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Zircon is the most useful mineral for studies in U-Pb geochronology and Hf and O isotope geochemistry. Matrix effect is a major problem of the microbeam techniques such as SIMS and LA-(MC)-ICPMS. Therefore, external standardization using well-characterized natural zircon standards is fundamental for accurate microbeam measurements. While the isotopic geochronology and geochemistry laboratories equipped with microbeam analytical facilities have been increasingly established in China during the past decade, applications of the isotopic microanalysis are still limited due to shortage of available standards. We report here the Qinghu zircon as a potential new working reference for microbeam analysis of zircon U-Pb age and O-Hf isotopes. This zircon was separated from the Qinghu quartz monzonite from the western Nanling Range, Southeast China. It is fairly homogeneous in U-Pb age and Hf and O isotopes in terms of large amounts of mircobeam measurements by LA-MC-ICPMS and SIMS at the scales of 20–60 μm. SIMS measurements yield consistent 206Pb/ 238U age within analytical uncertainties with that obtained by ID-TIMS. Precise determinations of O isotopes by IRMS and Hf isotopes by solution MC-ICPMS are in good agreement with the statistical mean of microbeam measurements. We recommend U-Pb age of = 159.5 ± 0.2 Ma (2SE), δ18O = 5.4‰± 0.2‰ (2SD) and 176Hf/ 177Hf = 0.283002 ± 0.000004 (2SD) as the best reference values for the Qinghu zircon. [ABSTRACT FROM AUTHOR]

Early deformation history of the Yanshan Tectonic Belt is an unsolved, important issue. We report early structures and their dating results in basement rocks south of the Kalaqin metamorphic core complex. The basement deformation zone is characterized by WNW-ESE steep gneissosity, WNW-ESE shallow mineral elongation lineation and many intrafolial or isoclinal folds. Many kinematic indicators show that it is a WNW-ESE steep, ductile sinistral deformation zone. LA-ICPMS zircon dating gives a crystallization age of 271 Ma for tatolly transposed, deformed monzonite granite dyke and crystallization ages of 251–250 Ma and 210 Ma for undeformed dyke, stock and pluton. The dating results demonstrate that the deformation related to regional shortening took place between 271 and 251 Ma, i.e. Middle-Late Permian. Combined with previous dating results for post-orogenic magmatism in the Yanshan Tectonic Belt, it is inferred that the shortening-related deformation happened in Middle Permian (271–260 Ma). Recent studies suggest that collision along the Solonker Suture took place in Middle Permian, and is then followed by post-collision extenion in Late Permian. We propose that the intense shortening deformation of the Middle Permian in the Yanshan Tectonic Belt belongs to foreland deformation along the norterhn margin of the North China Craton which is caused by continent-continent collision in the Xing-Meng Orogen. The belt was then oriprinted by shortening deformation of the Yanshanian Movement. [ABSTRACT FROM AUTHOR]

The poorly studied Douling Complex is a crystalline basement that developed in the Neoproterozoic-Paleozoic weakly metamorphosed to non-metamorphosed strata at the South Qinling tectonic belt. Five banded dioritic-granitic gneiss samples from the Douling Complex were chosen for LA-MC-ICPMS U-Pb zircon dating, which yielded protolith emplacement ages of 2469 ± 22 Ma, 2479 ± 12 Ma, 2497 ± 21 Ma, 2501 ± 17 Ma and 2509 ± 14 Ma, respectively. An important peak age of ∼2.48 Ga was also obtained for a metasedimentary rock in the same region. These discoveries suggest the occurrence of magmatic activity of 2.51-2.47 Ga at the northern margin of the Yangtze craton. The age-corrected ɛ( t) values obtained from in situ zircon Hf isotopic analysis are mainly between −5.5 and +0.3, and the two-stage zircon Hf model ages range from 3.30 to 2.95 Ga. Considering two important periods of ∼3.3-3.2 Ga and ∼2.95-2.90 Ga for the continental crustal growth in the Yangtze craton, we infer that the dioritic-granitic gneisses from the Douling Complex are the products of reworking of Paleo- to Mesoarchean crust at the northern margin of the Yangtze craton at ∼2.5 Ga. In addition, metamorphic ages of 837 ± 8 Ma and 818 ± 10 Ma were obtained for zircon overgrowth rims from a dioritic gneiss and a metasedimentary rock, indicating that the main phase amphibolite facies metamorphism of the Doulng Complex occurred during the Neoproterozoic, although its geological meaning remains ambiguous. [ABSTRACT FROM AUTHOR]

