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Papers by Shuan-Hong Zhang

Main Tectonic Events and Metallogeny of the North China Craton

The North China Craton (NCC) is characterized by multistages of extensional and continental rifti... more The North China Craton (NCC) is characterized by multistages of extensional and continental rifting and deposition of thick marine or interactive marine and terrestrial clastic and carbonate platform sediments without angular unconformity during Earth's middle age of 1.70-0.75 Ga. Factors controlling these multistages of extensional and continental rifting events in the NCC can be either from the craton itself or from the neighboring continents being connected during these periods. Two large igneous provinces including the ca. 1.32 Ga mafic sill swarms in Yanliao rift (aulacogen) in the northern NCC and the ca. 0.92-0.89 Ga Xu-Huai-Dalian-Sariwon mafic sill swarms in southeastern and eastern NCC, have recently been identified from the NCC. Rocks from these two large igneous provinces exhibit similar geochemical features of tholeiitic compositions and intraplate characteristics. Formation of these two large igneous provinces was accompanied by pre-magmatic uplift as indicated by the field relations between the sills and their hosted sedimentary rocks. The Yanliao and Xu-Huai-Dalian-Sariwon large igneous provinces represent two continental rifting events that have led to rifting to drifting transition and breakup of the northern margin of the NCC from the Columbia (Nuna) supercontinent and the southeastern margin of the NCC from the Rodinia supercontinent, respectively. As shown by the ca. 200 Ma Central Atlantic Magmatic Province related to breakup of the Pangea supercontinent and initial opening of the Central Atlantic Ocean and the ca. 180 Ma Karoo-Ferrar large igneous province related to initial breakup of Gondwana, magmatism related to continental breakup and rifting to drifting transition can occur as mafic dykes, sills, and/or lavas across the neighboring continents and is mainly tholeiitic in chemical composition. This kind of magmatism should be large in volume and constitute a large igneous province. In many cases, eruption or/and emplacement of breakup-related magmatism were accompanied by pre-magmatic uplift. Large volumes of mafic sill swarms near continental margins and accompanied pre-magmatic uplift in marginal rift basins can most likely be used as important indicators for continental breakup and paleogeographic reconstruction.

The mid-Cretaceous paleo-Pacific ocean witnessed increased mantle plume activity, high oceanic cr... more The mid-Cretaceous paleo-Pacific ocean witnessed increased mantle plume activity, high oceanic crust production rate, enhanced subduction-related magmatism, and widespread short-lived intense deformation. The Antarctic Peninsula located at the Pacific margin of Gondwana and strongly influenced by the exceptionally pan-Pacific tectonic events during the mid-Cretaceous. Therefore, plate reconstruction of the Antarctic Peninsula and its implication to the global geodynamics, paleo-ocean circulation and paleoclimate have become one major subject for panPacific geoscience studies. However, this is difficult because of the small number of reliable paleomagnetic data of the Antarctic Peninsula at the early stage of mid-Cretaceous. In this study, we obtained a key ca. 120-105 Ma paleopole from the Byers Peninsula, Livingstone Island, South Shetland Island, during the global ocean crust peak production period. Plate reconstruction reveals that the Western-Central Domain of the Antarctic Peni...

