X-ray nanotomography and electron backscatter diffraction demonstrate the crystalline, heterogeneous and impermeable nature of conodont white matter.
X-ray nanotomography and electron backscatter diffraction demonstrate the crystalline, heterogeneous and impermeable nature of conodont white matter.
复制标题
DOI：
10.1098/rsos.202013
复制
发表时间：
2021-08
影响因子：
3.5
通讯作者：
Donoghue PCJ
中科院分区：
文献类型：
--
作者：
Atakul-Özdemir A;Warren X;Martin PG;Guizar-Sicairos M;Holler M;Marone F;Martínez-Pérez C;Donoghue PCJ
牙形石元素是已灭绝的原始脊椎动物的微化石遗骸，通常被用作海洋化学的矿物档案，为了解过去海洋的古温度和化学成分提供了基本见解。地球化学分析传统上一直集中在所谓的层状和白色物质冠组织，然而，孔隙度和晶体学性质的白色物质和其推断的渗透性是有争议的，提高了关注其是否适合作为地球化学档案。在这里，我们限制这种组织的特点，并解决冲突的解释，使用ptychographic X射线计算机断层扫描（PXCT），孔隙网络分析，同步辐射X射线断层扫描显微镜（srXTM）和电子背散射衍射（EBSD）。基于这些数据的PXCT和孔隙网络分析显示，虽然白色物质是非常多孔的，但孔隙是不连通的，使得该组织接近于死后液体渗透。EBSD分析表明，白色物质是结晶的，由尺寸通常为数十微米的单晶组成。结合证据表明，牙形石元素生长的episodically，这些数据表明，白色的物质，其中包括牙形石元素的denominating，句法增长，表明个别晶体的时间异质性。总之，这些数据提供了支持解释牙形石白色物质作为一个封闭的地球化学系统，因此，其效用的牙形石化石记录作为一个历史档案的古生代和中生代早期海洋化学。
Conodont elements, microfossil remains of extinct primitive vertebrates, are commonly exploited as mineral archives of ocean chemistry, yielding fundamental insights into the palaeotemperature and chemical composition of past oceans. Geochemical assays have been traditionally focused on the so-called lamellar and white matter crown tissues; however, the porosity and crystallographic nature of the white matter and its inferred permeability are disputed, raising concerns over its suitability as a geochemical archive. Here, we constrain the characteristics of this tissue and address conflicting interpretations using ptychographic X-ray-computed tomography (PXCT), pore network analysis, synchrotron radiation X-ray tomographic microscopy (srXTM) and electron back-scatter diffraction (EBSD). PXCT and pore network analyses based on these data reveal that while white matter is extremely porous, the pores are unconnected, rendering this tissue closed to postmortem fluid percolation. EBSD analyses demonstrate that white matter is crystalline and comprised of a single crystal typically tens of micrometres in dimensions. Combined with evidence that conodont elements grow episodically, these data suggest that white matter, which comprises the denticles of conodont elements, grows syntactically, indicating that individual crystals are time heterogeneous. Together these data provide support for the interpretation of conodont white matter as a closed geochemical system and, therefore, its utility of the conodont fossil record as a historical archive of Palaeozoic and Early Mesozoic ocean chemistry.
登录
查看更多内容
影响因子：
2.7
作者：
Purnell, Mark A.;Jones, David
通讯作者：
Jones, David
影响因子：
1.6
作者：
Holler, M.;Raabe, J.;Bunk, O.
通讯作者：
Bunk, O.
影响因子：
2.4
作者：
Dong, Hu;Blunt, Martin J.
通讯作者：
Blunt, Martin J.
影响因子：
3.5
作者：
Cusack, M.;England, J.;Allison, N.
通讯作者：
Allison, N.
影响因子：
3.8
作者：
Guizar-Sicairos, Manuel;Johnson, Ian;Menzel, Andreas
通讯作者：
Menzel, Andreas