The Prydz Bay region of East Antarctica holds critical information regarding the assembly of both Rodinia and Gondwana. This study documents the discovery of high-pressure metapelitic granulites from the Søstrene Island, SW Prydz Bay, which are characterized by a two-stage decompression texture. Integrated petrological analyses, thermobarometric calculations and phase equilibria modeling reveal a clockwise P–T path with peak P–T conditions of 11.5–13.0 kbar and 850–900 °C, followed by two-stage decompression to 4.5–5.5 kbar and 760–820 ℃. Zircon, monazite and rutile U-Pb petrochronology constrains this metamorphic event to ∼1000 Ma, with sedimentary precursors deposited prior to this time. These findings refute the earlier hypothesized existence of a Neoproterozoic basin along the Prydz Bay, and provide robust petrological evidence for the involvement of the Prydz Bay region in the Rayner Orogeny. Coupled with published data, we propose that the ∼1000 Ma high-pressure granulite facies metamorphic event was likely related to the collision between the Indian Craton and Australo-Antarctica during Rodinia assembly. Subsequent transpressional movement facilitated Rayner’s southward drift and collision with Antarctica at 590–500 Ma, forming part of East Gondwana. We speculate that the Gondwana-forming suture lies near the Bunger Hills, extending into the hinterland of Antarctica. This study underscores the dual tectonic imprints of first the ∼1000 Ma Rayner Orogeny associated with the assembly of the supercontinent Rodinia, and then the Gondwana amalgamation that together shaped the crustal architecture of the Prydz Bay region, offers new insights into the spatiotemporal complexity of supercontinent assembly process.

华北吕梁地区出露的以陆源碎屑沉积为主的汉高山群为中元古界底界界线层型的理想候选剖面,其时代的确定对认识华北前寒武纪地质演化历史及初始盖层的确定及Nuna超大陆聚散的研究具有重要的意义.目前,汉高山群的时代、划分对比及其意义还存在较大争议.本研究使用SHRIMP(二次离子质谱仪)对汉高山群安山岩中的锆石进行了 U-Pb同位素分析,获得其207Pb/206Pb年龄加权平均值为1 769±9 Ma(2σ).这是首次直接测得汉高山群锆石U-Pb年龄.另测得同一层位的小两岭组3个不同部位火山岩中的锆石207Pb/206Pb年龄加权平均值分别为1 792±18 Ma、1 773±19 Ma和1 778±20 Ma,与汉高山群的年龄在误差范围内一致,故认为汉高山群和小两岭组的时代分别为1 769±9 Ma和1 792～1 773 Ma.结合前人的研究资料,认为汉高山群和小两岭组的形成时代为1 780 Ma左右.吕梁地区汉高山群的剖面地层连续,发育区域上分布较为稳定的安山岩,是华北克拉通中南部极好的区域等时标志层.该时期的裂谷沉积和火山岩在扬子陆块西部、劳伦大陆西北部、澳大利亚北部、南美巴西圣弗兰西斯科(Sao Francisco)克拉通、非洲刚果克拉通及西伯利亚克拉通均有产出,且可以对比,显示同时期由Nuna超大陆初始裂解引起的陆内裂谷沉积地层的全球分布特征,由此提出国际中元古界底界应该下移,并且汉高山剖面可作为国际上新的中元古界底界的候选层型剖面.

We report new geochronological data of the mafic gneiss and leucogneiss from the Windmill Islands, East Antarctica, in order to unravel the tectonothermal events related to the amalgamation of Rodinia. SHRIMP zircon U-Pb dating from the mafic gneiss (Hbl-Cpx-Opx-Bt-Pl-Qtz-Mag-Zrn) yielded early Mesoproterozoic magmatic ages of 1403±28 Ma from igneous cores, and middle Mesoproterozoic metamorphic ages of 1318±34 Ma from overgrown rims. The leucogneiss (Pl-Kfs-Qtz-Bt-Zrn) in the Bailey Peninsula has intrusive ages of 1257±51 Ma from magmatic origin zircon cores, and metamorphic ages of 1197±26 Ma from overgrown rims and/or structureless grains. The intrusive age of mafic gneiss indicates the existence of a ca.1.40 Ga igneous activity in the Windmill Islands. This is likely the earliest igneous record of the Windmill Islands, possibly relating to the final period of igneous activity of the Mawson Continent. The age of high-grade metamorphism of the mafic gneiss from the Bailey Peninsula can be constrained by the metamorphic zircon overgrowth at 1318±34 Ma, suggesting that the Windmill Islands was possibly involved in the Albany-Fraser-Windmill (East Antarctic) orogeny during the 1375~1151 Ma period. This study further supports the tectonic model in which the Windmill Islands and the Albany-Fraser Orogeny are parallel convergence during the Mesoproterozoic Rodinia amalgamation.

