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Petrology and geochemistry of Plio-Quaternary high-Nb basalts from Shahr-e-Babak area:Insights into post-collision magmatic processes in the Kerman Cenozoic Magmatic Arc Shahr-e-Babak地区上第四纪高铌玄武岩的岩石学和地球化学:对Kerman新生代岩浆弧碰撞后岩浆过程的认识
IF 1.5 4区 地球科学 Q3 Earth and Planetary Sciences Pub Date : 2022-08-31 DOI: 10.1344/geologicaacta2022.20.8
Sakine Moradi, T. Khaksar, Asma Nazarinia, Amjad Hussain
Post-collision Pliocene-Quaternary basaltic rocks outcrop in the Kerman Cenozoic Magmatic Arc (KCMA) to the northwest and east of Shahr-e-Babak city. These porphyritic and vesicular basaltic rocks are composed essentially of clinopyroxene, olivine, and plagioclase. These basalts display alkaline affinity and negative Ta, Zr, Rb anomaly, but slightly negative Nb anomaly, relative to elements with similar compatibility, and positive Ba, K, Sr anomaly, suggesting their magma source related to subduction-accretion with implication of subducted slab derived components to the source. In the primitive mantle and chondrite normalized diagrams, these rocks show trace elements (except depletion in Nb, Ta) and Rare Earth Element (REE) patterns similar to the Ocean Island Basalts (OIB) and share trace and major element characteristics similar to High-Nb Basalts (HNBs). Geochemical analyses for major and trace elements suggest that the Shahr-e-Babak HNBs have undergone insignificant crustal contamination and minor olivine + Fe-Ti oxide ±clinopyroxene fractional crystallization. These HNBs derived from a partial melting (~5%) of garnet-peridotite mantle wedge, which have already metasomatized by overlying sediments, fluids, and adakitic (slab-derived) melts as major metasomatic agents in post-collision setting in the KCMA. We conclude that asthenospheric upwelling arising from slab break-off followed by the roll-back of subducting Neotethys slab also triggered metasomatized peridotite mantle wedge and caused its partial melting in the subduction zone.
碰撞后的上新世-第四纪玄武岩在Shahr-e-Babak市西北和东部的克尔曼新生代岩浆弧(KCMA)中露头。这些斑状和泡状玄武岩主要由斜辉石、橄榄石和斜长石组成。这些玄武岩显示出碱性亲和性和负Ta、Zr、Rb异常,但相对于具有相似相容性的元素,显示出轻微的负Nb异常,以及正Ba、K、Sr异常,表明其岩浆源与俯冲吸积有关,并暗示俯冲板衍生成分与岩浆源有关。在原始地幔和球粒陨石归一化图中,这些岩石显示出类似于海岛玄武岩(OIB)的微量元素(Nb、Ta贫化除外)和稀土元素(REE)模式,并具有类似于高Nb玄武岩(HNBs)的微量和主元素特征。主要元素和微量元素的地球化学分析表明,Shahr-e-Babak HNBs经历了轻微的地壳污染和少量的橄榄石+Fe-Ti氧化物±单斜辉石分级结晶。这些HNBs来源于石榴石-橄榄岩-地幔楔的部分熔融(~5%),在KCMA碰撞后环境中,石榴石-橄榄石-地幔楔已经被上覆沉积物、流体和adakitic(板状)熔体交代为主要交代剂。我们的结论是,板块断裂引起的软流圈上升流伴随着俯冲的新特提斯板块的回滚,也触发了交代橄榄岩地幔楔,并导致其在俯冲带部分熔融。
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引用次数: 0
Modelling of the LTDE-SD radionuclide diffusion experiment in crystalline rock at the Äspö Hard Rock Laboratory (Sweden) 瑞典硬石实验室晶体岩石中LTE-SD放射性核素扩散实验建模
IF 1.5 4区 地球科学 Q3 Earth and Planetary Sciences Pub Date : 2022-07-28 DOI: 10.1344/geologicaacta2022.20.7
J. Soler, S. Meng, L. Moreno, I. Neretnieks, Longcheng Liu, P. Kekäläinen, M. Hokr, J. Říha, A. Vetešník, D. Reimitz, Jakub Višňák, D. Vopálka, Klaus-Peter Kröhn, Y. Tachi, Tsuyoshi Ito, U. Svensson, A. Iraola, P. Trinchero, M. Voutilainen, G. Deissmann, D. Bosbach, D. Park, S. Ji, L. Gvoždík, Martin Milický, M. Polak, B. Gylling, B. Lanyon
