你好,请
登录
首页
平台概况
新闻中心
中心新闻
行业新闻
媒体关注
平台资源
资源列表
平台服务
机时安排 A
机时安排 B
投诉建议
服务成效
服务成效
服务案例
下载中心
中心发布
调试工具
运行环境
关于
联系我们
发展历程
BJSHRIMP
平台组建背景
搜索
返回
SHRIMP U-Pb zircon dating on Nyainquetanglha granite in central Lhasa block
[
查看
]
LIUQisheng
、
WUZhenhan
、
HUDaogong
、
YEPeisheng
、
JIANGWan
、
WANGYanbin
、
ZHANGHancheng
Abstract The Nyainqentanglha granite, a batholith with an area of 1500 km2 in the central Lhasa block, comprises mainly medium-fine-grained biotite monzonitic granite and medium-coarse-grained biotite monzonitic granite. Their contact relationship suggests that the medium-fine-grained biotite monzonitic granite was crystallized earlier than the medium-coarse-grained monzonitic granite. A SHRIMP U-Pb dating on zircons from representative samples of the batholith shows that the crystallization age of the medium-fine-grained biotite monzonitic granite is 18.3 Ma and that of the medium-coarse-grained monzonitic granite is 11.01 Ma. The emplacement and crystallization of the Nyainqentanglha granite, the youngest granite batholith ever known inside the Lhasa block, have a close relationship with the collisional orogeny, crustal thickening, plateau uplifting,E-W crustal extension and have a dynamic genetic relationship with the crustal partial melting.
SHRIMP U-Pb zircon dating of the uppermost Cretaceous Furao Formation near the Heilong River:An age chosest to the KT boundary
[
查看
]
LIXianhua
、
LIWuxian
、
CHENPeiji
、
WANXiaoqiao
、
LIGang
、
SONGBiao
、
JIANGJianhong
、
LIUJicai
、
YINDeshun
、
YANWei
SHRIMP U-Pb zircon age of the Jinchuan ultramafic intrusion and its geological significance
[
查看
]
LIXianhua
、
SULi
、
SONGBiao
、
LIUDunyi
SHRIMP U-Pb zircon ages for the UHP metamorphosed granitoid gneiss in Altyn Tagh and their geological singificance
[
查看
]
ZHANGAnda
、
LIULiang
、
SUNYong
、
CHENDanling
、
WANGYan
、
LUOJinhai
Abstract Cathodoluminescence (CL) and mineral inclusions investigations show that zircons from Yinggelisayi UHP metamorphosed granitoid gneiss in Altyn Tagh exhibit core-mantle-rim internal texture with magmatic residual core, the metamorphic overgrowth mantle and the late stage rim. SHRIMP 206Pb/238U ages of 5 spots from the mantles vary from 484±11 to 491±12 Ma with Th/U ratios from 0.01 to 0.03, yielding a weighted average age of 487±10 Ma (2σ ) as the age of the UHP metamorphosed granitoid gneiss. The 206Pb/238U ages from the oscillatory zoned cores range from 809±19 to 885±21 Ma with Th/U ratios ranging from 0.42 to 0.83, which are interpreted as the crystallization age of the protolith of the granitoid gneiss. The metamorphic age (487±10 Ma) of the UHP metamorphosed granitoid gneiss,well consistent with the peak metamorphic age (about 500Ma) of the UHP eclogite with crystallization age of the protolith between 809±19 and 885±21 Ma at Jianggelisayi in western Altyn Tagh, indicates the existence of a UHPM belt along the south margin of the Altyn Tagh as a result of deep subduction during Early Paleozoic age of previously existing continental crust.
