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Paleozoic-Mesozoic thermal evolution along the East European Platform margin based on kerogen thermal maturity analysis combined with apatite and zircon low temperature thermochronology in NE Poland
Solid Earth ( IF 3.2 ) Pub Date : 2021-02-04 , DOI: 10.5194/se-2021-8
Dariusz Botor , Stanisław Mazur , Aneta A. Anczkiewicz , István Dunkl , Jan Golonka

Abstract. The Phanerozoic tectono-thermal evolution of the SW slope of the East European Platform (EEP) in Poland is reconstructed by means of thermal maturity, low temperature thermochronometry and thermal modelling. We provide a set of new thermochronometric data and integrate stratigraphic and thermal maturity information to constrain the burial and thermal history of sediments. Apatite fission track analysis (AFT) and zircon (U-Th)/He (ZHe) thermochronology have been carried out on samples of sandstones, bentonites, diabase and crystalline basement rocks collected from 17 boreholes located in central and NE Poland. They penetrated sedimentary cover of the EEP subdivided from the north to south into the Baltic, Podlasie and Lublin Basins. The average ZHe ages from Proterozoic basement rocks as well as Ordovician to Silurian bentonites and Cambrian to lower Carboniferous sandstones range from 848 ± 81 Ma to 255 ± 22 Ma with a single early Permian age of 288 Ma, corresponding to cooling after a thermal event. The remaining ZHe ages represent partial reset or source ages. The AFT ages of samples are dispersed in the range of 235.8 ± 17.3 (Middle Triassic) to 42.1 ± 11.1 (Paleogene) providing a record of Mesozoic and Cenozoic cooling. The highest frequency of the AFT ages is in the Jurassic and Early Cretaceous prior to Alpine basin inversion. Thermal maturity results are consistent with the SW-ward increase of the Palaeozoic and Mesozoic sediments thickness. An important break in a thermal maturity profile exists across the base Permian-Mesozoic unconformity. Thermal modelling showed that significant heating of Ediacaran to Carboniferous sedimentary successions occurred before the Permian with maximum paleotemperatures in the earliest and latest Carboniferous for Baltic-Podlasie and Lublin Basins, respectively. The results obtained suggest an important role of early Carboniferous uplift and exhumation at the SW margin of the EEP. The SW slope of the latter was afterward overridden in the Lublin Basin by the Variscan orogenic wedge. Its tectonic loading interrupted Carboniferous uplift and caused resumption of sedimentation in the late Viséan. Consequently, a thermal history of the Lublin Basin is different from that in the Podlasie and Baltic Basins, but similar to other sections of the Variscan foreland, characterised by maximum burial at the end of Carboniferous. The Mesozoic thermal history was characterised by gradual cooling from peak temperatures at the transition from Triassic to Jurassic due to decreasing heat flow. Burial caused maximum paleotemperatures in the SW part of the study area, where the EEP was covered by an extensive sedimentary pile. However, farther NE, due to low temperatures caused by shallow burial, the impact of fluids can be detected by VR, illite/smectite and thermochronological data.

中文翻译:

基于干酪根热成熟度分析与磷灰石和锆石低温热年代学相结合的波兰东北部沿东欧平台边缘的古生代-中生代热演化

摘要。通过热成熟度,低温热计时法和热模拟方法重建了波兰东欧平台(EEP)西南斜坡的生代构造热演化。我们提供了一组新的热计时数据,并整合了地层和热成熟度信息,以限制沉积物的埋藏和热历史。磷灰石裂变径迹分析(AFT)和锆石(U-Th)/ He(ZHe)热年代学是对从波兰中部和东北部的17个钻孔中收集的砂岩,膨润土,辉绿岩和结晶基底样品进行的。它们穿透了从北到南细分为波罗的海,波德拉西和鲁布林盆地的EEP的沉积覆盖层。从元古生代基底岩石,奥陶纪到志留纪膨润土,寒武纪到低石炭纪砂岩的平均ZHe年龄范围为848±81 Ma至255±22 Ma,其中二叠纪的单一早年龄为288 Ma,这对应于热事件后的冷却作用。剩余的ZHe年龄代表部分重置或来源年龄。样品的AFT年龄分布在235.8±17.3(中三叠纪)至42.1±11.1(古生代)之间,提供了中生代和新生代冷却的记录。AFT年龄的最高频率出现在侏罗纪和早白垩世,然后是高山盆地反转。热成熟度结果与古生代和中生代沉积物的西南向增加一致。整个二叠纪-中生代不整合面都存在热成熟度剖面的重要突破。热模型表明,在波罗的海-波德莱西盆地和鲁布林盆地最早和最新的石炭纪之前,二叠纪之前埃迪卡拉car对石炭纪的沉积演替发生了显着加热,古温度最高。获得的结果表明,早期石炭纪隆升和掘尸在EEP的西南边缘起着重要作用。后者的西南坡后来被瓦里斯坎造山楔覆盖在鲁布林盆地。它的构造负荷中断了石炭纪隆升,并导致维森后期的沉积恢复。因此,鲁布林盆地的热史不同于Podlasie和波罗的海盆地的热史,但与瓦里斯坎前陆的其他地区相似,其特征是石炭纪末期的最大埋葬量。中生代的热历史的特征是由于热流的减少,从三叠纪向侏罗纪过渡的峰值温度逐渐冷却。在研究区域的西南部,埋葬造成了最高的古温度,在该区域,EEP被大量沉积物覆盖。然而,更远的东北,由于埋藏浅而导致的低温,可以通过VR,伊利石/蒙脱石和热年代学数据来检测流体的影响。
更新日期:2021-02-04
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