山西黎城中元古代砂岩层面多种痕迹特征及成因初析

Miscellaneous Traces on the Bedding Planes of Mezoproterozoic Sandstones in Licheng,Shanxi:Characteristics and Origin Analysis

山西黎城地质公园中元古界砂岩夹页岩的层面上除波痕、泥裂等常见构造外,有"石蚯蚓"、弧形迹、星形迹等多种遗迹,用简单的力学原理难以解释它们的形成机制。初步分析认为,自由弯曲水平潜穴(meander burrows)或爬迹(Nereites)、交叉"S"或"8"字形遗迹可能为生物遗迹或与微生物席有关的构造;而星形迹两端变尖,常组成三射星形,与已报道的冰晶痕相似。更可贵的是,我们可以看到这些痕迹间具有渐变过渡的特征,这提示我们研究这些痕迹的成因必须统筹而系统地考虑问题。

Apart from common ripple marks,mudcracks, there are miscellaneous traces on the bedding planes of the Mezoproterozoic sandstones in Licheng Geopark, Shanxi Province, such as ＂ lithic earthworm＂,arcuate traces, starry traces, whose forming processes can hardly be understood on the basis of mechanics. Having a preliminary analysis, it is considered that the meander burrow or Nereites, crossed-S-liked traces, 8-liked traces should be trace fossils formed by worms or microbially induced sedimentary structures （MISS）; the starry traces, whose single trace is short line, commonly thins out on the two ends, and 3 single short lines composed a trilete, should be similar to reported ice-wedge traces. It is more valuable that gradually transitional characteristics can be found between these traces, which prompt that we should comprehensively and systematically study the origin of these traces.