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The Archean North China craton is composed of the Western block, Eastern block, and the intervening Central orogenic belt. A 4-10-km-wide and 85-km-long tectonic mélange belt informally called the Zanhuang tectonic mélange is documented in the Zanhuang Massif of the Central orogenic belt, separating the Eastern block from an Archean arc terrane in the Central orogenic belt. The mélange belt contains a structurally complex tectonic mixture of metapelites, metapsammites, marbles, and quartzites mixed with exotic tectonic blocks of volcanic, mafic, and ultramafic rocks, metabasalts that locally include relict pillow structures, and tonalitetrondhjemite- granodiorite (TTG) gneisses. The Zanhuang tectonic mélange marks the suture of an arc-continent collisional zone between the Western Zanhuang Massif in the Central orogenic belt and the Eastern block of the North China craton, and it is one of the best-preserved Archean tectonic mélanges in the world. Here, using zircon U-Pb dating of various types of blocks from the Zanhuang mélange, we show that the formation and associated deformation of the Zanhuang mélange occurred in the Neoarchean (ca. 2.5 Ga). High-precision (1:20-1:200) lithostructural mapping of three key outcrops reveals details of the internal fabrics and kinematics of the mélange and regional structural relationships along the arc-continent collisional zone. A synthesis of studies on the tectonic evolution of the North China craton, coupled with our new fabric and kinematic analysis of the Zanhuang mélange, further constrains the initial amalgamation timing and geometry of the arc-continent collision between the Fuping arc terrane in the Central orogenic belt and the Eastern block with a northwest-dipping subduction polarity. The asymmetric structures and mixture of different blocks and matrices with folding and thrusting events in the Zanhuang mélange record kinematic information that is consistent with the tectonic setting of an accretionary wedge that was thrust over the passive margin of the Eastern block by 2.5 Ga. Lithostructural mapping shows that the classic mélange and fold-and-thrust structures along the Neoarchean arc-continent collisional zone are broadly similar to Phanerozoic collisional belts. [ABSTRACT FROM AUTHOR]

Back-arc basins are pivotal sites for the generation and consumption of oceanic lithosphere in mature intra-oceanic convergent plate margins. However, the processes and mechanisms by which back-arc oceanic basins generate and terminate remain enigmatic. Here we document the life cycle of an extinct Paleozoic back-arc from an ophiolite-accretionary complex in the Proto-Tethyan North Qilian orogenic belt, northeastern Tibet, which records early spreading and subsequent closure through two episodes of subduction. Zircon U–Pb ages of gabbro and plagiogranite indicate two episodes of oceanic crust formation at ca. 480 Ma and ca. 452–448 Ma. Low-Ti gabbro, basalt, and plagiogranite (ca. 480 Ma) from the accretionary complex have back-arc geochemical signatures, whereas ultramafic rocks, gabbro, basalt, and plagiogranite suite from the ophiolite sheet (ca. 452–448 Ma) exhibit forearc characteristics. These data, together with recent structural and metamorphic evidence, indicate that the ophiolitic rocks were derived from both back-arc and forearc settings, and record the magmatic response to early spreading of the North Qilian back-arc basin and subsequent subduction initiation. Early subduction and slab rollback of the North Qilian oceanic lithosphere led to formation of the North Qilian arc and spreading of the back-arc, whereas later subduction initiation of the back-arc oceanic crust resulted in its termination and closure. These findings indicate that the subduction of back-arc oceanic crust is a primary mechanism in the closure of back-arc basins and thereby highlights the complex evolutionary tempo of back-arc basins in Earth history. • A life cycle of a Proto-Tethyan intra-oceanic back-arc basin was documented. • Geochronological data demonstrate two episodes of formation of oceanic crust. • Geochemical characteristics reveal back-arc spreading and subduction initiation. • Subduction plays a key role in the termination of back-arc basins. [ABSTRACT FROM AUTHOR]

The existence of coherent, large-scale, submarine landslides on modern continental margins implies that their apparent rarity in ancient orogenic belts is due to non-recognition. Two map-scale, coherent, pre-orogenic, normal-sense detachment structures of Ediacaran age are present in the Kaoko belt, a well-exposed arc-continent collision zone in northwestern Namibia. The structures occur within the Otavi Group, a Neoproterozoic carbonate shelf succession. They are brittle structures, evident only through stratigraphic omissions of 400 m or more, that ramp down to the west with overall ramp angles of 1.1° and 1.3° with respect to stratigraphic horizons. The separations of matching footwall and hangingwall stratigraphic cut-offs require horizontal translations >20 km for each detachment. One of the detachments is remarkably narrow (5 km) in the up-dip direction, just one fourth of its translation. The other detachment is stratigraphically dated at the shelf-foredeep transition, when the passive margin was abortively subducted westward, in the direction of submarine sliding. Trenchward sliding on the foreslope occurred concurrently with deep karstification of the autochthonous carbonate succession to the east, presumably due to forebulge uplift and (or) conjectural basin-scale base-level fall. We expect that similar detachments exist in other orogenic belts, and failure to recognize them can lead to misinterpretations of stratigraphy, sedimentary facies, and paleogeography. [ABSTRACT FROM AUTHOR]

Kevin Burke's original and thought-provoking contributions have been published steadily for the past 60 years, and more than a decade ago he set out to resolve how plate tectonics and mantle plumes interact by proposing a simple conceptual model, which we will refer to as the Burkian Earth. On the Burkian Earth, mantle plumes take us from the deepest mantle to sub-lithospheric depths, where partial melting occurs, and to the surface, where hotspot lavas erupt today, and where large igneous provinces and kimberlites have erupted episodically in the past. The arrival of a plume head contributes to continental break-up and punctuates plate tectonics by creating and modifying plate boundaries. Conversely, plate tectonics makes an essential contribution to the mantle through subduction. Slabs restore mass to the lowermost mantle and are the triggering mechanism for plumes that rise from the margins of the two large-scale low shear-wave velocity structures in the lowermost mantle, which Burke christened TUZO and JASON. Situated just above the core-mantle boundary, beneath Africa and the Pacific, these are stable and antipodal thermochemical piles, which Burke reasons represent the immediate after-effect of the moon-forming event and the final magma ocean crystallization. [ABSTRACT FROM AUTHOR]

