Seismic volcanostratigraphy of large, extrusive complexes in continental rift basins of Northeast China：Analysis of general bedding patterns in volcanostratigraphy and their seismic reflection configurations

The aim of this work is to establish volcanic seismic reflection configuration models in the rift basins of Northeast China from a new perspective,the volcanostratigraphic structure.Accordingly,the volcanostratigraphic structure of an outcrop near the Hailaier Rift Basin was analyzed to understand the characteristics and causal factors of physical boundaries.Further,3D seismic reflection data and analysis of deep boreholes in the Songliao Rift Basin were used to establish the relationship between volcanic seismic reflection configurations and volcanostratigraphic structures.These studies suggested that in volcanic successions,physical boundaries coincide with volcanic boundaries,and their distributions are controlled by the stacking patterns of volcanic units.Therefore,volcanic seismic reflection configurations can be interpreted in terms of the stacking patterns of volcanic units.These are also referred to as general bedding patterns in volcanostratigraphy.Furthermore,four typical seismic reflection configurations were identified,namely,the chaotic,the parallel continuous,the hummocky,the multi-mound superimposed and the composite.The corresponding interpretation models comprised single massive unit,vertical,intersectional,lateral multi-mound,and composite stacking patterns.The hummocky and composite reflection configurations with intersectional and composite stacking patterns are the most favorable for the exploration of volcanic reservoirs in rift basins.

Controls of accommodation to sediment-supply ratio on sedimentary architecture of continental fluvial successions

The applicability of sequence stratigraphic models to continental fluvial successions has long been topic for debate. To improve our understanding of how fluvial architectures record responses to changes in the ratio between accommodation rate and sediment-supply rate (A/S), two case studies are analyzed, including a densely drilled subsurface fluvial reservoir imaged with a seismic cube, and an outcropping fluvial succession. The subsurface dataset provides a larger, three-dimensional perspective, whereas the outcrop dataset enables observation at higher resolution. On the basis of both datasets, channel-body density, channel-body stacking patterns and their formative river types are interpreted at different scales, and how these may reflect responses to A/S change (the rate of accommodation creation relative to the rate of sediment supply) are discussed. The results indicate that (i) channel-body stacking patterns undergo four evolutionary stages along with the A/S increase, i.e., multi-story, mixed multi- and two-story, two-story, and isolated patterns;(ii) channel-body density decreases along with the channel-body stacking patterns varying from multi-story to isolated;(iii) formative rivers types are interpreted as evolving from braided planforms to braided-meandering planforms and then to meandering ones, with the increase of A/S.

Vertical structure and dominating factors of sand body during Late Triassic Chang 9 time of Yanchang Formation in Ordos Basin, NW China

Based on a synthetic geological study of drilling, well logging and core observations, two main genetic types of Chang 9sand body in Odors Basin were recognized, which included two effects, that is, delta environment and tractive current effects that lead to the development of mouth bar, distal bar, sheet sand and other sand bodies of subaerial and subaqueous distributary channel,natural levee, flood fan and delta front, and shore-shallow lake environment and lake flow transformation effects that result in the development of sandy beach bar, sheet sand and other sand bodies. Chang 9 sand body mainly developed five basic vertical structures, namely box shape, campaniform, infundibuliform, finger and dentoid. The vertical stacking patterns of multilayer sand body was complex, and the common shapes included box shape + box shape, campaniform + campaniform, campaniform + box shape, infundibuliform + infundibuliform, campaniform + infundibuliform, box shape + campaniform, box shape + infundibuliform,and finger + finger. Based on the analysis on major dominating factors of vertical structure of sand body, sedimentary environment,sedimentary facies and rise, fall and cycle of base level are identified as the major geological factors that control the vertical structure of single sand body as well as vertical stacking patterns and distribution of multistory sand bodies.

Sub-5 nm bilayer GaSe MOSFETs towards ultrahigh on-state current

Dielectric engineering plays a crucial role in the process of device miniaturization.Herein we investigate the electrical properties of bilayer GaSe metal-oxide-semiconductor field-effect transistors(MOSFETs),considering hetero-gate-dielectric construction,dielectric materials and GaSe stacking pattern.The results show that device performance strongly depends on the dielectric constants and locations of insulators.When highk dielectric is placed close to the drain,it behaves with a larger on-state current(I_(on))of 5052μA/μm when the channel is 5 nm.Additionally,when the channel is 5 nm and insulator is HfO_(2),the largest I_(on) is 5134μA/μm for devices with AC stacking GaSe channel.In particular,when the gate length is 2 nm,it still meets the HP requirements of ITRS 2028 for the device with AA stacking when high-k dielectric is used.Hence,the work provides guidance to regulate the performance of the two-dimensional nanodevices by dielectric engineering.

Sequence Characteristics of Foreland Basin and Its Difference from Those of Other Types of Basin

Based on the case history study of sequence stratigraphic framework,sequence model,and the controlling factors on sequence formation in the southern Junggar foreland basin,a contrasting comparison of the characteristics among the foreland basin,the faulted basin,and the sag basin is made in the aspects of sequence architecture,filling style,the controlling factors on sequence development,the migrations of basin center and depocenter,etc..The current study results show that there are major differences and these are documented as follows.（1） The accommodation space in foreland basin is mainly created by the subsidence caused by thrusting and napping in the foothill belt,resulting in progradational-dominated parasequence sets in the foothill area and retrogradational parasequence sets in the ramp region.（2） The accommodation space in an open-lake system in faulted basin is mainly created by the activities of the basin margin faults;thus,tectonic sequences are formed.However,in the closed-lake system,the subaqueous accommodation is mainly controlled by climatic-influenced lake-level fluctuations,and climatic sequence is formed.（3） In sag basin,a closed-lake system is easily formed due to its generation often within the cratons and isolation from the sea,and its accommodation space creation is mainly controlled by climatic lake-level fluctuations;thus,the sequence architecture in sag basin is similar to that formed on the passive continental margin.