现代与古代河流沉积中生物遗迹组成及分布规律类比研究

The study objects of this project are the modern traces in the point bar and floodplain of the middle-lower Yellow River and the trace fossils of Triassic fluvial deposits of western Henan and Upper Cretaceous fluvial deposits in Xixia area of Henan Province and western Sichuan Province. Using work methods of sedimentoloty and ichnology, this project will systematically research the individual morphology，structure，trace makers and their habit characters of representative modern traces and ichnofossils, and their deposits background as property of substrate and water body, climate, temperature, depth of water and the geochemistry variations, and also the composition, distribution and taphonomy of biologic traces and some factors controlling the distribution and change of these biologic trace in the fluvial sedimentary environment and so on. According to the analogy study of modern traces and trace fossils in fluvial deposits, this work will analysis the similarities and differences in individual trace morphology ,ichnocoenosis and their sedimentary environments. On these bases, the distribution mode of biologic trace in different sub-environments/subfacies of the fluvial deposit system will be established. This study will perfect the terrestrial ichnofacies and paleoecology study and fill the gap of absent Neoichnology and ecology study in fluvial sedimentary environment of our country. In the aspect of application, it will make sense in the identification of the different sub- environments of the fluvial sedimentary system. Moreover it will provide the biological evidence in the seeking and exploration of large scale terrestrial oil and gas field or hidden sedimentary reservoirs.

本项目选择黄河中下游河流边滩及泛滥平原中现代生物遗迹和豫西三叠系、西峡及川西地区上白垩统河流沉积中古代生物遗迹为研究对象，运用沉积学和遗迹学研究方法，系统研究古今河流沉积中典型生物遗迹的个体形貌、构造、造迹生物种类及其生态习性特点，沉积物底层与水体性质、气候、温度、水深及地球化学变化等沉积背景条件，以及生物遗迹群落组成、分布、埋藏特征及其受控因素等；通过对现代与古代河流沉积中生物遗迹群落的类比研究，分析二者在个体生物遗迹形貌、遗迹群落和沉积环境条件方面的异同点，并在此基础上建立河流沉积体系不同亚环境中生物遗迹群落的沉积环境分布模式。本项目研究在理论上将会完善陆相遗迹相及古生态学研究并填补我国在陆相河流沉积中缺少现代生物遗迹及其生态学系统研究的空白；在应用上，对陆相河流沉积体系不同沉积亚环境（亚相）的识别，以及对我国各大型陆相油气田地层或沉积隐蔽储集层的追寻和远景勘探提供重要的生物学证据。

本课题研究了黄河、长江、滦河中下游河漫滩以及入海口三角洲平原和潮滩的现代生物遗迹，发现造迹生物21大类，所造生物遗迹类似遗迹化石有38属；建立了9种现代生物遗迹群落以及潮上带、潮间带的高潮区和中-低潮区3个不同生态区的遗迹组合类型。在豫西白垩系和下三叠统河湖沉积中识别出遗迹化石12属26种，建立了以下11种遗迹组合：豫西潭头盆地上白垩统秋扒组中的 (1) Beaconites一 Scoyenia遗迹组合和(2) Palaeophycus一Rhizoliths遗迹组合，分别出现于湖泊扇三角洲及滨、浅湖沉积环境；汝阳盆地白垩系郝岭组中的 (3) Scoyenia一Skolithos组合及(4) Psilonichnus一Palaeophycus组合，分别形成在冲积扇扇端的河道漫滩环境及扇端积水洼地环境；西峡盆地上白垩统沉积中的（5）Skolithos—Beaconites组合，产生于较高能量的辫状河沉积环境，(6) Gastruichnus—Palaeophycus遗迹组合，出现于天然堤和决口扇近端沉积环境，（7） Beaconites—Palaeophycus遗迹组合，形成于干旱—半干旱条件下的泛滥平原环境，（8）Taenidium—Scoyenia遗迹组合，分布在冲积平原上的浅水洼地或浅水湖泊沉积环境；登封地区下三叠统刘家沟组及和尚沟组中的Scoyenia 遗迹组合，发育于周期性暴露的极浅水河漫滩及小型河漫湖泊环境，Arenicolites遗迹化石组合，产生于水体能量较高的滨湖沉积环境，Taenidium-Planolites遗迹化组合，形成于水体较平静的浅湖沉积环境。上述这些研究成果不仅大大丰富了我国陆相遗迹学和新遗迹学的研究内容，而且还将对我国遗迹学的发展具有积极地推动作用，在我国今后陆相油气田勘探和开发中具有良好的应用前景。