The recovered volcanic rocks consist of three flow units of alkalic basalt underlain by more than 105 flows or flow lobes. Other articles where tholeiitic basalt is discussed. Cooling and crystallization of tholeiitic basalt, 1965 makaopuhi lava lake, hawaii. Scroll down for a chart summarizing petrological differences between tholeiitic and alkali basalts.
Diverse basalt types from loihi seamount, hawaii geology. Tholeiitic basalt alkaline basalt usually finegrained, intergranular. Tholeiitic basalt synonyms, tholeiitic basalt pronunciation, tholeiitic basalt translation, english dictionary definition of tholeiitic basalt. Geochemistry of a komatiitic, boninitic, and tholeiitic. Tholeiitic basalt an overview sciencedirect topics. The geochemical provinciality of the parnaiba tholeiitic magmatism seems unrelated with the. Pdf detailed study of mineralogy and geochemistry of the basaltic rocks within the campus of. The tholeiitic basalts of the sardinha formation pre. Rapid formation of ontong java plateau by aptian mantle. The komatiite tholeiitic basalt association, interlayered with bif andor cherts. Basalt a basalt is a finegrained basic igneous rock containing essential calcic plagioclase feldspar and pyroxene usually augite, with or without olivine. Mid oceanic ridges are characteristic of tholeiitic, rather than andesitic basalts and are commonly termed ridge tholeiite. Silica activity and the classification of alkalic and. Hawaiian oibs tholeiites, picrites and alkali basalt series.
The rock is a tholeiitic basalt, containing olivine 11%, clino pyroxene 10%, orthopyroxene 5%, plagioclase 39%, and glass 30%. Four flows of alkalic basalt contain common small dunite xenoliths. We report new hf, pb, nd, and sr isotope compositions for 32 hualalai tholeiitic basalts collected from deep submarine portions of the north kona region. The hawaiian islands, like most within the great ocean basins, are entirely volcanic.
From the base to the top, it consists of a layered series dominated by troctolite and gabbro, an anorthositic upper border series and a dominantly granitic upper series. Tholeiites, picrites and alkali basalt series geochemistry. Tholeiitic basalt g residuum lherzolite is probably fertile unaltered mantle dunite and harzburgite are refractory residuum after basalt has been extracted by partial melting figure 101 brown and mussett, a. Olivine tholeiitic basalts of the snake river plain, idaho by william p. Principal types of ocean basins basalt table 101 common petrographic differences between tholeiitic and alkaline basalts tholeiitic basalt alkaline basalt usually finegrained, intergranular usually fairly coarse, intergranular to ophitic groundmass no olivine olivine common.
Tholeiitic basalt article about tholeiitic basalt by the. Experiments on liquid immiscibility along tholeiitic. More than 90% of all volcanic rock on earth is basalt. The last interstitial melt in the lake solidified late in. Seventeen dredge stations recovered transitional basalt, alkalic basalt, and basanite, in addition to the expected tholeiitic basalt. Physical properties of partly melted tholeiitic basalt. The eruption of kilauea volcano august 2123, 1963, left 600,000 cubic meters of basaltic lava in a lava lake as much as 15 meters deep in alae pit crater. Tholeiitic lavas often contain glass, but little or no olivine. Introduction a recent development in the classification of volcanic rocks is the application of the concept. Tholeiitic basalts are the most common eruptive rocks produced by submarine volcanism. They are built from a different kind of lava, much gummier than that of the freeflowing tholeiitic basalt. Tholeiite occurs as extensive plateaus volumes on the order of 200,000 to 800,000 cubic km 50,000 to 200,000 cubic miles in the pacific. Tholeiitic basalts that are interleaved with felsic rocks of the duffer formation but that do not. Basalt lava has a low viscosity, due to its low silica content.
Isotopic geochemistry of hualalai shieldstage tholeiitic. The following summary of the geology of basalts is. Tholeiitic basalt is found in field b in the tas diagram. Tholeiitic basalts that are interleaved with felsic rocks of the duffer formation but that do not form part of either recognized geochemical basalt dacite series i. The columbia river plateau basalts occupy a volume of 174, 300 km3 and cover an area of 163, 700 km2 and most of the basalt was. The basalt tetrahedron is a useful tool for classifying basalts. This rapid strengthening is believed to explain why sheets of segregation liquid in tholeiitic flood basalts have compositions that correspond to no more than 35% fractional crystallization of the host basalt.
As basic rocks they contain between 4550% silica, abundant fe, mg and ca, and little na and k. An alkali basalt contains more conspicuous plagioclase and pyroxene crystals. Contamination is fueled by persistent basalt flux that promotes crustal melting and basalt interaction with those melts. The petrogenesis of tholeiitic diabases in eastern parnaiba. Download acrobat pdf file 66kb recommended articles citing articles 0 references ahmad et al. Philpotts ar, doyle cd 1983 effect of magma oxidation state on the extent of silicate liquid immiscibility in a tholeiitic basalt. The sulfur isotope composition of basaltic rocks springerlink. Magmatic sulfiderich nickelcopper deposits related to picrite and or tholeiitic basalt dikesill complexes. Interstate state park, taylors falls, minnesota, usa 2 23733446026. The international union of geological sciences recommends that.
