The Problem of the Existence of a Strike-Slip Fault in the Arctic Ocean between Lomonosov Submarine Ridge and the Adjacent Shelf

Doklady Earth Sciences - The junction zone between Lomonosov submarine ridge and the shelf of the East Siberian Sea was studied. The aim was to prove the absence of a strike-slip fault in the...     

Seismic stratigraphy of sedimentary cover in the Podvodnikov Basin and North Chukchi trough

The multichannel seismic reflection data (MCS data) obtained in the Arktika-2014 expedition revealed the essential fact that must be taken into account by the tectonic model of the Central Arctic region. The Brookian, Lower Cretaceous, and Upper Jurassic unconformities are continuously traced from the North Chukchi offshore trough into the Podvodnikov Basin, indicating that the depocenter in the latter accumulated both Cretaceous sedimentary sequences and Early–Middle Mesozoic ones.     

Atmospheric Corrections Using MODTRAN for TOA and Surface BRDF Characteristics from High Resolution Spectroradiometric/ Angular Measurements from a Helicopter Platform

l. IntroductionThe cIassicaI definition of bi--directional reflectance--distribution function (BRDF) is aderivative, distribution function, relatlng the irradiance incident from one given direction tolts contribution to the radiance renected in another direct1on (N1codemus et al., l977).f r (0,, rp,; 0,, rp, )= dL, (0,, P,; 0,, 9,; E, )/ dE, (0,, 9,) [sr-- 1 ], (l)where 0 (zenith angle) and 9 (azimuth angle) together indicate a direction, the subscr1pt i indi-cates quantities associated wi…     

热液金刚石压腔在地质流体研究中的应用

热液金刚石压腔(HDAC)是专为模拟地壳温压条件下的地质作用而设计的，它尤其适用于观测水或其它流体与地质物质之间的相互作用。HDAC可时-190～1200℃，0～10GPa的热液体系进行实验，并可在实验的温压条件下．用各种先进的光学方法分析样品，更可以把实验的全程录像存档。充满流体的HDAC本身就可当做是一个人工合成的流体包裹体。因此它可以用来研究流体的状态方程和相关系。它又可时其它流体包裹体样品施加外压力，因此在热分析的过程中可免除包裹体的膨胀或爆破的困境。HDAC可应用到颇为宽广的温压范围，它已被广泛地用来观测各种化学体系的临界现象，包括在地质方面特别有用的含水硅酸盐体系。HDAC也可与同步辐射X光源相结合，而取得各种金属或稀土元素水溶液的x射线吸收精细结构(X-ray absorption fine structure；XAFS)光谱，因而时在热液里的金属或稀土元素络合物的组分和结构提供了最基本的资料。然而，X光的强度在透过金刚石时，因绕射和吸收而大大地减弱，因此应用一般的HDAC来获取那些吸收边在10keV以下的元素的XAFS光谱颇为困难。目前已有两种改良式的HDAC解除了这方面的困难，而时在元素周期表上的第一排过渡性金属元素和稀土元素的水溶液，提供清晰的XAFS光谱。这些资料可用来研究金属或稀土元素络合物在地质热液里的特性，及其在元素迁移和成矿作用方面的效应。而这些元素在地质应用方面特别重要。     

Seismic Attributes of the Podvodnikov Basin Basement

Doklady Earth Sciences - The purpose of this work was to study the seismic attributes of the Podvodnikov Basin basement. It was found that these attributes, first of all, P-wave velocities of...     

The Lomonosov Ridge as a natural extension of the Eurasian continental margin into the Arctic Basin

The inregrated geological and geophysical studies carried out in recent years in the Lomonosov Ridge and at its junction with the Eurasian shelf revealed evidence for thinned (reduced) crust in the ridge (20–25 km) and its relationship with shelf structures. We compared the parameters of deep seismic cross-sections of the shelf and Lomonosov Ridge, thus proving the existence of continental crust in the latter. Also, we analyzed the deep structure of the junction between the Lomonosov Ridge and the shelf and established a genetic geologic relationship, with no evidence that the Lomonosov Ridge moved as a terrane with respect to the shelf. In addition, seismological studies independently confirm the relationship between the Lomonosov Ridge and the adjacent shelf.The Lomonosov Ridge is a continental-crust block of a craton. The craton was reworked during the Caledonian tectonomagmatic activity with the formation of a Precambrian–Caledonian seismically unsegmented basement (upper crust) and an epi-Caledonian platform cover. Afterward, the block subsided to bathyal depths in the Late Alpine. This block and the adjacent areas of the Eastern Arctic shelf developed in the platform regime till the Late Mesozoic.     

Deep structure of the crust beneath the Sea of Okhotsk inferred from 3D seismic density modeling

Potential field anomalies of the Sea of Okhotsk region are analyzed for compiling a map of the basement’s tectonic structures. A 3D density model of the Earth’s crust is constructed using seismogeological and experimental-petrophysical data, which made it possible to obtain a visual image of main structures of the region reflecting the observable geophysical anomalies. The obtained data allow a domain located in the central part of the Sea of Okhotsk beyond the limits of the exclusive economic zone of the Russian Federation to be considered as a natural continuation of the continental shelf since the latter is structurally similar to western Kamchatka. The deep structural boundaries rise beneath the large sedimentary Deryugin and Tinro basins, which is characteristic of petroliferous basins.     

Typification of the Earth’s crust of Central Arctic Uplifts in the Arctic Ocean

The modern views on the structure of the oceanic and continental crust are discussed. The presented geological-geophysical information on the deep structure of the Earth’s crust of the Lomonosov Ridge, Mendeleev Rise, and Alpha Ridge, which make up the province of the Central Arctic Uplifts in the Arctic Ocean, is based on CMP, seismic-reflection, and seismic-refraction data obtained by Russian and Western researchers along geotraverses across the Amerasia Basin. It is established that the crust thickness beneath the Central Arctic Uplifts ranges from 22 to 40 km. Comparison of the obtained velocity sections with standard crust sections of different morphostructures in the World Ocean that are underlain by the typical oceanic crust demonstrates their difference with respect to the crustal structure and to the thickness of the entire crust and its individual layers. Within the continental crust, the supercritical waves reflected from the upper mantle surface play the dominant role. Their amplitude exceeds that of head and refracted waves by one to two orders of magnitude. In contrast, the refracted and, probably, interferential head waves are dominant within the oceanic crust. The Moho discontinuity is the only first-order boundary. In the consolidated oceanic crust, such boundaries are not known. The similarity in the velocity characteristics of the crust of the Alpha Ridge and Mendeleev Rise, on the one hand, and the continental crust beneath the Lomonosov Ridge, on the other, gives grounds to state that the crust of the Mendeleev Rise and Alpha Ridge belongs to the continental type. The interference mosaic pattern of the anomalous magnetic field of the Central Arctic Uplifts is an additional argument in favor of this statement. Such patterns are typical of the continental crust with intense intraplate volcanism. Interpretation of seismic crustal sections of the Central Arctic Uplifts and their comparison with allowance for characteristic features of the continental and oceanic crust indicate that the Earth’s crust of the uplifts has the continental structure.     

Rises of the Amerasia Basin,Arctic Ocean,and Possible Equivalents in the Atlantic Ocean

Oceanology - Abstract—The main positive morphostructures of the Amerasia Basin — the Lomonosov Ridge, Alpha Ridge, Mendeleev Rise, Chukchi Plateau, and Northwind Ridge — are...