This study shows a comparison and analysis of results from a modelling exercise concerning a field experiment involving the transport and retention of different radionuclide tracers in crystalline rock. This exercise was performed within the Swedish Nuclear Fuel and Waste Management Company (SKB) Task Force on Modelling of Groundwater Flow and Transport of Solutes (Task Force GWFTS).Task 9B of the Task Force GWFTS was the second subtask within Task 9 and focused on the modelling of experimental results from the Long Term Sorption Diffusion Experiment in situ tracer test. The test had been performed at a depth of about 410m in the Äspö Hard Rock Laboratory. Synthetic groundwater containing a cocktail of radionuclide tracers was circulated for 198 days on the natural surface of a fracture and in a narrow slim hole drilled in unaltered rock matrix. Overcoring of the rock after the end of the test allowed for the measurement of tracer distribution profiles in the rock from the fracture surface (A cores) and also from the slim hole (D cores). The measured tracer activities in the rock samples showed long profiles (several cm) for non- or weakly-sorbing tracers (Cl-36, Na-22), but also for many of the more strongly-sorbing radionuclides. The understanding of this unexpected feature was one of the main motivations for this modelling exercise. However, re-evaluation and revision of the data during the course of Task 9B provided evidence that the anomalous long tails at low activities for strongly sorbing tracers were artefacts due to cross-contamination during rock sample preparation. A few data points remained for Cs-137, Ba-133, Ni-63 and Cd-109, but most measurements at long distances from the tracer source (>10mm) were now below the reported detection limits.Ten different modelling teams provided results for this exercise, using different concepts and codes. The tracers that were finally considered were Na-22, Cl-36, Co-57, Ni-63, Ba-133, Cs-137, Cd-109, Ra-226 and Np-237. Three main types of models were used: i) analytical solutions to the transport-retention equations, ii) continuum-porous-medium numerical models, and iii) microstructure-based models accounting for small-scale heterogeneity (i.e. mineral grains, porosities and/or microfracture distributions) and potential centimetre-scale fractures. The modelling by the different teams led to some important conclusions, concerning for instance the presence of a disturbed zone (a few mm in thickness) next to the fracture surface and to the wall of the slim hole and the role of micro-fractures and cm-scale fractures in the transport of weakly sorbing tracers. These conclusions could be reached after the re-evaluation and revision of the experimental data (tracer profiles in the rock) and the analysis of the different sets of model results provided by the different teams.
本研究对结晶岩中不同放射性核素示踪剂迁移和保留的现场实验建模结果进行了比较和分析。这项工作是在瑞典核燃料和废物管理公司(SKB)地下水流动和溶质输送建模工作队(GWFTS工作队)内进行的。GWFTS工作组的任务9B是任务9中的第二个子任务,重点是对长期吸附扩散实验原位示踪剂测试的实验结果进行建模。该测试是在约410米深的硬石实验室进行的。含有放射性核素示踪剂混合物的合成地下水在裂缝的自然表面和在未改变的岩石基质中钻出的狭窄小孔中循环198天。试验结束后对岩石进行过钻孔,可以测量破裂面(A岩芯)和细孔(D岩芯)岩石中的示踪剂分布剖面。岩石样品中测得的示踪剂活性显示,非或弱吸收示踪剂(Cl-36、Na-22)以及许多强吸收放射性核素的示踪剂活性都很长(几厘米)。对这一意外特征的理解是此次建模活动的主要动机之一。然而,在任务9B过程中对数据的重新评估和修订提供了证据,证明强吸收示踪剂低活性的异常长尾是由于岩石样品制备过程中的交叉污染造成的伪影。Cs-137、Ba-133、Ni-63和Cd-109的一些数据点仍然存在,但在距离示踪剂源较远(>10mm)的大多数测量值现在都低于报告的检测限值。10个不同的建模团队使用不同的概念和代码为本次演习提供了结果。最终考虑的示踪剂是Na-22、Cl-36、Co-57、Ni-63、Ba-133、Cs-137、Cd-109、Ra-226和Np-237。使用了三种主要类型的模型:i)输运-滞留方程的分析解,ii)连续多孔介质数值模型,以及iii)基于微观结构的模型,考虑小规模非均质性(即矿物颗粒、孔隙率和/或微裂缝分布)和潜在厘米级裂缝。不同团队的建模得出了一些重要结论,例如,在裂缝表面和细孔壁附近存在扰动带(厚度为几毫米),以及微裂缝和厘米级裂缝在弱吸收示踪剂传输中的作用。这些结论可以在对实验数据(岩石中的示踪剂剖面)进行重新评估和修订,并对不同团队提供的不同模型结果进行分析后得出。
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引用次数: 3
The early middle Eocene transition at the Esera valley 埃塞拉山谷早、中始新世的过渡
IF 1.5 4区 地球科学 Q3 Earth and Planetary Sciences Pub Date : 2022-07-12 DOI: 10.1344/geologicaacta2022.20.6
