Isotopic constraints on crustal architecture and Permo‐Triassic tectonics in New Guinea: Possible links with eastern Australia

New U–Pb zircon ages and Sr–Nd isotopic data for Triassic igneous and metamorphic rocks from northern New Guinea help constrain models of the evolution of Australia's northern and eastern margin. These data provide further evidence for an Early to Late Triassic volcanic arc in northern New Guinea, interpreted to have been part of a continuous magmatic belt along the Gondwana margin, through South America, Antarctica, New Zealand, the New England Fold Belt, New Guinea and into southeast Asia. The Early to Late Triassic volcanic arc in northern New Guinea intrudes high‐grade metamorphic rocks probably resulting from Late Permian to Early Triassic (ca 260–240 Ma) orogenesis, as recorded in the New England Fold Belt. Late Triassic magmatism in New Guinea (ca 220 Ma) is related to coeval extension and rifting as a precursor to Jurassic breakup of the Gondwana margin. In general, mantle‐like Sr–Nd isotopic compositions of mafic Palaeozoic to Tertiary granitoids appear to rule out the presence of a North Australian‐type Proterozoic basement under the New Guinea Mobile Belt. Parts of northern New Guinea may have a continental or transitional basement whereas adjacent areas are underlain by oceanic crust. It is proposed that the post‐breakup margin comprised promontories of extended Proterozoic‐Palaeozoic continental crust separated by embayments of oceanic crust, analogous to Australia's North West Shelf. Inferred movement to the south of an accretionary prism through the Triassic is consistent with subduction to the south‐southwest beneath northeast Australia generating arc‐related magmatism in New Guinea and the New England Fold Belt.     

东南亚新生代两类埃达克岩的分布、成因和含矿性

东南亚的巽他群岛-巴布亚新几内亚是新生代埃达克岩和类埃达克岩发育的地区。这些中酸性岩浆岩广泛见于印度尼西亚几内亚岛、苏拉威西和巴布亚新几内亚, 零星见于苏门答腊、班达岛弧、西爪哇和中加里曼丹等地。本区埃达克岩和类埃达克岩岩石类型分别属于岛弧拉斑钙碱性系列和高钾钙碱性系列, 以重稀土元素Y, Yb含量低(分别为Y ≤19 ×10-6和Yb ≤1.8 ×10-6)和高Sr值(＞355 × 10-6)为特征。微量元素蛛网图上有明显的Ba、K、Sr正异常峰和负的Th、Nb (Ta)异常谷。大离子亲石元素(LILE)和高场强元素(HFSE)相对富集。本区埃达克岩和类埃达克岩的构造位置为新生代缝合线附近的大洋岛弧和陆缘造山带, 可划分为两种成因类型:第一种为岛弧拉斑/钙碱性系列, 其REE配分模式属于大洋岛弧型, 见于现代大洋岛弧, 称为岛弧型(O-型)埃达克岩; 另一种为高钾钙碱性系列, 其REE配分模式属于大陆型, 产于大陆板块边缘造山带, 与弧-陆碰撞和后碰撞构造环境有成因联系, 见于大陆边缘, 称为大陆型(C-型)埃达克岩。 研究结果表明:大陆型(C-型)埃达克岩和类埃达克岩分布区域与世界级斑岩铜-金矿分布相一致, 而大洋岛弧型(O-型)主要与浅成热泉金矿和喷气型有成因联系。      

Volcanic tsunami: a review of source mechanisms, past events and hazards in Southeast Asia (Indonesia, Philippines, Papua New Guinea)

Southeast Asia has had both volcanic tsunamis and possesses some of the most densely populated, economically important and rapidly developing coastlines in the world. This contribution provides a review of volcanic tsunami hazard in Southeast Asia. Source mechanisms of tsunami related to eruptive and gravitational processes are presented, together with a history of past events in the region. A review of available data shows that many volcanoes are potentially tsunamigenic and present often neglected hazard to the rapidly developing coasts of the region. We highlight crucial volcanic provinces in Indonesia, the Philippines and Papua New Guinea and propose strategies for facing future events.     

