Polar Science最新文献

Initial transformation and export of dense shelf water from the Prydz Bay and Cape Darnley regions: A Lagrangian perspective using clustered drifters 普里兹湾和达恩利角地区稠密陆架水的初始转化和输出：使用聚集漂移的拉格朗日视角

IF 2 4区地球科学 Q3 ECOLOGY

Polar Science

Pub Date : 2025-12-01 DOI: 10.1016/j.polar.2025.101261

Margaret Murakami , Aleksi Nummelin , Benjamin Keith Galton-Fenzi , Petteri Uotila

Antarctic Bottom Water (AABW) forms the deepest limb of the meridional overturning circulation (MOC) and is a key control in global heat, freshwater, and carbon exchanges. AABW originates in part from Dense Shelf Water (DSW) produced in Antarctic coastal polynyas. Prydz Bay and Cape Darnley host several productive polynyas that supply AABW to the Atlantic and Indian Ocean sectors. However, the pathways by which DSW travels from the shelf to the abyss, and the transformations it undergoes over its first year, remain poorly understood. We use a 10 km circum-Antarctic ocean-sea ice model (the Whole Antarctic Ocean Model) and Lagrangian particle tracking with a novel clustering analysis to examine how DSW from Prydz Bay region is exported and modified before contributing to AABW. Our results reveal that shelf mixing influences DSW’s fate. When DSW flows beneath the Amery Ice Shelf, it mixes with fresher Ice Shelf Water (ISW), becoming less dense and reducing its potential to sink. Along the shelf break, intrusions of Circumpolar Deep Water (CDW) mix with DSW to form modified CDW (mCDW), further altering its properties. We find that the DSW-to-AABW pathway is sensitive to these mixing processes, which can either facilitate or preclude descent. Cluster analysis of Lagrangian trajectories reveals distinct groups of particle pathways and transformations, highlighting the diverse outcomes of DSW export. This Lagrangian approach demonstrates a powerful tool for diagnosing shelf-to-deep water mass transformation, and provides insights into the processes regulating AABW formation in the Prydz Bay region.

南极底水（AABW）是经向翻转环流（MOC）的最深分支，是全球热量、淡水和碳交换的关键控制因素。AABW部分源于南极海岸冰融所产生的稠密陆架水（DSW）。普里兹湾和达恩利角拥有几个多产的冰礁，为大西洋和印度洋地区提供AABW。然而，DSW从大陆架传播到深渊的途径，以及它在第一年经历的转变，仍然知之甚少。我们使用了一个10公里环南极海洋海冰模型（全南极海洋模型）和拉格朗日粒子跟踪和一种新颖的聚类分析来研究Prydz湾地区的DSW在贡献AABW之前是如何输出和修改的。我们的研究结果表明，陆架混合影响DSW的命运。当DSW在Amery冰架下流动时，它与较新鲜的冰架水（ISW）混合，密度降低，降低了下沉的可能性。沿陆架断裂，环极深水（CDW）侵入物与深水（DSW）混合形成改性CDW (mCDW)，进一步改变其性质。我们发现，dsww - aabw通路对这些混合过程很敏感，可以促进或阻止下降。拉格朗日轨迹的聚类分析揭示了粒子路径和转换的不同群体，突出了DSW输出的不同结果。这种拉格朗日方法展示了一种诊断陆架到深水块体转化的强大工具，并为Prydz湾地区AABW形成的调节过程提供了见解。

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引用次数: 0

A geological cross section of Neogene to Quaternary sediments in the Larsemann Hills, East Antarctica 南极洲东部拉尔森山新近系至第四纪沉积物地质剖面

IF 2 4区地球科学 Q3 ECOLOGY

Polar Science

Pub Date : 2025-12-01 DOI: 10.1016/j.polar.2025.101214

Nikita Demidov , Sergey Verkulich , Zinaida Pushina , Elizaveta Rivkina , Denis Shmelev , Oksana Zanina , Natalya Belova , Martin Melles , Janet Rethemeyer