A. Barnolas, A. Rodríguez-Pintó, G. Bernaola, Emilio L. Pueyo, J. Tosquella, P. Arbués, R. Scholger
An integrated study including magnetostratigraphy, larger benthic foraminifera and calcareous nannofossil biostratigraphy is presented herein. This work was performed in shallow marine siliciclastics rich in larger foraminifera, around the Ypresian/Lutetian boundary in the Ésera valley (South-Central Pyrenees). Although the calcareous nannofossil content in the studied interval is low, not allowing a precise Y/L boundary to be recognised, the taxa found are enough to support the chronostratigraphic attribution.Data obtained in the Ésera valley section has improved the knowledge of larger benthic foraminifera (Nummulitesand Assilina) distribution through chron C21. SBZ 11 to SBZ 12 transition took place at the lowermost C21r, as shown in previous works. SBZ 12 assemblages extend into C21n, where the SBZ 12 to SBZ 13 boundary occurs. These data, obtained in shallow marine siliciclastic facies, with in situ fauna, results in a shift of the SBZ 12/SBZ 13 boundary to the Lower Lutetian, younger than previously believed. Accordingly, the Ypresian/Lutetian boundary occurs in SBZ 12.
本文对磁地层学、大型底栖有孔虫和钙质纳米化石生物地层学进行了综合研究。这项工作是在Ésera山谷(比利牛斯山脉中南部)Ypresian/Lutetian边界附近富含大型有孔虫的浅海硅塑料中进行的。虽然研究层段的钙质纳米化石含量较低,无法识别精确的Y/L边界,但所发现的分类群足以支持年代地层归属。通过C21时间,在Ésera流域剖面获得的数据提高了对大型底栖有孔虫(nummulites和Assilina)分布的认识。sbz11到sbz12的转变发生在最低的C21r,如之前的工作所示。sbz12组合延伸到C21n,在那里出现了sbz12和sbz13的边界。这些数据是在浅海硅岩相中获得的,具有原位动物群,结果表明sbz12 / sbz13边界向下鲁特梯的移动,比以前认为的要早。因此,Ypresian/Lutetian边界出现在sbz12。
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引用次数: 3
Distribution and provenance of heavy minerals from recent sediments of Green Lake, North Brazil, revisited 重访巴西北部绿湖近期沉积物中重矿物的分布和来源
IF 1.5 4区 地球科学 Q3 Earth and Planetary Sciences Pub Date : 2022-06-21 DOI: 10.1344/geologicaacta2022.20.5
A. C. S. Ribeiro, L. O. Santos, Paulo Cerqueira Dos Santos, R. M. Almeida, R. Mendes, A. Mendes
Geostatistical and multivariate statistical analyses were applied to heavy mineral data from an Amazonian fluvial-lake system near the Tapajós River mouth to investigate the spatial distribution and source-area of sediments. Twenty-one points were investigated, and the physical characteristics of the Green Lake deepest point were determined. Sand accumulates in the lake margins and mud quantity increases towards the lake center. Heavy mineral assemblage is composed of zircon, tourmaline, kyanite, rutile, staurolite, anatase, sillimanite, garnet, and spinel. Tourmaline, staurolite, and spinel are more abundant in the southeast area of the lake, while kyanite is dominant in the north area and zircon is in the whole lake except in its southeast area. Zircon - tourmaline and zircon - staurolite pairs are negatively correlated (r= -0.947 and -0.775, respectively), while tourmaline - staurolite and sillimanite - anatase pairs have a positive correlation (r= 0.628 and 0.675, respectively) which indicate different source rock types. Geostatistical analysis grouped the heavy minerals in three grups: Group 1 (tourmaline – staurolite – spinel - kyanite) and Group 2 (garnet – rutile – sillimanite - anatase) related to metamorphic source rocks ranging from medium to high grade, and Group 3 (zircon) related to acid igneous source rocks. The heavy mineral assemblage of Green Lake is analogous to the assemblage of the Alter do Chão Formation, indicating that this formation is the source of sediments of Green Lake.