巴布亚新几内亚铜金矿床大地构造背景、成因类型与成矿特征

巴布亚新几内亚地质构造格架复杂,包括地台、碰撞造山带、外来地体、俯冲带、岛弧和海底扩张中心。巴布亚新几内亚铜金矿床类型主要为斑岩型铜金矿床、浅成低温热液型金银矿床和夕卡岩型铜金矿床（三者之间具有密切的时间、空间和成因关系）,其次为海底块状硫化物矿床。铜金矿床分布比较集中,主要产出于碰撞造山带和岛弧上,其次产出于现代海底扩张中心。铜金矿床大多规模巨大或较大,埋藏较浅,易于勘探和适合露天开采。与铜金矿床有关的岩浆岩大多为钙碱性火山岩和浅成侵入岩,少数与富钾碱性火山岩（橄榄玄粗岩）或侵入岩伴生。铜金矿床蚀变带发育且分带性明显,大多与斑岩体系和／或火山机构有关。虽然许多铜金矿床的矿物成分比较复杂,但是其矿石较易处理和利用。     

Reference lines,fault classification,transform systems,and ocean-floor spreading: Discussion

Wellman (1971) has presented erroneous data relating to lineaments in Papua New Guinea. The main faults and folds in Papua New Guinea as determined by ground and remote-sensing surveys by the Bureau of Mineral Resources, the Geological Survey of Papua New Guinea and by oil exploration companies are shown on the new B.M.R.-G.S.P.N.G. 1:1,000,000 Geological Map of Papua New Guinea.     

两类埃达克岩的含矿性和成因:东南亚地区与东太平洋带对比

新生代埃达克岩是一种新型的火成岩(Sr/Y≥20),多产出于大洋岛弧、大陆边缘造山带(东南亚地区)和陆缘火山弧环境(东太平洋带),依据REE配分模式可将其划分为2种成因类型:大洋型(O型)和大陆型(C型)。埃达克岩分别广泛分布于东南亚地区的菲律宾群岛、苏拉威西、中加里曼丹、印度尼西亚几内亚岛、巴布亚新几内亚至所罗门群岛一带,及东太平洋带的北美洲、墨西哥、中美洲、南美洲的北部至南部。研究表明:不同成因类型的埃达克岩具有不同的含矿性,反映各自岩浆源区不同。C型埃达克岩(La/Yb12)是俯冲海洋板块部分熔融叠加增厚的地壳底部部分熔融MASH(熔融-混染-储存-均一化)和AFC(混染-分异-结晶)作用的产物,多半与世界级斑岩铜金矿床共生;O型埃达克岩(La/Yb≤12)则与平缓俯冲的海洋板片部分熔融作用有关,在东南亚地区主要与浅成热泉金矿有成因联系。     

Terpenoid composition and origin of amber from the Cape York Peninsula,Australia

The terpenoid composition of fossil resin from the Cape York Peninsula, Australia has been analysed by pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS) to determine its origin. The pyrolysis products were dominated by cadalene-based C₁₅ bicyclic sesquiterpenoids including some C₃₀–C₃₁ bicadinanes and bicadinenes typical of Class II resin derived from angiosperm plants of Dipterocarpaceae. This observation contrasts with the Araucariaceae (Agathis sp.) source previously suggested for the resin based on Fourier transform infrared (FTIR) analyses. Dipterocarpaceae are not known in Australian vegetation but grow abundantly in Southeast Asia including New Guinea, indicating that the geological origin of the amber is not the Australian mainland but could be traced to Southeast Asia.     

Impact of India–Asia collision on SE Asia: The record in Borneo

Borneo occupies a central position in the Sundaland promontory of SE Asia. It has a complex Cenozoic geological history of sedimentation and deformation which began at about the same time that India is commonly suggested to have started to collide with Asia. Some tectonic reconstructions of east and SE Asia interpret a large SE Asian block with Borneo at its centre which has been rotated clockwise and displaced southwards along major strike–slip faults during the Cenozoic due to the indentation of Asia by India. However, the geological history of Borneo is not consistent with the island simply forming part of a large block extruded from Asia. The large clockwise rotations and displacements predicted by the indentor model for Borneo are incompatible with palaeomagnetic evidence and there is no evidence that the major strike–slip faults of the Asian mainland reach Borneo. Seismic tomography shows there is a deep high velocity anomaly in the lower mantle beneath SE Asia interpreted as subducted lithosphere but it can be explained just as well by alternative tectonic models as by the indentor model. Very great thicknesses of Cenozoic sediments are present in Borneo and circum-Borneo basins, and large amounts of sediment were transported to the Crocker turbidite fan of north Borneo from the Eocene to the Early Miocene, but all evidence indicates that these sediments were derived from local sources and not from distant sources in Asia elevated by India–Asia collision. The Cenozoic geological history of Borneo records subduction of the proto-South China Sea and Miocene collision after this ocean lithosphere was eliminated, and a variety of effects resulting from long-term subduction beneath SE Asia. There is little to indicate that India–Asia collision has influenced the Cenozoic geological record in Borneo.     

