and in the study area of the NMAR, there is insufficient magmatism, and the number of faults may be controlled by both lithospheric thickness and magma supply, leading to a less obvious positive correlation between the distribution range of active faults and M.  相似文献   

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