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Geochemistry, petrogenesis and tectonic setting of the Paleoproterozoic Yanmenguan mafic-ultramafic intrusion in the Hengshan-Wutai-Fuping area
五台地区雁门关早元古代镁铁-超镁铁岩体的岩石地球化学特征、成因及其大地构造意义

WAN JiaLiang,WANG ZhiHong,
万加亮
,王志洪

岩石学报 , 2012,
Abstract: A detailed study of petrology, mineralogy, geochemistry and petrogenesis on the Paleoproterozoic Yanmenguan mafic-ultramafic intrusion in the Hengshan-Wutai-Fuping area is presented here. The intrusion is akin to Alaskan-type or arc-related magmatism in mineral geochemistry, especially in the compositions of spinel, clinopyroxene, and amphibole. The rock geochemistry is also comparative to those of Alaskan-type mafic-ultramafic complexes, as characterized by pronounced Nd (Ta), Zr (Hf), Y and Ti trough in primitive mantle normalized trace element patterns. In trace element discrimination diagrams, the Yanmenguan rocks plot in the field of subduction zone-related magmas, indicating a tectonic setting of continental arc. Therefore, we propose that the magma of the Yanmenguan mafic-ultramafic intrusion originated from lithospheric mantle in a continent marginal arc, and experienced fractional crystallization of olivine and clinopyroxene. This intrusion, together with contemporary granitic and volcanic rocks in this area, signifies an important stage of Paleoproterozoic magmatism developed in continent margin of the Trans-North China Orogen.
东昆仑中灶火地区超镁铁质辉石岩的成因
Petrogenesis of the Zhongzaohuo Ultramafic Pyroxenite Pluton, East Kunlun:Constraints from Petrology, Geochemistry and Genetic Mineralogy
 [PDF]

罗文行,钱莉莉,李德威,朱云海,刘德民,高成
LUO Wenxing
, QIAN Lili, LI Dewei, ZHU Yunhai, LIU Demin, GAO Cheng

地球科学(中国地质大学学报) , 2018, DOI: 10.3799/dqkx.2013.119
Abstract: 最近在青海东昆北中灶火地区发现超镁铁质岩的岩石学、地球化学以及成因矿物学等方面的研究成果.岩石主要由单斜辉石、斜方辉石和角闪石组成,另有少量斜长石、石英、黑云母和铁质不透明矿物.角闪石和黑云母为后期退变质矿物.斜方辉石成因判别分析结果为岩浆成因,故该超镁铁质岩为辉石岩而非麻粒岩.该辉石岩化学成分上表现为异常的高MgO、高CaO、低Al2O3特征,微量元素表现为Rb、Th富集而Nb、Ti的亏损,表明其来源于富集地幔.通过岩相学、稀土元素等特征与前人研究结果对比认为该辉石岩是俯冲洋壳部分熔融产生的富Si熔体与地幔橄榄岩发生交代反应产生辉石岩岩浆,然后底侵到地壳中部冷却结晶形成的.野外地质特征显示辉石岩的侵位晚于发生糜棱岩化的围岩,即晚于围岩的形成时代,即早二叠世,说明该辉石岩是在中二叠世古特提斯洋向北大规模俯冲及其所导致的弧后伸展的构造背景下形成的.
A ultramafic pyroxenite pluton has been discovered in Zhongzaohuo area in the East Kunlun orogen Recently. This paper reports the results of petrological, geochemical and genetic mineralogy research on the pyroxenite pluton. The rock is mainly composed of clinopyroxene, orthopyroxene and amphibole, and minor plagioclase, quartz, biotite and iron opaque minerals. Amphibole and biotite were formed during retrograde metamorphism. The discriminant analysis results suggest that the Opx are magmatogenic, thus the rock should be named pyroxenite rather than granulite. The rock has high MgO, CaO and low Al2O3 and enriched in Rb and Th and depleted in Nb and Ti, showing clear evidence for an enriched mantle source. Field occurrence of the pyroxenite pluton suggests that the pyroxenite pluton was formed after the mylonization of the surrounding rocks. Combined with the tectonic evolution of East Kunlun, we come to the conclusion that the subduction of an Paleo-Tethys(Anyemaqen) oceanic slab at the Middle Permian led to fluid and Si-rich?melt metasomatism, inducing partial melting of an enriched lithospheric mantle(peridotites) to form the ultramafic pyroxenite magma. The pyroxenite magma underplated the overlying lower crust, captured the metamorphic zircons of the granulite and exchanged some trace elements, but didnt result in the lower crust partial melting to form any felsic magma. The pyroxenite magma emplaced alone eventually
甘肃北山红柳沟基性-超基性岩体岩石成因及成矿条件
The Petrogenesis and Mineralization of the Hongliugou Mafic-ultramafic Rock in Beishan, Gansu Province
 [PDF]