The Rauer Group (Rauer Islands), located in the eastern margin of the Prydz Tectonic Belt in East Antarctica, represents a composite high-grade metamorphic terrane consisting of Archaean and Mesoproterozoic rocks. The Mesoproterozoic rocks contain Fe-Al-rich garnet-sillimanite-bearing Filla Paragneiss associations, and have experienced two phases of metamorphism involving Grenvillian and Pan-African events. The Archaean orthogneisses contain Mg-Al-rich sapphirine-bearing ultrahigh-temperature (UHT) pelitic granulite associations (Mather Paragneiss associations), and they consist mainly of sapphirine-bearing pelitic granulite, Mg-rich garnet-sillimanite-bearing pelitic paragneiss, orthopyroxene-sillimanite quartzite, garnet-bearing mafic granulite and calcsilicate granulite that experienced ultrahigh-temperature metamorphism. In the sapphirine-bearing pelitic granulite, typical post-peak decompression textures around garnet porphyroblasts and sillimanite aggregations (kyanite pseudomorph) developed as symplectite assemblages consisting of sapphirine-orthopyroxene and sapphirine-cordierite respectively. In the garnet-bearing mafic granulite, typical post-peak 'white-eye socket' decompression texture on garnet porphyroblast also developed as symplectite composed of orthopyroxene-plagioclase. Until recently, different researchers derived distinct-type clockwise P-T paths of various peak UHT conditions and pre-peak and post-peak evolution histories, whereas different opinions also exist regarding the timing of UHT metamorphic event and tectonic setting. For example, a UHT metamorphic event was considered to occur either during the Grenvillian period (~1000 Ma) associated with a collisional orogenesis and arc magmatism or during the Pan-African period (~590 Ma or~530 Ma) related to the Prydz orogenesis and the Gondwana continent assembly. Thus, in order to clarify the metamorphic evolution history and tectonic setting of the UHT granulites in the region, further detailed studies on analyses of the mineral assemblages and metamorphic textures and the reconstruction of P-T path as well as high-precesion zircon and monazite U-Pb chronological dating are needed, and regional geological comparison should also be undertaken.

北山造山带东南部梧桐井地区广泛出露一套奥陶纪—志留纪地层, 有关其形成时代和区域地层对比仍存在较大分歧,极大的限制了对区域地质演化的认识.为进一步确定其形成时代,本文对该地区奥陶系—志留系c岩组中的角闪绿帘黑云斜长片麻岩、白云母石英片岩及侵入其中的长英质岩脉进行了LA-ICP-MS锆石U-Pb定年.获得n( 206Pb)/n( 238U)加权平均年龄分别为419. 8±2. 7 Ma、421. 5±0. 8 Ma和417. 0±3. 4 Ma,前两者年龄在误差范围内一致,侵入其中的脉体的年龄限定了该岩组年龄的下限;由此将前人划分的奥陶系—志留系c岩组确切的形成时代确定为约420 Ma,属晚志留世.结合原定为奥陶系—志留系b岩组获得2个锆石U-Pb单峰年龄分别为427 Ma和428 Ma, 属中志留世(Song Dongfang et al. , 2016),由此,将原奥陶纪—志留纪地层确定为志留纪地层,结合前人研究认为可能形成于早古生代古亚洲洋向敦煌地块俯冲相关的弧前盆地.