Back-arc extension in the Aegean, which was driven by slab rollback since 45 Ma, is described here for the first time in two stages. From Middle Eocene to Middle Miocene, deformation was localized leading to ( i) the exhumation of high-pressure metamorphic rocks to crustal depths, ( ii) the exhumation of high-temperature metamorphic rocks in core complexes, and ( iii) the deposition of sedimentary basins. Since Middle Miocene, extension distributed over the whole Aegean domain controlled the deposition of onshore and offshore Neogene sedimentary basins. We reconstructed this two-stage evolution in 3D and four steps at Aegean scale by using available ages of metamorphic and sedimentary processes, geometry, and kinematics of ductile deformation, paleomagnetic data, and available tomographic models. The restoration model shows that the rate of trench retreat was around 0.6 cm/year during the first 30 My and then accelerated up to 3.2 cm/year during the last 15 My. The sharp transition observed in the mode of extension, localized versus distributed, in Middle Miocene correlates with the acceleration of trench retreat and is likely a consequence of the Hellenic slab tearing documented by mantle tomography. The development of large dextral northeast-southwest strike-slip faults, since Middle Miocene, is illustrated by the 450 km long fault zone, offshore from Myrthes to Ikaria and onshore from Izmir to Balikeshir, in Western Anatolia. Therefore, the interaction between the Hellenic trench retreat and the westward displacement of Anatolia started in Middle Miocene, almost 10 Ma before the propagation of the North Anatolian Fault in the North Aegean. [ABSTRACT FROM AUTHOR]

Since the Mesozoic, Africa has been under extension with shorter periods of compression associated with obduction of ophiolites on its northern margin. Less frequent than 'normal' subduction, obduction is a first order process that remains enigmatic. The closure of the Neo-Tethys Ocean, by the Upper Cretaceous, is characterized by a major obduction event, from the Mediterranean region to the Himalayas, best represented around the Arabian Plate, from Cyprus to Oman. These ophiolites were all emplaced in a short time window in the Late Cretaceous, from ∼100 to 75 Ma, on the northern margin of Africa, in a context of compression over large parts of Africa and Europe, across the convergence zone. The scale of this process requires an explanation at the scale of several thousands of kilometres along strike, thus probably involving a large part of the convecting mantle. We suggest that alternating extension and compression in Africa could be explained by switching convection regimes. The extensional situation would correspond to steady-state whole-mantle convection, Africa being carried northward by a large-scale conveyor belt, while compression and obduction would occur when the African slab penetrates the upper-lower mantle transition zone and the African plate accelerates due to increasing plume activity, until full penetration of the Tethys slab in the lower mantle across the 660 km transition zone during a 25 Myr long period. The long-term geological archives on which such scenarios are founded can provide independent time constraints for testing numerical models of mantle convection and slab-plume interactions. [ABSTRACT FROM AUTHOR]

Early Eocene fossil floras from British Columbia are a rich resource for reconstructing western North American early Cenozoic climate. The best known of these floras reflect cooler (MAT ≤ 15 °C) upland forest communities in contrast to coeval (MAT ≥ 18 °C) forests in lowland western North American sites. Of particular interest is whether Early Eocene climates were monsoonal (highly seasonal precipitation). The McAbee site is a 52.9 ± 0.83 Ma 0.5 km outcrop of bedded lacustrine shale interbedded with volcanic ash. In this report two historical megaflora collections that were collected independently from different stratigraphic levels and (or) laterally separated by ∼100-200 m in the 1980s (University of Saskatchewan) and 2000s (Brandon University) are investigated to ( i) assess whether they represent the same leaf population, ( ii) assess whether a combined collection yields more precise climate estimates, and ( iii) reconstruct paleoclimate to assess the character of regional Early Eocene precipitation seasonality. Combined, the two samples yielded 43 dicot leaf morphotypes. Analysis of leaf size distribution using ANOVA showed no difference between the two samples, and thus they were combined for climate analysis. Climate analysis using leaf physiognomy agrees with previous estimates for McAbee and other regional megafloras, indicating a warm (MAT ∼8-13 °C), mild (CMMT ∼5 °C), moist (MAP > 100 cm/year) ever-wet, non-monsoonal climate. Additionally, we recommend that climate analyses derived from leaf fossils should be based on samples collected within a stratigraphically constrained quarry area to capture a snapshot of climate in time rather than time-averaged estimates derived from multiple quarry sites representing different stratigraphic levels within a fossil site. [ABSTRACT FROM AUTHOR]

Western North America preserves a rich record of Eocene life and environments under globally warm climates, and represents an interval where significant coal and other minerals were deposited. The Eocene is of interest to biologists and paleontologists for its record of the appearance and rise to dominance of many plant, insect, and mammal groups now typical of the temperate forests of North America, admixed with groups now well represented in tropical areas or restricted to eastern Asia. This record is also of interest for its potential contribution to our understanding of interactions between climate, the biota, and the ecosystems they occupied, under atmospheric carbon dioxide levels much higher than today. Documentation of the Eocene in western North America offers insights into the effects of future greenhouse climates. A special symposium held at the 2014 Annual Meeting of the Geological Society of America in Vancouver, British Columbia, brought together geologists, paleontologists, and biologists with an interest in these questions. This paper introduces the special issue that includes a selection of papers drawn from that symposium as well as on related topics, spanning the Early to Late Eocene, and geographically from British Columbia to Colorado. [ABSTRACT FROM AUTHOR]

Subduction polarity reversal events following arc–continent, arc–arc or continent–continent collisions have been well-documented from Cenozoic, Mesozoic, and Paleozoic orogens, but not from the Archean. We here document a Neoarchean subduction reversal event after an arc–continent collision between the Eastern Block of the North China Craton (NCC) and the Fuping arc using field, geochemical and geochronological data. We focus our work on the Wangjiazhuang granite in the Zanhuang massif located along the eastern margin of the Central Orogenic Belt (COB) of the NCC, and a regional tectonic comparison with other granitic rocks with similar ages, geochemical and petrogenetic characteristics. The ca. 2.5 Ga A-type Wangjiazhuang granite intrudes the Neoarchean Zanhuang mélange belt and contains mafic and felsic inclusions. It has positive ε Nd (t) values (+ 0.12 to + 1.13) and T DM2 ages between 2784 Ma and 2869 Ma. This work shows clearly, from field structural relationships, geochemistry and geochronology, that the Wangjiazhuang granite formed after an arc–continent collision between the Eastern Block which is defined as a continental block and the Fuping arc, after a subduction polarity reversal event placed a new slab beneath the collisionally modified margin of the Eastern Block and converted it to an Andean-type margin. The subduction polarity reversal event at ca. 2.5 Ga resulted in melting of the enriched mantle. Meanwhile, the rising magma induced partial melting of the old and thickened TTG crust leading to the intrusion of ca. 2.5 Ga Wangjiazhuang granite into the Neoarchean Zanhuang mélange. There are other granitic rocks with similar ages and geochemical and petrogenetic features in the Central Orogenic Belt and Eastern Block of the North China Craton, suggesting that they formed in a similar tectonic setting as the circa 2.5 Ga granites across the Eastern Block. The Neoarchean subduction polarity reversal event and prior arc–continent collision provide strong evidence that plate tectonics was operating by the end of the Neoarchean. [ABSTRACT FROM AUTHOR]