Mineralizing age of the Rushan lode gold deposit in the Jiaodong PeninsulaSHRIMP U-Pb dating on hydrothermal zircon
[
查看
]
HUFangfang
、
FANHongrui
、
YANGJinhui
、
WANYusheng
、
LIUDunyi
、
ZHAIMingguo
、
JINChengwei
Abstract Zircons from the auriferous quartz vein in the Rushan gold deposit, Jiaodong Peninsula, have high common Pb contents (206Pbc = 2.00%—15.88%) and Th/U ratios (0.31—1.35), and trap primary CO2-H2O fluid inclusion similar to ore-forming fluids, indicating that they grew from high Th/U ratio ore-forming fluids responsible for gold mineralization.SHRIMP U-Pb analyses of these zircons gave an age of 117±3 Ma comparable with the ages reported by the former researches in the other areas in the Jiaodong Peninsula, which is interpreted as the age of gold mineralization at Rushan. The age of SHRIMP zircon U-Pb dating with 160±3 Ma from host rock Kunyushan monzogranite is different from that of the gold mineralization, indicating that there is no genetic relationship between gold mineralization and the granitic magmatism. SHRIMP U-Pb dating on hydrothermal zircons from auriferous quartz veins could be used to constrain the timing of lode gold mineralization and the relationship to relevant hydrothermal event.
Fluid inclusions hidden in coesite-bearing zircons in ultrahigh-pressure metamorphic rocks from southwestern Sulu terrane in eastern China
[
查看
]
LIUFulai
、
XUZhiqin
Abstract Primary fluid inclusions, together with coesite mineral inclusions, are identified in the same zircon domains by laser Raman spectroscopy, cathodoluminescence (CL)image and micro-texture analysis in paragneiss and eclogite from the main drilling hole of Chinese Continental Scientific Drilling Project in southwestern Sulu terrane. Most fluid inclusions are characterized by CO2 (gas)-H2O (liquid) two-phase, a few by H2O one-phase liquid inclusions. These features indicate that the eclogite and its country-rocks may be located in the “wet system” rather than in the “dry system”during UHP metamorphism. SHRIMP U-Pb dating indicates that the timing of trapping the fluid and coesite inclusions in metamorphic zircon domains is about 233.7 ± 4.3 Ma, which may represent the age of zircon growth in the stage of pressure decrease but temperature increase during the retrograde period of UHP metamorphism thus indicating the fluid activity still under the UHP conditions. The zircons further overgrew at about 213.2 ± 5.2 Ma in response to amphibolite-facies retrogression. Therefore, fluid activity in the Sulu UHP metamorphic rocks principally occurred during the exhumation of UHP slab in the Middle to Late Triassic.The present results not only provide insight into the fluid property and fluid-rock interaction mechanism in the Sulu-Dabie UHP terrane, but also present a new means to exactly identify the primary fluid inclusions preserved in zircons from the UHP metamorphic rocks.
Emplacement age and tectonic implications of the Xilinhot A-type granite in Inner Mongolia,China
[
查看
]
SHIGuanghai
、
MIAOLaicheng
、
ZHANGFuqing
、
JIANPing
、
FANWeiming
、
LIUDunyi
Abstract A new rock type of granite, approximate 45km2 in area and located about 10 km south of Xilinhot, Inner Mongolia, was found in the Sunitezuoqi (or called Suzuoqi)-Xilinhot tectonic belt and identified as an A-type miarolitic intrusion. The pluton has miarolitic structure and is composed chiefly of perthite, quartz, euhedral albite and potassium feldspar. Various types of textures occur in the pluton, such as perthitie, graphic and myrmekite textures.Only quartz is found in miarolitic cavity. This A-type granite with seagull-shaped REE patterns and obvious negative Eu anomaly (d Eu = 0.24—0.28) is high in SiO2 (76%—77%), K and Na (Na2O + K2O = 7.75%—8.15%) and low in Ca (CaO= 0.20%—0.22%), Fe and Mg. Both petrographical observations and chemical compositions indicate that it is an A-type granite. Zircon SHRIMP U-Pb analyses indicate that this A-type granite was emplaced at 276 ± 2 Ma and coeval with the same type of granites in the adjacent areas. Therefore, it suggests that this pluton was likely formed in a post-orogenic extensional setting and probably related to break-off of subducted slabs in Central Asian Orogenic Belt (CAOB), which indicate that the Sunitezuoqi-Xilinhot belt was tectonically evolved into post-orogenic stage since early Permian.
