The nature of geomagnetic anomalies in metamorphosed chromite-bearing dunites: a case study of the southern Klyuchevskoy complex, Central Urals / Sherendo T. A.,Vdovin A. G.,Martyshko P. S.,Mitrofanov V. Ya.,Alekseev A. V.,Zamyatin D. A.,Vazhenin V. A.,Pamyatnykh L. A. // RUSSIAN GEOLOGY AND GEOPHYSICS. - 2015. - V. 56, l. 3. - P. 476-486.

ISSN/EISSN:

1068-7971 / 1878-030X

Type:

Article

Abstract:

Chromite mineralization in metamorphosed dunites from the southern Klyuchevskoy dunite-harzburgite ultramafic complex (Central Urals) has been investigated using geomagnetic surveys along with laboratory studies of ore-forming and accessory spinels of the same genetic type. Magnetization in the study area is carried mainly by accessory Fe-Cr-spinel of a variable Fe2+(Cr2-xFex3+)O-4 composition. Metamorphism caused changes in element contents and in both crystal and magnetic structure of the primary nonmagnetic accessory spinel, unlike the almost fresh ore-forming spinel. Thus, ore bodies stand against their host rocks, which is a prerequisite for the use of geomagnetic surveys for exploration of podiform chromite deposits in dunite-harzburgite complexes. Ground magnetic surveys at a test site composed of faulted rocks bearing disseminated chromite mineralization in metamorphosed dunites resolved a chromite ore zone and a fault block boundary showing up as geomagnetic anomalies. Laboratory studies using high technologies (thermomagnetic analysis at 4 to 1000 K, as well as magnetic resonance and magnetic force spectroscopy) revealed, for the first time, magnetic clusters (superparamagnetic phases) in primary nonmagnetic accessory spinel, which are responsible for the magnetic properties of the host rocks. Microscale variations in Cr-spinel correlate with the geomagnetic anomalies recorded by field surveys at the test site. (C) 2015, V.S. Sobolev IGM, Siberian Branch of the RAS. Published by Elsevier B.V. All rights reserved.

Author keywords:

Fe-Cr-spinel; magnetization carrier; magnetic cluster; microscale phase; chromite mineralization; geomagnetic anomaly; dunite-harzburgite metamorphic complex MAGNETIC-PROPERTIES; SYSTEM; SPINEL; OPHIOLITE; MASSIF

DOI:

10.1016/j.rgg.2015.02.008

Web of Science ID:

ISI:000351313500008

Соавторы в МНС:

Другие поля

Поле	Значение
Month	MAR
Publisher	ELSEVIER SCIENCE BV
Address	PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS
Language	English
EISSN	1878-030X
Keywords-Plus	MAGNETIC-PROPERTIES; SYSTEM; SPINEL; OPHIOLITE; MASSIF
Research-Areas	Geology
Web-of-Science-Categories	Geosciences, Multidisciplinary
Author-Email	Tatyana\_Sherendo@mail.ru
ResearcherID-Numbers	Martyshko, Peter/R-5902-2016 Pamyatnykh, Lidia/C-7780-2017
ORCID-Numbers	Pamyatnykh, Lidia/0000-0001-5044-0838
Funding-Acknowledgement	Presidium of the Russian Academy of Sciences {[}12-P-5-2015]; Ministry of Education and Science {[}2582, 2457]
Funding-Text	The study was carried out as part of Program 23, Project 12-P-5-2015 of the Presidium of the Russian Academy of Sciences and Projects 2582 and 2457 of the Ministry of Education and Science.
Number-of-Cited-References	32
Usage-Count-Last-180-days	3
Usage-Count-Since-2013	14
Journal-ISO	Russ. Geol. Geophys.
Doc-Delivery-Number	CD7YZ