Ophiolitic podiform chromitites from Phanerozoic orogens have been shown to preserve a wealth of textures and inclusions that, in some way, trace earlier episodes of subduction and crust mantle interactions, including traces of the major elements Carbon – Hydrogen – Oxygen – Nitrogen – Sulfur - Phosphorous (CHONSP) needed to sustain a habitable planet. Here, we report the first comprehensive documentation of the textures and inclusions of an Archean (circa 2.55 Ga) podiform chromitite from an orogenic ophiolitic mélange in China, recording an ancient CHONSP cycle, during the start of Earth's transition from a reducing to an oxidized surface environment during the Great Oxidation Event, providing evidence for a dynamic link of Archean-Paleoproterzoic tectonics, and creation of a habitable planet. The composition of the inclusions indicates profound mixing of crustal and mantle sources in the Archean, and the textures show that they were included in chromite grains that began their growth as spherules that aggregated from immiscible silicate-oxide melts near the mantle transition zone at temperatures above 1900°C, forming host chenmingite at 14 GPa, or about 410 km. The melts then protruded upward in an extensional fore-arc, reacting with host harzburgites, progressively including a wide assortment of previously subducted mineral and rock fragments as xenocrysts and xenoliths in the progressively crystallizing chromite. The inclusions include ultra-high pressure TiO 2 (II) stable at 7.5 GPa (or about 270 km) at 1000 °C, plus carbonates, hydrous and nominally anhydrous silicates, oxides, base metals, platinum group minerals, previously unidentified OsIrS, and pure carbon as graphite polymers. As the chromite-bearing melts rose further, they finally crystallized near the crust-mantle boundary of a circa 2.55-billion-year-old fore-arc ophiolite, that was soon, by the dawn of the Paleoproterozoic, involved in an arc/continent collision that emplaced the mantle rocks onto a fragment of older continental crust. This early record of inclusion of previously deeply subducted minerals in an orogenic ophiolitic podiform chromitite shows that plate tectonics and subduction have regulated crust-mantle interactions and the life-sustaining deep CHONSP cycles on Earth at least since the Archean, consistent with numerical models showing how C-O-H cycling related to subduction led to a rapid oxygenation of the mantle in the late Archean. [Display omitted] • 2.55 Ga ophiolitic podiform chromite bodies preserved in ophiolitic mélange belt in 1600 km long Archean collisional orogen, Northern China • First terrestrial documentation of chenmingite (UHP phase of chromite, stable >14 GPa (~410 km near mantle transition zone) • Inclusions include crust-derived UHP TiO 2 (II) stable at 7.5 GPa (~270 km) at 1000°C, and previously unknown OsIrS phase • Chromitite-hosted crust-, mantle-, and melt-derived inclusions indicate deep crust-mantle carbon and CHONSP recycling through subduction in world's first Archean UHP oogen • Archean subduction and crustal recycling reached at least the top of the mantle transition zone [ABSTRACT FROM AUTHOR]

Abstract: The 1939 Erzincan Earthquake (M =7.8), occurred on the North Anatolian Fault Zone (NAFZ), was one of the most active strike-slip faults in the world, and created a 360-km-long surface rupture. Traces of this surface rupture are still prominently observed. In the absence of detailed mapping to resolve the fault characteristics, detailed observations have been conducted at 20 different points on the 70-km-long Kelkit Valley Segment (KVS) of the NAFZ''s between Niksar and Koyulhisar. Field data defining fault character and slip amounts were found at eight points and show right-lateral slip varying between 1.8 and 4.25m and the vertical slip varying between 0.5 and 2.0m. The KVS developed in the most morphologically prominent and narrowest part of the NAFZ. Therefore, the chances of finding evidence of more than one historical earthquake in trenches opened to investigate palaeoseismological aspects are higher. Faults observed in foundation and channel excavations opened for energy purposes in the Reşadiye region show this clearly and evidence for up to four seismic events including the 1939 Erzincan Earthquake have been discovered. Further studies are required to discover whether right-lateral deformation on at some locations on this segment is surface ruptures associated with the 1939 earthquake or later creep. [Copyright &y& Elsevier]

Abstract: Ongoing motion of Anatolia towards the west is caused by convergence of the Arabian and Eurasian plates coupled with suction towards the retreating Hellenic Arc. This regime is controlling the development of neotectonic structures in Turkey with the resulting distributed deformation accommodated primarily between the East and North Anatolian Intracontinental Transform Faults. The Erzincan Basin is developed along the eastern part of the latter fault and although it incorporates one of the largest Quaternary basins in Turkey, the duration and tectonic evolution are disputed. Tectonic models proposed to explain the basin range from simple rhomboidal pull-apart to a complex multi-phase evolution. To help constrain the age and tectonic regime(s) forming the basin we have conducted a palaeomagnetic and geochronologic study of volcanic domes which occur mainly in proximity to strike-slip faulting along the northern margin of the basin. The investigated sample comprises 27 lava sites located within 14 cones, 13 to the north and one in the south. Although difficult propositions for palaeomagnetic investigation because the young predominantly-pyroclastic constructive topography is susceptible to collapse, all sites show positive inclinations and mainly northerly declinations showing that they are the consequence of a tectonic regime confined to the Brunhes Chron. Whilst the limitation of directional data from these young constructive features is stressed, ten cones are found to show clockwise rotations ranging from 12° to 195° with three cones showing no significant rotation. Geochronological studies from 13 samples yield a range of ages with 6 providing meaningful results <0.3Myr in age and consistent with young ages evident from morphology and paleomagnetism. AMS (Anisotropy of Magnetic Susceptibility) studies identify a fabric related to downslope flow at most sites with the majority moving away from conduits controlled by fractures paralleling the dominant NW-SE trend of the master fault. The palaeomagnetic and geochronologic results show that the history of the Erzincan Basin has involved at least two phases with the later phase incoporating an extensional component permitting access to mantle melts and confined to the last ∼300,000 years. The earlier phase commenced in Late Miocene or Early Pliocene times and initiated the rift infill which currently attains a maximum thickness in excess of 2.7km. We propose that the Erzincan Basin is now segmented as a mature basin by strike-slip cross faults although these cannot explain the consistent clockwise rotations observed within the small blocks incorporating the volcanic cones because these are confined to a narrow zone between two master faults and appear to be subject to ball-bearing style rotation. [Copyright &y& Elsevier]

