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Aaron GRONSTAL Victoria PEARSON Andreas KAPPLER Craig DOORIS Mahesh ANAND Franck POITRASSON Terence P. KEE Charles S. COCKELL 《Meteoritics & planetary science》2009,44(2):233-247
Abstract— Batch culture experiments were performed to investigate the weathering of meteoritic material by iron‐oxidizing bacteria. The aerobic, acidophilic iron oxidizer (A. ferrooxidans) was capable of oxidizing iron from both carbonaceous chondrites (Murchison and Cold Bokkeveld) and iron meteorites (York and Casas Grandes). Preliminary iron isotope results clearly show contrasted iron pathways during oxidation with and without bacteria suggesting that a biological role in meteorite weathering could be distinguished isotopically. Anaerobic iron‐oxidizers growing under pH‐neutral conditions oxidized iron from iron meteorites. These results show that rapid biologically‐mediated alteration of extraterrestrial materials can occur in both aerobic and anaerobic environments. These results also demonstrate that iron can act as a source of energy for microorganisms from both iron and carbonaceous chondrites in aerobic and anaerobic conditions with implications for life on the early Earth and the possible use of microorganisms to extract minerals from asteroidal material. 相似文献
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Evidence for significant clockwise rotations of the Korean Peninsula during Cretaceous 总被引：1，自引：0，他引：1
Youn Soo Lee Hyun-Chul Han Jae Ha Hwang Weon-Seo Kee Bok Chul Kim 《Gondwana Research》2011,20(4):904-918
In an effort to evaluate the Cretaceous magnetostratigraphy for the Korean Peninsula and to establish the tectonic coherence of its various elements, we collected paleomagnetic data from 121 samples from 20 sites within the Chilgok Formation (108.3–109.9 Ma) in the Gyeongsang Basin. Together with previously published data, we evaluate the results from a total of 163 sites in the basin.We combine our age model with results from recent stratigraphic, paleomagnetic and radiometric geochemical studies. In this study, we found that two distinct declination shifts decrease with younging direction, indicating two clockwise rotational events of the Korean Peninsula with respect to the Eurasia continent. The earlier event took place during 130–100 Ma (Phase I, newly termed “Goguryeo Disturbance”) and a later one during 80–50 Ma (Phase III, belonging to “Bulguksa Orogeny”). The mean rotation rate in the interval from 115.2 to 103.8 Ma (Phase I) is about 0.74°/Ma, while the rate from 90.9 to 79.8 Ma (Phase II) is 0.19°/Ma. Based on paleolatitude change during Phase I, we infer that the Korean Peninsula (eastern part of the Sino-Korea Block) migrated southward about 300 km after the complete amalgamation of the Sino-Korea Block into the Eurasian continent resulting in N–S compression within the Korean peninsula and Manchuria. Large-scale strike-slip faults (e.g., Tan-Lu Fault, Okcheon Boundary Fault) were probably rejuvenated in the Sino-Korea Block during Phase I. 相似文献
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The Honam shear zone, dextrally running along the southern margin of the Ogcheon belt, Korea, has drawn much attention in reconstructing the Mesozoic tectonic framework of northeastern Asia. Here we present Rb–Sr data for the middle to southwestern part of the Honam shear zone, in an attempt to directly determine ages of deformation. In the middle part, the younger limit of deformation is constrained to be 162 ± 11 Ma by feldspar–biotite Rb–Sr dating of the deformed Sunchang granodiorite. On the other hand, an early Cretaceous deformation age is estimated for synkinematic fibers in ultramylonites from the southwestern part by two reproducible Rb–Sr errorchrons at 138 ± 4 and 139 ± 23 Ma. This deformational time scale is consistent with earlier interpretations based on field evidence, magnetic susceptibility data, and age data for Jurassic plutons within the shear zone. Our data demonstrate that the Honam shear zone is not a Permian to Triassic tectonic feature related to the Chinese continental collision. 相似文献
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