Mar 4, 2006 · A hypabyssal rock is an igneous intrusive rock that crystallizes at intermediate depths with medium grain sizes and textures. These rocks are formed near the surface where temperatures are relatively low, and the cooling of the magma is neither rapid nor slow. Examples include microgranites, porphyry, microgranodiorites, microdiorites, and ...

Jun 20, 2008 · Hypabyssal kimberlites have remarkably similar mineralogical characteristics on a world-wide basis regardless of age indicating that similar kimberlite magmas are formed repeatedly in space and time. These characteristics have been used to formulate the standard petrological definition of kimberlite ( Mitchell, 1995 , Woolley et al., 1996 ).

Jun 20, 2008 · Hypabyssal kimberlites provide the best material for understanding the character of the kimberlite magma prior to the formation of diatreme and pyroclastic facies kimberlites. Unlike most other magma types, kimberlites do not typically occur as lavas, as these magmas do not quench to glass or holocrystalline rocks under subaerial conditions.

Feb 2, 2011 · Hypabyssal mafic rocks and their spatially associated basalts with inter-pillow cherts and terrigenous sediments that occur in the vicinity of the Kolyuchinskaya Bay in eastern Chukotka show trace elements, Sr- and Nd-isotope compositions that are similar to the tholeiitic flood basalts of the main plateau stage of the Siberian LIP.

Jan 1, 2019 · The hypabyssal albitite is leucocratic and pale yellow to white or grey in colour. It shows typically medium-grained granitoid textures, consisting essentially of randomly oriented euhedral to subhedral albite crystals (95–97%) as the major constituent with very minor quartz (<4%), orthoclase (1–4%) and biotite (<1%).

Jan 31, 2010 · Emplacement model for the differentiation of the Panzhihua plutonic-hypabyssal-volcanic complex. a) Eruption of the Emeishan flood basalts, b) intrusion of the parental magma followed by fractional crystallization to produce the cumulate gabbro, syenodiorite, granite and trachyte, c) cooling of trachytes to columnar joints.

Nov 1, 2009 · Hypabyssal kimberlites with high modal proportions of calcite or dolomite have also been excluded on the basis that these represent fractionated kimberlites, due to magmatic differentiation via crystal — liquid, flowage seggregation and/or filter pressing processes (e.g., Mitchell, 1986, Kjarsgaard, 2007, Mitchell, 2008).

Jul 1, 2011 · This hypabyssal kimberlite is slightly different from the hypabyssal kimberlite observed in the sills and dykes described above. The major difference is the absence of aegirine and sanidine. The hypabyssal kimberlite is comprised of altered olivine, phlogopite, diopside and spinel set in calcite and clay minerals.

Jul 1, 2017 · The hypabyssal igneous intrusions of this region intruded into a thick sequence of Paleocene to middle Eocene volcanic and volcanosedimentary rocks. The magmatic belt contains numerous dikes and domes, ranging in composition from trachybasaltic andesite, trachyandesite, andesite, dacite, and trachyte, to gabbro.

Jan 1, 1981 · Chapter 3 VOLCANIC AND HYPABYSSAL ROCKS INTRODUCTION Volcanic rocks and associated hypabyssal intrusive rocks (dikes, sills, plugs, etc.) are the dominant rocks in Archean greenstone belts. Many detailed descriptions of these rocks are available in the literature and suggest that magmatic eruptions were largely subaqueous.