In the Archean Blake River Group, mafic to intermediate fragmental units have controversially been proposed to have formed during the collapse of a giant submarine caldera. This paper describes and interprets these rocks, summarizing their physical characteristics, inferred origins, age relationships, and geochemical signatures. The widespread Stadacona member, south of Rouyn-Noranda, consists of several hundred metres of bedded volcaniclastic rocks interpreted to have been mostly deposited from aqueous density currents fed directly by explosive eruptions. The magmas involved in these eruptions were plagioclase-phyric, tholeiitic to transitional basalts. The similarly widespread D'Alembert tuff, in the northern part of the Blake River Group, shares many physical characteristics with the Stadacona member and is thought to have a similar origin. However, the D'Alembert tuff is approximately six million years younger than the Stadacona member. It is composed mostly of transitional to calc-alkaline andesites and basaltic andesites with very distinct trace element profiles. Volcaniclastic rocks from other areas, such as Tannahill Township in Ontario and the Monsabrais area in Quebec, are interpreted to represent mostly in situ to remobilized hyaloclastite, with no explosive eruptions involved in their genesis. Our observations and interpretations are not compatible with models in which the volcaniclastic units are emplaced during a catastrophic event in relation with the collapse of a giant caldera. Instead, the fragmental rocks were produced by various mechanisms at many distinct times during the evolution of the Blake River Group. [ABSTRACT FROM AUTHOR]

[Display omitted] • Deciphering the Eoarchean geological record must come from observation, not modelling. • Tectonic interleaving (including mantle over crustal rocks) shows crustal shortening. • Greenland's Eoarchean mafic rocks formed by fluid-fluxing of depleted upper mantle. • Formation of Greenland's Eoarchean crust matches convergent plate boundary processes. • Greenland's Eoarchean geology is inconsistent with stagnant-lid/heat-pipe models. It is 50 years since the landmark paper where Black et al. (1971) presented whole-rock Pb-Pb and Rb-Sr isotopic evidence for some rocks in Greenland surviving from Earth's first billion years; the ≥ 3700 Ma Amîtsoq gneisses. This overturned ideas prevalent at that time that the young Earth was far too violent for such ancient rocks to survive. In the following few years it emerged how 'normal' this early Earth appeared to be, with a retained hydrosphere (oceans) by 3700 Ma and 'continental' crust dominated by rather normal granitic sensu lat o rocks. By several decades ago this led to a vision of Eoarchean lithosphere development being controlled by a geodynamic regime with definite similarities to that in the Phanerozoic, particularly with evidence for lateral lithosphere movement (mobile lid) such as exemplified by arc-like magmatism and Barrovian metamorphism (the latter requiring tectonic crustal thickening). However, the literature in recent years is increasingly emphasising model-driven non-uniformitarian stagnant lid geodynamic scenarios to explain the Eoarchean geological record. This paper reviews the broad range of field and laboratory evidence extracted from the Eoarchean geological record in Greenland. We argue that the non-uniformitarian sagduction within a stagnant lid regime interpretation does not fit Eoarchean facts. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ultra-high pressure TiO 2 II identified in Archean ophiolitic podiform chromite mélange. • Crustal minerals subducted to > 270 km at 2.55 Ga, then recycled to surface. • UHP mélange is part of paired metamorphic Central (Taihang) Orogenic Belt of North China. • Data shows operation of subduction-related deep carbon cycle in Archean. • Convergent margin processes in Archean were similar to those of Phanerozoic. The discovery of ultrahigh pressure (UHP) minerals in orogenic belts has revolutionized our understanding of subduction and the return flow of previously deeply subducted material to Earth's surface as part of the cycling and interaction of crustal and mantle systems. One class of UHP minerals is found as inclusions in orogenic peridotite-hosted podiform-chromite systems, within Phanerozoic ophiolites and ophiolitic mélanges. Such inclusions have opened a window into processes of recycling of crustal materials to the deep mantle and back through subduction and mantle convection in Phanerozoic orogens. Here, we document the first occurrence of an UHP mineral hosted in an ophiolitic podiform chromitite mélange from the Neoarchean paired metamorphic belt of the Central (Taihang) Orogenic Belt, Northern China. Numerous inclusions of rutile, apatite, dolomite, and amphibole are interpreted to be crustal-derived; they occur in podiform chromite grains hosted in a 2.6–2.5 Ga ophiolitic mélange now part of the North China Craton and formed by subduction of oceanic and continental material. Microstructures and phase relationships in a multi-phase inclusion of TiO2(II), rutile, apatite, and tremolite yield minimum P-T conditions of 7.5 GPa at 1000 °C, indicating that the crustal host, including carbonates, were subducted to depths > 270 km, transferred to the mantle of the overriding plate, and returned to the surface by 2.5 Ga. We suggest that slab rollback forced upward mantle flow, incorporating entities from the lower plate, perhaps in serpentinite diapirs, resulting in adiabatic melting that allowed crustal material to be trapped in chromite grains crystallizing in high-Mg melts. Contrasting bulk moduli and thermal contraction of the inclusions and host chromite protected the inclusions from P-induced back-reaction during exhumation. Together, these features show that the 1600 km long Central (Taihang) Orogenic Belt is emerging as the world's first well-documented Phanerozoic style orogen, with classic tectonic zonation, ophiolitic mélanges, paired metamorphism, local evidence for UHP conditions, foreland basins, and late to post orogenic magmatism. Applying the null hypothesis, we explain this high degree of similarity by invoking the operation of Phanerozoic style plate tectonics, at least throughout the 1600 km length of the COB, and by geological comparison, in other similar aged geological terrains globally. From this we infer modern-style plate tectonics was operating in the Neoarchean. [ABSTRACT FROM AUTHOR]