将地统计学和多元统计分析应用于Tapajós河口附近亚马逊河湖系统的重矿物数据,以调查沉积物的空间分布和来源区域。对21个点进行了调查,确定了绿湖最深点的物理特征。沙在湖边缘堆积,泥量向湖中心增加。重矿物组合由锆石、电气石、蓝晶石、金红石、十字石、锐钛矿、硅线石、石榴石和尖晶石组成。电气石、十字石和尖晶石在湖的东南部地区更为丰富,蓝晶石在北部地区占主导地位,锆石除东南部地区外在整个湖中都有分布。锆石-电气石和锆石-十字石对呈负相关(r=-0.947和-0.775),电气石-十字石和硅线石-锐钛矿对呈正相关(r=0.628和0.675),表明不同的烃源岩类型。地质统计分析将重矿物分为三组:第1组(电气石-十字石-尖晶石-蓝晶石)和第2组(石榴石-金红石-硅线石-锐钛矿)与中高级变质烃源岩有关,第3组(锆石)与酸性火成烃源岩关系。绿湖的重矿物组合与Alter do Chão组的组合相似,表明该组是绿湖沉积物的来源。
{"title":"Distribution and provenance of heavy minerals from recent sediments of Green Lake, North Brazil, revisited","authors":"A. C. S. Ribeiro, L. O. Santos, Paulo Cerqueira Dos Santos, R. M. Almeida, R. Mendes, A. Mendes","doi":"10.1344/geologicaacta2022.20.5","DOIUrl":"https://doi.org/10.1344/geologicaacta2022.20.5","url":null,"abstract":"Geostatistical and multivariate statistical analyses were applied to heavy mineral data from an Amazonian fluvial-lake system near the Tapajós River mouth to investigate the spatial distribution and source-area of sediments. Twenty-one points were investigated, and the physical characteristics of the Green Lake deepest point were determined. Sand accumulates in the lake margins and mud quantity increases towards the lake center. Heavy mineral assemblage is composed of zircon, tourmaline, kyanite, rutile, staurolite, anatase, sillimanite, garnet, and spinel. Tourmaline, staurolite, and spinel are more abundant in the southeast area of the lake, while kyanite is dominant in the north area and zircon is in the whole lake except in its southeast area. Zircon - tourmaline and zircon - staurolite pairs are negatively correlated (r= -0.947 and -0.775, respectively), while tourmaline - staurolite and sillimanite - anatase pairs have a positive correlation (r= 0.628 and 0.675, respectively) which indicate different source rock types. Geostatistical analysis grouped the heavy minerals in three grups: Group 1 (tourmaline – staurolite – spinel - kyanite) and Group 2 (garnet – rutile – sillimanite - anatase) related to metamorphic source rocks ranging from medium to high grade, and Group 3 (zircon) related to acid igneous source rocks. The heavy mineral assemblage of Green Lake is analogous to the assemblage of the Alter do Chão Formation, indicating that this formation is the source of sediments of Green Lake.","PeriodicalId":55107,"journal":{"name":"Geologica Acta","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2022-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49192588","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Neotectonics of Turkey (Türkiye) and surrounding regions: a new perspective with block modelling 土耳其及其周边地区的新构造:块体建模的新视角
IF 1.5 4区 地球科学 Q3 Earth and Planetary Sciences Pub Date : 2022-04-28 DOI: 10.1344/geologicaacta2022.20.4
G. Seyitoğlu, B. Aktuğ, Korhan Esat, B. Kaypak
This paper aims to present a new neotectonic perspective concordant with the seismic activities in Turkey and surrounding regions. The neotectonic structures have been re-evaluated mainly by using focal mechanism solutions and high-resolution satellite (Google Earth) images. The Southeast Anatolian Wedge explains thrust/blind thrust and asymmetrical folding relationship in SE Turkey, Syria, and Northern Iraq. The neotectonic structures of the Turkish-Iranian Plateau are enlightened by the rhomboidal cell model which creates a base to determine multiple intersection points between the region-wide left- and right-lateral shear zones. The releasing stepover between the North Anatolian Fault Zone and Southeast Anatolian-Zagros