Distribution patterns of Oriental Cicadoidea (Homoptera) East of Wallace's Line and Plate Tectonics

The Cicadoidea fauna of Wallacea, New Guinea and Melanesia is in great majority of Oriental origin, but shows high endemism at the generic and specific levels. In general the patterns of distribution of cicadas in this eastern archipelagic part of the Oriental region quite closely reflect the changing positions of land in past ages, perhaps more distinctly than in many other groups of insects because cicadas are less dispersive. Aspects of the immigration of an Oriental group of cicadas eastwards of Wallace's Line into the Papuan and Melanesian areas are analyzed in a taxonomic and biogeographic study of the subtribe Cosmopsaltriaria. The phylogenetic reconstruction of this subtribe reveals certain patterns of vicariance between sister-groups. The two genera Dilobopyga (13 species and subspecies) and Brachylobopyga (1) from Sulawesi and the Moluccas vicariate with a sister-group comprising all other genera of the subtribe from the Papuan and Melanesian subregions. In the latter group Diceropyga (27) and Aceropyga (13) form a monophyletic entity, which is essentially distributed over northern New Guinea and the island chain from the Bismarck Archipelago to the Tonga Is. The sister-group of these two genera is Cosmopsaltria (22), which focusses in central New Guinea, without speciation in the island chain east of New Guinea. In Cosmopsaltria, the mimica complex (16), which is basically distributed in the central mountain ranges of New Guinea, vicariates with its sister-group, the gracilis group (3) in North and SE New Guinea. Comparison of a combined taxon-area cladogram of the Cosmopsaltriaria with the palaeogeography of the area involved reveals that the distribution patterns found can be explained by dichotomic dispersal of ancestral species along the Tertiary island arcs of Sulawesi and the Inner and Outer Melanesian Arcs. Dilobopyga and Brachylobopyga developed in the Sulawesi arcs. Diceropyga, Aceropyga and the Cosmopsaltria gracilis group evolved primarily in the Outer Melanesian Arc, probably since the Miocene. The Cosmopsaltria mimica complex is an Inner Melanesian Arc group, which developed after ancestral invasion from the outer arc probably in the Late Miocene or Pliocene when the inner arc approached the outer arc. The term vicariant dispersal is introduced here for the dispersal of sister-groups along dichotomic routes resulting in vicariant patterns.     

香港近海第四纪研究──(香港)地区与全球对比表

通过对ＷＢ７钻孔的研究及过去资料的分析，香港近海第四纪地层层序至少可以识别出１０个海相与陆相交替的沉积序列。ＷＢ７钻孔位于香港西薄寮海峡，对该钻孔进行了连续取样。本文列出了两张地区性与全球沉积序列对比表，最早的海相沉积和陆相沉积年龄分别早于倒数第４次间冰期和倒数第５次冰期，地层对比表中把香港的第四纪地层与磁性地层、氧同位素地层、超微体化石组合及澳大利亚南部滨岸沙丘序列，新几内亚Ｈｕｏｎ半岛和印度尼西亚Ｓｕｍｂａ半岛的海岸阶地，美国大西洋海岸平原氧同位素序列，中国黄土阶段及海侵，东南亚的海岸和近海沉积进行了初步的对比。     

Seismotectonics of the Papua New Guinea—Solomon Islands region

Earthquakes for the period 1964–1973 are relocated by the method of Joint Hypocenter Determination in order better to resolve the configuration and the structure of the New Guinea—New Britain—Solomon Islands region. Focal mechanism solutions are integrated with the seismicity and interpreted closely with it. A zone of subduction exists beneath New Britain and the Solomon Islands, a zone of left-lateral strike-slip movement extends from New Ireland to New Guinea. The zone of seismicity in northern New Guinea has developed as a result of a continent—island-arc collision in late Oligocene—Miocene times and does not exhibit a well-developed inclined seismic zone. It is proposed that plate tectonics theory does not apply rigorously, but slip-line field theory allows the presentation of a new geodynamic model for this region.     