Podiform chromitites are unique rock units of ophiolites and ophiolitic mélanges and represent invaluable repositories that reliably record the formation environment and evolution of their source and host rocks. However, there are relatively few podiform chromitites reported from Archean terranes. Here we document the major, minor, and trace element characteristics of podiform chromitites from the Archean Zunhua ophiolitic mélange in the North China Craton. The Zunhua ophiolitic mélange includes blocks of serpentinized peridotite (dunite and harzburgite), podiform chromitite, pyroxenite, amphibolite, metabasites (basalt and diabase), chert, and tectonic lenses of banded iron formation in a strongly sheared metapelitic matrix. The chromitites, host peridotites, and granitic dikes cutting the mélange all have ages between 2.6 and 2.5 Ga. Chondrite-normalized, whole-rock platinum group element (PGE) patterns of the Zunhua chromitites show a negative sloping PGE trend enriched in Ir and depleted in Pt, similar to typical Phanerozoic podiform chromitites. The geochemical characteristics of the calculated parental magma of the Zunhua chromitites closely resemble those of podiform chromitites in Phanerozoic ophiolites and ophiolitic mélanges but different from those of continental stratiform chromite deposits. The calculated major, minor, and trace element concentrations of the parental melt of Zunhua chromitites are similar to those of boninitic melts found in forearc settings. Geochemical characteristics and calculated parental melt composition of the chromites with the high Mg# values of their host peridotites suggest that the Zunhua podiform chromitites formed by magmatic processes including reactions between boninitic melt and harzburgite in a supra-subduction zone environment. • Major and minor elements of primary chromite in Zunhua chromitites are studied. • The compositions of Zunhua chromitites are comparable to typical podiform chromitites. • The Zunhua podiform chromitites may formed from a boninitic melt in a forearc setting. [ABSTRACT FROM AUTHOR]

The middle Mesoproterozoic is a crucial time period for understanding the Precambrian tectonic evolutionary history of the northern Yangtze Block and its relationship with the supercontinent Columbia. The Dagushi Group (Gp) is one of the Mesoproterozoic strata rarely found at the northern margin of the Yangtze Block. U–Pb geochronology and Lu–Hf isotopic analyses of detrital zircons were analyzed for three metamorphic quartz sandstone samples collected from the Luohanling and Dangpuling formations of the Dagushi Gp. These metasandstones yielded major zircon populations at ~2.65 Ga and ~1.60 Ga, respectively. The ~1.60 Ga ages first discovered yield a narrow range of ɛHf(t) values from −1.8 to +1.8, which lie above the old crust evolutionary line of the Yangtze Block, suggesting the addition of mantle material. Trace element data indicate that ~1.60 Ga detrital zircons share a basic provenance, whereby they have low Hf/Th and high Nb/Yb ratios. Zircon discrimination diagrams suggest that the ~1.60 Ga detrital zircon source rocks formed in an intra-plate rifting environment. Dagushi Gp provenance studies indicate that the ~1.60 Ga detrital zircon was most likely sourced from the interior Yangtze Block. Thus, we suggest that the late Paleoproterozoic to early Mesoproterozoic continental break-up occurred at the northern margin of the Yangtze Block. [ABSTRACT FROM AUTHOR]

• Zunhua ophiolitic mélange preserves entire range of 2.55–2.52 Ga residual mantle and derivative crustal fore-arc units. • Subduction initiation recorded by boninite/harzburgite reaction, leaving podiform chromite/dunite residues. • Mélange emplaced over continent, cut by xenocryst-bearing 2.50 Ga dikes, and metamorphosed at 2.48–2.46 Ga. • Obduction of the forearc killed NW-subduction, but initiated short-lived SE-subduction through arc–polarity reversal. • Zunhua mélange records birth, maturity, death and re-birth of an Archean subduction zone. Subduction initiation and arc–polarity reversal have rarely been recognized in the Archean rock record. We document Neoarchean subduction initiation, fore-arc magmatism, and an arc–polarity reversal event from the Zunhua ophiolitic mélange along the eastern margin of the Central Orogenic Belt (COB) of the North China Craton (NCC). The Zunhua ophiolitic mélange is a mappable unit characterized by blocks of metamorphosed harzburgite/lherzolite, podiform chromite–bearing dunite, pyroxenite, amphibolite, metabasites (basalt and diabase) with rare intermediate volcanics, chert, and tectonic lenses of banded iron formation in a strongly sheared metapelitic matrix. New geochronological and geochemical analyses of magmatic blocks within the ophiolitic mélange show that the crustal magmatic rocks were produced in a fore-arc region at 2.55–2.52 Ga from depleted harzburgitic–lherzolitic mantle tectonites. Chemical, petrological, and temporal links between the depleted mantle blocks, and the suite of magmatic blocks derived from partial melting and metasomatism of these depleted mantle blocks, unequivocally shows that they represent part of the same original Neoarchean fore-arc ophiolite suite. After formation and accretion in the oceanic realm, the mélange was emplaced on the continental margin of the Eastern Block between 2.52 and 2.50 Ga, and underwent two stages of metamorphism at ca. 2.48–2.46 Ga and 1.81 Ga. Metamorphosed intermediate–mafic volcanic blocks exhibit systematic successive geochemical variations, from MORB-like to volcanic arc-like, and the N-MORB-like meta-basalts show remarkable similarity with the subduction initiation-related Izu–Bonin–Mariana (IBM) fore-arc basalts. We suggest that the Zunhua fore-arc complex records continuous geodynamic processes from subduction initiation to arc magmatism. The Zunhua ophiolitic mélange is part of a ca. 2.5 Ga suture between an oceanic arc of the COB and Eastern Block of the NCC. After the arc–continent collision, an arc–polarity reversal event initiated a new eastward–dipping subduction zone on the western side of the COB. This arc–polarity reversal is traced for more than 1600 km along the length of the orogen, similar in scale, geometry, and duration between collision and polarity flip to the present-day arc–polarity reversal of the Sunda–Banda arc during its ongoing collision with the Australia continent. This indicates that a life cycle of an Archean subduction zone, including birth (subduction initiation), maturity (arc magmatism), death (arc-continent collision) and re-birth (arc–polarity reversal), is recorded in the Zunhua ophiolitic mélange, and the geodynamics of plate tectonics at the end of the Archean was similar to those of today. [ABSTRACT FROM AUTHOR]