The shallow depths of magma production along the constructive mid oceanic ridge and earthquake zone, form alkalipoor tholeiitic magma jokat et al, 1992. Olivine tholeiitic basalts of the snake river plain, idaho. Basalts, basalt series, and basalt classification basalt. The compressive strength of the mush increases dramatically from 336 to 4333 pa as the percentage of crystals increases from 33% to 37%.
The parent magma of the layered series is inferred to be an ironrich tholeiitic basalt 48 wt % sio 2. Plumose marking on joint surface in tholeiitic basalt clam falls volcanics, mesoproterozoic, 1. Temporal and crustal effects on differentiation of. A magma series is a chemically distinct range of magma compositions that describes the evolution of a mafic magma into a more evolved, silica rich end member. Pdf effect of water on tholeiitic basalt phase equilibria. Basalts are a group of finegrained extrusive igneous rocks that have a relatively low silica content, but otherwise vary significantly in composition and appearance. The sulfur isotope composition of tholeiitic basalts, olivine alkali basalts and alkalirich undersaturated basalts were. Generation of magma free download as powerpoint presentation.
Wholerock compositions from the chilled margin, dykes crosscutting the layered series and silicic rocks from the upper series display continuous major and trace element geochemical trends ranging from basalts to ferroan. Cotectic proportions of olivine and spinel in olivine. Continental flood basalt provinces such as the columbia river plateau, usa, the parana in brazil and the deccan traps of india are characterized by huge volumes of tholeiitic basalt erupted over a short period of time. Mineralogy of tholeiitic basalthide essential minerals these are minerals that are required within the classification of this rock. Pdf documents opened from your browser may not display or. From winter 2001 an introduction to igneous and metamorphic petrology. Resistivity data from logging suggest that the hole was terminated at the top of another thick mas. Download fulltext pdf differentiation of tholeiitic basalt to atype granite in the sept iles layered intrusion, canada article pdf available in journal of petrology 523.
Field studies of the lake began august 27 and include repeated core drilling, measurements of temperature in the crust and melt, and precise level surveys of the lake surface. Spider diagram for a typical alkaline ocean island basalt oib and tholeiitic midocean ridge basalt morb. Origin of hawaiian tholeiite and alkalic basalt nature. Tholeiite, finegrained extrusive igneous rock, a basalt that contains plagioclase feldspar labradorite, clinopyroxene augite with pigeonite, and iron ore magnetite and ilmenite. Tholeiitic basaltic lavas are characterized by calcic plagioclase with augite, pigeonite or hypersthene, and olivine rarely as the dominant mafic minerals. Both pigeonite tholeiites and alkali basaltic etnaites may be derived from a primitive olivine tholeiite magma by subtraction or addition of phases crystallized at. Can we differentiate between calcalkaline and tholeiitic. Traceelement geochemistry of tholeiitic basalts from site 433c. Tholeiitic basalt magmatism of mount etna and its relations with the. The geochemical data of hualalai tholeiitic basalts allow extension of the temporal variations established at mauna loa back in time, and provide important information for the longterm temporal variation of the hawaiian lavas. As a function of decreasing age, lace, bala, nbla, rbsr and 143nd144nd increase but. Crystallization of tholeiitic basalt in alae lava lake, hawaii.
Tholeiitic basalt definition of tholeiitic basalt by the. Haleakala volcano consists of a tholeiitic basalt shield overlain by alkalic lavas. Depending on the water activity, the oxygen fugacity varied between 1 and 4 log units above the quartzmagnetitefayalite buffer. The undeformed 564 ma sept iles layered intrusion quebec, canada is a large igneous body of c. A tholeiitic basalt contains more conspicuous plagioclase and pyroxene crystals.
Magmatic sulfiderich nickelcopper deposits related to. Both pigeonite tholeiites and alkali basaltic et naites may be derived from a primitive olivine tho leiite magma by subtraction or addition of phases crystallized at. Any of a series of igneous rocks similar in composition to basalt but having more silica and iron and less aluminum. They may, for instance, be compact, smooth, and glassy or porphyritic and can exhibit a wide range of colors, such as dark green, reddish brown, gray, or black. Effect of water on tholeiitic basalt phase equilibria. Tholeiitic basalts, which contain 45 to 63 percent silica, are rich in iron and include the tholeiites. The massive flows are mostly less than 3 m thick but one is 28 m thick, comparable in thickness to flows in continental flood basalt provinces. The parent magma of the layered series is inferred to be an ironrich tholeiitic basalt 48wt sio2. Crustal assimilation drives a strongly calcalkaline trend from a tholeiitic parent thi index for our suite is 0.
Leeman abstract basalts of the snake river plainyellowstone plateau province are dominantly olivine tholeiites that can be distinguished into two groupsvariably fractionated for example, differentiated lavas. The tetrahedron is constructed using the normative components olivine, quartz, clinopyroxene, and nepheline. Media in category tholeiitic basalts the following 2 files are in this category, out of 2 total. Tholeiitic basalt geochemistry and detailed petrography, kadaganchi, karnataka 9 figure 9 total alkali silica modified diagram after sugisaki and tanaka, 1971 showing high k tholeiite basalts. You can read more about the different magma series here.
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