ISSN 1028�334X, Doklady Earth Sciences, 2012, Vol. 443, Part 1, pp. 388–391. © Pleiades Publishing, Ltd., 2012.Original Russian Text © V.A. Poselov, V.V. Butsenko, V.D. Kaminsky, T.S. Sakulina, 2012, published in Doklady Akademii Nauk, 2012, Vol. 443, No. 2, pp. 232–235.

388

At present, most researchers dealing with the Arc�tic hold the common opinion that the system of sub�marine rises Mendeleev–Alpha is a part of the HighArctic Large Igneous Province (HALIP), but the ori�gin of the crust beneath these rises is highly disputed.The main opposing viewpoints are an extended sub�sided continental crust and a hotspot�type oceanicplateau.

The studies by the deep seismic sounding (DSS)and seismic reflection (SR) methods (Gramberg All�Russia Research Institute of Geology and MineralResources) and the multichannel seismic reflectionmethod (MCSR; by the Sevmorgeo Company),implemented in the period of 2000–2009 along theArktika�2000, Arktika�2005, and 5�AR profiles (Fig. 1),have yielded information providing a new insight intothe deep structure of the crust beneath MendeleevRise (MR) and its junction with the East Siberianshelf.

The implemented systems of wide angle seismicsoundings have produced records of the refracted andreflected P�waves at offsets up to 200–250 km [2]; inturn, the modern technique of ray�tracing and syn�thetic modelling [9] has allowed decoding of wavefields and solution of the direct seismic problem about

selection of crustal velocity models in a correct way. Inthe DSS seismic records, the waves refracted in theupper and lower crust (Pg and Pl), reflected from themantle surface (PmP) and refracted in the mantle(Pn), and those reflected from the intràcrustal bound�aries have been interpreted.

The first key question for understanding of thecrust beneath the MR was estimation of velocities inthe lower crust. The waves that relate to the lower crust(Pl and PmP), as well as their synthetic analogs, whichwere visualized with reduced time of 6.8 km/s, haveindicated that the P�wave velocities in the lower crustbeneath the MR do not exceed 6.8–6.9 km/s, whichmakes doubtful similarity of the MR to hotspots likeIceland [6].

A brief description of the ultimate velocity modelsis given below (Fig. 1).

Arktika�2000. This model contains the followingprincipal components:

(a) Two sedimentary units divided by the pre�Miocene regional unconformity that merged (in thescale of the model) with the post�Campanian one(these two unconformities correspond to two main hia�tuses in the sections of IODP ACEX�2004 wells) [2–4].The velocities are 1.8–2.8 km/s for the upper unit and3.0–3.5 km/s for the lower one. The total thickness ofboth units is maximal (about 3.5 km) in the MakarovBasin, while the minimal value (about 0.5 km) in theaxial part of the MR is beneath the Akademik FedorovRise.

(b) An intermediate complex having velocities inthe interval of 4.5–5.6 km/s and thickness from 1 to4 km, with the maximal one in the axial part ofthe MR.

Mendeleev Rise (Arctic Ocean) as a Geological Continuation of the Continental Margin of Eastern Siberia

V. A. Poselova, V. V. Butsenkoa, V. D. Kaminskya, and T. S. Sakulinab

Presented by Academician A.O. Gliko September 5, 2011

Received October 20, 2011

Abstract—The implemented deep seismic soundings have provided records of refracted and reflected P�waves upto offsets of 200–250 km, whereas the modern technique of ray�tracing and synthetic modelling enabled thewave fields to be decoded and the direct seismic problem about selection of velocity models of the crust to besolved correctly. The data acquired through the multichannel seismic reflection method have allowed us toidentify the Late Paleozoic sedimentary unit on the shelf and trace it to the Mendeleev Rise as an intermedi�ate complex. It has been shown that the principal structural elements of the consolidated crust and sedimen�tary cover of the East Siberian shelf are continued to the Mendeleev Rise, which has obvious tectonic featuresof an extended continental crust.

DOI: 10.1134/S1028334X12030191

a Gramberg All�Russia Research Institute of Geologyand Mineral Resources, St. Petersburg, Angliiskii pr. 1, 190121 Russiab Sevmorgeo Federal State Unitary Research and Production Company for Geological Sea Survey,ul. Rozenshteina 36, St. Petersburg, 198095 Russiae�mail: poselov2009@mail.ru

GEOPHYSICS

DOKLADY EARTH SCIENCES Vol. 443 Part 1 2012

MENDELEEV RISE (ARCTIC OCEAN) AS A GEOLOGICAL CONTINUATION 389

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(c) The upper crust. Its velocities are from 6.0–6.1to 6.3–6.4 km/s. The thickness of this componentbeneath the MR is 4–5 km and decreases to about1.5 km beneath the Makarov Basin and to about 2 kmbeneath the Mendeleev Basin.

(d) The lower crust has velocities varying from 6.75to 6.9 km/s. Its thickness is about 20 km beneath theMR axial part and decreases to approximately 10 kmin the Makarov Basin and 7 km in the MendeleevBasin.

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390

DOKLADY EARTH SCIENCES Vol. 443 Part 1 2012

POSELOV et al.

(e) The upper mantle’s velocities are estimated ataround 8.0 km/s. The Moho discontinuity’s depthchanges from approximately 30 km beneath the axialpart of the MR to about 20 and 15 km beneath theMakarov and Mendeleev basins, respectively.

