The fidelity of paleomagnetic records carried by magnetosome chains
The fidelity of paleomagnetic records carried by magnetosome chains
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磁小体链携带的古地磁记录的保真度
DOI：
10.1016/j.epsl.2013.09.031
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发表时间：
2013-04
影响因子：
5.3
通讯作者：
Pan YX
中科院分区：
文献类型：
--
作者：
Paterson, GA;Wang YZ;Pan YX
趋磁细菌（MTB）利用磁小体（磁性晶体）的排列链作为导航工具，广泛存在于现代海洋、河流和湖泊环境中，其化石遗迹在地质记录中越来越多地被认识。尽管越来越多的人认识到，生物来源的磁性颗粒可能在沉积磁化中发挥关键作用，但很少有人知道它们可能对古地磁记录的保真度产生的影响。使用培养的磁细菌菌株AMB-1，我们进行了简单的2D（即，零倾角）沉积实验，以评估磁小体链沿沿着磁场线排列的效率以及这对古地磁记录的影响。我们的研究结果表明，沉积MTB获得的自然反射磁化（NRM）与外加磁场（0-120 μT）接近线性，但NRM的获得并不完全遵循假设的线性趋势，并且在外加磁场增加6倍以上时，仅观察到NRM强度增加了2.55倍（即，比假设的趋势低9%）。无滞后剩磁（ARM）和饱和等温剩磁（SIRM）归一化相对古强度（RPI）都可以成功地恢复相同情况下的场强变化。当初始溶液的MTB浓度变化（高达因子8）时，由MTB携带的NRM以预期的方式响应（即，细菌的加倍产生NRM强度的加倍）。然而，ARM和SIRM都没有像预期的那样响应：浓度加倍对应于SIRM强度增加1.76，ARM强度仅增加1.63。两者都受到静磁相互作用的影响，静磁相互作用产生于细菌细胞的紧密堆积或单个细菌细胞内的子链相互作用。然而，一阶反转曲线（FORC）图太不敏感，不能指示古地磁相关磁相互作用的存在。基于剩磁的方法（即，ARM比率）更适合于检测这种相互作用。
Magnetotactic bacteria (MTB), which use aligned chains of magnetosomes (magnetic crystals) as a navigation tool, are found in a wide range of modern day marine, river and lacustrine environments and their fossilized remains are being increasing recognized in geological records. Despite an increasing realization that biogenically derived magnetic particles may play a key role in sedimentary magnetizations, little is known about the influence that they may have on the fidelity of paleomagnetic recordings. Using culturedMagnetospirillum magneticumstrain AMB-1, we have conducted simple 2D (i.e., zero-inclination) deposition experiments to assess the efficiency with which magnetosome chains align along magnetic field lines and the implications that this has for paleomagnetic records. Our results indicate that the natural remanent magnetization (NRM) acquired by deposited MTB is near linear with applied field (0–120 μT), but that NRM acquisition does not perfectly follow the assumed linear trend and over a six-fold increase in applied field only a factor ∼5.5 increase in NRM intensity is observed (i.e., ∼9% lower than the assumed trend). Both anhysteretic remanent magnetization (ARM) and saturation isothermal remanent magnetization (SIRM) normalized relative paleointensities (RPIs) can successfully recover field strength variations under identical situations. When the MTB concentration of the initial solution is varied (up to a factor 8), NRM carried by MTB responds in the expected fashion (i.e., a doubling of bacteria produces a doubling of NRM intensity). Both ARM and SIRM, however, do not respond to as expected: A doubling of concentration corresponds to an increase of ∼1.76 in SIRM intensity and an increase of only ∼1.63 in ARM intensity. Both are influenced by magnetostatic interactions that arise from the close packing of bacterial cells or subchain interactions within a single bacterial cell. First-order reversal curve (FORC) diagrams, however, are too insensitive to indicate the presence of paleomagnetically relevant magnetic interactions. Remanence based methods (i.e., the ARM ratio) are more appropriate to detect such interactions.
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DOI：
10.1007/978-0-387-75692-9_9
发表时间：
2008
期刊：
--
影响因子：
--
作者：
D. Hinkley
通讯作者：
D. Hinkley
磁各向异性、静磁相互作用和磁化石鉴定
影响因子：
3.5
作者：
Jinhua Li;Wenfang Wu;Qingsong Liu;Yongxin Pan
通讯作者：
Yongxin Pan
DOI：
10.1036/1097-8542.yb120421
发表时间：
2012
期刊：
Access Science
影响因子：
--
作者：
G. Acton
通讯作者：
G. Acton
影响因子：
5.3
作者：
Pan, YX;Petersen, N;Zhu, RX
通讯作者：
Zhu, RX
影响因子：
5.3
作者：
J. Kirschvink
通讯作者：
J. Kirschvink