Timing of Upper Carboniferous-Permian horst-basin formation and magmatism in the NW Thuringian Forest, central Germany: a review
Timing of Upper Carboniferous-Permian horst-basin formation and magmatism in the NW Thuringian Forest, central Germany: a review
复制标题
德国中部图林根森林西北部上石炭统-二叠纪地垒盆地形成和岩浆作用的时间：综述
DOI：
--
复制
发表时间：
2004
期刊：
影响因子：
--
通讯作者：
H. Brätz
中科院分区：
文献类型：
--
作者：
A. Zeh;H. Brätz
摘要德国图林根森林地区晚石炭世-早二叠世沿着北西向弗兰肯断裂系和平行断裂的右旋扭张运动，引起复杂的块断作用，并伴有强烈的岩浆活动。这是很好的约束地质年代学数据（207 Pb/206 Pb单锆石，SHRIMP，40 Ar/39 Ar云母，锆石裂变径迹年龄），现场关系，和沉积记录从Ruhla晶体复杂（RCC）和周围环境。综合数据表明，Ruhla结晶杂岩断裂成三个近南北走向的段，经历了不同的剥露历史，在晚石炭世-二叠纪时代。RCC的中央部分被挖出了几公里，作为一个地垒块，而东部和西部部分同时下沉，分别形成了Oberhof和Eisenach磨拉石盆地的基底。中段晚石炭世-二叠纪的隆升受到白云母和黑云母的~（40）Ar/~（39）Ar冷却年龄（311 ± 3）Ma和~（294-288 ± 3）Ma、锆石裂变径迹加权年龄（272 ± 7）Ma以及上覆的Zechstein沉积物的制约。而东段的40 Ar/39 Albiotite冷却年龄在336 ± 4 ~ 323 ± 3 Ma之间，出露时间约为c. 300 ~ 300 Ma，被磨拉石沉积和火山岩覆盖。275 Ma.西段也被下二叠统火山岩覆盖，单颗粒锆石裂变径迹年龄为297 ± 29 Ma，因此推测西段也经历了类似的晚石炭世演化。同时地垒和盆地的形成还受到Oberhof和Eisenach盆地砾岩中花岗岩卵石的限制。这些卵石部分来源于碾压混凝土中心段的花岗岩。Ruhla结晶杂岩及其周围的花岗岩体和岩墙的年龄数据和方向提供了证据，300和294 Ma之间的NE向结构的开放，以及290和275 Ma之间的W-到NW向结构的形成或重新激活。图林根森林地区的岩浆活动可能是由晚石炭世-早二叠世期间欧洲中部广泛的地幔上涌造成的。
Abstract During Late Carboniferous-Early Permian times dextral transtensional movements along the NW-trending Franconian Fault System and parallel faults caused complex block faulting in the Thuringian Forest region, Germany, accompanied by intense magmatism. This is well constrained by geochronological data (207Pb/206Pb single zircon, SHRIMP, 40Ar/39Ar mica, zircon fission-track ages), field relations, and the sedimentary record from the Ruhla Crystalline Complex (RCC) and surroundings. The combined dataset indicates that the Ruhla Crystalline Complex was faulted into three nearly N-S-trending segments, which underwent different exhumation histories during Late Carboniferous-Permian times. The central segment of the RCC was exhumed by several kilometres as a horst block, while the eastern and western segments subsided simultaneously, forming the basement to the Oberhof and Eisenach molasse basins, respectively. Late Carboniferous-Permian uplift of the central segment is constrained by 40Ar/39Ar cooling ages of 311 ± 3 (muscovite) and 294–288 ± 3 Ma (biotite), a weighted zircon fission-track age of 272 ± 7 Ma and overlying Zechstein sediments. In contrast, the eastern segment shows much older 40Ar/39Albiotite cooling ages between 336 ± 4 and 323 ± 3 Ma, was exposed at c. 300 Ma, and subsequently covered by molasse sediments and volcanic rocks between 300 and c. 275 Ma. A similar Late Carboniferous evolution is inferred for the western segment, as it is also overlain by Lower Permian volcanic rocks and has a 297 ± 29 Ma single zircon fission-track age. Simultaneous horst and basin formation is additionally constrained by granite pebbles in conglomerates of the Oberhof and Eisenach basins. These pebbles can partly be derived from granites in the central segment of the RCC. Age data and the orientation of granitoid bodies and dykes in the Ruhla Crystalline Complex and its surroundings provide evidence for the opening of NE-trending structures between 300 and 294 Ma, and formation or reactivation of W- to NW-trending structures between 290 and 275 Ma. Magmatic activity in the Thuringian Forest region may have been caused by widespread mantle upwelling in central Europe during the Late Carboniferous-Early Permian.