城市钻孔数据地下三维地质建模软件的实现

介绍了基于钻孔数据的城市地下三维地质建模软件的实现过程,提出了基于钻孔数据三维地质建模的总体思路、钻孔数据管理和层序分层方法,还介绍了软件的模块组成及应用实例。建立的软件实现了对城市钻孔数据的三维建模、可视化分析和科学管理,具有丰富的二维成图和三维显示功能,实例的应用也说明本软件是分析城市第四系构造格架和演化的有力工具。

Seismic sequence and depositional evolution of slope basins in mid-northern margin of the South China Sea

As one of the biggest marginal seas in the western Pacific margin, the South China Sea （SCS） experienced continental rifting and seafloor spreading during the Cenozoic. The northern continental margin of the SCS is classified as a passive continental margin. However, its depositional and structural evolution remains controversial, especially in the deep slope area. The lack of data hindered the correlation between continental shelf and oceanic basin, and prevented the establishment of sequence stratigraphic frame of the whole margin. The slope basins in the mid-northern margin of SCS developed in the Cenozoic; the sediments and basin infill recorded the geological history of the continental margin and the SCS spreading. Using multi-channel seismic dataset acquired in three survey cruises during 1987 to 2004, combined with the data of ODP Leg 184 core and industrial wells, we carried out the sequence stratigraphic division and correlation of the Cenozoic in the middle-northern margin of SCS with seismic profiles and sedimentary facies. We interpreted the seismic reflection properties including continuity, amplitude, fi＇equency, reflection terminals, and 15 sequence boundaries of the Cenozoic in the study area, and correlated the well data in geological age. The depositional environment changed from river and lake, shallow bay to open-deep sea, in correspondence to tectonic events of syn-rifting, early drifting, and late drifting stages of basin evolution.

Study on the base-level cycle and the sedimentology of Permian in Jiyang area

The identification of sequence boundaries is the key point for sequence stratigraphic classification. Both the higher-order sequences and the units within the sequences are bounded with the key sediments or isochronous surfaces. Eight sequences can be divided in the whole Permo-Carboniferous strata （the Shiqianfeng Formation is not included）, which is from the Benxi Formation, Taiyuan Formation, Shanxi Formation, Xiashihezi Formation, Wanshan Section, and Kuishan Section to the Xiaofuhe Section. Also, different system tracts （Iowstand system tract, transgression system tract and highstand system tract） and some parasequences can be recognized in each sequence. Parasequence analysis was on the basis of the division of the base-level cycle. The base-level cycle was mainly identified according to the change of the water area, which was reflected by the depositional sequence. The physical characteristic of the strata was reflected by the well log. It was supplied by the test of the minerals and rocks and the analysis of the micro-element in the lab. The paleogeographic characteristic of the Iowstand system tract in the sequence Ⅵ is that the east-north part takes the river system as its feature; the south part is the lake system, the river channel spreads from north to south, and the area of the flooding plain is great. The paleogeographic characteristic of the water-transgressive system tract is that the range of the lake in the south extended distinctively, the range of the river channel in the east reduced. The coastal shallow lake deposit is the main characteristic in the water-transgressive system tract. The paleogeographic characteristic of the highstand system tract is similar to the one of the Iowstand system tract.

Sedimentary filling and sequence structure dominated by T-R cycles of the Nenjiang Formation in the Songliao Basin

The Nenjiang Formation in the Songliao Basin is a symmetrical sequence of progradation-retrogradation,and is formed in the transgression cycle and regression cycle(T-R cycles)of the base level of deposition.We analyzed the drilling,well logging,core data,and seismic profiles of basin level,and by using the sequence stratigraphy,identified one secondary sequence boundary,two third-order sequence boundaries,and eight fourth-order sequence boundaries in the Nenjiang Formation.These eleven sequence boundaries can be divided into structural unconformity,depositional unconformity,flooding surface,and forced regression surface.Therefore the Nenjiang Formation can be subdivided into one secondary sequence,three third-order sequences,and ten fourth-order sequences.We have restored the sedimentary filling evolution within the stratigraphic framework of fourth-order sequences in the Nenjiang Formation.The sedimentary period of the first member of the Nenjiang Formation was corresponded to the global transgression period,which is also the development period of transgression cycle(T cycle),when the lake basin had the largest scope and deepest sedimentary water,the SB07(the maximum flooding surface)was formed on the top of strata during this period;covering above the SB07,there developed a set of condensation layer-oil shale,which is distributed in the whole basin and is the important source bed and regional cover.Therefore,a retrogradation sequence was formed in the T cycle of the first member of the Nenjiang Formation,characterized by the retrograding delta at a low angle.The delta has a giant front,a small plain,and many underwater distributary channels.Meanwhile,large gravity flow channels and sublacustrine fans are developed in the front of the delta.During the depositional period of the second member of the Nenjiang Formation,the R cycle began to develop due to the compression of the pacific tectonic domain;the source direction rotated 90°along with the eastern uplifting of the basin,and formed a series of east-west prograded and forced retrogradations.The prograding delta at high angel was developed in the interior of the sequence;the delta had a small front,a giant plain,and fewer underwater distributary channels,with the collapse at the foreslope,forming a series of slump fans.The slump fans can be divided into three types:discrete type,superimposed type,and fluid type.We built a whole"triad model"of the slump fan.Pointed out that the sequence of forced retrogradation formed by R cycle is a good structural mark of basin optimization,and rejected the viewpoint of"transgression"in the Nenjiang Formation of the Songliao Basin.