Mélanges represent a significant component of collisional and accretionary orogenic belts. We present a comparison of subduction-accretion mélanges of different ages to test how mélange-forming processes at convergent margins changed through time. We describe the Mesozoic McHugh mélange in Alaska, and the Paleozoic Proto-Tethyan Laohushan mélange of the Qilian Orogenic Belt of the Alpine-Himalayan chain, together with documentation of a Neoarchean mélange that marks the suture between the Eastern Block and Central Orogenic Belt of the North China Craton (NCC). The McHugh is a classic accretionary mélange that has not yet experienced a collision, and the Laohushan is an accretionary/collisional mélange with structures related to both stages of its evolution. We compare the characteristics of these mélanges with the world's largest Archean mélange, the newly-documented circa 2.5 Ga 1600 km long Jianping-Zunhua-Zanhuang-Dengfeng (JZZD) mélange of the North China Craton. The JZZD is a classical mélange in terms of map patterns, lithological relations, structural characteristics, including mixed rock types of different ages, origins, and metamorphic histories, and preserves both paired metamorphic features and local blocks preserving ultra-high pressure (UHP) assemblages. It shows high stratal disruption, with both block-in-matrix, and highly-mixed thrust-bounded tectonic slices types of map patterns. The mélange is part of an arc/accretionary complex that was emplaced over a 2.7–2.5 Ga passive margin sequence on the western edge of the Eastern Block of the NCC at 2.5 Ga. The frontal zone of the accretionary complex marks the suture between the Eastern Block and an oceanic arc terrane in the Central Orogenic Belt (COB), and exhibits significant along-strike N-S variations. In the north the Jianping pyroxenite mélange contains blocks of 2.52 Ga metapyroxenite, metabasalt, tonalite-trondhjemite-granodiorite-diorite (TTGD) gneisses, in a metasedimentary and serpentinite matrix, intruded by 2.49–2.47 Ga plutons, metamorphosed to amphibolite-granulite conditions at 2.47 Ga. The Zunhua/Shangying ophiolitic mélange contains relatively intact 2.5 Ga ophiolitic sheets in a 2.5 Ga metasedimentary mélange, intruded by 2.48 Ga granitic dikes. The Zunhua ultra-high pressure (UHP) podiform chromite mélange has blocks of pillow basalt, BIF, dikes, gabbros, pyroxenite, harzburgite, some with 2.55 Ga podiform chromites in dunite envelopes, enclosed in a 2.52–2.46 Ga metasedimentary matrix, metamorphosed and intruded by granitic dikes at 2.46 Ga. The chromites and dunite pods formed through reaction of a boninitic melt and harzburgite during subduction initiation bewtween 2.6–2.55 Ga. UHP conditions are documented by TiO 2 II inclusions in chromites, indicating subduction to at least 270 km depth. The Zanhuang mélange includes blocks of metapsammites, metagabbros, metabasalts, and ultramafic rocks in a metapelitic matrix, intruded by 2.49–2.54 Ga granites, then imbricated with >2.65 Ga marble-metapelite-quartzite of the passive margin of the Eastern Block. The Dengfeng mélange includes upper-plate blocks of metagabbro, metabasalt, BIF, and felsic rocks in a sandy to pelitic matrix, thrust over a turbiditic broken-formation mélange unit in the east. Circa 2.5 Ga metamorphic conditions record a relatively high T/P anatexis (>950 °C/GPa) in the west, whereas the central part of the belt records intermediate T/P metamorphism (<650 °C/GPa) with tectonic burial in the accretionary wedge to at least 30 km, making this the world's first well-documented Archean paired metamorphic belt. This belt of mélanges records the life-cycle of an Archean subduction zone, from subduction initiation, processes of fore-arc oceanic crust and mantle generation during arc evolution, their incorporation as the upper plate in an accretionary mélange, and later disruption during collision, emplacement, and imbrication with the older passive margin of the Eastern Block on the lower plate, marking the death of the subduction zone. Arc polarity reversal 5–10 Ma after collision records the birth of a new subduction zone outboard of the accreted arc, and continued accretion of outboard terranes to the proto-North China craton. The mélange was metamorphosed at greenschist to amphibolite grade at 2.5 Ga, and locally up to granulite facies at 1.85 Ga during amalgamation of the NCC with the Nuna Supercontinent. Structures, rock types, subduction zone geothermal gradients (low-intermediate dT/dP), paired with high dT/dP in the arc section, and the history of the forearc mélanges of the Central Orogenic Belt are remarkably similar to those of the younger mélanges, except for the absence of blueschists and biogenic cherts, showing that convergent margin processes have remained similar for the past 2.5 billion years, and that plate tectonics was extant on Earth at least by the end of the Archean. The combination of rock types, structures, ages, geochemistry, and metamorphic relationships show that the Central Orogenic Belt is the world's first documented Archean paired metamorphic UHP orogen. Unlabelled Image • A plate-scale 1600 km long Neoarchean accretionary prism mélange in the North China Craton delineates the world's largest Archean mélange, and first Archean UHP paired metamorphic orogen. • Mélange blocks and matrix of diverse origins and metamorphic grade include a complete forearc ophiolite suite of harzburgites, podiform chromitites, pyroxenites, gabbros, diabases, pillow lavas, BIFs, and deep sea sediments. • UHP minerals record deep (>270 km) subduction, return flow, juxtaposition of upper plate ophiolites and lower plate OPS in paired spatially and temporally linked belts of high and intermediate dT/dP assemblages. • Mélange was deformed and imbricated with a passive margin on an old cratonic fragment during emplacement at 2.5 Ga, then overlain by an orogen-derived foreland basin flysch sequence by 2.45 Ga. • Archean mélange of the North China Craton is remarkably similar to Phanerozoic mélanges except for the absence of blueschists and biogenic cherts, demonstrating minor secular change in convergent plate tectonics. [ABSTRACT FROM AUTHOR]