谢燮,杨建国,王小红,王磊,江磊,姜安定,
XIE Xie
, YANG Jian-guo, WANG Xiao-hong, WANG Lei, JIANG Lei,JIANG An-ding

- , 2015,
Abstract: 摘要: 甘肃北山红柳沟基性-超基性岩体位于塔里木板块北缘北山裂谷带, 岩体侵位于敦煌岩群,主要岩石类型有辉长岩、橄榄辉长岩、橄榄苏长辉长岩、橄榄角闪苏长岩、橄榄辉长苏长岩、二辉橄榄岩、橄榄辉石岩和辉石岩等。橄榄石Fo介于66.97%~82.92%之间,属贵橄榄石,斜方辉石En成分范围为68.49~77.65,属古铜辉石;单斜辉石En成分范围为45.85~48.81,主要为斜顽辉石和透辉石;斜长石An为58.70~72.69,以拉长石为主;角闪石以普通角闪石为主。岩体母岩浆Mg#值为0.59~0.62,属于高镁拉斑玄武质岩浆,岩浆演化过程中主要发生了橄榄石、斜方辉石、单斜辉石和斜长石的分离结晶作用,主要分离结晶矿物受单斜辉石和斜方辉石的控制,岩浆上升侵位过程中遭受到下地壳物质混染。从构造环境、母岩浆、岩体类型、岩浆分异程度、同化混染等方面综合分析认为红柳沟岩体具有形成铜镍硫化物矿床的较大潜力。
Abstract: The Hongliugou mafic-ultramafic rock in Beishan of Gansu is located in the Beishan rift belt on the northern margin of the Tarim Plate, rock mass was emplaced in the Dunhuang rock Group. The main rock types include gabbro, olive gabbro, olive norite-gabbro, olive hornblende norite, olive gabbro-norite, lherzolite, olive pyroxenite and pyroxenite. The olivine belongs to chrysolite, and its Fo is between 66.97% and 82.92%; meanwhile, the orthopyroxene and clinopyxene are bronzitite and oblique/diopside, their composition of En ranged from 68.49 to 77.65 and 45.85 to 48.81; the plagioclase is labradorite, and its An is between 58.70 and 72.69; amphibole is hornblende. The Mg# of parental magma ranged from 0.59 to 0.62, indicating that the parental magma belongs to high magnesium tholeiitic magma. The process of magmatic evolution experienced fractional crystallization, such as olivine, orthopyroxene, clinopyroxene and plagioclase, which controlled by clinopyroxene and orthopyroxene.The process of magma emplacement has suffered contamination of the lower crust. By the research of the tectonic environment, parent magma, rock type, degree of magmatic differentiation, contamination, we consider that the Hongliugou intrution has a potential to form a sulphide deposit
Petrogenesis of the Poyi mafic-ultramafic layered intrusion, NE Tarim Plate
塔里木板块东北部坡一镁铁质-超镁铁质层状侵入体岩石成因

JIANG ChangYi,GUO NaXin,XIA MingZhe,LING JinLan,GUO FangFang,DENG XiaoQin,JIANG HanBing,FAN YaZhou,
姜常义
,郭娜欣,夏明哲,凌锦兰,郭芳放,邓小芹,姜寒冰,范亚洲

