Afanasy Nikitin Research Articles

Несколько замечаний к запискам Афанасия Никитина «Хожение за три моря» (XV в.)

The paper is devoted to several nonobvious places in the Afanasy Nikitin’s travel notes “Journey Beyond Three Seas” and proposes to revisit their discussion. The first part of the paper deals with toponyms. Thus, it is explained why Afanasy prefers the Arabic toponym Misyur to Egypt. In the next section attempts are made to interpret the doubtful toponym Myar/Myara, which is usually identified with Baku without sufficient justification, although among other toponyms it would be more appropriate to see in this name a distorted Myakka – Mecca. Then a new localization of the country of Shabat and the Shabait shelter of the Indian Sea on the map of the Indian peninsula is proposed, which connects geographical realities with the ethno-political context of the Bengal Sultanate. Further in the article, based on an analysis of the text, an assumption is made about which books might have been lost by Afanasy, on what the traveler’s lamentations about their absence are based, and why they could not have helped Afanasy to celebrate Christian holidays on time. It is proved that Afanasy can be considered as an “unbalanced bilingual,” since the text of the notes reflects the process of his loss of a sense of language. It is justified that the preserved version of the notes was created later, almost at the end of the journey.

Специфика конструирования этнической идентичности в межкультурном дискурсе (к вопросу о лингвокультурной адаптации средневекового автора «Хожения за три моря Афанасия Никитина»)

The article is devoted to the consideration of a previously unexplored aspect: the monument of medieval culture “Walking across the Three Seas of Afanasy Nikitin” will be considered in the focus of text-creation strategies of autobiographical discourse, the events of which represent the ethnic identity of the author. This article describes the text-generating strategies of the ethnic identity of a medieval author who lived in the East for several years and partially mastered the language of a “foreign” culture for him from the standpoint of the anthropological approach in linguistics, methods of semiotics and discourse analysis. The study includes such research parameters, as well as characteristics of the phenomenon of ethnic identity, as the linguistic picture of the world, the author’s discursive strategies, his self-consciousness in the context of acculturation (secondary socialization) and inculturation (symbolization of “foreign” culture). The study confirmed the model of ethno-cultural hybridization of cultures, dating back to the concept of M. Bakhtin. Based on the analysis of the specifics of the linguistic portrait in the autobiographical narrative of merchant Afanasy Nikitin and the description of cultural associations, archetypal images and meanings in the linguistic picture of the medieval author of the XV century. The theoretical significance of this study lies in the proposal of the concept of linguistic and cultural adaptation, which makes it possible to identify the conditions for successful socialization of the individual and productive as a strategy for the study of the phenomenon of identity.

Dating of Afanasy Nikitin’s Journey Beyond the Three Seas: A Fresh Approach

The article proposes a new dating of Afanasy Nikitin’s journey. An analysis of the information from A Jorney Beyond the Three Seas showed that Afanasy Nikitin distinguished between the holidays of Eid al-Fitr and Eid al-Adha and correlated them with various Christian holidays—Easter and St. Peter’s Day respectively. Before his fourth Easter, Afanasy Nikitin was no more able to correlate Christian and Muslim holidays. Afanasy’s suggested that Eid al-Fitr was celebrated 9–10 days from Easter, but in 1469, Easter fell on April 2, and Eid al-Fitr on April 14. In 1468, Easter fell on April 17, Eid al-Adha on April 24. In 1468, Eid al-Adha fell on June 21, and in 1469, on July 1. Afanasy also suggests that Eid al-Adha was celebrated on the same day as St. Peter’s day, June 29. This information allows putting forward the hypothesis that the traveler tried to determine the day of Easter in 1470, remembering the past two years of his journey, when he could still correlate Christian and Muslim holidays. In conclusion, Afanasy Nikitin’s journey began in 1467, and he returned from the trip and died near Smolensk in winter of 1472/73.

Afanasy Nikitin’s multilingual travel account: translating an encounter between East and West

Afanasy Nikitin’s Voyage Beyond Three Seas [Khozhenie za tri morya], one of the most famous Old Russian travel accounts, was created in the second half of the fifteenth century, at the boundary of the late medieval and early modern periods. By understanding travel writing as a translation phenomenon, this paper will focuson how this merchant from Muscovite Russia translates an encounter between East and West during his seven-year journey through Persia, India, and other foreign lands, adapting linguistically to the exotic environment. Nikitin’s multilingual travelogue, written in Old East Slavic and a patois of Arabic, Persian, and Turkic, reveals a complex hybrid identity manifested through the traveller’s syncretic Christian-Muslim habits.