Based on studies of the geochemical elements of core sediments collected from the subaqueous Yangtze River delta front, combined with 210Pb and 137Cs nuclide dating, element recording profiles were set up and anthropogenic impacts on the sedimentary records were considered. The results suggest that (1) The core formed since 1945, of homogeneous clay and silt sediments. (2) The content of most elements underwent little change, but the content of S and Nb increased gradually. In particular concentrations of these elements and heavy metals increased rapidly and were maintained at high levels in the surface and sub-surface layers (i.e. since the 1990s). The elements S, As and Nb and principal factor 4 (F4), which were sensitive to anthropogenic impacts, could be used as indicators of human activities. (3) The value of each indicator has increased gradually since 1945, with a sharp increase over the last 20 years. When divided according to changing values of the indicators at 185 cm (1955), 97 cm (1978), 47 cm (1992), and 7 cm (2003), five periods of the geochemical elements records were obtained. These corresponded to the ages of from the Chinese Civil War to the early stages of planned economy, the implementation of planned economy, the reform and opening-up period, the market economy establishment phase and the environment control and protection stage after 2003, respectively. [ABSTRACT FROM AUTHOR]

The Huashanguan rapakivi pluton in Zhongxiang, Hubei Province, China, is the first discovered Proterozoic rapakivi pluton in the Yangtze block. Based on field and petrographical observations, a typical rapakivi texture was found in the northern portion of the Huashanguan granitic pluton. Almost all the K-feldspar phenocrysts were round to oval in shape and most had plagioclase coatings known as rapakivi phenocrysts. Alkali feldspars and quartz had two or more generations. Petrochemically, the Huashanguan rapakivi granites were characterized as having high values of Si, K, Fe, Th, U, La, Ga, Ce, Sm and LREE, low values of Ca, Mg, Sr, Nb, Y and HREE, and a negative Eu anomaly. These geochemical characteristics of the Huashanguan granites were concordant with typical rapakivi granites, and had an affinity to A-type granites. LA-ICP-MS U-Pb zircon dating also was conducted. The dating yielded a207Pb/206Pb weighted mean age of 1851±18 Ma (MSWD =1.2), which represents the age of the pluton emplacement. The age of 803±170 Ma at the lower intercept in the concordia diagram corresponds to the age of a later deformation event which affected the pluton, and suggests that the Huashanguan pluton was influenced by Neoproterozoic thermo-tectonic events after its formation. The discovery of Paleoproterozoic Huashanguan rapakivi granites indicates continental rifting or a post-orogenic extensional event that took place in the Paleoproterozoic in the Yangtze block. These events may be related to the breakup of the Paleoproterozoic Columbia supercontinent. [ABSTRACT FROM AUTHOR]

In the "Central Uplift" of Qiangtang, Northern Tibet, a large scale of mafic dyke swarms extended in E-W direction. Zircon SHRIMP U-Pb dating on two representative samples of diabase dyke yield weighted mean ages of 284 ± 3 Ma and 302 ± 4 Ma, respectively, suggesting they emplaced in the Late Carboniferous to Early Permian. Zircon 176Hf/177Hf ratios range from 0.282852 to 0.283041, with ϵHf(f) values of +12.1 to +12.2 and Hf modal (TDM) ages of -440-460 Ma. These data indicate that these mafic dykes were mainly derived from the depleted mantle. In addition, geochemical data suggest that these mat ic dyke swarms are of intra-plate origin. Therefore, the mafic dyke swarms represent products during the extensional process associated with the opening of the Paleo-Tethys Ocean in the area. [ABSTRACT FROM AUTHOR]

