Age and nature of Triassic magmatism in the Netoni Intrusive Complex, West Papua, Indonesia

Webb, Max

doi:10.1016/j.jseaes.2016.09.019

Cited by 21 publications

(24 citation statements)

References 46 publications

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“…North‐western New Guinea currently marks a section of the boundary between the Australian, Caroline, and Pacific plates (Figure ). A plate boundary has existed north of New Guinea since the Devonian where New Guinea represented the northern edge of eastern Gondwana (e.g., Baldwin et al, ; Davies, ; Gunawan et al, ; Jost et al, ; Webb & White, ). However, widespread deposition of carbonate sequences along the northern margin of New Guinea during the Cretaceous to early Eocene indicates that there was a period of relative tectonic quiescence on the southern (“Australian”) side of the plate boundary during this time (e.g., Gold, White, et al, ; Pieters et al, ; Visser & Hermes, ).…”

Section: Geologic Settingmentioning

confidence: 99%

“…These rocks have been considered to represent metamorphosed granitoids (Dow et al, ; Dow & Ratman, ; Dow & Sukamto, ; Robinson, Ryburn, Harahap, Tobing, Achdan, et al, ). If true, the gneisses could represent granitoids found in the Bird's Head and Cenderawasih Bay which range in age from Devonian to Triassic (see Bladon, ; Jost et al, ; Webb & White, ). The mineralogy of the schists is more variable (i.e., quartz + biotite ± garnet ± muscovite ± kyanite ± staurolite ± sillimanite ± tourmaline), with some exposures having garnets up to 10 cm in diameter (Francois et al, ).…”

Section: Geologic Settingmentioning

confidence: 99%

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Tectonic Mode Switches Recorded at the Northern Edge of the Australian Plate During the Pliocene and Pleistocene

et al. 2019

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We report new data from medium-high grade metamorphic rocks found at the northern margin of the Lengguru Fold Belt in West Papua. The study involved a systematic analysis of cross-cutting structures to establish the relative timing of deformation, together with isotopic dating to define when these tectono-thermal events occurred. These data show that the region underwent multiple episodes of deformation within the last six million years. Metamorphic mineral growth was associated with the development of ductile shear zones. This episode occurred during a phase of crustal stretching associated with the formation of a metamorphic core complex. Metamorphic zircon growth at 4.9 to 5.3 Ma was documented in two of the dated samples. These data are interpreted to postdate the peak pressure and temperature conditions of the phase of regional crustal stretching. The shear fabrics associated with the metamorphic core complex were later overprinted by at least two generations of folds. The change in mode from crustal extension to shortening reflects a tectonic mode switch. A subsequent mode switch is documented by numerous brittle extensional faults that cross-cut the earlier formed ductile fabrics. We interpret ca. 0.75-1.51 Ma (U-Th)/He age data to reflect cooling associated with the later stages of crustal shortening (marked by folds) or the later extensional unroofing of the peninsula. This work demonstrates that an orogen can record multiple tectonic mode switches within several million years. These outcomes should be considered in studies of ancient orogens where analytical uncertainties associated with isotopic dating may mask short-lived mode switches.Plain Language Summary How much time is required for a mountain belt to develop? Our knowledge of mountain building is somewhat limited because many of the best-studied mountain belts are quite old and our ability to date tectonic events is less precise the farther back we look through time. The work presented here investigates a mountainous peninsula that developed at the northern margin of the Australian Plate within the last six million years. This region records multiple episodes of deformation-we show that the relatively young rocks have been stretched, then pushed together and then stretched again (much like an accordion). These cycles must occur over a period of one to two million years, which is very fast compared to numerous studies of ancient mountain belts that consider the same processes occur over tens of millions of years.

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Section: Geologic Settingmentioning

confidence: 99%

Section: Geologic Settingmentioning

confidence: 99%

Tectonic Mode Switches Recorded at the Northern Edge of the Australian Plate During the Pliocene and Pleistocene

et al. 2019

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“…This Abukuma-type metamorphism likely occurred when the region was part of an active continental arc system and heat flux to the crust was high ( Fig. 13A; e.g., Gunawan et al, 2012;2014;Metcalfe, 2013;Webb and White, 2016). This scenario is comparable to other HT/LP metamorphic terranes of the world where similar lithologies are observed, e.g., the Abukuma Plateau in Japan (e.g., Miyashiro, 1973) or the Cooma Metamorphic Complex in the Lachlan Fold Belt in SE Australia (e.g., Williams, 2001).…”

Section: Submitted To Lithosmentioning

confidence: 99%

“…The Permian-Triassic arc is also considered to extend through eastern Gondwana (what is now eastern Australia, Zealandia and Antarctica) ( Fig. 13A; Amiruddin, 2009;Charlton, 2001;Crowhurst et al, 2004;Gunawan et al, 2012;2014;Hill and Hall, 2003;Metcalfe, 2013;Webb and White, 2016).…”