The disrupted ophiolitic belt of the southwest Pacific: Evidence of an Eocene subduction zone

The Papua-New Guinea, Solomon, New Hebrides and New Caledonia ophiolitic massifs come from an Eocene intra-oceanic subduction occurring in the southwest Pacific. This hypothesis is suggested by the age of the ophiolite-related metamorphic soles which would be the result of a metamorphism arising at the expense of volcanic and sedimentary series of oceanic supracrustal origin when involved in a subduction zone. When this subduction also involves a continental crust portion, amphibolites and blue schists are formed, as observed in Papua-New Guinea and New Caledonia. When the subduction occurs in an intra-oceanic environment, as in the Solomon islands and New Hebrides, only amphibolites and green schists are to be found.The ophiolitic belt (basic-ultrabasic massifs and their related metamorphic soles) created by the Eocene subduction has been disrupted by later transcurrent faults, more recent spreading phenomena and two other subductions (Oligocene-Miocene and Recent).     

The history of Cenozoic magmatism and collision in NW New Guinea – New insights into the tectonic evolution of the northernmost margin of the Australian Plate

Evidence of Cenozoic magmatism is found along the length of New Guinea. However, the petrogenetic and tectonic setting for this magmatism is poorly understood. This study presents new field, petrographic, U–Pb zircon, and geochemical data from NW New Guinea. These data have been used to identify six units of Cenozoic igneous rocks which record episodes of magmatism during the Oligocene, Miocene, and Pliocene. These episodes occurred in response to the ongoing interaction between the Australian and Philippine Sea plates. During the Eocene, the Australian Plate began to obliquely subduct beneath the Philippine Sea Plate forming the Philippine–Caroline Arc. Magmatism in this arc is recorded in the Dore, Mandi, and Arfak volcanics of NW New Guinea where calc-alkaline and tholeiitic rocks formed within subduction-related fore-arc and extension-related back-arc settings from 32 to 27 Ma. Collision along this plate boundary in the Oligocene–Miocene jammed the subduction zone and caused a reversal in subduction polarity from north-dipping to south-dipping. Following this, subduction of the Philippine Sea Plate beneath the Australian Plate produced magmatism throughout western New Guinea. In NW New Guinea this is recorded by the middle Miocene (18–12 Ma) Moon Volcanics, which include an early period of high-K to shoshonitic igneous activity. These earlier magmatic rocks are associated with the subduction zone polarity reversal and an initially steeply dipping slab. The magmatic products later changed to more calc-alkaline compositions and were emplaced as volcanic rocks in the fore-arc section of a primitive continental arc. Finally, following terminal arc–continent collision in the late Miocene–Pliocene, mantle derived magmas (including the Berangan Andesite) migrated up large strike-slip faults becoming crustally contaminated prior to their eruption during the Plio–Pleistocene. This study of the Cenozoic magmatic history of NW New Guinea provides new data and insights into the tectonic evolution of the northern margin of the Australian Plate.     

Hyperaccumulation of nickel by some plants of Southeast Asia

A herbarium collection of plants from Obi Island (North Moluccas) was analyzed for nickel and other elements in order to identify new hyperaccumulators (> 1000 μg/g dry weight) which are indicative of ultrabasic substrates. Ultrabasic substrates are usually hosts for important economic minerals. Planchonella oxyedra Dubard and Trichospermum kjellbergii Burret were found to be hyperaccumulators of nickel and the work was therefore followed up by analysis of further specimens of these two species from localities throughout their range in Southeast Asia and Oceania. The data pinpointed previously known ultrabasic areas in Sulawesi (Celebes) and West Irian (Indonesian New Guinea) as well as one in Ambon (South Moluccas) which is not recorded on geological maps.     

大洋洲地区境外地质工作的现状与思考

在对大洋洲优势矿产资源的成矿地质背景、成矿区带划分、矿床类型和资源潜力进行初步研究的基础上,对澳大利亚及巴布亚新几内亚等国的投资环境和中国地勘矿业“走出去”工作现状等进行分析,认为澳大利亚和巴布亚新几内亚两国的铁、锰、铜、铝、镍,以及具有战略意义的金、铀、稀土等矿产的资源储量潜力巨大,与中国形成良好的矿产资源互补性,是中国企业“走出去”进行矿业开发的理想对象,并结合自身经验提出长期和短期“走出去”的相关建议。     

