Fission-track-age records of the Mesozoic tectonic-events in the southwest margin of the Ordos Basin, China

Abstract

Based on the analysis of apatite and zircon fission track (FT), the FT age distribution and the peck-ages of the Mesozoic tectonic events in the southwest margin of the Ordos Basin (OB) were discussed.(1) The early event mainly occurred at 213-194 Ma with a peck-age of 205 Ma, and corresponded to the tectonic uplift and the mega-clastic deposit in the southwest OB during the Late Triassic. (2) The middle event included at least two episodes. One was at 165-141 Ma with a peck-age of 150 Ma, and the other was at 115-113 Ma with a peck-age of 114 Ma, corresponding to the over-thrusting and the megaclastic deposits in the southwest OB during the Late Jurassic to the Early Cretaceous. (3) The late event mainly demonstrated the regional uplifting and included at least two episodes. One was at 100-81 Ma with a peck-age of 90 Ma, and the other was at 66-59 Ma with a peck-age of 63 Ma. Additionally, the relationship analysis of the tectonic event and the mineralizing chronology revealed that the extreme environment of the peck-age event and the subsequent moderate activity could be the key factors of the multiple resources coupling and coexistence in the OB.Ordos Basin (OB), Mesozoic, fission-track (FT) age, unconformity, tectonic event Ordos Basin (OB) is a sedimentary energy basin with abundant multi-resources of oil, gas, coal and uranium deposits. Much more important progress has been made in the studies on the tectonic evolution and the Yanshanian tectonic-thermal event of the OB, as well as the petroleum generation and accumulation [1][2][3][4][5][6][7][8] . The exploration and research indicated that the OB was a Mesozoic depressive-basin dominated by polycyclic fluviallacustrine sediments, which had developed in the Paleozoic neritic-offshore marine sedimentary sequences of the North China cratonic-basin and experienced the later uplift reformation since the Late Cretaceous and the differential margin-faulted depression since the Paleogene. The coupling coexistence of the multi-resources as well as the coal and uranium mineralization and the petroleum charging were largely related to the Mesozoic tectonic evolution and the tectonic-thermal events of the OB. Recently, it has been emphasized that the critical tectonic event largely controlled the dynamic evolution and the multiple resources well-coexistence of a sedimentary basin [9 -15] . Therefore, the tectonic-event chronology of the dynamic-regime transition in relation to the multi-resources coexistence is becoming an important frontier for the tectonic research and resources exploration in the OB [16][17][18][19][20][21][22][23] .In recent years, the chronology of the Mesozoic thermal event in the OB has been discussed from different aspects through the apatite fission track (FT) analysis

Differential deformation mechanism of E–W‐trending Weiningbeishan fold‐thrust belt from central Ningxia, NW China

“…Combined with the views of predecessors (Li, 2006;Yang & Dong, 2020;Zhang et al, 2020;Zhao, 2003), we think that the approximately E-Wtrending Dafosigou fold system was mainly formed during the Middle-Late Triassic, which is the same as the activity time of Xinjinggou thrust fault and Jijigou fold system. The zircon FT age of the WFTB shows that there was a significant erosion event in the Late Triassic, which suggests the existence of tectonic compression event in the Late Triassic (Chen et al, 2007).…”

“…Based on regional geological surveys and Google Earth images, we found that the folds formed in the Devonian strata in the eastern part of the WFTB are mainly E-Wtrending open folds (Figures 3 and 4a) with large interlimb angles, while the folds formed in the Carboniferous strata in the central part of the WFTB are mainly E-W-trending chevron folds (Figures 3 and 4b) with small interlimb angles. Previous researchers mainly focused on the tectonic evolution of the WFTB (Chen et al, 2007;Yang & Dong, 2020;Zhang et al, 2020;Zhang, Li, et al, 2009) In this article, based on the detailed geologic mapping and Google Earth image interpretation, we finely reveal the differential deformation between the Devonian and Carboniferous strata through structural analysis. Subsequently, we construct three cross-sections and constrain the magnitude of N-S shortening strains of the Upper Devonian Zhongning Formation (D 3 z) and Carboniferous strata, respectively.…”

Longitudinal profile of the Upper Weihe River: Evidence for the late Cenozoic uplift of the northeastern Tibetan Plateau

“…The breaking up of the erosion surface indicates the beginning of the tectonic uplift (Coltorti & Ollier, 2000;Galadini, Messina, Giaccio, & Sposato, 2003), and the watershed of modern rivers commenced forming. The formation age of the watershed between the Weihe River and Taohe River has also been dated to~1.4 Ma by electron spin resonance (ESR; Figure 12; Zhang, 2006 is based on the paleochannel reconstruction (Figure 7), indicates that (Chen et al,2007;Chen et al, 2015;Clark et al,2010;Duvall et al,2013;Enkelmann et al,2006;Lin, 2009;Liu et al,2013;Song & Qian, 2013;Wang et al, 2011;Wang, 2014;Yang et al,2013;Zheng et al, 2004Zheng et al, ,2006…”

Mesozoic and Cenozoic Tectono-Thermal Reconstruction of the Southern Ordos Basin: Revealed by Apatite Fission Track and (U-Th)/He Dating

“…Among various thermochronology methods, apatite fission track (AFT) and (U-Th)/He dating (AHe) are often used to study hydrocarbon-bearing basins [37,38] due to their ability to recover the basin evolution temperature range • C) [39][40][41], which is close to the temperature of oil and gas generation [8,42]. Although low-temperature thermochronology methods have been applied in the Ordos Basin, there are still some shortcomings: one is that most previous studies used AFT [43,44], whereas AHe, which is a technology developed in recent years, has not been widely used in the Ordos Basin [36]; the other is that the southern part of the basin, especially the Weibei Uplift, has a relatively low level of research due to the lack of oil and gas discoveries in the early stage, and vitrinite reflectance [45,46] and bitumen reflectance [25,26] have mostly been used to reconstruct the thermal history of the region.…”