کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
9526909 | 1636976 | 2005 | 24 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Crustal structure of the Lofoten-Vesterålen continental margin, off Norway
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کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
علوم زمین و سیارات
فرآیندهای سطح زمین
پیش نمایش صفحه اول مقاله
![عکس صفحه اول مقاله: Crustal structure of the Lofoten-VesterÃ¥len continental margin, off Norway Crustal structure of the Lofoten-VesterÃ¥len continental margin, off Norway](/preview/png/9526909.png)
چکیده انگلیسی
By compiling wide-angle seismic velocity profiles along the â¼400-km-long Lofoten-VesterÃ¥len continental margin off Norway, and integrating them with an extensive seismic reflection data set and crustal-scale two-dimensional gravity modelling, we outline the crustal margin structure. The structure is illustrated by across-margin regional transects and by contour maps of depth to Moho, thickness of the crystalline crust, and thickness of the 7+ km/s lower crustal body. The data reveal a normal thickness oceanic crust seaward of anomaly 23 and an increase in thickness towards the continent-ocean boundary associated with breakup magmatism. The southern boundary of the Lofoten-VesterÃ¥len margin, the Bivrost Fracture Zone and its landward prolongation, appears as a major across-margin magmatic and structural crustal feature that governed the evolution of the margin. In particular, a steeply dipping and relatively narrow, 10-40-km-wide, Moho-gradient zone exists within a continent-ocean transition, which decreases in width northward along the Lofoten-VesterÃ¥len margin. To the south, the zone continues along the Vøring margin, however it is offset 70-80 km to the northwest along the Bivrost Fracture Zone/Lineament. Here, the Moho-gradient zone corresponds to a distinct, â¼25-km-wide, zone of rapid landward increase in crustal thickness that defines the transition between the Lofoten platform and the Vøring Basin. The continental crust on the Lofoten-VesterÃ¥len margin reaches a thickness of â¼26 km and appears to have experienced only moderate extension, contrasting with the greatly extended crust in the Vøring Basin farther south. There are also distinct differences between the Lofoten and VesterÃ¥len margin segments as revealed by changes in structural style and crustal thickness as well as in the extent of elongate potential-field anomalies. These changes may be related to transfer zones. Gravity modelling shows that the prominent belt of shelf-edge gravity anomalies results from a shallow basement structural relief, while the elongate Lofoten Islands belt requires increased lower crustal densities along the entire area of crustal thinning beneath the islands. Furthermore, gravity modelling offers a robust diagnostic tool for the existence of the lower crustal body. From modelling results and previous studies on- and off-shore mid-Norway, we postulate that the development of a core complex in the middle to lower crust in the Lofoten Islands region, which has been exhumed along detachments during large-scale extension, brought high-grade, lower crustal rocks, possibly including accreted decompressional melts, to shallower levels.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Tectonophysics - Volume 404, Issues 3â4, 1 August 2005, Pages 151-174
Journal: Tectonophysics - Volume 404, Issues 3â4, 1 August 2005, Pages 151-174
نویسندگان
Filippos Tsikalas, Olav Eldholm, Jan Inge Faleide,