River profiles along the Himalayan arc as indicators of active tectonics

Longitudinal profiles along sixteen major transverse Himalayan rivers add important constraints to models of active continental subduction and its evolution. These profiles are characterized by a zone of relatively high gradient that cannot be associated with differential resistence to erosion in all cases. The base of the zone of increased gradients correlates with (1) the topographic front between the Lesser and High Himalayas, (2) the narrow belt of intermediate-magnitude thrust earthquakes, (3) the Main Central Thrust zone (MCT). These features define a small circle in the central portion of the Himalayan arc. These correlations suggest that the discontinuity in the river profiles and the other features are controlled by a major tectonic boundary between the rising High Himalayas and the Lesser Himalayas. No sharp increases in gradient are observed near the Main Boundary Thrust (MBT), except on a few rivers, such as the Jhelum or Kundar, where the MBT lies close to both the MCT and the seismic belt. Thus, it is unlikely that the MBT is a major tectonic boundary. The diversion of river courses along the MBT and around anticlines in the Sub Himalayas has probably been caused by aggradation near the rosion-deposition boundary, upstream of uplifts in the Mahabharat range and Sub Himalayas.A parallel is drawn between the Himalayas and New Guinea based on the hypothesis that continent-arc collision, of the type occurring in northern Australia, preceded continent-continent collision in the Himalayas. The present sedimentary/tectonic phase in New Guinea resembles the Subathu (Paleocene-Eocene) phase in the Himalayas. Incipient counterparts of the major Himalayan structures, including the MCT and the MBT, are recognized in New Guinea. The drainage patterns in the Himalayas and in New Guinea bear a similar relation to major structures. This suggests that (1) the tectonic evolution of the Himalayas has been rather uniform since early stages of collision, and (2) the Himalayan drainage was also formed at these early stages and is therefore antecedent to the rise of the High Himalayas.     

The phanerozoic sedimentary basins of Australia and their tectonic implications

The stratigraphy, structure and tectonics of Australia's Phanerozoic sedimentary basins are described briefly in terms of three settings: younger internal basins, older internal basins and peripheral basins.The younger internal basins developed successively following part by part cratonization of the Palaeozoic Tasman Fold Belt System. Most of the older internal basins probably had late Proterozoic beginnings and all have Precambrian cratonic basements. The peripheral basins occur around the present continental margins and in New Guinea; the oldest of them may be Devonian.The peripheral basins are the simplest to explain in terms of plate tectonics: some can be related to Australia breaking away from Gondwanaland, others to plate convergence in the east and in New Guinea. An attempt is made to fit the internal basins into a platetectonic geological history.     

The city of Moscow and the Moscow agglomeration

Lower rainfall and a longer dry season appear to have characterised SE Asia during the Quaternary Glacials. This had an important effect on vegetation and on landform development, particularly on weathering, river regimen, coastal features and planation. The low Glacial sea levels are generally thought not to have caused river incision and deposition of rather coarse-textured materials is considered more characteristic. Incision was mainly tied to the Interglacial and Holocene humic tropical conditions when vegetation interfered with non-concentrated surface wash. Clay blankets were deposited off-shore and also above the waterline. This concept has consequences for the Quaternary chronology in SE Asia.     

Quaternary climatic changes and natural environment in SE Asia

Lower rainfall and a longer dry season appear to have characterised SE Asia during the Quaternary Glacials. This had an important effect on vegetation and on landform development, particularly on weathering, river regimen, coastal features and planation.The low Glacial sea levels are generally thought not to have caused river incision and deposition of rather coarse-textured materials is considered more characteristic. Incision was mainly tied to the Interglacial and Holocene humic tropical conditions when vegetation interfered with non-concentrated surface wash. Clay blankets were deposited off-shore and also above the waterline. This concept has consequences for the Quaternary chronology in SE Asia.     

Myanmar and Asia united,Australia left behind long ago

It is well known that western Myanmar is underlain by a continental fragment, the West Burma Block, but there are arguments about its origin and the time of its arrival in SE Asia. This study presents the first petrological, XRD diffraction, heavy mineral and detrital zircon U-Pb age data from turbidite sandstones in the Chin Hills that were deposited on West Burma crust in the Triassic. These sandstones contain detritus derived from areas surrounding West Burma and thus help resolve arguments about its location in the Palaeozoic and Mesozoic. West Burma, Sibumasu and Western Australia have similar populations of Archean zircons derived from Western Australian cratons. Until the Devonian all formed part of the Gondwana supercontinent. The abundance of Archean zircons decreases from Western Australia to West Burma and then to Sibumasu. This is consistent with their relative positions in the Gondwana margin, with Sibumasu furthest outboard from Western Australia. Differences in zircon populations indicate that Indochina was not close to West Burma or Sibumasu in Gondwana. West Burma contains abundant Permian and Triassic zircons. These are unknown in Western Australia and different from those of the Carnarvon Basin; they were probably derived from SE Asian tin belt granitoids. Cr spinel is present in most West Burma sandstones; it is common in SE Asia but rare in Western Australia. These new data show that West Burma was part of SE Asia before the Mesozoic and support suggestions that the Argo block that rifted in the Jurassic is not West Burma.