茹尔群岛(又称赖于尔群岛)位于东南极普里兹构造带的东部边缘,是一个由太古宙和中元古代岩石组成的复合高级变质地体.中元古代岩石是含有富Fe-Al的含石榴子石-矽线石的费拉副片麻岩组合,经历了格林维尔和泛非两期变质作用.太古宙正片麻岩是含有富Mg-Al的含假蓝宝石的超高温泥质麻粒岩组合(梅瑟副片麻岩组合),主要由经历超高温变质作用的含假蓝宝石的泥质麻粒岩、 富Mg的石榴子石-矽线石泥质片麻岩、 斜方辉石-矽线石石英岩、 含石榴子石镁铁质麻粒岩和钙硅酸盐麻粒岩等组成.其中,含假蓝宝石泥质麻粒岩中石榴子石变斑晶和矽线石集合体(蓝晶石假象)周围分别发育峰期后由假蓝宝石+斜方辉石和假蓝宝石+堇青石后成合晶组成的典型减压结构.含石榴子石镁铁质麻粒岩中石榴子石变斑晶周围则发育峰期后由斜方辉石+斜长石后成合晶组成的典型白眼圈减压结构.不同研究者得出了具有不同超高温峰期条件、 峰期前及峰期后演化历史、 不同形式的顺时针变质P-T轨迹.对超高温变质事件发生的时间和构造背景的认识也存在较大分歧,有认为超高温变质事件发生于格林维尔期(～1000 Ma)并与碰撞造山和弧岩浆作用有关,也有研究认为发生于泛非期(～590 Ma或～530 Ma)并与普里兹造山及冈瓦纳大陆聚合有关.因此,为理清该区超高温麻粒岩的变质演化历史和构造背景,需要对其进一步进行详细深入的矿物组合-变质结构分析、P-T轨迹重建及高精度的锆石-独居石U-Pb年代学研究,并进行区域上对比.

Borosilicate minerals, tourmaline, grandidierite and prismatine are present in the high-grade quartzofeldspathic gneisses in the Larsemann Hills, East Antarctica. The borosilicates ( except tourmaline) generally don't crystallize contemporaneously with the common rock-forming silicate minerals. Several generations of tourmaline have been discerned. As to the specific grandidierite and prismatine, rarely can be observed that two or more borosilicate minerals formed at the same time, and the common pattern is the progressive evolution between the borosilicates. In the crystallization of the borosilicates, the activity of SiO2 was constrained while that of the B2O3 and A1(2)O(3) were enhanced, suggesting the component differentiation and fluctuation and the dissynchronization of the complex anions SiO44-, BO33-, and PO43- activity. Thus the effect of volatile components to anatexis may be limited. The media or solution condition of different borosilicate minerals may vary, i. e., tourmaline crystallized in the Ca-rich and slight acid solution, grandidierite in the near neutral to alkalescent, and prismatine in the F-bearing alkaline media. Meanwhile, the crystallizing metal cations may differentiate successively. Besides the pressure and temperature factors, the multi-stages or generations may also be controlled by the volatile components and the media compositions. This was finally responsible for the complexity of the mineral associations in metamorphism. The contents of boron and other volatile components in the high-grade quartzofeldspathic gneisses of the area can be inherited from the protoliths or derived from metamorphism-anatexis process, in which the components could be preferentially absorbed in the melt ( the first enrichment of boron), and again enriched in the residues during cooling and crystallization of the melt ( the second enrichment of boron). The occurrence of the borosilicates demonstrates the existence of the high-grade metamorphism with dehydration partial melting. The volatile components were in open system on the outcrops scale, but nearly closed on the wider system. In anatexis, the existence of the B, F can affect the composition of the melt, decreasing the melting point and viscosity. On the other hand, the volatiles carried in the melt could be exsolved in the cooling and concentrated along the structurally favorable positions.