Drilling of 5 holes between the lakes Reid and Nella in the Larsemann Hills oasis of East Antarctica revealed up to 15 m thick Neogene - Quaternary deposits above bedrock. Laboratory analyses comprise cryolithological, geochemical, and micropaleontological investigations, as well as radiocarbon (¹⁴C) dating. The lowermost sediments according to key biostratigraphical taxa are of early Pliocene age and were deposited in shallow marine conditions. This unit is overlain by sediments, which according to ¹⁴C dating were deposited ca. 48.1–29.6 ka BP. Their formation in lacustrine-marine conditions, as reflected by results of multi-proxy laboratory studies, suggests that the relative sea level during Marine Isotope Stage 3 has been at least 32 m higher than present, in order to allow lagoon-type deposition, when fresh lake water mixed with sea water during high tides, or near coastal marine sedimentation, when sea water mixed with melt water from adjacent glaciers. The sediments at the top of the record are tills, consisting of a lateral moraine and an end moraine. Their distribution marks the extend of the last glaciation in the area, with ice masses moving northward during the pre-Antarctic Cold Reversal glaciation 14 ka BP, or during a minor Holocene ice advance.

在南极洲东部Larsemann Hills绿洲的Reid湖和Nella湖之间钻了5个洞，在基岩上发现了厚达15米的新近纪-第四纪沉积物。实验室分析包括冰晶学、地球化学和微古生物学调查，以及放射性碳（14C）测年。根据主要生物地层分类群划分的最底层沉积物为上新世早期，沉积于浅海环境。该单元被沉积物覆盖，根据14C测年，沉积时间约为48.1-29.6 ka BP。它们是在湖海条件下形成的，正如多代理实验室研究的结果所反映的那样，表明海洋同位素阶段3期间的相对海平面比现在至少高出32米，以便在涨潮期间允许淡水湖与海水混合的泻湖型沉积，或在靠近沿海的海洋沉积，当海水与邻近冰川的融水混合时。记录顶部的沉积物是由侧冰碛和终冰碛组成的斜坡。它们的分布标志着该地区末次冰期的延伸，在14 ka BP的南极前冷逆转冰期或全新世的一次小冰期期间，冰团向北移动。

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引用次数: 0

Evolution of the Archean crust in the Indian Ocean coastal sector (Napier Complex, and nearby areas) of Antarctica – Review 南极洲印度洋沿岸板块（纳皮尔杂岩及其附近地区）太古宙地壳演化综述

IF 2 4区地球科学 Q3 ECOLOGY

Polar Science

Pub Date : 2025-12-01 DOI: 10.1016/j.polar.2025.101266

Tomokazu Hokada , Simon L. Harley

The Antarctic continent preserves a long crustal history from Eoarchean through Proterozoic to Phanerozoic. This article summarizes the evolution of Archean crustal fragments in the Indian Ocean coastal sector of Antarctica (Dronning Maud Land, Enderby Land, Kemp Land and MacRobertson Land). The Napier Complex in Enderby Land and western Kemp Land is an Archean craton measureing 400 km by 200 km. It is characterized by old fragments >3850 Ma and high-T to ultrahigh-T regional metamorphism at about 2550–2480 Ma, thus recording a crustal history spanning nearly the entire Archean. The available data, which are sparse relative to the large area covered, suggest that several crustal components of different ages have come together to form the terrane. Numerous studies have focused on the UHT metamorphism of this terrane, with >1000–1100 °C peak metamorphic temperatures and subsequent isobaric cooling evident along with some local variations in the P–T evolutions. In addition to the Napier Complex, the surrounding Proterozoic metamorphic terranes, such as in the Lützow-Holm Complex, the Western Rayner Complex, the Rayner Complex, and the Rauer Islands, include several relatively small Archean crustal blocks. Some areas of the Rayner Complex are thought to be reworked parts of the Napier Complex (Oygarden Islands and the Edward VIII Gulf area). UHT metamorphism of Neoproterozoic to Cambrian age has also been demonstrated in these complex, polymetamorphic areas containing Archean protoliths (Rundvågshetta, Forefinger Point, Mather Supracrustals).