Arktika�2005. The model contains the followingstructural components in the section:

(a) Two sedimentary units divided by the regionalunconformity (see above): the velocities of the upperone are from 1.9–2.7 km/s in the North ChukchiTrough (NCT) to 1.6–1.9 km/s in the MR; those ofthe lower one are from 3.9–4.5 km/s in the NCT to3.1–3.3 km/s in the MR. The total thickness ofthe units reaches its maximum (10–11 km) in theNCT depocenter, while it does not exceed ~2.5 km inthe MR.

(b) In addition to this, a third sedimentary complexis identified in the NCT: its velocities are 4.8–5.8 km/sand the thickness in the NCT depocenter is 16–18 km.

(c) The intermediate complex is traced along theMR to the north slope of the NCT and lies immedi�ately upon the upper crust. Its velocities are 4.8–5.1 km/s, and the thickness does not exceed ~3 km.

(d) The upper crust has velocities varying in theinterval of 6.1–6.3 km/s; its thickness is minimalbeneath the NCT (2–3 km), while it is 4–8 kmbeneath the MR.

(e) The lower crust has velocities increasing from6.6–6.8 km/s in the NCT to 6.7–6.9 km/s in the MR.The thickness is 9–10 km beneath the NCT and growsto 20–22 km beneath the MR.

(f) The upper mantle’s velocity is estimated at~8.0 km/s; the depth of the Moho discontinuitychanges from ~30 km in the NCT to 31–34 km inthe MR.

Note the very surprising resemblance between thedescribed model of the MR (in terms of both velocityand deep structures) and that of the Greenland conti�nental margin [5], where the principal peculiarity ofthe deep structure—substantial thickening of thelower crust in comparison with the upper one—is alsofound. We explain thickening of the lower crustbeneath the MR by volcanic activity that formedthe HALIP.

The second key question is the origin of the inter�mediate complex in the MR.

The MCSR data along the 5�AR profile were col�lected by an 8�km streamer. The width of the seismicaperture allowed multiple waves to be rejected and thehigh�resolution migrated section to be obtained (Fig. 2,profile 5�AR). Extrapolating the datings of the uncon�formities based on drilling data [7, 8] acquired for theAmerican sector of the Chukchi Sea into the NCT, weinterpret the Upper Permian, Upper Jurassic, LowerCretaceous, and Paleocene unconformities within thetrough (Fig. 2, profile 5�AR). As is seen from compi�lation of the time sections along the 5�AR and Ark�tika�2005 profiles (Fig. 2), the supposedly Late Paleo�zoic sedimentary complex is traced from the NCT tothe MR, and in the latter it becomes seismicallyunstratified (probably due to an abundant volcaniccomponent) and is interpreted as an intermediate one.

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Fig. 2. Compilation of time sections along the 5�AR (MCSR) and Arktika�2005 (SR) profiles. Indexes and supposed age of prin�cipal unconformities: RU is the regional pre�Miocene, pCU/MBU is the post�Campanian/Paleocene, LCU is the Early Creta�ceous (Hauterivian–Barremian), JU is the Late Jurassic, PU is the Late Permian, IL is the top of intermediate complex, B is thebasement.

DOKLADY EARTH SCIENCES Vol. 443 Part 1 2012

MENDELEEV RISE (ARCTIC OCEAN) AS A GEOLOGICAL CONTINUATION 391

The profile of the multibeam echosounder/profilo�graph across the Akademik Fedorov Rise (made in2010) has identified slopes of up to 20° and bedrockexposures on the MR scarps. Based on samples fromthe same place of rock material in 2000, the bedrock isdated as the Late Paleozoic [1]. Hence, all these dataon aggregate indirectly evidence for the continuationof the Late Paleozoic sedimentary complex from theNCT to the MR.

Thus, the principal structural elements of the con�solidated crust and sedimentary cover are continu�ously traced from the East Siberian shelf to the MR,and the latter possesses obvious tectonic features of theextended continental crust. The signs of extension alsoinclude formation of a deep trough with a depocenterbeneath the shelf edge in the junction zone betweenthe rise and the shelf. Note that extension�causedthinning of the whole crust in the MR is slightly cam�ouflaged by thickening of its lower layer due to volca�nic activity (LIP�thickening).

REFERENCES

1. V. Ya. Kaban’kov, I. A. Andreeva, and V. N. Ivanov,Dokl. Earth Sci. 399, 1088–1090 (2004).

2. V. A. Poselov, V. V. Verba and S. M. Zholondz, Geotec�tonics 41, 296–305 (2007).

3. J. Backman, K. Moran, D. B. McInroy, and L. A. Mayer,Proc. Integrated Ocean Drilling Program 302, 1–115(2006).

4. V. V. Butsenko and V. A. Poselov, in Proc. Fourth Int.Conf. Arctic Margins (ICAM IV), Dartmouth, Canada, 2003,Ed. by R.A. Scott and D.K. Thurston (U.S. Department ofthe Interior, Anchorage, 2006), pp. 125–131.

5. T. Funck, H. R. Jackson, S. A. Dehler, and I. D. Reid,Polarforschung 74 (1–3), 97–112 (2006).

6. W. Jokat, Geophys. J. Int. 152, 185–201 (2003).7. S. L. Klemperer, E. L. Miller, A. Grantz, and

D. W. Scholl, Geol. Soc. Am. Spec Pap. 360, 1–24(2002).

8. K. W. Sherwood, P. P. Johnson, J. D. Craig, et al., Geol.Soc. Am. Spec Pap. 360, 39–70 (2002).

9. C. A. Zelt, Geophys. J. Int. 139, 183–204 (1999).