东南极Windmill群岛变质杂岩经历的变质和岩浆事件与西澳大利亚Albany-Fraser造山带在时间上相对应,并可能与罗迪尼亚超大陆的拼合有关。Windmill群岛Bailey半岛的镁铁质片麻岩（角闪石-单斜辉石-斜方辉石-黑云母-斜长石-石英-磁铁矿-锆石）被认为具有较早的形成年龄,其中还出露属于正片麻岩的淡色片麻岩（斜长石-钾长石-石英-黑云母-锆石）。对这两种片麻岩中的锆石分别进行了SHRIMP U-Pb年龄测定,首次获得该区镁铁质片麻岩锆石核部207Pb/206Pb加权平均年龄1403±28 Ma,该年龄记录了本区中元古代早期岩浆事件,这是Windmill群岛地区记录的最早一期岩浆事件,可能受到了东部莫森大陆（Mawson Continent）构造岩浆活动的影响。铁镁质片麻岩锆石增生边的年龄为1318±34 Ma,则记录了早期构造热事件。淡色片麻岩中锆石核部年龄为1257±51 Ma,与Bailey半岛的片麻状含石榴子石花岗岩侵位年龄一致,共同记录了该区的一期岩浆活动。淡色片麻岩中锆石增生边的年龄为1197±26 Ma,记录了晚期的变质事件。这些新的年龄数据强烈支持1375～1151 Ma期间东南极Windmill群岛与西澳大利亚Albany-Fraser造山带相连接的构造模型,同时也为罗迪尼亚超大陆拼合过程提供了重要的年代学约束。

在全球岩浆活动静寂期,人们在华北克拉通内相继识别出大量～2.3 Ga的地质体,对探讨华北克拉通古元古代地质演化过程具有十分重要的意义.选择中条山地区横岭关二长花岗岩进行了地球化学、锆石U?Pb年代学和Hf同位素研究.横岭关二长花岗岩LA-ICPMS锆石U?Pb年龄结果为2308±12 Ma,代表岩体的形成时代.横岭关二长花岗岩高硅、高钾、高铝、富碱,贫钙、低钠和低钛,A/CNK主要集中在1.0～1.1之间,为高钾钙碱性偏铝-过铝质花岗岩系列.岩石的稀土元素含量相对高,轻重稀土元素分异强烈,并具有明显的Eu负异常.高场强元素Nb、Ta、Zr、Hf、U和大离子亲石元素Rb等相对富集,亏损V、Cr、Co、Ni等相容元素,具有I型花岗岩的特征.横岭关二长花岗岩锆石εHf(t)为0.52～6.24,平均值为2.06,单阶段和两阶段模式年龄分别为2419～2642 Ma和2438～2738 Ma.横岭关二长花岗岩具有同碰撞花岗岩的特征,推测来源于～2.5 Ga古老地壳岩石在挤压碰撞环境下的部分熔融,揭示了华北克拉通在古元古代全球岩浆静寂期并不静寂.

太古宙末期钾质花岗岩的广泛发育是陆壳成熟和稳定化的重要标志,对了解早期陆壳的形成与演化具有重要的意义.发育于华北克拉通南缘中条山地区涑水杂岩中的烟庄正长花岗岩的形成年龄和成因还没有被很好地限定,构造背景还存在争议.对烟庄花岗岩进行了锆石U?Pb年代学和Hf同位素以及全岩地球化学和Nd同位素研究.烟庄花岗岩锆石SHRIMP U?Pb年龄为2515±7 Ma.岩石具有高硅(SiO2=73.05％～74.85％)、高钾(K2O=4.46％～5.86％)、富碱(ALK=8.32％～9.36％)、贫钙(CaO=0.55％～0.98％)、低TFeO*(0.73％～1.28％)和MgO(0.31％～0.52％)的特征,A/CNK=1.01～1.04,为弱过铝质的钾玄系列.稀土总量变化较大(ΣREE=63.80×10-6～250.02×10-6)),轻重稀土元素分异明显((La/Yb)N=25.44～92.87),Eu异常变化较大(Eu/Eu*=0.47～0.79).岩石低Sr、Ba,富集Rb、Th、U等元素,亏损Nb、Zr、Y、Yb、Cr、Co、Ni等元素,具有较高的Rb/Sr、Rb/Ba和Sr/Yb比值以及较低Sm/Nd和Nd/Th比值,具有高分异I型花岗岩的特征.烟庄花岗岩具有0附近的全岩εNd(t)值,岩浆锆石具有正的εHf(t)值(2.85～3.66),两阶段Hf模式年龄为2258～2883 Ma,多数在2600～2883 Ma之间.结合其他方面研究,烟庄花岗岩具有同碰撞和后碰撞花岗岩的特征,推测为新生地壳在由挤压向伸展转换的构造背景下部分熔融所形成,可能有少量地幔物质添加.这期钾质花岗岩的形成,标志着华北克拉通太古宙末期强烈岩浆活动的结束以及稳定陆壳的形成.