This paper presents geochemical analyses of a lamprophyre intruding the Caledonian Doushui granite body in Shangyou County, southern Jiangxi Province. U-Pb dating and Hf-isotope analyses are especially carried out for zircons from it. Petrological and geochemical features show that the lamprophyre belongs to a high-K, weakly alkaline pyroxene-biotite lamprophyre. It is characterized by high Mg# (0.74), Ni (253 μg/g) and Cr (893 μg/g) contents, and also enriched in incompatible elements, such as REE, Rb, Sr, Ba and K. It is suggested that its primitive melt probably derived from enriched mantle metasomatized by non-crust-derived agent. Morphology and LAM-ICPMS dating results of zircons in the lamprophyre indicate that they are xenocrysts captured from deep crustal rocks. Most xenocrystic zircons formed at -.1.86 Ga, and a few in different Phanerozoic periods. The Paleoproterozoic zircons are of magmatic origin and have similar 176Hf/177Hf and 176Lu/177Hf ratios, indicating that they probably are from the same igneous basement rock. The ages and Hf-isotope compositions of zircons from this basement rock are similar to those of Paleoproterozoic Danzhu granite in the southern Zhejiang Province, but extremely distinguished from the Nanhing basement, suggesting that the study area probably is a westward extension part of Paleoproterozoic Wuyishan terrane in the eastern Cathaysia Block. These Paleoproterozoic zircons have low Hf-isotope compositions, characteristic of crustal source. Hf model ages of these zircons and the presence of older inherited cores within them, coupled with available other data reported by previous studies, suggest that the source of Paleoproterozoic magma is Neoarchaean crust, implying the existence of older basement in the Wuyishan terrane. U-Pb ages and Hf isotopes of five Phanerozoic zircons indicate that Paleoproterozoic basement underwent multi-reworking occurring in Caledonian, Indosinian and early Yanshanian, respectively. The Caledonian magmatism also involves reworking of juvenile crust. [ABSTRACT FROM AUTHOR]

In West Liaoning-North Hebei, the Tiaojishan Formation volcanic rocks are developed and many isotopic ages with a very wide age range were obtained in them as well. These different ages have direct influence on confirming and interpreting the related geological issues in West Liaoning-North Hebei and have restricted the study of geological problems related. In the field, the Tiaojishan Formation and the overlying Tuchengzi Formation are in parallel unconformable contact. By systematical sampling and dating of LA-ICP-MS in the Tiaojishan Formation (especially in the upper part) in Luanping, Chengde basins of Northern Hebei Province and in Lingyuan, Jinlingsi-Yangshan basins of Western Liaoning Province, combined with the dating data obtained by previous researchers, results indicate that the upper boundary age of the Tiaojishan Formation is from 156 to 153 Ma, and the lower boundary age of the Tiaojishan Formation is about 165 Ma, the Tiaojishan Formation was formed from the late of middle Jurassic to late Jurassic Epoch. [ABSTRACT FROM AUTHOR]

The Maomaogou nepheline syenite is located at the inner zone of the Emeishan large igneous province and exhibits Intrusive contact with the Emeishan basalts. SHRIMP U-Pb dating on zircons from this syenite yields an age of 261.6±4.4 Ma, in agreement with the age of the Panzhihua layered intrusion and the eruption age of the Emeishan basalts as constrained by stratigraphic data. Geochemical data further suggest that the Maomaogou syenite has a source analogue to the Emeishan basalt, and may have been formed by partial melting of gabbroic cumulates underplated in the lower crust. As s result, temporal and spatial relationships and petrogenetic constraints provide evidence for the genetic link between basalts, mafic/ultramafic and Intermediate/acidic intrusives in the Panxi area. [ABSTRACT FROM AUTHOR]