南极大陆保存了从太古宙到元古代到显生宙的漫长地壳历史。本文综述了南极洲印度洋沿岸板块（Dronning Maud Land、Enderby Land、Kemp Land和MacRobertson Land）太古宙地壳碎片的演化。恩德比地和肯普地西部的纳皮尔复合体是一个面积为400公里乘200公里的太古宙克拉通。以3850 Ma的古碎块和2550 ~ 2480 Ma左右的高t至超高t区域变质为特征，记录了几乎跨越整个太古代的地壳历史。现有的数据相对于覆盖的大面积来说是稀疏的，表明不同年龄的几种地壳成分聚集在一起形成了地体。大量的研究集中在该地块的超高温变质作用上，发现了1000-1100℃的峰值变质温度和随后的等压冷却，以及P-T演化的一些局部变化。除了纳皮尔杂岩，周围的元古代变质地体，如l佐-霍尔姆杂岩、西雷纳杂岩、雷纳杂岩和劳厄尔群岛，包括几个相对较小的太古代地壳块体。雷纳建筑群的一些区域被认为是纳皮尔建筑群（Oygarden群岛和爱德华八世海湾地区）的一部分。在这些含有太古宙原岩的复杂多变质区（rundv gshetta, Forefinger Point， Mather上地壳）也证实了新元古代至寒武纪的超高温变质作用。

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引用次数: 0

Atmospheric pressure waves and seismic signatures of the Hunga Tonga-Hunga Haʻapai eruption in Antarctica 南极洲Hunga Tonga-Hunga Ha wai apai火山喷发的大气压力波和地震特征

IF 2 4区地球科学 Q3 ECOLOGY

Polar Science

Pub Date : 2025-12-01 DOI: 10.1016/j.polar.2025.101233

Vivek Kumar , Rahul Kumar , B. Padma Rao , Anand K. Singh , Shailendra Saini , Vijay K. Soni

The eruption of the Hunga Tonga-Hunga Ha'apai volcano on January 15, 2022, marked a significant geological occurrences, deemed to be rare and powerful explosive event was observed globally. This research paper presents the detection of atmospheric pressure waves and seismic waves at Indian research bases in Antarctica, representing the first documented evidence of the detection of these volcanic seismic and air waves from Antarctica. Despite the considerable distance of 8560 km from the volcano eruption site to Bharati, and 9839 km to Maitri, seismic observations unveiled heightened volcanic activity during the eruption period, signaling increased detection of tectonic and magmatic activity in the region. The Broadband Seismological Observatory (code is BRTI) effectively detected and recorded seismic waves from the eruption, which released energy comparable to that of an earthquake with a surface wave magnitude (Ms) of ∼5.8. The waves took 11.91 min to reach BRTI, aligning precisely with the signal at ∼04:26:49 UTC. Analysis indicates the multiple eruptions of the HT-HH volcanic activity. Further, the findings of Atmospheric data underscore the significance of comprehensive monitoring and research to gain a comprehensive understanding of the intricate interactions between volcanic activity, atmospheric conditions, and the environment. Atmospheric waves, traveling at velocities of 313.5 m/s and 305.9 m/s, reached Bharati and Maitri in Antarctica, respectively.