Section: Submitted To Lithosmentioning

confidence: 99%

“…Apart from the results of a recent study of the Netoni Intrusive Complex (Fig. 1, Webb and White, 2016), the only other isotopic age control on the timing of magmatism in this region are K-Ar ages from 19 samples (Bladon, 1988;Dow et al, 1988). None of these K-Ar ages have been formally published, some lack associated uncertainties or Submitted to Lithos sampling locations, and 14 were determined on alluvial boulders collected from river detritus (a common last resort in remote rainforest locations where few exposures exist).…”

Section: Introductionmentioning

confidence: 99%

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The Mesozoic and Palaeozoic granitoids of north-western New Guinea

Jost¹,

Webb²,

White³

2018

Preprint

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A large portion of the Bird's Head Peninsula of NW New Guinea is an inlier that reveals the pre-Cenozoic geological history of the northern margin of eastern Gondwana. The peninsula is dominated by a regional basement high exposing Gondwanan ('Australian') Palaeozoic metasediments intruded by Palaeozoic and Mesozoic granitoids. Here, we present the first comprehensive study of these granitoids, including field and petrographic descriptions, bulk rock geochemistry, and U-Pb zircon age data. We further revise and update previous subdivisions ofgranitoids in the area. Most granitoids were emplaced as small to medium scale intrusions during two episodes in the Devonian-Carboniferous and the Late Permian-Triassic, separated by a period of apparent magmatic quiescence. The oldest rocks went unrecognised until this study, likelydue to the younger intrusive events resetting the K¬-Ar isotopic system used in previous studies. Most of the Palaeozoic and Mesozoic granitoids are peraluminous and in large parts derived from partial melts of the country rock. This is corroborated by local migmatites and country rockxenoliths. Although rare, the metaluminous and mafic rocks show that partial melts of mantle-derived material played a minor role in granitoid petrogenesis, especially during the Permian-Triassic. The Devonian-Carboniferous granitoids and associated volcanics are locally restricted, whereas the Permian-Triassic intrusions are found across NW New Guinea and further afield. The latter were likely part of an extensive active continental margin above a subduction system spanning the length of what is now New Guinea and likely extending southward through easternAustralia and Antarctica.

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Age, origin and tectonic controls on rapid recent exhumation of the Sibela Mountains, Bacan, Indonesia

Hennig-Breitfeld,

Hall,

White

et al. 2024

Int J Earth Sci (Geol Rundsch)

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The Sibela Mountains of the island of Bacan in eastern Indonesia contain one of the Earth’s youngest metamorphic complexes that is now exposed at elevations up to 2000 m. New mica 40Ar/39Ar and apatite (U–Th–Sm)/He data from metamorphic and igneous rocks indicate that these rocks were rapidly exhumed in the Pleistocene (c. 0.7 Ma). Exhumation of the metamorphosed Permo-Triassic basement (c. 249–257 Ma) was accompanied by metamorphism (recorded by schists) as well as partial melting (recorded by c. 1.4 Ma granitic dykes). These processes must have occurred at extremely high cooling and exhumation rates. The rapid exhumation on land was associated with significant subsidence in adjacent basins offshore that reach depths up to 2.4 km. Neogene metamorphic core complexes and other metamorphic complexes are well-known from eastern Indonesia, but they usually record much higher exhumation rates than those reported from older classic metamorphic core complexes found in other parts of the world and require a different formation mechanism. Unlike classic metamorphic core complexes that are characterized by low-angle detachment faults, the Bacan metamorphic rocks were exhumed on steep bounding normal faults forming a rectilinear block pattern. We suggest such complexes are termed metamorphic block complexes (MBC). The Bacan MBC is exceptionally young and like the other east Indonesian complexes was rapidly exhumed during subduction rollback. A flexure formed during arc-arc collision as the Sangihe forearc loaded the Halmahera forearc which reactivated steeply-dipping faults in a rectilinear chocolate block pattern. Graphical abstract

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Age and nature of Triassic magmatism in the Netoni Intrusive Complex, West Papua, Indonesia

Cited by 21 publications

References 46 publications

Tectonic Mode Switches Recorded at the Northern Edge of the Australian Plate During the Pliocene and Pleistocene

Tectonic Mode Switches Recorded at the Northern Edge of the Australian Plate During the Pliocene and Pleistocene

The Mesozoic and Palaeozoic granitoids of north-western New Guinea

Age, origin and tectonic controls on rapid recent exhumation of the Sibela Mountains, Bacan, Indonesia

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