Zircon LA-ICP MS U-Pb dating of six metamorphic rocks and a metagranite (breccia) from southern basement of the Songliao Basin are reported In order to constrain the formation ages of basement. The basement metamorphic rocks in the Songliao Basin mainly consist of metagabbro (L45-1), amphibolite (SN117), metarhyolitical tuff (G190), sericite (Ser) schist (N103), chlorite (ChI) schist (T5-1), blotite (Bi)-actlnolite (Act)-quartz (Q) schist (Y205), and metagranite (L44-1). The cathodoluminesence (CL) Images of the zircons from metagabbro (L45-1) and metagranite (L44-1) Indicate that they have cores of magmatic origin and rims of metamorphic overgrowths. Their U-Pb isotopic ages are 1808±21 Ma and 1873±13 Ma, respectively. The zircons with oscillatory zoning from amphibolite (SN117) and Chi schist (T5-1), being similar to those of mafic igneous rocks, yield ages of 274 ± 3.4 Ma and 264 ± 3.2 Ma, respectively. The zircons from metarhyolitical tuff (G190) and Ser schist (N103) display typical magmatic growth zoning and yield ages of 424 ± 4.5 Ma and 287 ± 5.1 Ma, respectively. Most of zircons from Bi-Act-Q schist (Y205) are round in shape and different in absorption degree in the CL Images, Implying their sedimentary detritals. U-Pb dating yield concordant ages of 427 ± 3.1 Ma, 455 ± 12 Ma, 696 ± 13 Ma, 1384±62 Ma, 1649±36 Ma, 1778±18 Ma, 2450±9 Ma, 2579±10 Ma, 2793±4 Ma and 2953±14 Ma. The above-mentioned results indicate that the Precambrian crystalline basement (1808-1873 Ma) exists in the southern Songliao Basin and could be related to tectonic thrust, and that the Early Paleozoic (424-490 Ma) and Late Paleozoic magmatisms (264-292 Ma) also occur in the basin basement, which are consistent with the ages of the detrital zircons from Bi-Act-Q schist in the basement. [ABSTRACT FROM AUTHOR]

The Bangong Lake ophiolite is located in the westernmost part of the Bangong Lake-Nujiang River suture zone. It is a tectonic mélange consisting of numerous individual blocks of peridotite, pillowed and massive lavas and mafic dykes with SSZ-type ophiolitic geochemical affinity formed at the end of a Wilson circle. The SHRIMP U-Pb ages of the co-magmatic zircon domains from one gabbroic dyke (Sample 01Y-155) range from 162.5±8.6 Ma to 177.1±1.4 Ma with an average of 167.0±1.4 Ma (n = 12, MSWD = 1.2), suggesting that the subduction of the Bangong Lake Neo-Tethyan Ocean started before the Middle Jurassic. It is inferred that the tectonic transform from spreading to subduction of the Neo-Tethyan Ocean began before the Middle Jurassic in the Bangong Lake area. [ABSTRACT FROM AUTHOR]

An attempt was made to use CO2 laser step-heating method to date the late Pleistocene basaltic groundmass (DF-2) from Tengchong volcanic field. Among the fourteen heating steps, ten define a good inverse isochron (MSWD = 1.4) with an age of 32.2 ± 7.1 ka (2 σ).The inverse isochron also shows that the initial argon isotopic ratio is 297.1±2.0 (2σ) which is the same as the atmospheric argon at the 2σ error level. Study indicates that it is a useful means to date young volcanic groundmass with low K content by using CO2 laser step-heating 40Ar/39Ar method. [ABSTRACT FROM AUTHOR]

SHRIMP U-Pb zircon dating was carried out for the Daohugou Biota near Ningcheng of Inner Mongolia and for lavas overlying or underlying salamander-bearing strata at Reshuitang in Lingyuan of West Liaoning. The results suggest that the Daohugou Biota occurred at an interval from 168 Ma to 164 – 152 Ma. Both the Daohugou Biota and the salamander-bearing fossil assemblage are the same biota and thus developed from 168 to 152 Ma, i.e. from late Middle Jurassic to the early Late Jurassic. The Daohugou Biota-bearing rocks, resting on the Jiulongshan Formation in disconformity and being overlain in unconformity by Late Jurassic Tuchengzi Formation and Early Cretaceous rocks containing the Jehol Biota, are mainly composed of volcanic-sedimentary rocks in a normal sequence. It is recommended that the Daohugou Biota and the related stratigraphy should be correlated with the Tiaojishan Formation (Lanqi Formation in West Liaoning) or its synchronous rocks. It is suggested that the Daohugou Biota and the Jehol Biota would be neither taken into one biota nor considered as the earliest elements of the Jehol Biota. The Daohugou Biota and the related rocks and the Yixian Formation were respectively formed in different periods of volcanic-sedimentary tectonics. [ABSTRACT FROM AUTHOR]