The Pan-African event is widely distributed in East Antarctica craton. Many terranes or outcrops of the craton bear more or less signs of the event. From characteristics of the shear zones, granites, pegmatites, feature and time of high grade metamorphism and detrital zircon ages peaks of the downflowing sediments from the plateau, the Pan-African event in the East Antarctica and adjacent areas in the Gondwana reconstruction, like SE Africa, southern India and SW Australia, wasdistributed as special zones or areas in many localities, including both the coastal regions and interior of the East Antarctica. In geochemistry, the granites are generally anorogenic, ocassionally with some gabbros or dolerite dykes, showing sign of bi-modal feature. The water or fluid available along the shear zones were responsible for retrogression of the earlier, e.g., Grenville age, high grade outcrops to later Pan-African amphibolite facies metamorphism. Meanwhile, the Pan-African event has influenced most isotopic systems, including the U-Pb, Sm-Nd, Rb-Sr and Ar-Ar systems, giving younger apparent ages. Manifestation of the Pan-African event is distributed from possibly locally granitic magmatism, to wider medium-high grade metamorphism, and mostly widespread in resetting for some isotope systems, suggesting the prevailing thermal effect.Before Gondwana formation, local depressions in the East Antarctica could be filled with sediments, implying the initial breakup period of the Rodinia. The later Pan-Gondwana counterrotating cogs shaped the interstitial fold belts between continent blocks and formed a set of shear zones. The mafic underplating in the Gondwana may be responsible for the widespread granites, pegmatites and more or less isotopic resetting due to strong thermal effect from the deep. That is, the Pan-African event is a possible response of the plate movement surrounding the continent swarms in the non-stable interior of theyet consolidated Gondwana. The Pan-African event may be an overwhelmingly extensional and transcurrent tectonics in mechanism.

To better constrain the evolution of the early Palaeozoic orogenesis along the northern margin of Gondwana, we present new petrological, geochronological, and geochemical studies of the Cambrian–Ordovician granitic gneiss in the Dinggye area, central Himalaya. The granitic gneiss is medium‐coarse grained, with porphyritic, augen, banded, or gneissic structure, and has undergone strong deformation. The mineral assemblages are quartz, plagioclase, K‐feldspar, muscovite, and biotite, with minor amounts of accessory minerals. The granitic gneiss samples are characterized by high SiO2, Al2O3, and Rb/Sr contents but low MgO, TiO2, FeOt, and MnO contents, with A/CNK of 1.08–1.38. The REE patterns of the granitic gneiss show high LREE/HREE and negative Eu anomalies. In the trace‐element chondrite‐normalized diagram, the samples show enrichment in LILE (e.g., Rb, Th, U, and K) and depletion in some HFSEs (Nb and Ti). These features indicate that the protolith was a calc‐alkaline and peraluminous S‐type granite. Six analysed samples yielded zircon U–Pb crystallization ages between 480 and 500 Ma, which support the existence of the early Palaeozoic magmatism in the Dinggye area, central Himalaya. High δ18O values (7–10‰, >> a mantle value of 5.3 ± 0.6‰) of magmatic zircon domains and abundant inherited zircons with variable ages (558‐2523 Ma) indicate that the magma was derived from a supracrustal source. Combined with whole‐rock Sr–Nd data (average εNd(t) = −8.1) published previously, we suggest that the granitic gneiss originated from partial melting of old crust, most likely to be the sedimentary rocks of the Himalayan Crystalline Complex. The early Palaeozoic granitic gneiss with a continental arc affinity may have formed in an Andean‐type orogeny involving subduction of the Proto‐Tethyan Oceanic crust beneath the northern margin of the Gondwana supercontinent.

