Palaeomagnetism of Middle Ordovician Carbonate Sequence, Vaivara Sinimäed Area, Northeast Estonia, Baltica

IF 2 4区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Acta Geophysica Pub Date : 2016-12-02 DOI:10.1515/acgeo-2016-0066

J. Plado, U. Preeden, A. Jõeleht, L. Pesonen, S. Mertanen

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引用次数: 5

Abstract

The hill range of Vaivara Sinimäed in northeast Estonia consists of several narrow east- to northeast-trending glaciotectonic fold structures. The folds include tilted (dips 4–75°) Middle Ordovician (early Darriwilian) layered carbonate strata that were studied by mineralogical, palaeomagnetic, and rock magnetic methods in order to specify the postsedimentational history of the area and to obtain a better control over the palaeogeographic position of Baltica during the Ordovician. Mineralogical studies revealed that (titano)magnetite, hematite, and goethite are carriers of magnetization. Based on data from 5 sites that positively passed a DC tilt test, a south-easterly downward directed component A (Dref = 154.6°± 15.3°, Iref = 60.9°± 9.7°) was identified. The component is carried by (titano)magnetite, dates to the Middle Ordovician (Plat = 17.9°, Plon = 47.3°, K = 46.7, A95 = 11.3°), and places Baltica at mid-southerly latitudes. Observations suggest that in sites that do not pass the tilt test, the glaciotectonic event has caused some rotation of blocks around their vertical axis.

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波罗的海爱沙尼亚东北部Vaivara Sinimäed地区中奥陶世碳酸盐岩层序古地磁

爱沙尼亚东北部的Vaivara Sinimäed山脉由几个狭窄的东至东北走向的冰川构造褶皱结构组成。褶皱包括倾斜(倾角4 ~ 75°)中奥陶世(Darriwilian早期)的层状碳酸盐岩地层，通过矿物学、古地磁和岩石磁等方法对其进行了研究，以明确该地区的沉积后历史，更好地控制波罗的海奥陶世的古地理位置。矿物学研究表明，(钛)磁铁矿、赤铁矿和针铁矿是磁化的载体。根据5个通过直流倾斜测试的位点的数据，确定了东南向下方向的分量a (Dref = 154.6°±15.3°，Iref = 60.9°±9.7°)。该成分由(钛)磁铁矿携带，年代为中奥陶世(plat= 17.9°，Plon = 47.3°，K = 46.7, A95 = 11.3°)，表明波罗的海位于中南纬度。观测结果表明，在没有通过倾斜测试的地点，冰川构造事件导致了一些块体围绕其垂直轴的旋转。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Acta Geophysica 地学-地球化学与地球物理

CiteScore

3.90

自引率

13.00%

发文量

251

审稿时长

5.3 months

期刊介绍： Acta Geophysica is open to all kinds of manuscripts including research and review articles, short communications, comments to published papers, letters to the Editor as well as book reviews. Some of the issues are fully devoted to particular topics; we do encourage proposals for such topical issues. We accept submissions from scientists world-wide, offering high scientific and editorial standard and comprehensive treatment of the discussed topics.