Electron microprobe chemical dating was carried out on monazites enclosed in two generations of mineral paragenesis of St + Ky + Grt and Sil + And + Gil + St, respectively, from the Qinling Group. Two different ages, 520±23 Ma and 435±9 Ma, were obtained from these monazites. This indicates that the Qinling Group experienced a metamorphism during the Early Cambrian, which is probably in response to the Late Pan-African subduction-accretion tectonothermal event. [ABSTRACT FROM AUTHOR]

The Maoling gold deposit, one of the large gold deposits in eastern Liaoning Province, NE China, is an arsenopyrite-disseminated gold deposit with a resource of approximately 25 t Au and an average Au grade of 3.2 Wt. Six arsenopyrites closely related to Au mineralization of the Maoling gold deposit are dated by Re-Os technique and define a Re-Os isochron with an age of 2316±140 Ma, which suggests that the deposit was formed in the Paleoproterozoic era rather than in the Indosinian period as some early researchers suggested. High initial 187Os/188Os ratio of 1.32±0.48 indicates a crustal derivation of the ore-forming material of the deposit, which may be derived from rocks of the Gaixian formation of the Liaohe Group. Furthermore, the result also implies that the age of the Gaixian Formation in the Maoling district is older than 2316±140 Ma. [ABSTRACT FROM AUTHOR]

Geologic and geomorphologic evidence from the Shaluli Mountain indicates that the planation surface that formed in the Late Tertiary disintegrated during the Late Pliocene-Early Quaternary. At the same time, rift basins appeared on some parts of the planation surface, and began to accumulate fluvial-lacustrine sediment. These are interpreted as being the response of this region to Phase-A of the Qingzang Tectonic Movement. After this, the Shaluli Mountain continued to rise in several pulses. Faulting and incision by some large tributaries of the Jinsha and Yalong Rivers resulted in several rift river valleys and the earliest terraces. Generally, the planation surface in this region had been uplifted to about 3500–3700 m a.s.l. no later than 550–600 ka BP, after the Kunlun­Huanghe Tectonic Movement, and coupled with global glacial climate, and resulted in the earliest glaciation recognized so far in the Hengduan Mountains. At the same time, loess was deposited in the Ganzi area of the northern Shaluli Mountain. During the last glacial period, the Shaluli Mountain approached its present altitude and developed several large ice caps, such as the Daocheng Ice Cap and Xinlong Ice Cap, as well as several huge valley glaciers. These paleoglaciers produced some of the most spectacular glacial topography on the Tibetan Plateau. [ABSTRACT FROM AUTHOR]

Six pyrite samples from the giant Bayan Obo REE-Nb-Fe deposit are dated by Re-Os technique. Pyrite studied is associated with barite and separated from a vein cutting REE mineralization. Pyrites analyzed contain 16–30 ng Re and 0.10–0.16 ng Os, and yield a Caledonian isochron age of 439 ± 86 Ma. High Re/Os ratio, low Os concentration and highly radiogenic Os isotopic ratios of these samples suggest that they are of crustal origin. The northern margin of the North China Block was a passive continental margin, but not a subduction zone with enormous volcanic activities in the Early Paleozoic Era. Our Re-Os result provides new evidences, showing that Bayan Obo deposit experienced a thermal disturbance of crustal origin in the Caledonian time and some isotopic systems recorded only the time of the disturbance, not the mineralization age. [ABSTRACT FROM AUTHOR]

Alkali-feldspar syenites from the Maomaogou area of Huili County in Panxi of Sichuan Province, SW China are sodium alkaline rocks, the minerals of which are mainly composed of calcic ferroaugite, ferroamphibole and biotite. Most of the zircons (>80%) selected for SHRIMP U-Pb dating are magmatic compound zircons and they have relict inner cores and growing outer shells. The age of zircon SHRIMP U-Pb dating is 224±8 Ma, suggesting that the Maomaogou alkali-feldspar syenite was formed in the late Triassic period. At the same time, two old age periods of relict cores of zircon are determined, they are the Archean age (2692–2818 Ma) and Neoproterozoic age (622–691 Ma), respectively. These periods indicate that the cores derived from the crystal basement. Furthermore, the Archean age of zircon provides the first reliable SHRIMP U-Pb zircon dating evidence of >2.8 Ga basement in the Xikang-Yunnan Axis of southwest China. [ABSTRACT FROM AUTHOR]