岩石学报 , 2012,
Abstract: The Pobei rock body is located in northeastern Tarim Plate.As one of many small intrusions of Pobei body,the Poyi intrusion formed during the third stage of the magmatism and dated at 278±2Ma by the SHRIMP zircon U-Pb method.The Poyi layered intrusion,which is mainly composed of ultramafic rocks,develops cumulate texture and rhythmic layering.The magma differentiated thoroughly and formed many types of rocks,which range from dunite to quartz diorite.In the ultramafic rocks,all olivine and most orthopyroxene occur as cumulate phase,while small part of orthopyroxene,most clinopyroxene,brown hornblende and biotite are intercumulate.In the mafic rocks,all olivine and orthopyroxene are cumulate phase,while all brown hornblende,biotite and quartz are intercumulate.But the clinopyroxene and plagioclase may be cumulate or intercumulate.The ultramafic rocks are tholeiitic series and the mafic ones are calc-alkalic.Xenoliths occurred in the intrusion,geochemistry of trace elements and EMⅡ evolutionary trend of Nd-Sr isotopic composition,fully demonstrate that the contamination increased as magma evolving.At the same time,contamination promoted magmatic differentiation and brought about the transformation of geochemical series.Geochemistry of platinum group and thiophile elements,as well as isotopic composition of sulfur,show that sulfur mainly came from mantle-derived magma and sulfide formed during magmatic stage.The sulfide segregation began in the late stage of the crystallization of peridotites and went on as the magma evolving.The Fo value of olivine and FeO content of whole-rock show that the primary magma was picritic and formed by partial melting of axis plume.The main rocks of magmatic source should be garnet-pyroxenolite.The other Permian magmatite in northeastern Tarim Plate,which derived from asthenospheric or depleted continental lithospheric mantle,also should be part of the Tarim large igneous province(LIP).
Petrogenesis and implication of the andesites at ~ 113Ma in the Nagqu region in the northern Lhasa subterrane
西藏北部拉萨地块那曲地区约113Ma安山岩岩石成因与意义

HUANG Yu,ZHU DiCheng,ZHAO ZhiDan,ZHANG LiangLiang,Don DEPAOLO,HU ZhaoChu,YUAN HongLin,MO XuanXue,
黄玉
,朱弟成,赵志丹,张亮亮,Don DEPAOLO,胡兆初,袁洪林,莫宣学

岩石学报 , 2012,
Abstract: The nature of magma source region and petrogenesis of the Early Cretaceous igneous rocks,which are widely distributed in the northern Lhasa subterrane,are not well constrained so far largely due to the limitation of high quality geochronological and geochemical data.This paper reports the petrological,zircon U-Pb dating,whole-rock geochemical and zircon Hf isotopic data of the andesites from Nagqu area,northern Lhasa subterrane.The andesites have been dated to be 112.7 ± 0.7Ma by zircon U-Pb dating method.These rocks are high-K calc-alkaline,enriched in large-ion lithophile elements(LILEs),Th,U,and light rare earth elements(LREEs),and depleted in high field strength elements(e.g.,Nb,Ta,P,and Ti;HFSEs).The andesites show high(87Sr/86Sr) i values(0.7100 ~0.7126),negative εNd(t) values(-10.5 ~-7.8),and negative zircon εHf(t) values(-9.9 ~-4.7),yielding ancient two-stage Nd model ages of 1.5 ~ 1.8Ga and zircon Hf isotope mantle model ages of 1.0 ~ 1.6Ga.The data reported here,combined with regional geological background of the northern Lhasa subterrane,we propose that the Nagqu andesites can be considered as the products of partial melting of ancient lithospheric mantle of the Amdo microcontinent that was modified by fluids or/and melts of the sediments,and subsequently experienced varying degrees of fractional crystallization.This magma event is most likely resulted from the slab break-off of the southward subduction of the Bangong-Nujiang Ocean seafloor.
Ultramafic Hornfelses in Central Iran Ophiolites  [PDF]
Ghodrat Torabi
Journal of Applied Sciences , 2008,
Abstract: There are leucocratic gabbro intrusions in serpentinized mantle peridotites of Central Iran ophiolites (Jandaq, Anarak, Naein and Ashin-Zavar). In contacts of gabbro intrusions and serpentinized mantle peridotites, ultramafic hornfelses are formed by contact metamorphism. These ultramafic hornfelses are different with host mantle peridotite in petrography, texture and mineral chemistry. Two-pyroxene thermometry of hornfelses and intact mantle peridotites that are far from contact metamorphism, present 987 and 1200°C, respectively. To occuring the reaction between the gabbro intrusions and mantle peridotites, the host rock should be serpentinized previously.
PGE and geochemistry of Wajilitag ultramafic cryptoexplosive brecciated rocks from Tarim Basin: Implication for petrogenesis.
塔里木瓦吉里塔格超镁铁质隐爆角砾岩铂族元素和微量元素地球化学特征及其岩石成因探讨