2022年1月15日，Hunga Tonga-Hunga Ha'apai火山爆发，标志着一次重大的地质事件，被认为是罕见的、全球观测到的强大爆炸事件。本研究报告介绍了印度在南极洲的研究基地对大气压力波和地震波的探测，这是探测到这些来自南极洲的火山地震波和空气波的第一个文献证据。尽管从火山喷发点到巴拉蒂的距离为8560公里，到迈特里的距离为9839公里，但地震观测显示，火山喷发期间火山活动加剧，表明该地区构造和岩浆活动的探测增加。宽带地震观测站（代码BRTI）有效地探测并记录了火山喷发产生的地震波，释放的能量相当于表面波震级（Ms）为~ 5.8级的地震。波花了11.91分钟到达BRTI，与UTC 04:26:49的信号精确对齐。分析表明，HT-HH火山活动为多次喷发。此外，大气数据的发现强调了全面监测和研究的重要性，以全面了解火山活动、大气条件和环境之间复杂的相互作用。大气波以313.5米/秒和305.9米/秒的速度分别到达南极洲的巴拉蒂和迈特里。

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引用次数: 0

Origin of retrograde saline fluids during collision zone high-temperature metamorphism constrained from whole-rock sulfur isotope composition, the Sør Rondane Mountains, East Antarctica 东南极洲Sør Rondane山碰撞带高温变质过程中逆行含盐流体的成因及全岩硫同位素组成

IF 2 4区地球科学 Q3 ECOLOGY

Polar Science

Pub Date : 2025-12-01 DOI: 10.1016/j.polar.2025.101213

Tetsuo Kawakami , M. Satish-Kumar , Tokuya Mitsubori , Silpa Ammini Sasidharan , Hayato Ikeda , Fumiko Higashino , Tatsuro Adachi , Masaoki Uno

Origin of saline fluids infiltrated during the retrograde metamorphism in the Sør Rondane Mountains (SRM), East Antarctica is constrained using whole-rock sulfur isotopic compositions. The SRM exposes granulite facies lower crust of ca. 650-500 Ma continental collision zone from which syn-metamorphic Cl-rich fluid infiltrations have been reported. In this study, we determined whole-rock sulfur isotopic compositions of felsic and mafic gneisses with or without the evidence for saline fluid infiltrations. The felsic gneisses gave a wide range of δ³⁴S from −7.0 to +12.0 ‰ that overlap with δ³⁴S of modern sedimentary sulfides and sulfides in granitoids. The mafic gneisses mostly gave δ³⁴S from −6.0 to +3.9 ‰, consistent with δ³⁴S of sulfides in basalts and gabbros. A mafic wall rock of the Cl-rich hornblende-garnet selvage formed by retrograde saline fluid infiltration gave δ³⁴S of +12.8 ‰, which is higher than δ³⁴S of sulfides in basalts and gabbros, suggesting that the saline fluid added high δ³⁴S to the mafic wall rock. Since the Cl-rich selvages are connected to granitic veins, the source of saline fluid is considered as granitoids that intruded during the retrograde metamorphism. Felsic gneisses with high δ³⁴S have microstructural evidence of retrograde S-bearing fluid infiltration, such as garnet rim replaced by sulfide-bearing assemblage. Therefore, both mafic and felsic gneisses in the SRM are shown to have been affected by the saline-fluid infiltrations to rehydrate the collision zone lower crust. The hydration of the SRM by the saline fluids is likely caused by the post-kinematic granitoid intrusions postdating ca. 560 Ma.

利用全岩硫同位素组成分析了东南极洲Sør Rondane Mountains （SRM）逆变质过程中渗透的含盐流体的来源。SRM揭示了约650-500 Ma大陆碰撞带的麻粒岩相下地壳，并报道了同变质富cl流体的渗透。在这项研究中，我们测定了长英质和基性片麻岩的全岩硫同位素组成，无论是否有盐水渗透的证据。长英质片麻岩的δ34S范围为−7.0 ~ +12.0‰，与现代沉积硫化物和花岗岩类硫化物的δ34S有重叠。基性片麻岩的δ34S值大都在−6.0 ~ +3.9‰之间，与玄武岩和辉长岩硫化物的δ34S值一致。盐液逆行渗透形成的富cl角闪-石榴石镶边基性围岩δ34S值为+12.8‰，高于玄武岩和辉长岩硫化物的δ34S值，表明盐液对基性围岩增加了较高的δ34S。由于富cl边缘与花岗岩脉相连，盐液的来源被认为是在逆变质过程中侵入的花岗岩质。高δ34S长硅片麻岩具有含硫流体逆行渗透的显微结构证据，如石榴石边缘被含硫化物组合取代。因此，SRM中的基性和长英质片麻岩都受到了盐流体渗透的影响，以使碰撞带下地壳再水化。盐化流体对SRM的水化作用可能是由约560 Ma后运动后的花岗岩类侵入引起的。