Fault Zone plus their connections with the Northeast Anatolian Fault Zone and the East Anatolian Fault Zone are described in a more meaningful way with the Anatolian Diagonal concept. It also clarifies the role of left-lateral shear zone in the west-southwest movement of Anatolian plate and its relationship with the Aegean and Cyprus arcs. A neotectonic region under the influence of NW-SE contraction is determined between the North Anatolian, Eskişehir, and Kırıkkale-Erbaa fault zones in which the Elmadağ-Eldivan and Abdüsselam pinched crustal wedges and the Beypazarı Blind Thrust Zone are developed. A new route for the southern branch of the North Anatolian Fault Zone is determined between Bolu and Değirmenlik (Milos) Island in the Aegean Sea via Mudurnu, Bursa, Balıkesir, and İzmir. All main neotectonic structures mentioned in this paper are evaluated by the elastic dislocation modelling and new neotectonic provinces are suggested.
本文旨在提出一种与土耳其及周边地区地震活动相一致的新构造观点。主要利用震源机制解和高分辨率卫星(Google Earth)图像对新构造进行了重新评价。东南安纳托利亚楔解释了土耳其东南部、叙利亚和伊拉克北部的逆冲/盲冲和不对称褶皱关系。土耳其-伊朗高原的新构造结构受到菱形单元模型的启发,该模型为确定全区域左右横向剪切带之间的多个交点奠定了基础。用安纳托利亚对角线的概念对北安纳托利亚断裂带和东南安纳托利亚-扎格罗斯断裂带之间的释放阶跃及其与东北安纳托利亚断层带和东安那托利亚断层区的连接进行了更有意义的描述。它还阐明了左侧剪切带在安纳托利亚板块西-西南运动中的作用及其与爱琴海弧和塞浦路斯弧的关系。在北安那托利亚、埃斯基希尔和Kırıkkale Erbaa断裂带之间确定了一个受NW-SE收缩影响的新构造区,其中Elmadağ-Eldivan和Abdüsselam挤压地壳楔和Beypazarı盲冲断带发育。北安那托利亚断层带南部分支的新路线是在博卢和爱琴海的德米尔门里克岛之间确定的,途经穆杜努、布尔萨、巴尔凯希尔和伊兹密尔。利用弹性位错模型对本文所述的所有主要新构造进行了评价,并提出了新构造区。
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引用次数: 3
A new elasmobranch fauna from the early Miocene of Sharbithat (Sultanate of Oman) reveals the teeth of an ancient fantail stingray 在Sharbithat(阿曼苏丹国)中新世早期发现的一种新的板鳃科动物群揭示了一种古代扇尾黄貂鱼的牙齿
IF 1.5 4区 地球科学 Q3 Earth and Planetary Sciences Pub Date : 2022-03-01 DOI: 10.1344/geologicaacta2022.20.2
V. Charpentier, S. Adnet
Here we describe a new elasmobranch assemblage consisting of isolated dental material from the Aquitanian near-shore marine deposits of the Shuwayr and Warak formations at Sharbithat, in eastern Sultanate of Oman. The faunal composition clearly indicates affinities to other early Miocene elasmobranch-bearing localities worldwide. This assemblage is predominantly composed of large and common pelagic sharks as well as teeth attributable to a new species of fantail stingray, Taeniurops tosii, as old as the oldest undisputable fossil records of Taeniurops. The study of this fossil assemblage presented here improves the knowledge of the ancient elasmobranchs that frequented the eastern Arabian coasts during the closure of the Neotethys and the birth of the Arabian Sea.DOI: 10.1344/GeologicaActa2022.20.2
在这里,我们描述了一个新的火山分支组合,该组合由阿曼苏丹国东部Sharbithat的Shuwayr和Warak地层的Aquitanian近岸海洋沉积物中的孤立牙齿材料组成。动物区系的组成清楚地表明,它们与世界各地其他中新世早期的埃兰支植物区系有亲缘关系。这一组合主要由大型和常见的远洋鲨鱼以及扇尾黄貂鱼新物种tosii的牙齿组成,该物种的历史与最古老的无争议的无争议化石记录一样古老。对这一化石组合的研究提高了对在新特提斯关闭和阿拉伯海诞生期间经常出现在阿拉伯东部海岸的古代蓝鳃类的了解
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引用次数: 0
The paleoecology and depositional model of the Oligo-Miocene coral reefs in the Mohammad Abad Area, the west of Baft, SW Kerman, Iran 伊朗西南克尔曼Baft西部Mohammad Abad地区渐新世-中新世珊瑚礁的古生态与沉积模式
IF 1.5 4区 地球科学 Q3 Earth and Planetary Sciences Pub Date : 2022-01-31 DOI: 10.1344/geologicaacta2022.20.1
Fatemeh Hosseinipour