Monazite dating is an important technique in geochronological studies. However, monazite U-Pb dating by SHRIMP is much less popular than zircon in geochronological applications. This paper compares the results of SHRIMP U-Pb dating of monazites and zircons separated from two granite samples, indicating that monazite SHRIMP U-Pb dating at the Beijing SHRIMP Centre is feasible and provides identical results within error. [ABSTRACT FROM AUTHOR]

Various shaped mafic microgranular enclaves (MMEs) together with several mafic massifs are developed within the Yuegelu granitoid pluton in the eastern part of the Eastern Kunlun. On the basis of detailed field geological surveying and of the results of the petrological and geochemical studies it is suggested that there must be some genetic relationship among the granodiorite host, the MMEs and the hornblende (Hb)-gabbro massifs. Magmatic zircon grains are extracted from samples of granodiorite host rock, Hb-gabbro and the MMEs for U-Pb dating. The U-Pb ages are determined by using SHRIMP II technique, which yields the ages of 242±6 Ma, 239±6 Ma and 241±5 Ma, respectively. The overall correspondence in the U-Pb dating results of them excludes the possibility that the MMEs in the granitoids are solid refractory relics from the source region or that they are xenoliths from the wall rocks. It can also rule out the possibility of a later emplacement of basic magma after the solidification of the granitoids. This dating result indicates that they are the products of magma mixing in early-mid Triassic epoch. Among them the granitoid host is chemically akin to the acidic end member during the magma mixing process, the Hb-gabbro is akin to the basic ones while the MMEs are the incompletely mixed basic magma clots trapped in the acidic magma. Combined with the results from other researches on this pluton it is reasonable to consider that in the mid-Triassic the Eastern Kunlun granitoid belt had undergone a process of magma mixing between the mantle-derived basic magma and the crustal acidic magma which indicates that the injection of mantle materials and energy into the crust and the reactions between them played an important role in the formation of the granitoid rocks. [ABSTRACT FROM AUTHOR]

Discusses the Daqingshan thrust system, which is south of the Shiguai Mesozoic basin and is a complex system of top-to-the-north thrusting tectonic sheets. Complicated evolution of the thrust system because of multi-stage thrusting; Dating of the thrusting events via syntectonic muscovite and biotite grains, which are analyzed with normal 40Ar/39Ar dating and laser 40Ar/39Ar dating; Determination that the system is 2 isochron ages, or 193.74 ± 3.88 Ma and 121.6 ± 1.6 Ma; Suggestion that the Daqingshan system faults formed during 2 stages of thrusting; The Indosinian deformation showing top-of-the-north thrusting; The Yanshanian thrusting characterized by top-to-the-NNW thrusting, which is on top of and modifies the earlier Indosinian faults.

Reports on scheelite Sm-Nd and quartz Ar-Ar dating for the Woxi Au-Sb-W deposit in western Hunan. High level of Sm and Nd concentrations of scheelite; Finding that the disseminated scheelites demonstrate a good linear array, which corresponds to an isochron age of 402 ± 6 Ma; Indication that the Ar-Ar age spectra for 2 quartz samples show the saddle shape; Overlap in the minimum apparent age, plateau age and isochron age of each quartz sample; Suggestion that the minimum apparent ages of 420 ± 20 and 414 ± 19 Ma coincide with the scheelite Sm-Nd age; Assertion that the Au-Sb-W mineralization at Woxi district took place in the Late Caledonian period, which agrees with the tectonic evolution of the Xuefengshan district and with geochronological data available for Au, Sb and W deposits in this area; Inference from the low initial Nd isotope ratio of scheelites that the fluid responsible for Au-Sb-W mineralization is of deep crustal origin; Suggestion that it originated from the Archacan continental basement rather than the Proterozoic strata.

Presents an analyzation about the use of the in situ zircon U-Pb dating method of LA-ICPMS. Consideration of the investigation of a 31 Ma old SHRIMP U-Pb age of the Yongsheng nepheline syenite from southern Jilin Province under different spot sizes; Reference to how the obtained ages are comparable with that of SHRIMP in both accuracy and precision; Findings that the age is also identical to that of the Yinmawanshan gabbro from the Liaodong Peninsula within error; Trend for both the Yongsheng nepheline syenite and the Yinmawanshan gabbro to represent the youngest known exposed intrusions in northeastern and even eastern China; Indication from the results that the Eocene mantle-derived magmatic underplating, and the rapid crustal uplifting of this region since 30 Ma; How the analyses also document extremely high LREE concentrations and relatively flat REE patterns for the zircons from the Yongsheng nepheline syenite, which represent a new type of zircon REE pattern.

