灵山岛早白垩世软沉积物变形构造触发机制及其古环境意义探讨

发布时间：2018-10-29 14:00

【摘要】：灵山岛早白垩灵山岛组发育丰富的软沉积物变形构造。野外踏勘船厂、灯塔和千层崖三个剖面,根据沉积外观可分为变形层段和非变形层段两个部分。软沉积物变形构造在变形层段和非变形层段均有发育。其中,变形层段中可见褶皱变形、变形层理及大型负载构造。非变形层段可见火焰构造、同沉积布丁构造和同沉积微断层。研究发现,变形层段软沉积物变形构造尺度大(厚度可至十多米,长度可至数百米),侧向连续性好;非变形层段软沉积物变形构造尺度小(厚度仅几个厘米),侧向连续性差。且变形层段和未变形层段厚度统计数据表明,变形层段软沉积物变形构造与砂岩厚度无必然联系,而非变形层段软沉积物变形构造多出现在粒序砂岩层底部或旋回砂岩层变厚过程中。沉积环境表明,非变形层段和变形层段为一深水低角度斜坡沉积产物。软沉积物变形构造发育形态和数量受到斜坡地形的控制。结合沉积环境及沉积特征分析,认为变形层段软沉积物变形构造触发机制为地震,而非变形层段软沉积物变形构造触发机制为负载作用。锆石测年数据表明灵山岛组与上覆流纹岩沉积时间相近,因此地震活动可能与岩浆侵入或早期火山喷发活动相关。此外,汇总早白垩世重要事件,发现灵山岛组沉积、变冷事件、恐龙迁移、海平面变化和同位素偏移具有时间一致性,因此推断这些事件可能共同对应了早白垩世一次与火山活动相关的短期灾难性事件(如早白垩世缺氧事件)。
[Abstract]:The early Cretaceous Lingshan Island formation of Lingshan Island is rich in soft sediment deformation structure. The three sections of field exploration shipyard, lighthouse and Qianliangya can be divided into two parts according to the sedimentary appearance: deformed layer and non-deformed layer. The deformation structures of soft sediments are developed in both deformable and non-deformed layers. Among them, fold deformation, deformation bedding and large load structure can be seen in the deformed layer. Flame structure, synsedimentary pudding structure and synsedimentary micro fault can be seen in non-deformed strata. It is found that the deformation structure of soft sediment in the deformed layer is of large scale (up to more than ten meters in thickness and hundreds of meters in length), and the lateral continuity is good. The soft sediments in the non-deformable layer have a small scale of deformation structure (thickness of only a few centimeters) and poor lateral continuity. The statistical data of the thickness of deformed and undeformed strata show that the deformation structure of soft sediments in deformed strata is not necessarily related to the thickness of sandstone. However, the deformation structures of soft sediments in the non-deformable strata are mostly in the process of thickening the sandstone layers at the bottom of the grained sequence sandstone or in the cyclic sandstones. The sedimentary environment shows that the non-deformable and deformed strata are the product of deep-water low-angle slope deposition. The shape and quantity of deformation structures in soft sediments are controlled by slope topography. Based on the analysis of sedimentary environment and sedimentary characteristics, it is considered that the trigger mechanism of deformation structure of soft sediment in deformed zone is earthquake, but the trigger mechanism of deformation structure of soft sediment in non-deformed layer is load action. Zircon dating data show that the Lingshandao formation and the overlying rhyolite deposit time are close, so the seismic activity may be related to magmatic intrusions or early volcanic eruptions. In addition, summarizing the important events of early Cretaceous, it is found that the deposit, cooling event, dinosaur migration, sea level change and isotopic migration of Lingshan Island formation are consistent in time. It is inferred that these events may be associated with a short-term catastrophic event associated with volcanic activity (such as the early Cretaceous anoxic event) in the early Cretaceous.
【作者单位】：中国石油大学地球科学与技术学院;
【基金】：国家自然科学基金资助项目(编号:41572088)的成果~~
【分类号】：P534.53;P542

【相似文献】