Deep-sea mineral deposits as a future source of critical metals, and environmental issues - a brief review

For the whole world to deliver net zero by 2050, large-scale mining is more critical for metals such as lithium, cobalt, platinum, palladium, REE, gallium, tungsten, tellurium, and indium as these metals are essential for green technology applications such as making wind turbines, solar panels, fuel-cells, electric vehicles, and data storage systems required to transition to a low-carbon economy. Since land-based mineral deposits are depleting fast, seabed resources are seen as a new resource frontier for mineral exploration and extraction. They include mainly deep-ocean mineral deposits, such as massive sulfides, manganese nodules, ferromanganese crusts, phosphorites, and REE-rich marine muds. Manganese nodules contain mainly manganese and iron, but also valuable metals like nickel, cobalt, and copper, as well as REE and platinum, which are used in making several high-technology and green technology products. For example, deep-sea mud enriched in REE (> 2000 µg/g) was found in the western North Pacific Ocean. High concentrations of REE range from 1,727 to 2,511 μg/g in the crust samples collected from the Afanasy Nikitin Seamount (ANS) in the Indian Ocean. However, these deposits usually have lower REE grades than land-based REE deposits such as carbonatite-hosted deposits but form greater potential volumes. Though the mining companies and their sponsoring countries are in the process of developing the required technologies to mine the three deep-sea environments: abyssal plains, seamounts, and hydrothermal vents, due to severe concerns about the possible environmental damages, the International Seabed Authority (ISA) has not granted any mining permissions so far, although deep-sea mining becomes inevitable in the future green energy revolution.

To the Question of Magmatism and Origin of the Afanasy Nikitin Rise Due to Discovery of Ancient Zircon by Three Billion Years Age

To the Question of Magmatism and Origin of the Afanasy Nikitin Rise Due to Discovery of Ancient Zircon by Three Billion Years Age

Do the 85°E Ridge and Conrad Rise form a hotspot track crossing the Indian Ocean?

Age-progressive volcanic chains are generally considered as surface expressions of deep-rooted mantle plumes, whereas non-age progressive volcanic groups or solitary volcanic edifices are generally attributed to shallow sources. The Buried Hills, Partly Buried Hills, Afanasy Nikitin Rise and newly discovered Southern Seamount Chain, located between the Kerguelen and Reunion hotspot tracks in the Indian Ocean, form the curved and discontinuous 85°E volcanic track. With the exception of the Afanasy Nikitin Rise, characterized by the most enriched mantle one (EMI) compositions in an ocean basin, no other parts of this volcanic track have been previously sampled. Although some models favor a hotspot origin for the 85°E Ridge track associated with the Crozet, Marion or Conrad Rise plumes, its origin remains highly controversial. We report new 40Ar/39Ar age and geochemical (major, trace element and Sr-Nd-Pb-Hf isotope) data from the 85°E Ridge. Our age data display a progression of decreasing ages (82–66 Ma) from the north to south, suggesting formation by a relatively stationary sub-lithospheric melt anomaly. The geochemistry of the 85°E Ridge can be explained by mixing of Indian-type plume material with Indian mid-ocean-ridge basalt (MORB) and detached continental lithospheric (mantle and/or lower crustal) material in the upper mantle. Plate reconstructions demonstrate that the southern portion of the 85°E Ridge and Conrad Rise could be derived from the Conrad Rise hotspot/plume. A weak, pulsating mantle plume could explain the weak morphological expression and intermittent nature of this hotspot track, compared to the Reunion and Kerguelen tracks.

The bent prolongation of the 85°E Ridge south of 5°N – Fact or fiction?

The enigmatic 85°E Ridge crosses the Bay of Bengal from north to south. Its strong gravity anomaly low is associated with Cretaceous hotspot volcanism. South of 5°N, the gravity low bends into a SW-NE orientation and continues as far SW as the Afanasy Nikitin Seamounts. This change has been interpreted to represent a bent hotspot track. We report new constraints on the crustal structure and genesis beneath the SW-trending gravity low based on new refraction seismic, reflection seismic, and shipborne gravity data. Our findings show that the crustal structure across the gravity low does not differ significantly from the adjacent, 4.5 to 7 km thick oceanic crust. No basement ridge, significant crustal thickening, or magmatic underplating were identified. We found no evidence for a southern prolongation of the 85°E Ridge. Instead, our P-wave velocity and density models reveal the gravity low to express a flexural basin, which is a result of widespread mid-Miocene to recent lithospheric deformation in the Indian Ocean. The ~25 mGal negative gravity anomaly is therefore not related to the passage of the Indian plate over a mantle plume, casting doubt on the possibility that volcanism at the Afanasy Nikitin Seamounts might be related to the same plume as the northern 85°E Ridge. The northern 85°E Ridge may have been generated at the northern prolongation of the 86°E Fracture Zone.