Presents the in situ analysis of oxygen isotopes carried out by ion microprobe for zircons from localities of HP-UHP metamorphic rocks including eclogites in the Dabie-Sulu terrane. Significance of zircon isotopes in archeological dating; Possibility to trace zircon value with a particular geological time or event for complicated evolution of given rocks; Interest from international geoscientists of the Dabie-Sulu terrain for its coesite and diamond-bearing eclogites.

Reports on the discovery of evidence for crustal evolution in China. Analysis of the sample from the Eastern Nanling Range with neodymium (Nd) isotopic characteristics of post-Archean sediments; Similarity on the Nd age and value of most sediments to those of Paleoproterozoic Mayuan Group; Indication for the recycling of the Paleoproterozoic crustal materials product.

Discusses the Zircon SHRIMP uranium-lead dating for the Cangshuipu volcanic rocks and its implications for the lower boundary age of the Nanhua strata in South China. Occurrence of the continental volcanic rocks and volcaniclastic sedimentary conglomerates of the Cangshuipu Formulation in Yiyang of Hunan Province; Configuration of the strata in the Yiyang region; Representation of the lower boundary with a younger age than previously reported.

Reports on the zircon SHRIMP U-Pb dating of granulite xenoliths in Cenozoic alkali basalt in paleoproterozoic lower crust beneath Nushan in Anhui Province, China. Geochemical similarities between Nushan granulite xenoliths and Archean-Paleoproterozoic granulite terrains in the North China craton; Occurrence of Pb-loss in the Nushan zircons.

Examines the Wulian complex occurring in the northwestern part of the Sulu oxorgen which consists of metaigneous and metasedimentary rocks at greenschist-facies. Zircon U-Pb dating for three granite intrusions which yields concordant ages of (672±4), (742±9) and (747±14) Ma, respectively. Ages which indicate that the granites are the Neoproterozoic intrusions in the northern margin of the Yangtze plate, which correspond to the magmatic complex at Luzhenguan in the eastern part of the Beihualiyang belt in the Dabie orogen. Belief they were tectonic slices scraped off from the Yangtze plate during Triassic subduction and as such belong to a part of the accretionary wedge of the Yangtze plate subduction. Discovery of extensive Neoproterozic magmatic rocks in the Wulian area which suggests that the suture location between the North China and the Yangtze plates lies north of the Wulian complex.

Reports on K-Ar dating of late Mesozoic volcanism in the Dabie orogenic belt. Identification of two eruption episodes; K-Ar dating of the volcanic rocks in the North Huaiyang belt (NHB); The earlier volcanic suite termed Maotanchang Fm. (Fm.) occurring at Jinzhai, Xianhualing and Maotanchang, etc. and erupting from 149 Ma to 138 Ma; The Xiaotian Fm. occurring at Xiaotian, Shucheng, etc. forming between 132 Ma and 116 Ma; The two volcanic suites depositing a volcano-sedimentary conglomerate layer during the eruption gap; Composition of the multi-compositional gravels, which included the North Dabie orthogneiss complex (NDOC), volcanic gravels, etc.; Volcanic gravels in the conglomerate layer showing identical geochemical and isotopic compositions (87Sr/86Sr(t) = 0.7084-0.7092, εNd (t) = -21.8-24.4) to the Maotanchang Fm. volcanic rocks (87Sr/86Sr = 0.7086-0.7102, εNd = -19.2 to -24.4); Distinction from those of Xiaotian Fm. (87Sr/86Sr = 0.7076-0.7084, εNd = -17.2 to -19.2); Indication from K-Ar dating that underlying and overlying volcanic sequences in the conglomerate layers were deposited at ∼135 Ma and the NDOC rapidly exhumed to the surface during or shortly before this time to become the volcano-sedimentary basins in the NHB; Division of the NHB sequence from base to top into Fanghushan Fm., Yuantongshan Fm., Maotanchang Fm. and Xiaotian Fm.