LI YinQi,LI ZiLong,SUN YaLi,CHEN HanLin,YANG ShuFeng,YU Xing,
励音骐
,厉子龙,孙亚莉,陈汉林,杨树锋,余星

岩石学报 , 2010,
Abstract: Wajilitag ultramafic cryptoexplosive brecciated rocks, as one of the most important rock types of the Tarim Permian Large Igneous Province, were studied on platinum group elements (PGE), major, trace and rare earth elements in this study. The results show that these rocks have Os, Ir, Ru, Rh, Pt and Pd contents of 0.36×10-9~1.08×10-9, 0.23×10-9 ~0.44×10-9, 0.29×10-9~0.92×10-9, 0.11×10-9~0.18×10-9, 1.88×10-9 ~3.16×10-9 and 1.39×10-9~3.52×10-9 respectively, which are lower than those of the primitive mantle and can be compared with the Hawaiian picrites. The Pd/Ir ratios range from 3.6 to 11.9 and the PGE patterns take a shape of positive inclined curve, showing a trend of differentiation and a PGE affinity of basic-ultrabasic rocks under within-plate environment. Generally, the brecciated rocks have higher and concentrated Cu/Pd ratios (5.1×104 ~12.1×104) compared to the primitive mantle, indicating that no obvious sulfur oversaturation and segregation occurred during the magma upwelling, but the magma source may have some residual sulfide during its process of partial melting. The positive correlations for IPGE vs. MgO and negative correlations (or no obvious correlation) for PPGE vs. MgO suggest that the PGE differentiation was probably controlled by differentiation of olivine. Geochemically, the brecciated rocks are much enriched in total REE amounts (964.1×10-6~1299×10-6) and have strong fractionation between LREE and HREE . On the primitive mantle normalized spidergram, the brecciated rocks show humped distribution patterns, with LILE enrichment, slight depletion of Nb and Ta, and negative Zr and Hf anomalies, suggesting that the rocks may have undergone mantle metasomatism. However, similar PGE patterns from the breccias and matrix show that mantle metasomatism might not be a main factor for the PGE fractionantion of the brecciated rocks, indicating that the PGE may be existed in the sulphide inclusions in the silicate minerals.
PETROLOGY AND PETROGENESIS OF THE CENOZOIC BASALTIC ROCKS FROM MT.QIXINGSHAN,JILIN PROVINCE
吉林双辽七星山新生代玄武岩的特点及其成因探讨