This paper deals with the Oligo-Miocene coral reefs in the Mohammadabad Area, W Baft, SW Kerman. The studied coral reefs include 11 families, 25 genera and 33 species of the scleractinian corals. The coral reef successions have deposited in three cycles on a mixed siliciclastic-carbonate platform. To understanding the paleoecology, reef architecture and depositional model of studied reefal successions, statistical analyses based on the coral niches, sedimentology analyses based on the grain size of the marly strata and microfacies analyses on limestone strata have used. Based on the statistical analyses, the coral community includes eight ecotypes. The distribution of these ecotypes indicates that, despite of various thicknesses, in all three coral reef successions, the branching and fast growth ecotypes are present at the basal parts and the massive, placoid and meandroid colonies are recorded in the slope, crest and distal parts of the reefs. The main disruptive phenomenon that stopped the reef development and affected the reef architecture has been the addition of clastic deposits to the carbonate system. This sediment load increase is recorded as marly strata. By The addition of clastic sediment load to the system, the carbonate content of the system has diluted, the salinity, water transparency and photic level is decreased, the favorable attachment hard substrate for coral polyps is limited, the nutrient and oxygen flux is disrupted and the coral reefs are suffocated.
本文研究了位于W Baft, SW Kerman的Mohammadabad地区的渐新世-中新世珊瑚礁。研究的珊瑚礁包括石珊瑚11科25属33种。珊瑚礁序列在一个硅-塑料-碳酸盐混合台地上分三个旋回沉积。为了了解所研究的珊瑚礁演替的古生态学、礁体结构和沉积模式,采用了基于珊瑚生态位的统计学分析、基于泥灰岩地层粒度的沉积学分析和基于灰岩地层微相分析的沉积学分析。根据统计分析,珊瑚群落包括8个生态型。这些生态型的分布表明,尽管厚度不同,但在所有3个珊瑚礁演替中,基部均存在分枝型和快速生长型生态型,而在珊瑚礁的斜坡、顶部和远端均存在块状、平片状和锥形生态型。停止礁体发育并影响礁体结构的主要破坏现象是碎屑沉积加入碳酸盐体系。这种泥沙负荷的增加被记录为泥灰地层。碎屑沉积物负荷的加入,稀释了体系的碳酸盐含量,降低了盐度、水体透明度和光照水平,限制了珊瑚虫有利的附着硬基质,破坏了营养和氧通量,使珊瑚礁窒息。
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引用次数: 0
The enriched Variscan lithosphere of NE Iberia: data from postcollisional Permian calc-alkaline lamprophyre dykes of Les Guilleries 伊比利亚东北部富Variscan岩石圈:Les Guilleries碰撞后二叠纪钙碱性煌斑岩脉资料
IF 1.5 4区 地球科学 Q3 Earth and Planetary Sciences Pub Date : 2021-12-07 DOI: 10.1344/geologicaacta2021.19.15
Esteban Mellado, M. Corbella, Didac Navarro, Andrew R. C. Kylander
Post-collisional mafic dykes crosscut the Paleozoic metamorphic basement and late-Variscan plutons in Les Guilleries massif (Catalan Coastal Ranges, NE Iberia). The predominance of mafic phenocrysts, porphyritic texture, abundant amphibole, high MgO and volatile content, together with crustal-like trace-element patterns indicate that the dykes correspond to calc-alkaline lamprophyres, mainly spessartites. Their enrichment in LILE, HFSE and REE and initial Sr-Nd isotopic compositions (87Sr/86Sri between 0.70851 and 0.71127, epsilon Ndi between -5.23 and -4.63) are consistent with an enriched subcontinental lithospheric mantle source. U-Pb ages of matrix titanite crystals yield concordia ages of 262±7Ma, congruent with crosscutting relationships. Postmagmatic processes are evidenced by intense chloritization and albitization of the lamprophyres, together with systematic variations of Na2O vs SiO2, K2O, CaO, Ba, Rb, Cs, Pb, Sr, Tl, and Zn, and possibly the removal of F. The geochemical and geochronological data support an orogenic geochemical affinity, in accordance with the transitional tectonic regime between Variscan compression/transpression and post-collisional transtension/extension, related to the fragmentation of Pangea and thinning of the lithosphere. The lamprophyre dykes studied could represent the youngest pulse of Variscan orogenic magmatism and, therefore, mark its end in NE Iberia before the onset of the generalized Triassic extension.