Discusses the idea that manganese oxides in association with paleoweathering can offer insight into the factors affecting the formation and evolution of weathering profiles. Finding from laser probe step-heating analysis of supergene hollandite and cryptomelane samples collected from central Queensland, Australia; Indication the plateaus and consistent isochron ages confirm the feasibility dating of supergene manganese oxides by the 40Ar/39Ar technique; Identification of two distinct structural sites hosting Ar isotopes; Mention of degassing behaviors discovered by incremental heating analyses; Assertion there is no significant Ar gas released at laser power higher than 1.0 W, which suggests the breakdown of tunnel sites hosting the radiogenic and nucleogenic components; Suggestion that some isotopes occupy crystallographic sites; Evidence that 39ArK loss from the tunnel site during neutron irradiation and/or bake-out procedure preceding isotopic analysis does not occur; Assertion that neither the overwhelming atmospheric 40Ar nor the very-fined nature of the supergene manganese oxides will be a problem in extracting significant information from the analysis of supergene manganese oxides minerals.

Presents research on zircon and garnet ages of a mafic granulite from the Variscan belt in the Black Forest of Germany. The isotope closure temperature of garnet Sm-Nd and U-Pb systems; The age of zircon grains found by the U-Pb and evaporation methods; The Sm-Nd and Pb-Pb isochron ages of garnet; Suggestion that many zircons might have lost radiogenic Pb due to metamictization or recrystallisation during the granulite-facies metamorphism at ∼340 Ma; Evidence of pro-grade metamorphism in the garnet Sm-Nd and U-Pb systems; Possibility of a fluid-absence metamorphic environment; Assertion that garnet mineral could be a better candidate than zircon when dating high-grade metamorphism by the U-Pb and Sm-Nd methods.

Focuses on the Louzidian normal fault, the eastern detachment fault of the Kalaqin metamorphic core complex. Finding from field observations and microstructural analyses that the Louzidian-Dachengzi ductile shear zone is related to sinistral strike-slips and extensional faulting; The plateau ages determined with two samples from this ductile shear zone; How the Kalaqin Quasi-metamorphic core complex differs from the Cordilleran metamorphic core complex; Implication of this geochronological data for estimating the formation age and genesis of ductile shear zones.

Presents a study which conducted single-grain zircon uranium-lead and amphibole argon-argon dating on a metamorphosed diorite in the middle Proterozoic Kuhai Group exposed in Qinghai Province, China. Geological background and sampling of the area; Discussion on the results of the study; Conclusions.

Describes the primary results of a study which analyzed growing micas collected from the Altyn Fault in China. Method used to determine the date of the micas; Geology of the research area; Insight on laser probe Ar/ Ar isotopic dating; Discussion on its tectonic implications.

Discusses a possible approach to assess the fine grain OSL dating through comparison of equivalent dose values and ages obtained by IRSL and GLSL of fine grains samples in China. Region in China where the samples were taken; Thermal stability and optical bleaching characteristics; Methodology of the study; Discussion of the results of the study.

Presents the Samarium-Neodymium dating results of 1.95 gallium metamorphism of high-grade Archean rocks in Kongling terrain of the continental nucleus of Yangtze Block in South China. Sample analysis of the Kongling high-grade rocks; Discussion on the elemental geochemistry of the rocks; Insight on the Sm-Nd chronology.

Focuses on a study that analyzed the radiolarian fauna found from the Tieshidas Group in the Qimantag branch of the East Kunlun Mountains, China. Geological age of the radiolarian fauna; Methodology of the study; Results and discussion; Conclusion.

Presents information on a study which described the high-precision thermal ionization mass spectrometry dating of young volcanic rocks of Tengchong in Yunnan Province, China using U-series method. Information on the Tengchong volcanic field; Procedure for U and Th separation and purification.

Presents information on a study which discussed lead-lead (Pb-Pb) dating of garnet by stepwise dissolution technique using the granulite sample from Huangtuling, Dabie Mountain in China. Limitations of uranium-lead and Pb-Pb geochronometer; Advantages of stepwise dissolution technique; Methods of the study; Results and discussion.