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引用次数: 0

Neoproterozoic to Cambrian granitoids of northern Mozambique and Dronning Maud Land Antarctica: Implications for the assembly of Gondwana 莫桑比克北部和南极洲Dronning Maud大陆新元古代至寒武纪花岗岩类：对冈瓦纳组装的启示

IF 2 4区地球科学 Q3 ECOLOGY

Polar Science

Pub Date : 2025-12-01 DOI: 10.1016/j.polar.2025.101264

G.H. Grantham , P.H. Macey , M.P. Roberts , B.A. Ingram , R.A. Armstrong , K. Shiraishi , T. Hokada , B. Eglington , P. le Roux , G. Cune

The field relationships, petrography, whole rock major, trace element and radiogenic isotope chemistry and geochronology of Cambrian Granites granites from the Nampula Terrane (NT) Mozambique are reported. These data are compared with published data from Neoproterozoic to Cambrian granites from Central Dronning Land (CDML). Age comparisons include data from the Cabo Delgado/Namuno Terrane of northern Mozambique (CDNMT). Whereas there is significant overlap in the chemistry and ages of the granites from the NT, compared to those from CDML and CDNMT, indicating their possible genesis within the same broad orogenic event, subtle differences in mineralogy, chemistry and age are seen. These differences include subsolvus peraluminous mica-dominated granites with ages < ∼530 Ma in all three areas but concentrated in the NT, in contrast to dominantly metaluminous hypersolvus charnockitic syenogranites with ages > ∼530 Ma in CDML and CDTNM, but absent from the NT and western Sverdrupfjella. The differences between the two granite varieties are inferred to reflect differences in tectonic setting during genesis, with the marginally older CDML and CDTNM granites/charnockites resulting from decompression dehydration melting, dominantly of amphibole in the hanging wall of a mega-nappe. In contrast the marginally younger NT granites were generated dominantly from dehydration melting of mica in the footwall of the mega-nappe structure. Geophysical data indicate the thickened crust underlying the mega nappe in DML extends far in to Antarctica indicating much of East Antarctica may be underlain by allochthonous crust.

报道了莫桑比克南普拉地体（NT）寒武系花岗岩的野外关系、岩石学、全岩量、微量元素和放射性成因同位素化学及年代学。将这些资料与已发表的中央洼地（CDML）新元古代—寒武系花岗岩资料进行了比较。年龄比较包括来自莫桑比克北部Delgado/Namuno地块（CDNMT）的数据。与来自CDML和CDNMT的花岗岩相比，来自NT的花岗岩在化学成分和年龄上有明显的重叠，表明它们可能是在同一大造山事件中形成的，但在矿物学、化学成分和年龄上却存在细微的差异。这些差异包括亚溶质过铝云母为主的花岗岩，在所有三个地区，年龄为<； ~ 530 Ma，但主要集中在新界，而在CDML和CDTNM，年龄为>； ~ 530 Ma的高溶质炭质正长花岗岩则主要是成矿的，但在新界和西部Sverdrupfjella中没有。两种花岗岩品种的差异反映了成因时期构造环境的差异，CDML和CDTNM花岗岩/沙诺克岩的年龄稍老，主要是由减压脱水熔融形成的，主要是巨型推覆体上盘的角闪孔。相对较年轻的北系花岗岩主要由巨型推覆构造下盘云母脱水熔融形成。地球物理资料表明，DML巨型推覆体下的增厚地壳一直延伸到南极洲，这表明南极洲东部的大部分地区可能是由异源地壳下垫的。