伊比利亚东北部加泰罗尼亚海岸山脉Les Guilleries地块古生代变质基底和晚variscan岩体的碰撞后基性岩脉横切。基性斑晶为主,斑状结构,角闪孔丰富,MgO和挥发物含量高,并伴有类地壳微量元素模式,表明其为钙碱性煌斑岩,以花斑岩为主。它们在LILE、HFSE和REE中的富集和初始Sr-Nd同位素组成(87Sr/86Sri在0.70851 ~ 0.71127之间,epsilon Ndi在-5.23 ~ -4.63之间)与富集的次大陆岩石圈地幔源相一致。基体钛矿的U-Pb年龄为262±7Ma,符合横切关系。岩浆作用表现为煌斑岩强烈的绿岩化和钠长岩化,Na2O对SiO2、K2O、CaO、Ba、Rb、Cs、Pb、Sr、Tl和Zn的系统变化,可能还有f的消失。地球化学和年代学数据支持造山带地球化学亲和力,符合Variscan压缩/压迫和碰撞后拉伸/伸展之间的过渡构造制度。与盘古大陆的破碎和岩石圈的变薄有关。研究的煌斑岩脉可以代表Variscan造山岩浆活动的最年轻脉冲,因此标志着它在广义三叠纪伸展开始之前结束于伊比利亚东北部。
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引用次数: 0
Carbon and oxygen stable isotope record of upper Kimmeridgian shallow-marine ramp carbonates (Iberian Basin, NE Spain): the imprint of different burial and tectonic histories 西班牙东北部伊比利亚盆地上kimmeridian浅海相斜坡碳酸盐岩碳氧稳定同位素记录:不同埋藏和构造历史的印记
IF 1.5 4区 地球科学 Q3 Earth and Planetary Sciences Pub Date : 2021-11-26 DOI: 10.1344/geologicaacta2021.19.14
C. Sequero, G. Della Porta, B. Bádenas, M. Aurell
Bulk carbon and oxygen stable isotopes of ancient shallow-marine carbonates can record the effects of multiple palaeoenvironmental factors, but also the imprint of several post-depositional processes, which may alter the original marine isotopic composition. In this study, carbon and oxygen stable isotope analyses were performed on bulk carbonate, bivalve calcitic-shell (Trichites) and calcite vein samples from two stratigraphic sections (Tosos and Fuendetodos, present-day distance 15km), representing proximal inner- and distal mid-ramp environments, respectively, of the uppermost Kimmeridgian ramp facies deposited in the northern Iberian Basin (NE Spain). These successions underwent different diagenetic pathways that altered the primary marine isotopic composition in each section in different ways. Different burial histories, tectonic uplift and a variable exposure to meteoric diagenesis from the end of the Kimmeridgian to the Cenozoic (following Alpine tectonic uplift) are reflected in the different alteration patterns of the carbon and oxygen stable isotope signatures. A significant deviation to lower values in both δ13O and δ18O is recorded in those carbonates mostly exposed to meteoric diagenesis (distal mid-ramp Fuendetodos section), because of post-depositional tectonic uplift (telogenesis). On the other hand, the deposits mainly affected by burial diagenesis (proximal inner-ramp Tosos section) only record low δ18O with respect to expected values for pristine Kimmeridgian marine carbonates. The different burial and tectonic uplift histories of these deposits in each sector, due to their different tectonic evolution in this part of the basin, resulted in a variable degree of diagenetic resetting. However, in spite of the different diagenetic resetting reported of the carbon and oxygen stable isotope signatures in each section, these carbonates show similar cement types in termsof fabrics and cathodoluminescence properties. The diagenetic resetting reported for these carbonates prevents the use of the δ13O and δ18O records for addressing palaeoenvironmental interpretations, but instead highlights useful features regarding the variable diagenetic overprint of the studied shallow-marine carbonate successions concerning their specific post-depositional history.
