Northern Sichuan Research Articles

Two Species of Zosterophyllum from South China and Dating of the Xujiachong Formation with a Biostratigraphic Method

Abstract: Zosterophyllum longa sp. nov. is reported from the Lower Devonian Pingyipu Formation, Jiangyou District, northern Sichuan of China. This new plant has vertically elongate sporangia differing from all known species of Zosterophyllum, demonstrating morphological variations in Zosterophyllophytina. New materials of Zosterophyllum yunnanicum from the Lower Devonian Xujiachong Formation, Qujing District, eastern Yunnan of China show that fertile axes of this species are anisotomous or pseudomonopodial or K‐shaped in branching. Sometimes fertile lateral axes are very short and bear an axillary axis at the dividing point. Distinct thickening occurs along the whole margin of a sporangium, with sporangial lobes undeveloped. The evolution of Zosterophyllum is tentatively discussed. A biostratigraphic method of Gerrienne and Streel is introduced and applied to dating of the Lower Devonian Xujiachong Formation, which is considered as of the late Pragian‐early Emsian.

GPS-derived crustal deformation in southwestern China

The Sichuan – Yunnan region is divided into nine active secondary crustal blocks, based on several GPS repeat surveys at more than 200 GPS sites during the period 1999 – 2005. Velocities of the nine secondary blocks are calculated and analysed. The strain field within the area related to the 2004 Sumatra – Andaman earthquake event is also analysed. Results indicate that the crustal movement in the northern and western areas of the Sichuan – Yunnan region is stronger than that in the south and east. The horizontal velocities change from 19 – 20 mm/y in the northern and the central rhombic block to 11.7 mm/y in the southern rhombic block. The orientations of block motion vary from 99° in the north to 126 – 150° in the central area and 156 – 188° in the south, implying that the motion of the Sichuan – Yunnan rhombic block is dominated by a clockwise rotation. The velocity differences between blocks inside and outside the rhombic block are about 6.5 – 7.7 mm/y in the northern and central Sichuan – Yunnan region. The southeastward extrusion rate of the Tibetan Plateau shows a remarkable downtrend of up to 47% along the Xianshuihe Fault, suggesting an increase in strain accumulation and hence an area prone to strong earthquakes. The horizontal coseismic deformation caused by the Mw9.0 Sumatra – Andaman earthquake is <10 mm with a south-southeast orientation towards the earthquake epicentre. The dilatational strain rates from coseismic displacements reveal a possible interaction between the extrusion from the Tibet plateau interior and the underthrust effects from the Sumatra – Andaman earthquake.

End-Permian extinction and volcanism-induced environmental stress: The Permian–Triassic boundary interval of lower-slope facies at Chaotian, South China

In order to reveal environmental changes across the Permo-Triassic boundary (PTB), the detailed lithostratigraphy of the PTB interval is analyzed at Chaotian in northern Sichuan, China. The studied section is composed of the Changhsingian (Upper Permian) Dalong Formation and the Induan (Lower Triassic) Feixianguan Formation of a lower-slope facies deposited on the northwestern margin of the Yangtze carbonate platform. The 12-m-thick interval across the PTB consists mainly of bedded carbonates and mudstone, and is lithologically divided into 7 units, i.e., Units A to G, in ascending order. The main extinction horizon of Permian taxa is recognized at the Unit D/E boundary where various fossil metazoans and protists, such as ammonoids, brachiopods, bivalves, conodonts, and radiolarians, rapidly disappeared or became scarce. The complete disappearance of radiolarians at the Unit D/E boundary emphasizes that the PTB extinction affected not only various Late Permian benthic and free-swimming metazoans but also planktonic protozoans. The lowest Induan index conodont Hindeodus parvus first occurs at the base of Unit F, marking the biostratigraphically defined PTB horizon. Unit E composed of unique bedded marl between the main extinction horizon and the first occurrence of Triassic taxon represents a period of strong environmental stresses that suppressed productivity both of silica- and carbonate-secreting organisms. By changing their size, radiolarians reacted most sensitively to the environmental change that already started in the late Changhsingian, appreciably before the final extinction event. The frequent intercalation of rhyo-dacitic tuff beds, particularly in Unit D and the lower part of Unit E across the main extinction horizon, suggests that intermittent felsic volcanism and relevant environmental change may have been responsible for the mass extinction of the Permian taxa and for the prolonged post-extinction lag time before the initial recovery. The frequent ash falls during the late Changhsingian indicate that the volcanism-induced environmental change had already started earlier than the main extinction. All the biological production (carbonate, silica, and organic matter) collapsed at the Unit D/E boundary when the environmental stresses may have passed a critical threshold for maintaining ecological stability. The PTB interval between the extinction and the first appearance of Triassic taxon at Chaotian is ca. 1.4 m thick, apparently almost eight times thicker than that at the Global Stratotype Section and Point of PTB in Meishan (19 cm). The Chaotian section, as well as the neighboring Shangsi section in northern Sichuan, may provide a better chance for high-resolution chemostratigraphic analyses that may allow detection and correlation of subtle environmental changes across the PTB.