A Comparative Analysis of the Structure of the Tectonosphere of the Conrad and Afanasy Nikitin Rises (Indian Ocean) Using Geophysical Data

Abstract—2D density modeling was performed for profiles crossing seamounts of the Conrad Rise (Lena, Ob’ and Marion Dufresne), which is located in the southwestern part of the Indian Ocean and the Afanasy Nikitin Rise, which is located in the central part of the Indian Ocean. According to widespread belief, the Marion Dufresne Seamount and the Afanasy Nikitin Rise were formed by a hotspot 83–73 Ma ago. The 2D density modeling revealed a similar structure of the crust and lithosphere within those formations, thus confirming that they were formed 83–73 Ma ago as a result of the action of the same hotspot. The results we obtained also confirmed that the Lena and Ob’ seamounts of the Conrad Rise were formed later due to the resumed activity of the hotspot under the Antarctic Plate.

Comparative analysis of the structure of the tectonosphere of the Conrad and Afanasy Nikitin Rises by geophysical data (the Indian Ocean)

A two-dimensional density modeling is performed for profiles crossing the seamounts of the Conrad Rise (Lena, Ob and Marion Dufresne), which are located in the southwestern part of the Indian Ocean and the Afanasy Nikitin Rise, which is located in the central part of the Indian Ocean. According to the assumptions of a number of researchers, the seamount Marion Dufresne and the Afanasy Nikitin Rise were formed as a result of the hotspot 83–73 million years ago. The results of two-dimensional density modeling showed a similar structure of the crust and lithosphere, which confirms the probability of their formation 83–73 million years ago as a result of the action of a single hotspot. Also on the basis of the obtained results, the assumption is confirmed that the seamounts Lena and Ob of the Conrad Rise were formed afterwards due to the continuation of the action of the hotspot under the Antarctic Plate.

Lithosphere structure and upper mantle characteristics below the Bay of Bengal

The oceanic lithosphere in the Bay of Bengal (BOB) formed 80–120 Ma following the breakup of eastern Gondwanaland. Since its formation, it has been affected by the emplacement of two long N-S trending linear aseismic ridges (85oE and Ninetyeast) and by the loading of ca. 20-km of sediments of the Bengal Fan. Here, we present the results of a combined spatial and spectral domain analysis of residual geoid, bathymetry and gravity data constrained by seismic reflection and refraction data. Self-consistent geoid and gravity modeling defined by temperature-dependent mantle densities along a N-S transect in the BOB region revealed that the depth to the Lithosphere-Asthenosphere boundary (LAB) deepens steeply from 77 km in the south to 127 km in north, with the greater thickness being anomalously thick compared to the lithosphere of similar-age beneath the Pacific Ocean. The Geoid-Topography Ratio (GTR) analysis of the 85°E and Ninetyeast ridges indicate that they are compensated at shallow depths. Effective elastic thickness (Te) estimates obtained through admittance/ coherence analysis as well as the flexural modeling along these ridges led to the conclusions: i) 85°E Ridge was emplaced in off-ridge environment (Te = 10–15 km); ii) the higher Te values of ?25 km over the Afanasy Nikitin Seamount (ANS) reflect the secondary emplacement of the seamount peaks in off-ridge environment, iii) that the emplacement of the Ninetyeast Ridge north of 2°N occurred in an off-ridge environment as indicated by higher Te values (25-30 km). Furthermore, the admittance analysis of geoid and bathymetry revealed that the admittance signatures at wavelengths >800 km are compensated by processes related to upper mantle convection.