古浅海碳酸盐岩的体碳和氧稳定同位素可以记录多种古环境因素的影响,也可以记录几个沉积后过程的印记,这些过程可能会改变原始海洋同位素组成。在这项研究中,对来自两个地层剖面(Tosos和Fuendetodos,目前距离15km)的大块碳酸盐、双壳钙化壳(Trisites)和方解石脉样品进行了碳和氧稳定同位素分析,分别代表近端内斜坡和远端中斜坡环境,沉积在伊比利亚盆地北部(西班牙东北部)的最上层Kimmeridian斜坡相。这些序列经历了不同的成岩途径,以不同的方式改变了每个剖面的原始海洋同位素组成。碳和氧稳定同位素特征的不同蚀变模式反映了从Kimmeridgian末期到新生代(阿尔卑斯构造抬升之后)的不同埋藏历史、构造抬升和对大气成岩作用的不同暴露。在那些主要暴露于大气成岩作用的碳酸盐岩(远中斜坡Fuendetodos剖面)中,由于沉积后构造抬升(终生作用),记录到δ13O和δ18O均显著偏离较低值。另一方面,主要受埋藏成岩作用影响的矿床(近端内斜坡Tosos剖面)相对于原始Kimmeridian海相碳酸盐岩的预期值,仅记录到较低的δ18O。由于盆地这一部分的构造演化不同,这些矿床在每个区段的埋藏和构造抬升历史不同,导致了不同程度的成岩重置。然而,尽管每个剖面中碳和氧稳定同位素特征的成岩重置不同,但这些碳酸盐在组构和阴极发光特性方面表现出相似的胶结物类型。据报道,这些碳酸盐岩的成岩重置阻止了使用δ13O和δ18O记录来处理古环境解释,而是突出了所研究的浅海碳酸盐岩序列的可变成岩叠加的有用特征,这些特征涉及其特定的沉积后历史。
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引用次数: 0
Pliocene marine Bivalvia of Vale do Freixo (Pombal, Portugal): updated taxonomic list and discussion 葡萄牙庞巴尔Freixo谷上新世海相双壳类:更新的分类表和讨论
IF 1.5 4区 地球科学 Q3 Earth and Planetary Sciences Pub Date : 2021-11-24 DOI: 10.1344/geologicaacta2021.19.13
R. Pimentel, P. Callapez, P. Legoinha
The exceptional Pliocene marine faunal assemblages of west central Portugal have been known since the late 19th century. They include highly diverse molluscan faunas whose study is far to be completed. Discovered nearly 40 years ago, Vale do Freixo (Carnide, Pombal) is perhaps the most outstanding fossil site. Neverthless, the bivalves remain relatively unknown. This study focuses on the taxonomy of this relevant group of marine Mollusca. The research, based on a detailed sampling of three fossiliferous beds from the Carnide Formation, yielded a list of 85 species belonging to 75 genera and 32 families. Forty-three species are new for the Carnide area and twenty-three are reported for the first time in the Portuguese Pliocene, increasing to 115 the number of known species in the Mondego Basin in the Beira Litoral.
自19世纪后期以来,葡萄牙中西部独特的上新世海洋动物群就已为人所知。它们包括高度多样化的软体动物,对它们的研究还远未完成。近40年前发现的Vale do Freixo (Carnide, Pombal)可能是最杰出的化石遗址。尽管如此,双壳类动物仍然相对不为人所知。本文对这一相关类群的海洋软体动物进行了分类研究。这项研究基于对食肉动物组的三个化石层的详细采样,得出了32科75属85个物种的名单。在Carnide地区发现了43种新物种,在葡萄牙上新世首次报道了23种,使贝拉沿岸Mondego盆地的已知物种数量增加到115种。
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引用次数: 0
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Geologica Acta
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