• We document newly discovered ca. 2.5 Ga epidosites in the Zanhuang ophiolitic mélange of the North China Craton. • This work has important implications for understanding the seafloor hydrothermal activity of subduction zones in the Neoarchean. • Results show modern seafloor hydrothermal activity operated at ca. 2.5 Ga. Epidosites are suggested to form in up-flow zones located at the base of ore-forming oceanic hydrothermal systems, and are commonly preserved in ophiolitic sequences. However, occurrences of epidosites in Archean tectonic mélanges are rarely documented. In this study, we report the presence of late Neoarchean epidosites in the Zanhuang ophiolitic mélange in the North China Craton using meter-scale litho-structural and petrologic analysis, zircon U-Pb dating, major and trace element, and oxygen and strontium isotopic geochemistry. Field studies show that the epidosites are mainly preserved as the cores of meta -pillow lavas, and are distributed as blocks in different matrices within the tectonic mélange. The pillow rims are used as protolith to estimate the element mobility during the alteration process. The epidosites display strong depletion in Na 2 O (0.01–0.27 wt%), MgO (0.43–3.01 wt%), depletion in large ion lithophile elements (LILE) (e.g. Rb, Ba, Cs, U) and transition metals (e.g., Co, Sc, Cu, Ni, Zn), and show enrichment of CaO (13.35–21.0 wt%), Sr and Pb. The high field strength elements (HFSE) (e.g. Zr, Hf, Ta, Th) of epidosites are varied but rare earth elements (REE) are unchanged. The amphibolitic pillow rims are characterized by enrichment of LILE, flat heavy rare earth elements (HREE) patterns, and depletion in HFSE with negative Ti anomalies and positive Pb and Ba anomalies. Oxygen and strontium isotopic ratios of epidosites are 5.0–8.6‰ and 0.70284–0.70551, respectively, both of which are greater than those of fresh basalts. The major and trace elements, oxygen and strontium isotopic values and extensive element migration indicate that the protolith was altered by a submarine hydrothermal system in the absence of continental influence. Magmatic zircons from two samples of epidosites yield 207Pb/206Pb ages of 2512 ± 13 Ma (MSWD = 0.51) and 2542 ± 13 Ma (MSWD = 1.4), confirming that the epidosites were generated at ca. 2.51–2.54 Ga. Based on geochemical data and field observations, we suggest that the protolith of the epidosites formed in an arc-related tectonic setting during the late Neoarchean. This study shows that hydrothermal activity operating in the late Neoarchean was similar to that of the modern ocean floor. [ABSTRACT FROM AUTHOR]

• We document a Neoarchean paired metamorphic belt in the southern North China Craton. • Intermediate T / P metamorphism is consistent with thermal models of 'warm' subduction zones. • Our results support the operation of plate tectonics at the end of the Archean. Paired metamorphism is the hallmark of asymmetric subduction at Phanerozoic convergent plate margins, yet spatially and temporally linked paired metamorphic belts have rarely been documented in the Archean rock record. Here, we investigate the Neoarchean Dengfeng Complex, a typical granite–greenstone belt in the southern part of the North China Craton (NCC). Using petrography, geochronology, and phase equilibrium constraints on rocks from different lithostructural units, we suggest the ca. 2.54–2.50-Ga Dengfeng Complex represents a remnant of a spatially and temporally linked Neoarchean paired metamorphic belt. In the western part of the complex, a garnet amphibolite from a dominantly metabasic unit (MBU) records near peak P – T conditions of 6.3–10 kbar and ∼675–750 °C, corresponding to a high thermobaric ratio (T / P) of ∼720–1200 °C/GPa. Tonalite–trondhjemite–granodiorite (TTG) gneisses preserve evidence for partial melting, also consistent with relatively high T / P (∼875–1400 °C/GPa). In the eastern part of the Dengfeng Complex, two garnet amphibolites and three garnet quartz–mica schists from a dominantly metasedimentary unit (MSU) record peak P – T conditions of >9.8 kbar and ∼525–655 °C, corresponding to intermediate thermobaric ratios of ∼425–600 °C/GPa. Zircon and titanite U–Pb dating, coupled with existing ages of post-kinematic intrusions, constrain the metamorphic age to ca. 2.52–2.50 Ga. The metamorphic P – T data indicate that the MSU was buried to >30 km then exhumed to the near-surface by the early Paleoproterozoic. Our metamorphic results, when combined with recent structural and geochemical data, suggest the Dengfeng Complex records Neoarchean paired metamorphism, in which the higher thermal gradients reflect the arc–forearc region and the lower thermal gradients correspond to the accretionary complex. Our data indicate that the southern NCC experienced accretionary-to-collisional orogenesis with intra-oceanic subduction, forearc accretion (ca. 2.54–2.50 Ga), and subsequent arc–continent collision (ca. 2.50–2.47 Ga). The recognition of paired metamorphism in the NCC is consistent with widespread subduction and the operation of a plate tectonic regime in the late Archean. [ABSTRACT FROM AUTHOR]

The article presents a study on Ophiolites which represents fragments of the ancient oceanic lithosphere. Topics discussed include the importance of ophiolites in determining the mechanism of the tectonic plates, global tectonic evolution and reconstruction of the supercontinent, Metamafic-ultramafic rocks commonly occurring as lenses and metamafic–ultramafic complex and metasupracrustalrocks combined into an ophiolitic mélange suffered paleoproterozoic amphibolitegranulite facies metamorphism.

The article discusses the Zanhuang tectonic mélange in the Zanhuang Massif of the Central Orogenic Belt in China which seperates the Eastern Block from an Archean arc terran. It is one of the best-preserved Archean tectonic mélanges in the world and contains complex tectonic mixture of metapsammites, quartzites mixed with volcanic rocks and metapelites. The article also presents diagrams of the kinematic framework in the mélange.

The article discusses a Neoarchean subduction polarity reversal event in the North China craton. It states that this event resulted in melting of the enriched mantle thereby giving rise to the intrusion of mafic dikes hence providing strong evidence that plate tectonics has operated by the end of the Neoarchean.

The article presents a study on the subduction initiation and generation of the Xigase ophiolite in Southern Tibet as of December 2015. Based on the composition of the Xigaze peridotites, the ophiolite are residues of partial melting and then modified by infiltration of light rare earth element (LREE)-enriched boninitic melts. It claims that the Xigase rocks belong to the Mid-Ocean-Ridge-Basalt (MORB)-like rocks and boninitic rocks.

The coexistence of divergent (spreading ridge) and convergent (subduction zone) plate boundaries at which lithosphere is respectively generated and destroyed is the hallmark of plate tectonics. Here, we document temporally- and spatially-associated Neoarchean (2.55-2.51 Ga) rock assemblages with mid-ocean ridge and supra-subduction-zone origins from the Angou Complex, southern North China Craton. These assemblages record seafloor spreading and contemporaneous subduction initiation and mature arc magmatism, respectively, analogous to modern divergent and convergent plate boundary processes. Our results provide direct evidence for lateral plate motions in the late Neoarchean, and arguably the operation of plate tectonics, albeit with warmer than average Phanerozoic subduction geotherms. Further, we surmise that plate tectonic processes played an important role in shaping Earth's surficial environments during the Neoarchean and Paleoproterozoic., (© 2022. The Author(s).)