Conodont biostratigraphy across the Permian–Triassic boundary at Chaotian, in Northern Sichuan, China

Detailed conodont biostratigraphy of the Permian–Triassic boundary (PTB) interval was analyzed at the fossiliferous Chaotian section in northern Sichuan, China. The PTB interval at Chaotian is composed of the uppermost Permian mudstone/limestone of the Dalong Formation and the lowermost Triassic marl/limestone of the Feixianguan Formation both representing deep basinal facies. The PTB interval is enriched in ammonoids and conodonts, and is divided into 6 conodont zones including 1) Clarkina changxingensis changxingensis– C. subcarinata Assemblage Zone, 2) C. postwangi– C. sp. B Assemblage Zone, 3) C. taylorae– C. zhejiangensis– C. changxingensis yini Assemblage Zone, 4) barren intra-zone, 5) Hindeodus parvus Zone, and 6) Isarcicella Zone in ascending order. The first four zones correspond to the Changhsingian, whereas the latter two to the Lower Induan (Griesbachian). The first occurrence (FO) of H. parvus in the lowermost Feixianguan Formation is regarded as the conodont biostratigraphic boundary. From the uppermost Dalong Formation, various taxa of the genus Clarkina occurred abundantly, and suddenly disappeared at the top of the Dalong Formation, therefore, the top of the Dalong Formation is interpreted as a horizon of the eventostratigraphic boundary. On the basis of conodont zones, the Chaotian section is correlated with the Shangsi and Meishan (GSSP of the PTB) sections in South China, and the Zal section in Iran.

The Copula and Existential Verbs in Qiang

This paper discusses the copula and existential verb constructions in Qiang, a Tibeto-Burman language of northern Sichuan, China. There is only one copula verb in Qiang, which can be used in equational, identificational, attributive, naming, and cleft constructions, as well as one type of possessive construction. There are five existential verbs in Qiang, the use of which depends on the semantics of the referent being predicated as existing and its location. The existential verbs have a number of the characteristics of adjective-like stative verbs, and can be modified by adverbs of degree, but they cannot directly modify nouns. Also, the meaning of reduplication of existential verbs is different from that of adjective-like stative verbs: reduplication of existential verbs results in transitivization, while reduplication of adjective-like stative verbs results in emphasis of degree.

Forest Conservation Policies and Rural Livelihood in North Sichuan Tibetan Areas

Comparing three rural townships in Northern Sichuan, this paper analyses the challenges and the constraints associated with forest protection and biodiversity conservation programs in China. We highlight the importance of the local economic and institutional environment in the effectiveness of implementation of the national guidelines and the diversity in possible answers at the local level. The natural forest protection program and the sloping land conversion program analyzed in this paper, also stress the difficulty to implement effective and sustainable forest resources protection policies as well as the strategic role of the government in the implementation of such policies.

Contribution of atmospheric pollutants into groundwater in the northern Sichuan Basin, China

Anthropogenic pollution of groundwater was investigated from the source area to the uppermost densely populated city, Dujiangyan, along the Minjiang River, a tributary of the Yangtze River, in the Sichuan Basin, in China, based on the chemistry of major dissolved ions and stable isotopic ratios (H, O and S). In the source area above 2,900 m, groundwaters were rarely polluted by human activities. Groundwater pollution was found to be limited to populated areas, where the pollutants come mainly from household wastes. The groundwaters in Dujiangyan and the surrounding area were mixtures of waters from the upper streams along the Minjiang River and local precipitation. The groundwater of this area was found to contain high amounts of anthropogenic Cl-, NO3--N, and SO42-. Among these anions, most SO42- was derived from air pollutants. The present study demonstrates that air pollution seriously affects the quality of groundwaters in areas where the Minjiang River emerges from the bottom edge of the Sichuan Basin.

Forest Protection Policies

This article compares three rural townships in northern Sichuan to assess the challenges and the constraints affecting China’s national forest protection and biodiversity conservation programmes. It highlights the importance of the local economic and institutional environment for the ways in which it affects the implementation of national directives, giving rise to a wide variety of local responses. Our analysis of the natural forest protection programme and the sloping land conservation programme shows both the difficulties in launching a sustainable policy to protect the forests, and the strategic role of the government in ensuring their implementation.