Goldschmidt2021 abstracts

Journal of Geophysical Research: Solid Earth

Precambrian Research

The existence of Paleo-Mesoproterozoic supercontinent Columbia (aka Nuna) was established decades... more The existence of Paleo-Mesoproterozoic supercontinent Columbia (aka Nuna) was established decades ago, but the position of North China Craton within Columbia is still highly debated due to the paucity of available highquality paleomagnetic and reliable geological constraints. Precise geochronological dating of extensive Mesoproterozoic mafic dyke swarms in Western Shandong Province (also named the Luxi area), China reveals two phases of dyke emplacement at~1.68 Ga and~1.63 Ga. In this paper, we report new paleomagnetic and rock magnetic results obtained from approximate 160 samples (16 sites) collected from these two phases of mafic dyke swarms in the Luxi area with the aim of pinpointing the location of North China Craton within Columbia supercontinent in this time interval. Rock magnetic experiments confirm that either magnetite or titanomagnetite is the main magnetic carrier in these dykes. Stepwise thermal demagnetization revealed two paleomagnetic poles. For the~1.63 Ga dykes, normal and reversed high-temperature remanent magnetization directions yield a mean direction (D/I) of 86.1°/53.5°(κ = 43.3, α 95 = 7.9°, N = 9). These directions pass a reversal test and are interpreted as primary remanences. The corresponding paleomagnetic pole is calculated at 20.8°N, 182.5°E (κ = 28.3, A 95 = 8.3°, N = 9). This pole passes the examination of secular variation of geomagnetic field (Deenen et al., 2011, 2014). It fulfills a Van der Voo (1990) value Q = 6 and is therefore suggested to be a 'key' pole demarcating the Precambrian North China Craton. For the~1.68 Ga dykes, only the normal directions are isolated with a mean direction (D/I) of 89.1°/47.1°(κ = 35.0, α 95 = 13.1°, N = 5) with a corresponding paleomagnetic pole of 17.8°N, 184.9°E (κ = 29.6, A 95 = 14.3°, N = 5). This pole passes the examination of secular variation of geomagnetic field. Finally we select the~1.63 Ga high-quantity paleomagnetic pole in order to depict a more detailed apparent pole wander path (APWP) to compare with the other major Precambrian cratons. Combined with other geological evidence, our reconstruction scenario supports the spatiotemporal connection between the Baltica, North Australian Craton and North China Craton.

International Geology Review

Jurassic coal-bearing strata are widely distributed in the North China Craton (NCC) and other are... more Jurassic coal-bearing strata are widely distributed in the North China Craton (NCC) and other areas of northern China. These coal-bearing strata were previously considered to be Early-Middle Jurassic in age based on plant fossils, particularly the fossil assemblage of Coniopteris-Phoenicopsis. Since coal-bearing strata are interbedded with volcanic units in the basins of the Yanshan Fold-and-Thrust Belt (YFTB), northern NCC, isotopic dating of the volcanic units can therefore provide age constraints on the coal-bearing strata and the Coniopteris-Phoenicopsis assemblage. In this paper, we performed a systematic geological survey and present the results of zircon U-Pb dating of the volcanic units and a pluton in typical basins of the YFTB. These data, combined with the results of previous studies, indicate that the ages of the Nandaling/ Xinglonggou, Haifanggou, Jiulongshan, and Tiaojishan/Lanqi formations are 180-168, 169-161, 161-157, and 161-153 Ma, respectively. The ages of the interbedded coal-bearing Yaopo and Beipiao formations are constrained to be 169-161 and 177-169 Ma, respectively. Our results demonstrate that both the coal-bearing strata and the Coniopteris-Phoenicopsis assemblage are Middle Jurassic in age, which is younger than that previously considered. This fossil assemblage plays a critical role in age constraints on the Jurassic coal-bearing strata. The refinement of its age permits a more precise dating of the coal-bearing strata, especially in northwestern China, where datable interbedded volcanic units are lacking. • Stratigraphical framework for the Jurassic strata of Yanshan region is established. • The fossil assemblage of Coniopteris-Phoenicopsis occurred in Middle Jurassic. • The Jurassic coal-bearing strata in northern China are mainly Middle Jurassic.

Journal of Asian Earth Sciences

Abstract We present new laser ablation–inductively coupled plasma–mass spectrometry (LA–ICP–MS) z... more Abstract We present new laser ablation–inductively coupled plasma–mass spectrometry (LA–ICP–MS) zircon U–Pb ages and provenance data for the Yanshanian basins in western and northern Beijing, North China, with the aims of demonstrating the relationship between basin evolution and “Yanshanian tectonism” and constraining the Late Jurassic–Early Cretaceous tectonic evolution of the region. The inherited Yanshanian basin in western Beijing has a Late Jurassic–Early Cretaceous tectonic history similar to that of typical Yanshanian basins in the Yanshan Fold–Thrust belt (YFTB), and it became inactive at ∼138 Ma. The Qianjiadian basin (QJB) in northern Beijing is only infilled by the sediments of the Tuchengzi Formation. Our new zircon U–Pb ages (160–156 Ma) for the pyroclastic and volcanic rocks of the Tuchengzi Formation suggest that formation of the QJB commenced at ∼160 Ma, consistent with the main episode of “Yanshanian tectonism”. The QJB developed in the footwall of the Pingquan-Gubeikou thrust fault (PGF), and records the syn-tectonic unroofing and erosion of the hanging wall of that fault. It was later reformed by the post-depositional Qianjiadian thrust fault (QJF) along the western margin. The formation and development of the QJB in northern Beijing and the inherited Yanshanian basin in western Beijing were related to the “Yanshanian tectonism”, especially at ca. 160 Ma, when the intense deformation and large-scale magmatism occurred. The tectonic transition from N–S to NW–SE shortening is attributed to the northwest-ward subduction of the Paleo-Pacific Plate, and is constrained to ∼156–135 Ma in the YFTB and eastern China.

