Types of enclaves and their features and origins in intermediate-acid;intrusive rocks from the Tongling district, Anhui Province, China

	Types of enclaves and their features and origins in intermediate-acid;intrusive rocks from the Tongling district, Anhui Province, China
	Wu, CL 3; Wang, ZH ; Qiao, DW ; Li, HB ; Hao, MY ; Shi, RD
刊名	ACTA GEOLOGICA SINICA-ENGLISH EDITION
	2000
卷号	74 期号:1 页码:54-67
关键词	enclave petrology relics cumulate enclaves mixtite enclaves chilled border enclaves Tongling
ISSN号	1000-9515
英文摘要	Enclaves in intermediate-acid plutons from Tongling can be divided into three types: xenoliths, relies and magmatogenic enclaves. The magmatogenic enclaves consist of cumulates, micrograined dioritite mixtite and dioritic chilled border enclaves. Petrologically, relies with eyed and meta-poikilitic texture are characterized by high content of biotite (>80%) and low content of cordierite and grossular. The cumulates with accumulate texture consist of a great amount of pyroxene, hornblende and minor spinel and phlogopite. The micrograined dioritic mixtite is composed of more hornblendes and feldspar and less needle apatites and an ellipsoid basic core included in plagioclase. The chilled border enclaves have the same mineral association, but more dark minerals than the host rocks consisting of plagioclase, quartz, alkaline feldspar, hornblende and biotite. Geochemically, the relies exhibit high REE content (455.8x10(-6)) and high ratio of LREE/HREE, more obvious Eu negative anomaly and are rich in Cr and Ni, poor in Ba, Nb and Sr. All kinds of magmatogenic enclaves have the same REE pattern without Eu anomaly, and the total REE is 74.9x10(-6) for spinel pyroxene cumulate, 179.7x10(-6) for hornblende cumulate, 226.9x10(-6) for hornblende cumulate crystal, 289.9x10(-6) for micrograined dioritic mixtite and 131.2x10(-6) for chilled border enclaves. Calculation with the thermometer and barometer for minerals shows that the temperature and pressure of formation are 1126 degrees C and 8.44 kbar (7.15-9.04 kbar) for the spinel pyroxene cumulate, 1065 degrees C-1029 degrees C and 8.23 kbar (7.13-9.50 kbar) for the hornblende pyroxene cumulate, 959 degrees C and 3.40 kbar (2.86-4.09 kbar) for the micrograined dioritic mixtite enclaves, and 951 degrees C and 0.59 kbar for the dioritic chilled border enclaves, respectively. Thus, the following conclusions can be drawn. Relic enclaves were derived from the crustal partial melting and all cumulate enclaves originated from deep magma chambers near the Moho in the lower crust, which are cumulate fragments formed by fractional crystallization of basic magma; mixtite came from shallow magma chambers in the middle-upper crust, formed by the mixture of mantle-derived magma and acid magma derived from the crustal partial melting; and the chilled border enclaves came from the border fragments of early intrusive bodies.
学科主题	火成岩岩石学
WOS关键词	ORTHO-PYROXENE ; GARNET ; HORNBLENDE ; ALUMINUM
WOS研究方向	Geology
语种	英语
出版者	GEOLOGICAL SOC CHINA
WOS记录号	WOS:000085807700007
内容类型	期刊论文
源URL	[http://119.78.100.197/handle/2HKVOGP0/37423]
专题	中国地质科学院地质研究所
作者单位	1.Chinese Acad Geol Sci, Inst Geol, Beijing, Peoples R China. 2.Xian Engn Coll, Xian, Peoples R China. 3.中国地质科学院地质研究所
推荐引用方式 GB/T 7714	Wu, CL,Wang, ZH,Qiao, DW,et al. Types of enclaves and their features and origins in intermediate-acid;intrusive rocks from the Tongling district, Anhui Province, China[J]. ACTA GEOLOGICA SINICA-ENGLISH EDITION,2000,74(1):54-67.
APA	Wu, CL,Wang, ZH,Qiao, DW,Li, HB,Hao, MY,&Shi, RD.(2000).Types of enclaves and their features and origins in intermediate-acid;intrusive rocks from the Tongling district, Anhui Province, China.ACTA GEOLOGICA SINICA-ENGLISH EDITION,74(1),54-67.
MLA	Wu, CL,et al."Types of enclaves and their features and origins in intermediate-acid;intrusive rocks from the Tongling district, Anhui Province, China".ACTA GEOLOGICA SINICA-ENGLISH EDITION 74.1(2000):54-67.