Magneto-biostratigraphic constraints of the Eocene micrite–calciturbidite transition in New Caledonia: tectonic implications
Magneto-biostratigraphic constraints of the Eocene micrite–calciturbidite transition in New Caledonia: tectonic implications
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DOI：
10.1080/00288306.2018.1443946
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发表时间：
2018-03
影响因子：
2.2
通讯作者：
E. Dallanave;C. Agnini;K. Pascher;P. Maurizot;V. Bachtadse;C. Hollis;G. Dickens;J. Collot;Edoardo Monesi
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文献类型：
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作者：
E. Dallanave;C. Agnini;K. Pascher;P. Maurizot;V. Bachtadse;C. Hollis;G. Dickens;J. Collot;Edoardo Monesi
摘要我们对努美阿（新喀里多尼亚）附近两个地点的37 m厚复合剖面进行了综合磁性生物地层学研究。该部分包含从远洋泥晶灰岩到陆源富钙浊积岩的过渡。在新喀里多尼亚同时代的区域记录中观察到的这种过渡，标志着从稳定的大陆海底高原上的远洋沉积到浊流沉积的转变，表明在会聚构造体系中斜坡的发展。研究剖面横跨磁极性年代C22 r至C20 r、钙质超微化石带CNE 5至CNE 10和放射虫带RP 9至RP 11（49.5至c.泥晶-浊积岩转变发生在45.3Ma左右（中始新世早期）。这种过渡可能是陆上相关的区域开关从构造伸展到压缩，这已推断出从塔斯曼-北Zealandia地区获得的新的地震剖面分析，并已被解释为汤加Kermadec俯冲开始的前兆。
ABSTRACT We conducted an integrated magneto-biostratigraphic study of a 37 m-thick composite section exposed at two sites near Nouméa (New Caledonia). The section contains a transition from pelagic micrite to terrigenous-rich calciturbidites. This transition, observed regionally in coeval records of New Caledonia, marks a shift from pelagic sedimentation on a stable continental submarine plateau to turbidite deposition indicating development of a slope in a convergent tectonic regime. The studied section spans magnetic polarity Chrons C22r to C20r, calcareous nannofossil zones CNE5 to CNE10, and radiolarian zones RP9 to RP11 (49.5 to c. 44 Ma), and the micrite–turbidite transition occurred around 45.3 Ma (early middle Eocene). This transition could be the onshore correlative of a regional switch from tectonic extension to compression, which has been inferred from analysis of new seismic profiles acquired for the Tasman–northern Zealandia area, and that has been interpreted as precursor of the Tonga–Kermadec subduction initiation.