Bacterial Diversity in Deep-Sea Sediments from Afanasy Nikitin Seamount, Equatorial Indian Ocean

Deep-sea sediments can reveal much about the last 200 million years of Earth history, including the history of ocean life and climate. Microbial diversity in Afanasy Nikitin seamount located at Equatorial East Indian Ocean (EEIO) was investigated. Deep sea sediment collected at 150 cm depth (∼67 ky BP) exhibited a dominance of clones clustering in the phylum Firmicutes (63%), followed by γ-Proteobacteria (37%). The bacterial diversity within sediment at 200 cm depth (∼84 ky BP) was dominated by γ-Proteobacteria (66%) followed by β- Proteobacteria (34%), whereas no Firmicutes clones were retrieved. Notably, 29% clones from 150 cm and 18% of clones from 200 cm sediment showed high identity to sequences previously reported from mining sites, while 21% of clones from 150 cm depth and 10% from 200 cm sediments showed identity to sequences previously reported from volcanic areas. Further, many of the sequences were from uncultured clones. Overall, these data may help elucidate the nature of microorganisms inhabiting these sites and unravel the molecular diversity of the deep sea from an evolutionary perspective.

Growth of the Afanasy Nikitin seamount and its relationship with the 85°E Ridge, northeastern Indian Ocean

The Afanasy Nikitin seamount (ANS) is a major structural feature (400 km-long and 150 km-wide) in the Central Indian Basin, situated at the southern end of the so-called 85°E Ridge. Combined analyses of new multibeam bathymetric, seismic reflection and geochronological data together with previously described magnetic data provide new insights into the growth of the ANS through time, and its relationship with the 85°E Ridge. The ANS comprises a main plateau, rising 1200 m above the surrounding ocean floor (4800 m), and secondary elevated seamount highs, two of which (lie at 1600 and 2050 m water depths) have the morphology of a guyot, suggesting that they were formed above or close to sea-level. An unbroken sequence of spreading anomalies 34 through 32n.1 identified over the ANS reveal that the main plateau of the ANS was formed at 80–73 Ma, at around the same time as that of the underlying oceanic crust. The 40Ar/39Ar dates for two basalt samples dredged from the seamount highs are consistent, within error, at 67 Ma. These results, together with published results of late Cretaceous to early Cenozoic Indian Ocean plate reconstructions, indicate that the Conrad Rise hotspot emplaced both the main plateau of the ANS and Conrad Rise (including the Marion Dufresne, Ob and Lena seamounts) at 80–73 Ma, close to the India–Antarctica Ridge system. Subsequently, the seamount highs were formed by late-stage volcanism c. 6–13 Myr after the main constructional phase of the seamount plateau. Flexural analysis indicates that the main plateau and seamount highs of the ANS are consistent with Airy-type isostatic compensation, which suggest emplacement of the entire seamount in a near spreading-center setting. This is contrary to the flexural compensation of the 85°E Ridge further north, which is interpreted as being emplaced in an intraplate setting, i.e., 25–35 Myr later than the underlying oceanic crust. Therefore, we suggest that the ANS and the 85°E Ridge appear to be unrelated as they were formed by different mantle sources, and that the proximity of the southern end of the 85°E Ridge to the ANS is coincidental.

The breakup of East Gondwana: Assimilating constraints from Cretaceous ocean basins around India into a best‐fit tectonic model

AbstractPublished models for the Cretaceous seafloor‐spreading history of East Gondwana result in unlikely tectonic scenarios for at least one of the plate boundaries involved and/or violate particular constraints from at least one of the associated ocean basins. We link East Gondwana spreading corridors by integrating magnetic and gravity anomaly data from the Enderby Basin off East Antarctica within a regional plate kinematic framework to identify a conjugate series of east‐west‐trending magnetic anomalies, M4 to M0 (~126.7–120.4 Ma). The mid‐ocean ridge that separated Greater India from Australia‐Antarctica propagated from north to south, starting at ~136 Ma northwest of Australia, and reached the southern tip of India at ~126 Ma. Seafloor spreading in the Enderby Basin was abandoned at ~115 Ma, when a ridge jump transferred the Elan Bank and South Kerguelen Plateau to the Antarctic plate. Our revised plate kinematic model helps resolve the problem of successive two‐way strike‐slip motion between Madagascar and India seen in many previously published reconstructions and also suggests that seafloor spreading between them progressed from south to north from 94 to 84 Ma. This timing is essential for tectonic flow lines to match the curved fracture zones of the Wharton and Enderby basins, as Greater India gradually began to unzip from Madagascar from ~100 Ma. In our model, the 85‐East Ridge and Kerguelen Fracture Zone formed as conjugate flanks of a “leaky” transform fault following the ~100 Ma spreading reorganization. Our model also identifies the Afanasy Nikitin Seamounts as products of the Conrad Rise hotspot.