Whether modern-style plate tectonics operated on early Earth is debated due to a paucity of definitive records of large-scale plate convergence, subduction, and collision in the Archean geological record. Archean Alpine-style sub-horizontal fold/thrust nappes in the Precambrian basement of China contain a Mariana-type subduction-initiation sequence of mid-ocean ridge basalt blocks in a 1600-kilometer-long mélange belt, overthrusting picritic-boninitic and island-arc tholeiite bearing nappes, in turn emplaced over a passive margin capping an ancient Archean continental fragment. Picrite-boninite and tholeiite units are 2698 ± 30 million years old marking the age of subduction initiation, with nappes emplaced over the passive margin at 2520 million years ago. Here, we show the life cycle of the subduction zone and ocean spanned circa 178 million years; conservative plate velocities of 2 centimeters per year yield a lateral transport distance of subducted oceanic crust of 3560 kilometers, providing direct positive evidence for horizontal plate tectonics in the Archean., (© 2021. The Author(s).)

The Great Oxidation Event signals the first large-scale oxygenation of the atmosphere roughly 2.4 Gyr ago. Geochemical signals diagnostic of oxidative weathering, however, extend as far back as 3.3-2.9 Gyr ago. 3.8-3.7 Gyr old rocks from Isua, Greenland stand as a deep time outpost, recording information on Earth's earliest surface chemistry and the low oxygen primordial biosphere. Here we find fractionated Cr isotopes, relative to the igneous silicate Earth reservoir, in metamorphosed banded iron formations (BIFs) from Isua that indicate oxidative Cr cycling 3.8-3.7 Gyr ago. Elevated U/Th ratios in these BIFs relative to the contemporary crust, also signal oxidative mobilization of U. We suggest that reactive oxygen species were present in the Eoarchean surface environment, under a very low oxygen atmosphere, inducing oxidative elemental cycling during the deposition of the Isua BIFs and possibly supporting early aerobic biology.

We report partial melting of an ultrahigh pressure eclogite in the Mesozoic Sulu orogen, China. Eclogitic migmatite shows successive stages of initial intragranular and grain boundary melt droplets, which grow into a three-dimensional interconnected intergranular network, then segregate and accumulate in pressure shadow areas and then merge to form melt channels and dikes that transport magma to higher in the lithosphere. Here we show, using zircon U-Pb dating and petrological analyses, that partial melting occurred at 228-219 Myr ago, shortly after peak metamorphism at 230 Myr ago. The melts and residues are complimentarily enriched and depleted in light rare earth element (LREE) compared with the original rock. Partial melting of deeply subducted eclogite is an important process in determining the rheological structure and mechanical behaviour of subducted lithosphere and its rapid exhumation, controlling the flow of deep lithospheric material, and for generation of melts from the upper mantle, potentially contributing to arc magmatism and growth of continental crust.

Ischemia/reperfusion injury plays an important role in the pathogenesis of abdominal compartment syndrome, which is characterized by increased intra-abdominal pressure. The aim of this study was to investigate whether octreotide, a synthetic somatostatin analogue, improves the reperfusion injury after decompression of acute abdominal hypertension. This study was carried out in Wistar albino rats. With the rats under anesthesia, an arterial catheter was inserted intraperioneally and with the use of an aneroid manometer connected to the catheter, intra-abdominal pressure was kept at 20 mm Hg (ischemia group) for 1 hour. In the ischemia/reperfusion group, pressure applied for 1 hour was decompressed and a 1-hour reperfusion period was allowed. In another ischemia/reperfusion group, octreotide was administered (50 microg/kg intraperitoneally) immediately before the decompression of intra-abdominal pressure. At the end of the experiment, liver and intestinal tissues were taken and malondialdehyde (an index of lipid peroxidation) and glutathione (a key to antioxidant) levels and myeloperoxidase (an index of tissue neutrophil infiltration) activity were estimated. The results demonstrated that tissue levels of malondialdehyde and myeloperoxidase activity were elevated, whereas glutathione levels were reduced in both the ischemia and ischemia/reperfusion groups. Octreotide treatment reversed these oxidant responses. In conclusion, increased intra-abdominal pressure causes oxidative organ damage and octreotide, by controlling the reperfusion of abdominal organs and inhibiting neutrophil infiltration, could improve the reperfusion-induced oxidative damage. Therefore its therapeutic role as a "reperfusion injury-limiting" agent must be further elucidated in intra-aortic pressure-induced abdominal organ injury.

Acutely increased intra-abdominal pressure (IAP) may lead to abdominal compartment syndrome (ACS), which ischaemia/reperfusion (I/R) injury plays an important role. The main goal of the management of ACS is to lower the intra-abdominal pressure despite reperfusion injury. Octreotide (OCT), a synthetic somatostatin analogue, lowers the splanchnic perfusion. The aim of this study was to investigate whether OCT improves the reperfusion injury after decompression of acute abdominal hypertension.Under anesthesia, a catheter was inserted intraperitoneally and using an aneroid manometer connected to the catheter, IAP was kept at 20 mmHg (ischemia group; I) for 1h. In the I/R group, pressure applied for an hour was decompressed and 1h reperfusion period was allowed. In another group of I/R, OCT was administered (50 microg/kg i.p.) immediately before the decompression of IAP. The results demonstrate that kidney and lung tissues of malondialdehyde (MDA; an end product of lipid peroxidation) levels and myeloperoxidase (MPO; index of tissue neutrophil infiltration) activity were elevated, while glutathione (GSH; a key to antioxidant) levels were reduced in I/R group (P<0.001). Moreover, OCT treatment applied in the I/R group reduced the elevations in blood urea nitrogen (BUN) and serum creatinine levels. Our results implicate that IAP causes oxidative organ damage and OCT, by reducing splanchnic perfusion and controlling the reperfusion of abdominal organs, could improve the reperfusion-induced oxidative damage. Therefore, its therapeutic role as a "reperfusion injury-limiting" agent must be further elucidated in IAP-induced abdominal organ injury.