Paragonimus skrjabini Chen, 1959 (Digenea: Paragonimidae) and related species in eastern Asia: a combined molecular and morphological approach to identification and taxonomy

A molecular and morphometric investigation is reported on the species complex of mammalian lungflukes of which Paragonimus skrjabini Chen, 1959 and P. miyazakii Kamo, Nishida, Hatsushika & Tomimura, 1961 are the best-known examples. This species complex (here called the P. skrjabini complex) is shown to be monophyletic using DNA sequences from the nuclear ITS2 region and the mitochondrial cox1 gene. The latter marker permits the discrimination of populations, some previously named as distinct species, from various geographical locations in China and Japan. Morphometric analysis of a number of variables accords remarkably closely with the molecular results. Main findings are that (1) nominal P.skrjabini from Fujian Province in eastern China is phylogenetically very close to P. miyazakii from Japan. It is proposed that both taxa should be referred to the same subspecies as P. krjabini miyazakii. (2) Populations from Guangdong Province, Guangxi Zhuang Autonomous Region, Sichuan and Hubei should be referred to P. skrjabini skrjabini. Specimens of P. skrjabini from the Yangtze basin in Sichuan and Hubei are remarkably similar to one another according to genetic and morphometric data, but are not so different from Guangdong populations that they should be referred to a different subspecies at this stage. Specimens of P. skrjabini from Yunnan have not been assigned to a subspecies at this stage. (3) Partly following earlier studies, we regard the following as synonyms of P. skrjabini: P. miyazakii (reduced to subspecific status); P. szechuanensis Chung & Tsao, 1962 (probably belongs to P. s. skrjabini); and P. hueitungensis Chung, Hsu, Ho, Kao, Shao, Chiu, Pi, Liu, Ouyang, Shen, Yi & Yao, 1975 (probably belongs to P.s.skrjabini ); P. veocularis (Chen & Li, 1979) (specimens from Fujian regarded as belonging to this species should be referred to P.skrjabini miyazakii: the subspecific status of specimens from the type-locality in northern Sichuan is unclear). A number of questions remain unresolved. The name P. hokuoensis Ho & Chung, 1964 was proposed for two individual metacercariae of distinctive appearance from southern Yunnan. DNA sequences from very similar metacercariae from the same locality place this nominal species within, or sister to, the P. skrjabini complex. As yet, nothing is known regarding adult morphology or biology of this taxon and we retain it here as a distinct species. P. heterorchis (Zhou, Pang & Hsiang, 1982) might be a synonym of P. skrjabini: the form of the metacercaria provides evidence against this view and further work is required. P. macrorchis Chen, 1962 has probably been confused with P. skrjabiniin China. Within China, the former probably occurs only on Hainan Island, although P. fukienensis Tang & Tang, 1962 from Fujian Province could be a synonym.

Lower Cambrian Small Shelly Fossils of northern Sichuan and southern Shaanxi (China), and their biostratigraphic importance

Extensive information has been acquired on the occurrence of Lower Cambrian Small Shelly Fossils (SSF) in the shallow water sediments of the western fringe of the Yangtze Platform (eastern Yunnan and central Sichuan Provinces) during the last two decades. However, less is known on the temporal and spatial distribution of SSFs on the northern margin of the Yangtze Platform. Here we report SSF associations from Kuanchuanpu (Ningqiang County, southern Shaanxi Province), Shatan, and Xinli (both Nanjiang County, northern Sichuan Province) representing the Southwest Shaanxi region and from Sanlangpu, and Xiaowan (Xixiang County, southern Shaanxi Province) of the Southeast Shaanxi – Northwest Hubei region. The thickness of the Lower Cambrian SSF-bearing strata strongly decreases in this region from West to East and the stratigraphic hiatus increases. An earliest Cambrian hiatus is widely distributed on the northern margin of the Yangtze Platform. At the same time, a syngenetic brecciation occurred in wide shallow shelf settings. A tectonic mobilization, possibly related to the assembly of Gondwana following the breakup of Rodinia, may be responsible for this. In sections near Kuanchuanpu (Ningqiang County), the Meishucunian (equivalent to the Nemakit-Daldynian to Tommotian of Siberia) succession comprises ca. 55 m of dark phosphatic carbonates, siltstones, and cherts. The SSF associations are similar to those of East Yunnan and, in ascending order, can be discriminated into the Anabarites trisulcatus – Protohertzina anabarica Zone, the Watsonella yunnanensis Zone (previously mentioned as Heraultipegma yunnanensis Zone), and the Sinosachites flabelliformis – Tannuolina zhangwentangi Zone. The Siphogonuchites triangularis – Paragloborilus subglobosus Zone cannot be unambiguously detected in the Southwest Shaanxi region. The occurrence of embryos and eggs within the Anabarites trisulcatus – Protohertzina anabarica Zone, which has been reported earlier, is remarkable. The previously reconstructed life cycle and taxonomic treatment of Olivooides / Punctatus are re-discussed. The earliest SSF associations ( Anabarites trisulcatus – Protohertzina anabarica Zone to Watsonella yunnanesis Zone) are missing in the Southeast Shaanxi – Northwest Hubei region and the Ninella tarimensis – Cambroclavus fangxianensis Assemblage Zone and Rhombocorniculum cancellatum Taxon Range Zone are introduced herein.