Numerous early Mesozoic magmatic rocks within the Tibetan Plateau ultimately have a geodynamic controll caused by the Paleo-Tethyan tectonic evolution and the assembly of Pangea. Based on their temporal variation and the timing of closure (235 +/- 10 Ma) of the Paleo-Tethys Ocean, they can be broadly divided into two groups by zircon U-Pb geochronology: an Early to Middle Triassic (252-235 Ma) group and a Late Triassic to Early Jurassic (ca. 235-190 Ma) group. Early magmatic rocks are mainly found in the middle northern Tibetan Plateau, whereas late magmatic rocks are more widespread in the whole Tibetan Plateau. Nd and Hf isotope mapping suggests that the eastern segment of the Qiangtang is underlain by old (late Archean to early Paleoproterozoic) basement, while Southern Lhasa is underlain by juvenile lower crust, which yields Neoproterozoic to early Paleozoic model ages. Early Mesozoic tectonomagmatism was likely caused by episodic southward opening of multi-Tethys oceans, punctuated by episodes of subduction and collision. The Middle to Late Permian tectonomagmatic history of Paleo-Tethys was dominated by continental arc-related systems. During the Early to Middle Triassic, the tectonomagmatic history was associated with the ongoing closure of the Paleo-Tethys Ocean and a tectonic transition from subduction to collision. Late Triassic tectonomagmatism formed in a post-collisional setting following the closure of the Paleo-Tethys Ocean and the ultimate assembly of Pangea. Early Mesozoic magmatism within the Tibetan Plateau thus provides crucial information on the history of oceanic-continental evolution and helps constrain the tectonic transition from subduction/accretion through to collision/postcollision for East Paleo-Tethys. Plain Language Summary The Tibetan Plateau was amalgamated by the successive northward drift of continental crustal fragments away from Gondwanaland and their subsequent collision with the southern margin of Asia during the Mesozoic to Cenozoic. However, our knowledge of the tectonic history of the Paleo-Tethys Ocean and continental amalgamation in the Tibetan Plateau prior to its demise during the early Mesozoic still remains poorly understood. Therefore, understanding the tectonomagmatic history and geodynamic evolution of the Paleo-Tethys Ocean and the ultimate assembly of Pangea in the early Mesozoic, and the subsequent opening and subduction history of the Meso/Neo-Tethys Ocean, is key to deciphering the evolution of Eurasia and Tethys, particularly for understanding the paleogeography and accretion-collision history that preconditioned the Tibetan lithosphere for subsequent collisional/postcollisional events and surface uplift. In our interpretations, Early Mesozoic tectonomagmatism requires episodic southward opening of multi-Tethys oceans, punctuated by episodes of subduction and collision with two-stages of magmatic evolution and crustal growth.

The Zanhuang Complex is located in central section of the Trans-North China Orogen (TNCO) in the North China Craton (NCC) with complicated tectonic history. The formation timing (Neoarchean or Paleoproterozoic) of the Guandu Group or Central Zanhuang Domain (CZD) is still under debate, while this question is critical for understanding the tectonic evolution of the Zanhuang Complex and the TNCO. The mafic rocks in the Guandu Group (or CZD) can be subdivided into three different types by petrological, geochronological, structural and petrogenetic differences. Type 1 consists of "pillow" epidosites and amphibolites, located at the west part of the Guandu Group; type 2 dominated by amphibolites and interbedding with various sedimentary rocks, located at the east part; and type 3 consists of mafic dikes beyond the scope of this paper. Type 1 mafic rock yielded zircon U-Pb age of 2501 +/- 12 Ma which constrains it formed at Neoarchean with older Nd Tom ages (2.8-3.0 Ga). Interbedded sedimentary rocks with younger than 2.1 Ga detrital zircon ages, and the much younger Nd T-DM model ages (2.2-2.3 Ga) of the amphibolites from type 2, together suggest that the type 2 mafic rocks and associated sedimentary rocks may have formed at Paleoproterozoic. Thus, we propose that the so-called Guandu Group is not a single and unitary tectonic-lithological unit but consists of at least two different volcanic-sedimentary successions formed at different times and pieced together by later tectonic event (s). A new two-period tectonic events model is proposed here. Before 2.5 Ga, the western margin of the Eastern Block deposited a series of volcanic-sedimentary rocks (type 1). At similar to 2.5 Ga, the Fuping arc (including the Western Zanhuang Domain) amalgamated with the Eastern Block by arc-continent collision. After a quiescent period, it underwent similar to 2.1 Ga extension and rifting. Later, the rift evolved into a small ocean basin with the deposition of volcanic-sedimentary sequences (type 2), then closed through west-dipping subduction and collision at 1.9-1.85 Ga, resulting in the final amalgamation of the NCC and the widespread deformation and metamorphism in the Zanhuang Complex as well as the whole TNCO.

