Browsing by Author "Wang, Houqi"

Now showing 1 - 2 of 2

Configuration and Timing of Collision Between Arabia and Eurasia in the Zagros Collision zone, Fars, Southern Iran
(American Geophysical Union, 2021-08) Cai, Fulong; Ding, Lin; Wang, Houqi; Laskowski, Andrew K.; Zhang, Liyun; Zhang, Bo; Mohammadi, Ali; Li, Jinxiang; Song, Peiping; Li, Zhenyu; Zhang, Qinghai
The configuration and timing of the Arabia-Eurasia continental collision, part of the broader Alpine-Himalayan collisional system, remains controversial. We conducted sandstone petrology, detrital zircon U-Pb-Hf isotopic and trace element analysis, and Cr spinel electron microprobe geochemical analysis of samples from Paleocene to Miocene peripheral foreland strata in interior Fars, southern Iran. These data were used to test competing models for ophiolite obduction and Arabia-Eurasia collision. In addition, we applied these data to compare the history of outward and upward growth of the Zagros and Himalayan-Tibetan segments of the Alpine-Himalayan collisional orogenic belt. The first appearance of radiolarian-rich chert conglomerate, 100–90 Ma detrital zircons with positive ɛHf(t) values from +1 to +20 and midocean ridge geochemical affinity, and suprasubduction zone (SSZ) affinity Cr-spinel is in the lower and middle Sachun Formation. These data indicate that obduction occurred before deposition of the upper Maastrichtian-lower Paleocene Sachun Formation and developed in an intra-oceanic setting rather than an Arabia-Eurasia collision setting. Abundant continental-arc affinity detrital zircon with 180–160 Ma and 50–27 Ma age-probability peaks and varied ɛHf(t) values are present in the upper Oligocene-lower Miocene Razak and Agha Jari formations, indicating sedimentary overlap with Eurasia. SSZ-affinity Cr-spinel in all samples indicates that ophiolitic rocks were a continual source of detritus in the foreland basin since Paleocene. The depositional age of the basal Razak Formation is between 25.7 and 21.5 Ma. Therefore, we interpret that collision between Arabia and Eurasia must have been initiated before deposition of the Razak Formation.
Regional Exhumation and Tectonic History of the Shanxi Rift and Taihangshan, North China
(American Geophysical Union, 2021-03) Clinkscales, Christopher; Kapp, Paul; Thomson, Stuart; Wang, Houqi; Laskowski, Andrew; Orme, Devon A.; Pullen, Alex
This study presents a comprehensive low-temperature thermochronometric data set from the Shanxi Rift, Taihangshan, and eastern Ordos block in North China, including new apatite fission track and apatite (U-Th-Sm)/He data and published apatite and zircon fission track and (U-Th-Sm)/He data. We use these data and new thermal history inversion models to reveal that the Shanxi Rift and Taihangshan experienced an increase in cooling rates between ca. 110–70 Ma and ca. 50–30 Ma. A preceding ca. 160–135 Ma cooling event is generally restricted to the western rift margin in the Lüliangshan and Hengshan. In contrast, the ca. 50–30 Ma cooling event was widespread and occurred coevally with the opening of the Bohai Basin and slip across the NNE-striking Eastern Taihangshan fault. In the southern rift zone, however, exhumation beginning ca. 50 Ma was likely associated with fault block uplift across the ESE–striking Qinling and Huashan faults, which accompanied the extensional opening of the Weihe Graben. Coeval fault slip along the NNE–striking Eastern Taihangshan faults and ESE–striking Qinling and Huashan faults was associated with NW-SE extension in North China related to oblique subduction of the Pacific plate under Eastern Asia and slow convergence rates. The Shanxi Rift is commonly attributed to Late Miocene and younger extension, but our new thermochronologic data do not precisely record the onset of rifting. However, our inversion models do suggest ≤∼50°C of Neogene–Quaternary cooling, consistent with ≤∼2 km of footwall uplift across most range-bounding faults.