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引用次数: 0

Isolation and primary characterisation of yeasts isolated from different ecosystems in East Antarctica 从东南极洲不同生态系统中分离的酵母的分离和初步特征

IF 2 4区地球科学 Q3 ECOLOGY

Polar Science

Pub Date : 2025-12-01 DOI: 10.1016/j.polar.2025.101262

Ekaterina A. Gribanova , Katsiaryna U. Akhremchuk , Ekaterina A. Semenchukova , Andrey V. Dolgikh , Veronika V. Shchur , Aleksey V. Yantsevich , Mikhail P. Andreev , Yury H. Hihiniak , Leonid N. Valentovich , Vladislav Y. Miamin

This study focused on the variety and biotechnological potential of yeast isolates from diverse ecosystems in East Antarctica (Thala Hills, Larsemann Hills, and Prince Charles Mountains). A total of 21 yeast strains were isolated from hypolithic and endolithic substrates, soil under moss-lichen communities, and meltwater ponds. Hypolithic communities harboured the highest microbial biomass and culturable yeast counts, suggesting their ecological significance in extreme habitats. Taxonomic identification was performed using MALDI-TOF MS and 18S rRNA gene sequencing, revealing affiliation with 10 genera (primarily Moesziomyces, Leucosporidium, Rhodotorula, and Sporobolomyces) across the phyla Ascomycota and Basidiomycota. The species Sporobolomyces phaffii was the most abundant. Physiological characterization demonstrated enzymatic activities (lipase, DNase, amylase, urease) of isolated yeasts at low temperatures; some strains exhibited antagonistic properties against bacteria. This work expands knowledge of cultivable Antarctic yeasts and highlights their adaptive traits for biotechnological applications, such as bioremediation and bioactive compound synthesis.

本研究重点研究了东南极洲（Thala Hills、Larsemann Hills和Prince Charles Mountains）不同生态系统中分离的酵母菌的种类和生物技术潜力。从土壤基质、内生基质、地衣群落土壤和融水池塘中分离到21株酵母菌。低产群落拥有最高的微生物生物量和可培养酵母菌数量，表明它们在极端生境中的生态意义。利用MALDI-TOF MS和18S rRNA基因测序对其进行分类鉴定，发现其隶属于子囊菌门和担子菌门的10个属（主要为Moesziomyces、Leucosporidium、Rhodotorula和Sporobolomyces）。phaffii孢子菌种类最多。生理特性证明了分离酵母在低温下的酶活性（脂肪酶、dna酶、淀粉酶、脲酶）；有些菌株对细菌有拮抗作用。这项工作扩大了对可栽培南极酵母的认识，并突出了它们在生物技术应用方面的适应特性，如生物修复和生物活性化合物合成。

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引用次数: 0

Geological evolution in East Antarctica and related Gondwana fragments 东南极洲的地质演化与相关的冈瓦纳碎片

IF 2 4区地球科学 Q3 ECOLOGY

Polar Science

Pub Date : 2025-12-01 DOI: 10.1016/j.polar.2025.101312

Tatsuro Adachi , Fumiko Higashino , Tomokazu Hokada

East Antarctica and its related Gondwana fragments offer a unique geological archive for understanding the evolution of Earth's continental crust and the assembly of supercontinents. These regions preserve Archean to Phanerozoic terranes which record crustal processes associated with supercontinent cycles such as Nuna, Rodinia, and Gondwana. Supercontinent formation is a one of the attractive topics in Earth science, not only for its role in crustal evolution but also for its broader impact on the dynamics of the crust–mantle–core system and on changes in climate and biological evolution. As a key region in Gondwana reconstruction, East Antarctica serves as an exceptional natural setting for investigating tectonic history. Comparative studies with fragments such as India, Sri Lanka, East Africa are essential for refining tectonic models and advancing our understanding of large-scale geological processes. This special issue presents recent advances in basement geology across these regions, aiming to establish a foundation for future integrative research on supercontinent dynamics.