Yu Yang,
余扬

岩石学报 , 1987,
Abstract: Mt. Qixingshan is a cluster of eight volcanic cones located in southern Songliao Basin in Northeast China, and the ultramafic xenoliths of various types have been found in four of these cones.The K-At isotope age determinations show that these volcanos erupted in Early Tertiary and even kate Cretaceous era. This fact can be regarded as an important discovery considering that no ultramafic xenoliths have been found so far in the basaltic rocks erupted earlier than Late Tertiary over the territory of China. Among the four types of volcanic rocks which cccur in the volcanos, the most distinctive ones are highly SiO_2-undersaturated and olivine-rich basanite enriched in FeO, MgO and with. quite low Al_2O_3,and high Al and alkali diabase with high Al-2O_3 and Na_2O contents. The other two types are. alkali olivine basalt and alkali doleritc. Ultramafic xenoliths are found mainly in basanite.Petrochemically, rare element geochemical and isotopic geochemical analyses have been made to reveal their possible petrogenesis. The Ni-content in primitive magmas was recalculated according to the Leeman's new equilibrium constant, and the depth of the magma sources was deteimined on the basis of P-T equilibrium conditions of ultramafic xenoliths calculated from thermodynamic models.All these studies show that olivine-rich basanite was consolidated from primitive magma, and its composition depends on the features of upper mantle source and partial melting process. Magmas of alkali olivine basalt and alkali dolerite were also originated from upper mantle, and probably have undergone crystalfractionation to a certain extent on their way to the Earth's surface.The other tonclusion made in. this study is that rocks from Mt. Qixingshan show no similarities to that from. Mt. Erkeshan, Heilongjiang Province and no evidences support the argument made by Japanese authors in 1939.
An overview of adakite petrogenesis
Paterno R. Castillo
Chinese Science Bulletin , 2006, DOI: 10.1007/s11434-006-0257-7
Abstract: The term adakite was originally proposed to define silica-rich, high Sr/Y and La/Yb volcanic and plutonic rocks derived from melting of the basaltic portion of oceanic crust subducted beneath volcanic arcs. It was also initially believed that adakite only occurs in convergent margins where young and thus still hot oceanic slabs are being subducted, but later studies have proposed that it also occurs in other arc settings where unusual tectonic conditions can lower the solidus of older slabs. Currently, adakite covers a range of arc rocks ranging from pristine slab melt, to adakite-peridotite hybrid melt, to melt derived from peridotite metasomatized by slab melt. Adakite studies have generated some confusions because (1) the definition of adakite combines compositional criteria with a genetic interpretation (melting of subducted basalt), (2) the definition is fairly broad and relies on chemistry as its distinguishing characteristic, (3) the use of high pressure melting experiment results on wet basalts as unequivocal proofs of slab melting and (4) the existence of adakitic rocks with chemical characteristics similar to adakites but are clearly unrelated to slab melting. Other studies have shown that adakitic rocks and a number of the previously reported a dakites are produced through melting of the mafic lower crust or ponded basaltic magma, high-pressure crystal fractionation of basaltic magma and low-pressure crystal fractionation of basaltic magma plus magma mixing processes in both arc or non-arc tectonic environments. Despite the confusing interpretations on the petrogenesis of adakite and adakitic rocks, their investigations have enriched our understanding of material recycling at subduction zones, crustal evolutionary processes and economic mineralization.
An overview of adakite petrogenesis
Paterno R Castillo,
Paterno
,R.,Castillo

科学通报(英文版) , 2006,
Abstract: The term adakite was originally pro- posed to define silica-rich, high Sr/Y and La/Yb vol- canic and plutonic rocks derived from melting of the basaltic portion of oceanic crust subducted beneath volcanic arcs. It was also initially believed that ada- kite only occurs in convergent margins where young and thus still hot oceanic slabs are being subducted, but later studies have proposed that it also occurs in other arc settings where unusual tectonic conditions can lower the solidus of older slabs. Currently, ada- kite covers a range of arc rocks ranging from pristine slab melt, to adakite-peridotite hybrid melt, to melt derived from peridotite metasomatized by slab melt. Adakite studies have generated some confusions because (1) the definition of adakite combines com- positional criteria with a genetic interpretation (melt- ing of subducted basalt), (2) the definition is fairly broad and relies on chemistry as its distinguishing characteristic, (3) the use of high pressure melting experiment results on wet basalts as unequivocal proofs of slab melting and (4) the existence of ada- kitic rocks with chemical characteristics similar to adakites but are clearly unrelated to slab melting. Other studies have shown that adakitic rocks and a number of the previously reported adakites are pro- duced through melting of the mafic lower crust or ponded basaltic magma, high-pressure crystal frac- tionation of basaltic magma and low-pressure crystal fractionation of basaltic magma plus magma mixing processes in both arc or non-arc tectonic environ- ments. Despite the confusing interpretations on the petrogenesis of adakite and adakitic rocks, their in- vestigations have enriched our understanding of material recycling at subduction zones, crustal evolu- tionary processes and economic mineralization.
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