The late Archaean witnessed a critical transition of the composition of the continental crust from predominantly sodic tonalite‐trondhjemite‐granodiorites (TTGs) to a combination of TTGs and increasing proportion of potassic calc‐alkaline granitoids. This shift is also well recorded in the Zanhuang Complex located in the central part of the North China Craton (NCC). In this work, we present a detailed geochemical study of these granitoids and subdivide them into four groups, that is, TTGs, sanukitoids, crustal‐sourced granitoids, and hybrid granitoids. The TTGs in the Zanhuang Complex may have formed at a longer and earlier period during ~2.7 to ~2.5 Ga as the first stage. They show typical TTG characteristics, such as high SiO2, Na2O, and Sr/Y and depletion of Nb, Ta, Ti, and HREE. The TTGs are interpreted to have formed in a subduction‐related environment. The other three groups of granitoids formed at a shorter and later stage. The sanukitoid sample shows high MgO and Mg# and other geochemical signatures of typical Archaean sanukitoid affinity, yielding a weighted mean zircon 207Pb/206Pb age of 2,517 ± 5 Ma as the crystallization age. The sanukitoid magma derived from partial melting of a hydrous mantle peridotite source metasomatized by slab‐derived melts or fluids. The crustal‐sourced granitoids, including a new sample (~2,510 Ma) in this work, the Jiandeng granite (~2,490 Ma), and the Huangcha/Wangjiazhuang granite (2,488 to 2,517 Ma) show signatures of a mainly crustal source such as high SiO2 and K2O, low MgO and Mg# values, and weakly peraluminous. The hybrid granitoids represented by the Haozhuang granitoid (2,511 to 2,528 Ma) are characterized by enrichment in both incompatible (LILE and LREE) and compatible (Mg, Ni, and Cr) elements and may have formed by mixing/contamination of multiple magmas or sources. The temporal and spatial distributions of these groups of granitoids indicate that the Zanhuang Complex experienced a subduction–collision event between the Fuping arc and the Eastern Block of the NCC at the end of Archaean.

新太古代—古元古代表壳岩系在华北克拉通广泛发育,在赞皇地区也出露有较典型的中低级变质的火山-沉积岩系,即从原赞皇群解体出来的官都群,其形成时代和成因目前仍有争议.官都群的主要岩石组合为变基性火山岩(包括角闪片岩和斜长角闪岩)、大理岩、石英片岩,以及一系列长英质副片麻岩等.对其中的长英质副片麻岩进行碎屑锆石定年研究,并结合前人已报道的碎屑锆石数据可知,碎屑锆石年龄主要峰值约为2.5Ga,部分样品出现2.0～2.2Ga的峰值.变质锆石记录主要有2个范围,分别为2.48Ga左右和1.85～1.9Ga,可能代表了2期不同的构造热事件记录.结合该地区近年来的研究,可以得到如下认识:①样品中存在形态完好的长柱状锆石,表明是近源沉积;②约2.48Ga的变质记录与核部岩浆锆石的年龄(约2.5Ga)非常接近,可能代表了物源区中酸性岩体侵位后遭受的一次构造热事件,而不代表沉积岩形成后遭受变质的记录,即沉积过程晚于2.48Ga;③官都群至少有一部分岩石组合形成于古元古代;④官都群可能是不同时代、不同岩性单元拼贴而成,需要进一步解体.