Lithos

Abstract This paper reports zircon U–Pb geochronology, whole-rock chemistry and Sr–Nd–Hf isotopic... more Abstract This paper reports zircon U–Pb geochronology, whole-rock chemistry and Sr–Nd–Hf isotopic data of intermediate-acid intrusive rocks from the Gerlache Strait area, Antarctic Peninsula. These intrusive rocks can be divided into three groups. Group #1 has an emplacement age of ca. 117 Ma, and is further subdivided according to K2O contents into High-K (HKS) and Low-K (LKS) Subgroups. The HKS monzogranites are weakly peraluminous, and yield eHf(t) and eNd(t) values of +0.9 to +2.3 and +0.1 to +2.3, respectively, with corresponding model Nd ages (TDMNd) of 766–471 Ma, indicating that they were derived from the partial melting of dominantly early Neoproterozoic to early Paleozoic juvenile basaltic materials with minor involvement of sediments. In contrast, the LKS granodioritic magma was derived from partial melting of early Paleozoic juvenile basaltic materials with eHf(t) and eNd(t) values of +10.3 to +12.5 and +5.4 to +5.5, respectively, and corresponding TDMNd ages of 548–500 Ma. Group #2 consists of granite porphyry that formed at ca. 82 Ma and is characterized by positive values of eHf(t) (+5.1 to +8.1) and eNd(t) (+1.9 to +3.1) with weakly peraluminous chemistry and corresponding TDMNd ages of 712–548 Ma, suggesting that it was generated from partial melting of dominantly Neoproterozoic juvenile basaltic materials with minor involvement of sediments. Group #3 comprises dioritic–granodioritic rocks that were emplaced at ca. 62–54 Ma. These rocks have Mg# values of 39–46, and eHf(t) and eNd(t) values of +6.7 to +12.2 and +3.6 to +7.2, respectively, with corresponding TDMNd ages of 529–307 Ma, indicating that they were derived from partial melting of Paleozoic juvenile basaltic materials with minor injection of mantle materials. Spatially, the lithology of these plutons roughly changes from acid to intermediate from east to west, concomitant with increasing eHf(t) and eNd(t) values and decreasing initial 87Sr/86Sr ratios and TDMNd ages. This trend reflects changes in source characteristics from a Gondwana affinity to a juvenile crust affinity. Overall, the southeast-to-northwest migration of magmatism in the northern Antarctic Peninsula since the Mesozoic may have been related to retreating subduction of the paleo-Pacific plate.

Geology

Phanerozoic large igneous provinces (LIPs) have a significant influence on global climate changes... more Phanerozoic large igneous provinces (LIPs) have a significant influence on global climate changes and mass extinction events (MEEs). Most of the Global Boundary Stratotype Section and Points in the Phanerozoic international chronostratigraphic scale are coeval with LIPs and are marked in the sedimentary record by global-scale MEEs and/or by ocean anoxic events represented by black shales. However, due to limited knowledge on atmospheric oxygen concentrations, ocean redox conditions, and early fossils during the Meso-Neoproterozoic Eras prior to the Ediacaran period, little is known on the climate and environmental effects of LIPs during this period of a billion years, the so-called "Boring Billion" (1.8-0.8 Ga). Here we provide geochronological and geological evidence for a temporal and genetic link between the intense ca. 1380 Ma LIP activity (found on many crustal blocks) and coeval black shales in the Nuna (Columbia) supercontinent. We further propose that the ca. 1380 Ma LIPs and black shales widely distributed in the Nuna supercontinent represent a global-scale geological event and provide a robust natural marker for the Calymmian-Ectasian boundary at 1383 Ma. Further investigation of the temporal and genetic link between the LIPs and black shales at other times can contribute to understanding the variations in atmospheric oxygen concentrations and ocean redox conditions during the Boring Billion, during which virtually nothing of Earth's climate and MEEs is known.