The Russian Merchant Afanasy Nikitin's Notes in the 15th Century, “A Journey beyond the Three Seas"

The Russian Merchant Afanasy Nikitin's Notes in the 15th Century, “A Journey beyond the Three Seas"

Development of the negative gravity anomaly of the 85°E Ridge, northeastern Indian Ocean – A process oriented modelling approach

The 85 ◦ E Ridge extends from the Mahanadi Basin, off northeastern margin of India to the Afanasy Nikitin Seamount in the Central Indian Basin. The ridge is associated with two contrasting gravity anomalies: negative anomaly over the north part (up to 5 ◦ N latitude), where the ridge structure is buried under thick Bengal Fan sediments and positive anomaly over the south part, where the structure is intermittently exposed above the seafloor. Ship-borne gravity and seismic reflection data are modelled using process oriented method and this suggest that the 85 ◦ E Ridge was emplaced on approximately 10–15 km thick elastic plate (Te ) and in an off-ridge tectonic setting. We simulated gravity anomalies for different crust-sediment structural configurations of the ridge that were existing at three geological ages, such as Late Cretaceous, Early Miocene and Present. The study shows that the gravity anomaly of the ridge in the north has changed through time from its inception to present. During the Late Cretaceous the ridge was associated with a significant positive anomaly with a compensation generated by a broad flexure of the Moho boundary. By Early Miocene the ridge was approximately covered by the postcollision sediments and led to alteration of the initial gravity anomaly to a small positive anomaly. At present, the ridge is buried by approximately 3 km thick Bengal Fan sediments on its crestal region and about 8 km thick pre- and post-collision sediments on the flanks. This geological setting had changed physical properties of the sediments and led to alter the minor positive gravity anomaly of Early Miocene to the distinct negative gravity anomaly.

Delineation of the 85°E ridge and its structure in the Mahanadi Offshore Basin, Eastern Continental Margin of India (ECMI), from seismic reflection imaging

The passive Eastern Continental Margin of India (ECMI) evolved during the break up of India and East Antarctica in the Early Cretaceous. The 85°E ridge is a prominent linear aseismic feature extending from the Afanasy Nikitin Seamounts northward to the Mahanadi basin along the ECMI. Earlier workers have interpreted the ridge to be a prominent hot spot trail. In the absence of conclusive data, the extension of the ridge towards its northern extremity below the thick Bengal Fan sediments was a matter of postulation. In the present study, interpretation of high resolution 2-D reflection data from the Mahanadi Offshore Basin, located in the northern part of the ridge, unequivocally indicates continuation of the ridge across the continent–ocean boundary into the slope and shelf tracts of the ECMI. Its morphology and internal architecture suggest a volcanic plume related origin that can be correlated with the activity of the Kerguelen hot spot in the nascent Indian Ocean. In the continental region, the plume related volcanic activity appears to have obliterated all seismic features typical of continental crust. The deeper oceanic crust, over which the hot spot plume erupted, shows the presence of linear NS aligned basement highs, corresponding with the ridge, underlain by a depressed Moho discontinuity. In the deep oceanic basin, the ridge influences the sediment dispersal pattern from the Early Cretaceous (?)/early part of Late Cretaceous times till the end of Oligocene, which is an important aspect for understanding the hydrocarbon potential of the basin.

Peculiarities of the deep structure of the lithosphere in the northeastern part of the Indian Ocean

The seismicity of the northeastern part of the Indian Ocean in connection with the general structural peculiarities of the main tectonic structures of the bottom is presented. The three main ranges of higher seismic activity at the depths of 0–17, 20–27, and 32–35 km divided by aseismic layers are revealed. The seismic activity at depths of more than 35 km is almost not detected both for the ocean and for the Indian peninsula. The nature of the distribution of the seismicity as such in the lithosphere is discussed. Using the results of anomalous au]gravitational field transformations, the prolongation of the East Indian Ridge structure is revealed to 19 degrees north, while the relationship of the Afanasy Nikitin Rise and the 85th Degree Ridge is not reflected at the tranforms. In the Cocos Basin, the mutually perpendicular disturbance zones of northeastern and northwestern strike, as well as the point of their crossing, where the maximal number of earthquake foci are concentrated, are distinguished. A conclusion concerning the substantial disturbance of the strength properties of the lithosphere in this zone as a consequence of the geodynamical processes, which are accompanied by fracture tectonics, is reached.