东南极洲及其相关的冈瓦纳碎片为了解地球大陆地壳的演化和超大陆的组合提供了独特的地质档案。这些地区保存了太古宙到显生宙的地体，记录了与努纳、罗迪尼亚和冈瓦纳等超大陆旋回相关的地壳过程。超大陆的形成不仅在地壳演化中起着重要的作用，而且对地壳-幔-核系统的动力学、气候变化和生物演化具有广泛的影响，是地球科学研究的热点之一。东南极洲作为冈瓦纳大陆重建的关键区域，为研究构造史提供了独特的自然环境。与印度、斯里兰卡、东非等碎片的比较研究对于完善构造模型和提高我们对大规模地质过程的理解至关重要。本期特刊介绍了这些地区基底地质的最新进展，旨在为今后超大陆动力学的综合研究奠定基础。

引用次数: 0

Zircon geochronology of Mt. McMaster and Aker Peaks, Napier Complex, East Antarctica 南极洲东部纳皮尔杂岩麦克马斯特山和阿克峰的锆石年代学

IF 2 4区地球科学 Q3 ECOLOGY

Polar Science

Pub Date : 2025-12-01 DOI: 10.1016/j.polar.2025.101304

Mami Takehara , Kenji Horie , Tomokazu Hokada , Allen Nutman

U–Th–Pb geochronology and Th/U ratio analysis of zircon were performed on felsic orthogneiss of Mt. McMaster and Aker Peaks to examine the thermal history of the north-eastern region in the Napier Complex, East Antarctica. Zircons from the Mt. McMaster sample have apparent ages ranging from 2985 to 2462 Ma. Two younger zircon age clusters, 2486 Ma with Th/U ratios <0.1 and 2475 Ma with high Th/U ratios (>1), suggest two-stage zircon growth during c. 2.5 Ga regional metamorphism. Among pre-metamorphic older zircon ages up to 2981 Ma, the c. 2583 Ma is regarded as the timing of the emplacement, namely, protolith age. The older age components (2981–2683 Ma) are considered to be the exotic components derived from the surrounding crustal materials. The two successive generations of phlogopite-bearing felsic orthogneiss (type-1 and type-2) samples from Aker Peaks yield magmatic zircons with apparent ages of 3658–3470 Ma and 3745–3393 Ma. The type-2 orthogneiss also has metamorphic zircons of c. 2498 Ma, with high Th/U ratios indicating the incorporation of Th from the breakdown of Th-rich accessory phases, such as monazite, that occurred during c. 2500 Ma regional metamorphism. The type-1 felsic gneiss is enclosed within the type-2 felsic gneiss and is consistent with the older type-1 formation (c. 3572 Ma), including inherited components (>c. 3614 Ma), predated the younger type-2 formation (c. 3393 Ma). Magmatic ages of the orthogneiss from Aker Peaks in this study are consistent with the protolith ages from the orthogneiss of Rippon Point in Kemp Land.