The Qinling Complex from the Qinling orogenic belt was generally considered to be part of the Caledonian orogeny, however information of the Grenville event of the Qinling Complex has been poorly recognized. Two granite samples of greenschist-facies and two paragneiss samples of amphibolite-faices are identified from the Qinling Complex. The granites occur along the regional gneissosity of the Qinling Complex, thus it is suggested that their magmatic zircon ages (≈970 Ma) mark the lower boundary of the main metamorphic age (amphibolite-granulite facies). In addition, some early-formed metamorphic zircons (≈1 000 Ma) are distinguished in the granites, which may reflect the information about the source area of the granites. Therefore the major metamorphism of amphibolite-granulite facies in the Qinling Complex is constrained at Early Neoproterozoic (≈1 000 Ma), not Early Paleozoic as conventionally considered. In the Early Paleozoic, the Qinling Complex was characterized by multiple extension- shear activities, overprint of greenschist-facies metamorphism and emplacement of extensive granites. These granites and related thermal events could reset the U-Pb isotopic system of the early-formed zircons, leading to the apparent zircon ages younger than their protolith age. As a result, the Qinling Complex is a modified Early Neoproterozoic orognenic belt or an independent block, which became a continental margin arc during the Early Paleozoic, being accompanied by metamorphism, deformation, and emplacement of continental arc granites. The Erlangping, Kuanping, and Taowan groups to the north of the Qinling Complex show more intensive deformation of the Caledonian, and their oblique subduction towards the Qinling Complex caused the formation of eclogites. Afterwards, the Qinling Complex was amalgamated with the Erlangping, Kuanping, and Taowan groups, which all experienced the same Caledonian orogeny, and possible later orogenies.

This paper has discussed the classical Barrovian metamorphism in the Grampian Orogeny, Scotland and focused on the recent progress on its driving mechanism. It is stressed that the Barrovian metamorphism occurred only during the transient, discrete period (similar to 8 Myr) of the whole orogeny evolutionary history (similar to 27 Myr). With temporal and spatial association with Grampian bimodal magmatism, the Barrovian metamorphic series is formed within the middle crust as the result of advection of heat from the lower crust and/or mantle. Thus, the conventional orogenic regional metamorphism as demonstrated by the classical Barrovian metamorphic series, was not produced through crustal thickening or thermal relaxation, instead, the typical metamorphism probably record large-scale contact metamorphism in the depth. Taking the Barrovian type as a reference, the metamorphism feature of the Qinling Complex of the Central Orogenic Belt of China is rather an analogue of the Barrovian metamorphism, during which the metamorphism P-T-t path in association with sillimanite and kyanite is possibly isobaric cooling or count clockwise, not isothermal decompression (clockwise) as generally thought. Up to now, the metamorphism time of the complex is ambiguous and more researches are needed. Through summary of some terranes with Barrovian features, we can deduce that metamorphism, migmatization and granitization involved possibly resulted from the same dynamic system and the granite is not the impetus for metamorphism. The basic magmatism is even not essential for Barrovian metamorphism which can not be taken as the symbol for collision orogeny. An alternative scenario is that the Barrovian series occurred under normal crustal thickness in which thermal gradient and some granite formed in anomalous heat flow during local deformation, such as pop-up structure.

金沙江缝合带是特提斯东段重要的缝合带之一,羊拉地区的金沙江缝合带处在青藏高原东构造结东侧,是研究金沙江古洋盆的碰撞闭合过程等构造事件的重要窗口。在前人工作的基础上,通过野外系统观察取样,结合花岗岩侵入体的锆石SHRIMP U-Pb年龄测定结果,对金沙江古洋盆的碰撞闭合过程做初步研究。结果表明,从南部加仁岩体的通吉格花岗闪长岩（加仁岩体之一部分）,经中部的路农—里农—江边岩体的花岗闪长岩,到北部的贝吾花岗闪长岩,岩体的侵位年龄分别为通吉格（246.1±3.5）Ma、路农花岗闪长岩（238.1±5.3）Ma、里农花岗闪长岩（239.0±5.7）Ma、江边岗闪长岩（227.9±5.1）Ma和贝吾花岗闪长岩（213.6±6.9）Ma,表明金沙江缝合带的碰撞关闭是从南向北逐渐闭合的,闭合的时限可达33 Ma,但闭合碰撞不是连续而是幕式的,碰撞闭合作用主要发生在约246 Ma、239 Ma、228 Ma、213 Ma 4个幕次。里农大沟还出现222 Ma的辉绿岩脉,与江边岩体时间上较为接近,似乎表明江边岩体侵入时期本区处于局部拉张的构造背景。