Instantaneous deformation and kinematics of the India-Australia Plate

SUMMARY Active intraplate deformation of the India‐Australia Plate is now being captured by far-field global positioning system (GPS) measurements as well as measurements on a few islands located within the deforming zone itself. In this paper, we combine global and regional geodetic solutions with focal mechanisms of earthquakes to derive the present-day strain field of the India‐Australia Plate. We first compile an updated catalogue of 131 Indian intraplate earthquakes (M > 5) spanning the period between the two Asian mega earthquakes of Assam 1897 and Sumatra 2004. Using Haines and Holt’s numerical approach applied to a fully deformable India‐Australia Plate, we show that the use of GPS data only or earthquakes data only has severe drawbacks, related, respectively, to the small number of stations and the incompleteness of the earthquakes catalogue. The combined solution avoids underestimation of the strain inherent to the Kostrov summation of seismic moments and provides details that cannot be reached by pure GPS modelling. We further explore the role of heterogeneity of the India‐Australia Plate and find that the best model, in terms of geodetic vectors fit, relative distribution of strain, style and direction of principal strain from earthquakes, is obtained using the surface heat-flow as a proxy for rheological weakness of the oceanic lithosphere. The present-day deformation is distributed around the Afanasy Nikitin Chain in the Central Indian Basin (CIB)—where it is almost pure shortening—and within the Wharton Basin (WB) off Sumatra—where it is almost pure lateral strike-slip. The northern portion of NinetyEast ridge (NyR) appears as a major discontinuity for both strain and velocity. The new velocity field gives an India/Australia rotation pole located at 11.3 ◦ S, 72.8 ◦ E( −0.301 ◦ Myr −1 )o verlapping with previous solutions, with continental India moving eastward at rates ranging from 13 mm yr −1 (southern India) to 26 mm yr −1 (northern India) with respect to Australia. Taking into account the intraplate velocity field in the vicinity of the Sumatra trench, we obtain a convergence rate of 46 mm yr −1 towards N18 ◦ Ea tthe epicentre of the 2004 Aceh megaearthquake. The predicted instantaneous shortening in the CIB and WB and extension near Chagos-Laccadive are in good agreement with the finite deformation measured from plate reconstructions and seismic profiles, suggesting a continuum of deformation since the onset of intraplate deformation around 7.5‐8 Ma. Since no significant change in India convergence is detected at that time, we suggest that the intraplate deformation started with the trenchward acceleration of Australia detaching from India along a wide left-lateral oceanic shear band activating the NyR line of weakness as well as north‐south fracture zones east of it. The predicted total amount of left lateral finite strain along these faults is in the range 110‐140 km.

Structure and evolution of the Afanasy Nikitin seamount, buried hills and 85°E Ridge in the northeastern Indian Ocean

Geophysical data of the Afanasy Nikitin seamount (ANS), partly buried hills and 85°E Ridge in the northeastern Indian Ocean were studied together with published seismic refraction results to understand genesis and evolution of the structures. The ANS joins the 85°E Ridge through isolated buried hills and intervening subsurface structures and together they form a linear ridge system. The gravity signature of the ridge system changes from negative to positive towards south of 5°N, which seems to coincide with termination/thinning of pre-collision continental sediments in the Bay of Bengal. Thick pile of Bengal Fan sediments had great impact on underneath pre-collision sediments as well as on basement rocks; the process resulted in attaining higher velocities, up to 6.6 and 7.1 km/s, respectively. Gravity model studies suggest that structures of the ridge system are compensated in different modes. The ANS is underlain by an 8 km thick, deep crustal body of magmatic rocks, while beneath other structures oceanic crust is down-flexed up to 2.5 km. The presence of metasediments, more dense than volcanic rocks, and flexure of the lithosphere would explain the negative gravity anomaly over the 85°E Ridge, whereas lack of metasediments and magmatic rocks at depth would explain the compensated positive anomaly over the ANS. The width of the 85°E Ridge, the wavelength (∼190 km) and amplitude (∼2.5 km) of the flexed oceanic crust and the intersection of the ridge with the Mesozoic fracture zones suggest that the ridge was formed in intraplate position when the lithosphere underneath was approximately 35 Myr old. Initial emplacement of the ANS was coeval with the formation of oceanic lithosphere at 80–73 Ma. The hotspot forming the 85°E Ridge had reactivated the ANS during the Paleocene and brought it to the sea surface. Then it underwent erosion and subsidence processes. The deformation activity had converged the north and south parts of the ANS at late Miocene and again at late Pleistocene and northward buried hills at early Pliocene.