The oleaginous Botryococcus from the Triassic Yanchang Formation in Ordos Basin, Northwestern China: Morphology and its paleoenvironmental significance

Upper Permian Junggar and Upper Triassic Ordos lacustrine source rocks in Northwest and Central China: Organic geochemistry, petroleum potential and predicted organofacies

“…3a). Detailed paleontological information about palynomorphs including an Asseretospora-Walchiites assemblage (Ji and Meng 2006), various flora of prolific Leiosphaeridia and Botryococcus (Ji et al 2010), and extensive fauna of Coelacanth suborder, Congiopodoidei, Ostracoda, and Amellibranchia (Chen et al 2007) have been reported from the Chang 7 Member. …”

Origin and Distribution of Carbonate Cement in Tight Sandstones: The Upper Triassic Yanchang Formation Chang 8 Oil Layer in West Ordos Basin, China

“…A series of Cenozoic rift basins separate the Ordos basin from adjoining mountains [17]. The Ordos basin can be divided into six structural units: the Yimeng uplift zone in the north, the Weibei uplift zone in the south, the Jinxi flexural fold zone in the east, the Yishan slope in the midsection, the Xiyuan obduction zone, and the Tianhuan depression in the west ( Figure 1(a); [16,[18][19][20][21][22][23]). The study area of this paper is located in the west Ordos basin (mainly the Yishan Slope and Tianhuan Depression), and abundant hydrocarbons are produced from the oil fields located in this area, including the Jiyuan, Heshui, Wu 464, Zhengning, and Huachi oil fields ( Figure 1).…”

“…The surrounding Yinshan and Qinling Mountains were thought to be the primary provenances for the Upper Triassic fluvial-deltaic sequences [17]. From the aspect of exploration and exploitation purposes, the Yanchang Formation could be subdivided into 10 informal oil reservoir units named Chang 10 to Chang 1 from the bottom to the top based on marker beds, lithological association, and sedimentary cycles, and these oil reservoir units are in conformity contact with each other [4,17,19,33,34]. Among them, the Chang 7 oil layers were deposited in a deep lacustrine environment [5,35,36], and the Chang 7 oil layers are good to very good source rocks [2,37].…”

Re-discussion on the detrital zircon provenance of the lower Yanchang Formation in the southern Ordos Basin

“…1). The basin overlays the Archean granulites and lower Proterozoic greenschists of the North China Platform and was filled with Paleozoic to Cenozoic sedimentary rocks with thicknesses that exceed 8 km in the southwestern part [17]. Since the Mesoproterozoic, the Ordos area has experienced several multicycle tectonic stages.…”

“…Prior to the Permian, the Ordos basin evolved as part of the North China block [14,17,21]. The Ordos Basin is superimposed on the marine basin in the Early Paleozoic.…”