Holocene coastal tectonics in NE Brazil
Holocene coastal tectonics in NE Brazil
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巴西东北部全新世海岸构造
DOI：
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发表时间：
1999
期刊：
影响因子：
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通讯作者：
Leão X. Costa
中科院分区：
文献类型：
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作者：
F. Bezerra;F. P. Lima;R. Amaral;Luciano Henrique de Oliveira Caldas;Leão X. Costa
摘要在巴西东北部，我们已经确定了两个海滩岩相，它们可以作为可靠的海平面指示器。相（a）代表下部前滨和上部滨面，主要特征为粗粒未分选砂岩，具有槽状交叉分层，而相（B）对应于沉积在中部至下部前滨的沉积物，通常特征为中至粗粒、分选较好的砂岩，形成向海倾斜的斜交床。海滩岩体的年龄范围从c。7000 - 1150 cal. a bp.虽然相对海平面记录由于可能是由于微小的气候变化而引起的振荡而变得复杂，但可以确定c处的普遍上升。7000 cal. abp，最大值为+2 m c。5000 cal.a bp，然后在大约300年后开始下降到目前的水平。我们的海平面数据与该地区的冰川水均衡模型一致，但在海拔+5米处生长的贝壳上的4080 cal. a bp和在Carnaubais断层以东的海平面上的海滩岩石上的2780 cal. a bp的数据表明，全新世晚期出现迅速，可能是同震。
Abstract We have identified two beachrock facies in NE Brazil which can be used as reliable sea-level indicators. Facies (a) represents the lower foreshore and the upper shoreface, being mainly characterized by coarse unsorted sandstones with trough cross-stratification, whereas facies (b) corresponds to sediments deposited on the middle to lower foreshore and is usually characterized by medium to coarse, better sorted sandstones which form seaward-dipping, swash cross beds. The age of the beachrock bodies ranges from c. 7000 to 1150 cal. a bp. Although the relative sea-level record is complicated by oscillations which are probably due to minor climatic changes, it was possible to identify a general rise at c. 7000 cal. a bp which reached its maximum of +2 m c. 5000 cal. a bp and then started to fall to its present level some 300 years later. Our sea-level data are consistent with glacio-hydroisostatic models for the region but dates of 4080 cal. a bp on shells in growth position at +5 m above sea level and 2780 cal. a bp on a beachrock at sea level east of the Carnaubais fault point to rapid, possibly coseismic, late Holocene emergence.