Zircon SHRIMP Dating for the Weiya Pluton,Eastern TianshanIts Geological Implications
[
查看
]
ZHANGZunzhong
、
GULianxing
、
WUChangzhi
、
LIWeiqiang
、
XIAihua
、
WANGShuo
Abstract The timing of the emplacement of the Weiya pluton remains controversial due to the absence of systematic and precise dating. This paper reports zircon SHRIMP U-Pb dating of different lithologic phases in the Weiya pluton, and discusses the genesis and tectonic environment. The ages of gabbro, quartz syenite, diorite porphyrite and fine-grained granite are 236±6 Ma, 246±6 Ma, 233±8 Ma and 237±8 Ma, respectively. All these phases were formed in early-middle Indosinian(Triassic) in a post-orogenic environment. In addition to underplating, intraplating of mantle-derived magmas is also a substantial mechanism for magma generation and vertical accretion of the continental crust. Granitoid rocks are important products of vertical continental accretion as underplating evolves gradually to intraplating. The existence of post-orogenic Indosinian granites shows that the middle Tianshan orogenic belt underwent an important tectonic conversion from the Paleo-Asian ocean subduction-collision system to the Paleo-Tethys ocean regime.
U-Pb dating of zircon from the bed parallel anatectic graniteic intrusion in the Baban group in Hainan Island and the tectonic implication
[
查看
]
DINGShijiang
、
HUJianmin
、
SONGBiao
、
CHENMulun
、
XIEShengzhou
、
FANYuan
Abstract The petrological and geochemical features of the bed parallel granitic intrusion in the Pre-Cambrian Baoban group in Hainan Island attest to the anatexis origin of the granites.U-Pb dating analyses of zircons from the anatectic granite and the biotite two-feldspar gneiss in the Baoban group, using SHRIMP II in the Beijing Ion-probe Center, acquire 206Pb/238U ages of 368±3.5 Ma (of granite, 95% confidence level, MSDW=1.23) and 362.9±6.1 Ma (of gneiss, 95% confidence level, MSDW= 2.04) respectively. The two late Devonian ages indicate consistently a tectonic- thermal event experienced in Hainan Island, and are the first discovered record of the Devonian geological process in the district. This event possibly resulted from the deep thermal-dynamic process when the Gondwana continent began to break up in the Devonian period.
Timg of Magma Mixing in the Gangdise Magmatic Belt during the India-Asia Collisionziron SHRIMP U-Pb Dating
[
查看
]
MOXuanxue
、
DONGGuochen
、
ZHAOZhidan
、
GUOTieying
、
WANGLiangliang
、
CHENTao
Abstract Abundant mafic microgranular enclaves (MMEs) extensively distribute in granitoids in the Gangdise giant magmatic belt, within which the Qüxü batholith is the most typical MME-bearing pluton. Systematic sampling for granodioritic host rock, mafic microgranular enclaves and gabbro nearby at two locations in the Qüxü batholith, and subsequent zircon SHRIMP II U-Pb dating have been conducted. Two sets of isotopic ages for granodioritic host rock,mafic microgranular enclaves and gabbro are 50.4±1.3 Ma, 51.2±1.1 Ma, 47.0±l Ma and 49.3±1.7 Ma, 48.9±1.1 Ma,49.9±1.7 Ma, respectively. It thus rules out the possibilities of mafic microgranular enclaves being refractory residues after partial melting of magma source region, or being xenoliths of country rocks or later intrusions.Therefore, it is believed that the three types of rocks mentioned above likely formed in the same magmatic event, i.e., they formed by magma mixing in the Eocene (c. 50 Ma). Compositionally, granitoid host rocks incline towards acidic end member involved in magma mixing, gabbros are akin to basic end member and mafic microgranular enclaves are the incompletely mixed basic magma clots trapped in acidic magma. The isotopic dating also suggested that huge-scale magma mixing in the Gangdise belt took place 15-20 million years after the initiation of the India-Asia continental collision, genetically related to the underplating of subduction-collision-induced basic magma at the base of the continental crust. Underplating and magma mixing were likely the main process of mass-energy exchange between the mantle and the crust during the continental collision, and greatly contributed to the accretion of the continental crust, the evolution of the lithosphere and related mineralization beneath the portion of the Tibetan Plateau to the north of the collision zone.
«
1
2
3
(current)
4
5
6
7
8
9
...
88
89
»
© BJSHRIMP 2013 - bjshrimp.cn