通过对麦克马斯特山和阿克峰的长英质正长石进行U - Th - pb年代学和锆石Th/U比值分析，探讨了南极东部纳比尔杂岩东北地区的热史。麦克马斯特山锆石样品的表观年龄在2985 ~ 2462 Ma之间。两个较年轻的锆石年龄团，2486 Ma Th/U比值<；0.1和2475 Ma Th/U比值较高（>1），表明锆石在c. 2.5 Ga区域变质作用中有两期生长。前变质锆石年龄高达2981 Ma，其中c. 2583 Ma被认为是侵位的时间，即原岩年龄。年龄较大的成分（2981 ~ 2683 Ma）被认为是来自周围地壳物质的外来成分。Aker峰连续两代含辉云母的长英质正长岩（1型和2型）样品中，锆石表观年龄分别为3658 ~ 3470 Ma和3745 ~ 3393 Ma。2型正长岩中也有c. 2498 Ma的变质锆石，Th/U比值高，表明在c. 2500 Ma区域变质作用中出现的富Th副相（如独居石）的破碎中掺入了Th。1型长英质片麻岩被包裹在2型长英质片麻岩中，与较老的1型地层（c. 3572 Ma）一致，包括继承成分(>c。3614 Ma)，早于较年轻的2型地层（约3393 Ma）。本文研究的Aker峰正长岩年龄与Kemp地块Rippon Point正长岩的原岩年龄一致。

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引用次数: 0

Pressure-Temperature-time (P-T-t) evolution of pelitic granulites from the Larsemann Hills, East Antarctica: Insights from accessory mineral geochronology and phase equilibria modeling 南极东部Larsemann Hills泥质麻粒岩的压力-温度-时间（P-T-t）演化：来自辅助矿物年代学和相平衡模型的见解

IF 2 4区地球科学 Q3 ECOLOGY

Polar Science

Pub Date : 2025-12-01 DOI: 10.1016/j.polar.2025.101306

Nilanjana Sorcar , Sankar Bose , J. Amal Dev , Sneha Mukherjee , J.K. Tomson

Pelitic granulites from the Larsemann Hills, Prydz Bay, East Antarctica, preserve a complex polymetamorphic history associated with the supercontinent assembly. This study integrates mineral chemistry, geothermobarometry, phase equilibria modeling, and accessory mineral petrochronology to reconstruct the pressure-temperature-time (P-T-t) evolution of these rocks. Peak metamorphic conditions of ∼950 °C at 8.5 kbar were followed by retrogression along a clockwise P-T path marked by a near-isothermal decompression and a near-isobaric cooling. In situ U-Pb dating of zircon and monazite constrains the timing of peak metamorphism to ∼565 Ma, while apatite U-Pb ages of ∼526 Ma records the subsequent cooling. Older Neoproterozoic ages (∼822–862 Ma) preserved in zircon and monazite indicate an earlier metamorphic episode, reflecting a protracted tectonothermal evolution. Rare earth element partitioning between garnet and zircon supports garnet growth during the Ediacaran-Cambrian high-grade metamorphism. These data collectively document a ∼50 Myr duration of orogenesis and slow cooling rates, consistent with a collisional tectonic setting during the final assembly of East Gondwana, linking Prydz Bay with contemporaneous high-grade terranes in South India, Sri Lanka, and Madagascar.

东南极洲Prydz湾Larsemann Hills的泥质麻粒岩保存了与超大陆组合有关的复杂的多变质历史。本研究结合矿物化学、地温测量、相平衡模拟和辅助矿物岩石年代学，重建了这些岩石的压力-温度-时间（P-T-t）演化过程。在8.5 kbar ~ 950°C的峰值变质条件之后，沿着顺时针的P-T路径退行，标志着近等温减压和近等压冷却。锆石和独居石的原位U-Pb年龄限制了变质峰的时间为~ 565 Ma，而磷灰石的U-Pb年龄为~ 526 Ma，记录了随后的冷却。锆石和独居石中保存的较早的新元古代年龄（~ 822 ~ 862 Ma）反映了较早的变质期，反映了漫长的构造-热演化。稀土元素在石榴石和锆石之间的配分支持了埃迪卡拉-寒武系高变质期石榴石的生长。这些数据共同记录了约50兆卢比的造山作用和缓慢的冷却速率，与东冈瓦纳最终组装期间的碰撞构造环境相一致，将Prydz湾与同期南印度、斯里兰卡和马达加斯加的高等级地体联系起来。

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