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 (tō′lə-īt′, thō′-)
Any of a series of igneous rocks similar in composition to basalt but having more silica and iron and less aluminum.

[After Tholei (Tholey), municipality in Saarland, Germany, where it is found.]

tho′lei·it·ic (-ĭt′ĭk) adj.
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.


a type of igneous or volcanic rock found on the ocean floor that is rich in aluminium and similar to basalt
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014
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This Archaean greenstone belt is predominantly composed of tholeiitic basalt lava and volcaniclastic deposits, ultramafic rocks, felsic volcanic rocks and sediments surrounded by younger Archaean granitoids.
The western segment is dominated by a thick sequence of tholeiitic basalt with common BIF units, typical of the Southern Cross Granite Greenstone Terrane (Wyche, 1999).
The Cuillin centre is a composite confluent intrusion ranging in composition from peridotite to gabbro (Stuart et al., 2000) Although they post-date most basalts, the Cuillin intrusive complex is most likely coeval with the latest Skye Main Lava Series tholeiitic basalt flows.
The 1970 sample from the northwestern knoll is transitional basalt, plotting on the Hawaiian tholeiite-alkalic basalt boundary, whereas the 1994 lava is tholeiitic basalt with a higher Si[O.sub.2] content (Fig.
The northwestern part of the island consists of early Jurassic tholeiitic basalt (Trembath 1973; Wade et al.
2) 2.88-2.74 Ga--deposition of sequences of tholeiitic basalt, komatiite, felsic turf, iron formation, and abundant clastic sedimentary rocks, accompanied by the emplacement of voluminous, synvolcanic tonalite-trondhjemite plutonic suites and coeval deformation.
This is overlain by voluminous tholeiitic basalt and minor komatiite (2740-2700 Ma), probably indicating rifting and/or plume activity, at a scale comparable to that of modern large igneous provinces.
This intercratonic area, including the westernmost fringe of the Parana Basin (PB), represents an undeformed basin along the western Gondwana (Figure 1), where the sedimentation, started in Cambrian times, was topped by Early Cretaceous tholeiitic basalts of the Serra Geral Formation [8, 9] and followed by younger sedimentation (Figure 2).