The Structure of the Tectonosphere in the Marginal Zones of the Kerguelen Plateau Based on Geological and Geophysical Da
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Structure of the Tectonosphere in the Marginal Zones of the Kerguelen Plateau Based on Geological and Geophysical Data E. P. Dubinina, *, A. A. Shaikhullinab, **, A. A. Bulychevb, ***, G. L. Leitchenkovc, d, ****, and A. A. Maksimovae, ***** a
Earth Science Museum, Moscow State University, Moscow, 119991 Russia Department of Geology, Moscow State University, Moscow, 119991 Russia c VNIIOkeangeologia, St. Petersburg, 190121 Russia d St. Petersburg State University, St. Petersburg, 199034 Russia eUniversity of Bremen, Bremen, 28195 Germany *e-mail: [email protected] **e-mail: [email protected] ***e-mail: [email protected] ****e-mail: [email protected] *****e-mail: [email protected]
b
Received October 29, 2019; revised January 15, 2020; accepted January 15, 2020
Abstract—The Kerguelen Plateau is the largest submarine rise in the southern Indian Ocean. The heterogeneous structure of the crust, plume magmatic activity, and different ages of the adjacent basins indicate different structures of different marginal zones of the plateau. On the basis of geological and geophysical information, various morphodynamic types of margins of the Kerguelen Plateau are identified. Analysis of the bottom topography and potential field data, together with two-dimensional density modeling, allows us to specify the deep structure of the tectonosphere in the Kerguelen Plateau margins and take a fresh look at their nature. Keywords: Kerguelen Plateau, margins, potential fields, crust, Indian Ocean DOI: 10.3103/S0145875220040043
INTRODUCTION The Kerguelen Plateau is the largest igneous province in the Indian Ocean. The Late Mesozoic rifting between India and Antarctica and the subsequent oceanic opening were accompanied by the emplacement of a mantle plume, which formed the volcanic Kerguelen Plateau and significantly influenced the character of spreading and morphostructural plan of the Indian Ocean floor. The Kerguelen Plateau is located in the southern central segment of the Indian Ocean between 46° and 64° S, being enclosed between the Southwest Indian (SWIR) and Southeast Indian (SEIR) spreading ridges and the Antarctic continent. The plateau is bounded by the Australian–Antarctic Basin in the northeast, by the Crozet Basin in the northwest, and by the Enderby Basin in the southwest (Fig. 1a). The Princess Elizabeth Trough, which is more than 3500-m deep, separates it from Antarctica. The plateau stretches in the northwest direction for a distance of ~2300 km; its width is 500–1000 km, and its average height above the ocean floor is ~3 km. According to the peculiarities of the geological and geophysical structures, it is subdivided into the south-
ern, central, and northern provinces (Fig. 1). The Elan and Skiff banks, the ridge, as well as the William and Labuan basins, are distinguished within the plateau (Borissova et al., 2002; Leitchenkov et al., 2018). The northern province of the plateau, which includes the Kerguelen Islands, is located at a shallower depth (
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