Detailed Stratigraphy across the Permo-Triassic Boundary at Chaotian in Northern Sichuan, China

To reveal environmental changes across the Permo-Triassic boundary (PTB), detailed lithostratigraphy was analyzed of the PTB interval at Chaotian in northern Sichuan, China. The study interval is composed mainly of shelf carbonates that are lithologically divided into 7 units, i.e., Units A to G in ascending order. Units A-E (8.5 m) correspond to the uppermost Permian, and Units F-G (3.5 m) to the lowermost Triassic. On the basis of a field study and microscopic observations of more than 200 thin sections, the main extinction horizon is recognized at the Unit DIE boundary. Various fossils, such as ammonoid, brachiopod, bivalve, radiolaria, and conodont occur abundantly in Units A-D, while they are absent (or nearly absent) in Units E-G. Radiolarians in particular, show a clear contrasting mode of occurrence : abundant in Unit D to its top, while barren in Unit E and above. The Unit D/E boundary is thus identified as the event PTB horizon with major extinction. The PTB extinction terminated various Late Permian organisms, particularly radiolarians, which are representative planktons in open ocean, suggesting a sharp decline in total marine productivity. On the other hand, the Griesbachian (Early Triassic) index conodont Hindeodus parvus first appears at the base of Unit F, thus the Unit E/F boundary is recognized as the biostratigraphically-defined PTB horizon. The marl of Unit E represents the interval of strong environmental stress that appeared around the PTB. The population of the latest Permian radiolarians decreased remarkably across the Unit B/C boundary, while their mean shell size stayed constant, and even increased rapidly within Unit D. As large-shelled radiolarians often predominate in the cool waters of modern oceans, the radiolarian size increase in Unit D may indicate that the depositional site may have been invaded by a cooler water mass at the end of Permian period.

Stratigraphy of the Middle-Upper Permian and Lowermost Triassic at Chaotian, Sichuan, China Record of Late Permian double mass extinction event

Precise stratigraphic analysis of Middle-Upper Permian and Lower Triassic sequence at Chaotian in northern Sichuan, China, identified two remarkable mass extinction horizons, one at the Middle-Upper Permian (Guadalupian-Lopingian; G-L) boundary and the other at the Upper Permian-Lower Triassic (P-T) boundary. Across each of the boundaries, biodiversity declined sharply in fusulinid, rugose coral, brachiopod, ammonite, conodont, and radiolaria. Both boundaries are characterized by two biohorizons, i.e., one marked by major extinction of pre-existing fauna and the other by the first appearance of younger fauna. It is noteworthy that a peculiar rhyo-dacitic tuff bed occurs at each of the extinction horizons. Thus the Late Permian biosphere was strongly affected twice by highly explosive, severe volcanism. Regional correlation of the G-L and P-T boundary tuff beds throughout South China, and partly to Japan, positively suggests a cause-effect link between large-scale explosive volcanism and mass extinction. (Communicated by Tatsuro MATSUMOTO, M.J.A., Jan. 13, 2004)

Pictorial 2 : Permo-Triassic Boundary Section at Chaotian in Northern Sichuan, China

Pictorial 2 : Permo-Triassic Boundary Section at Chaotian in Northern Sichuan, China

Distribution and conservation status of the endemic Chinese mountain cat Felis bieti

Records of the Vulnerable Chinese mountain cat Felis bieti are known from the eastern border of the Tibetan Plateau, mostly from Qinghai province, but also from other areas further north, east and north-west. Disagreement regarding the reliability of some records has led to uncertainty about the species' distribution. In order to obtain information about its current distribution and status we conducted surveys in various Chinese provinces and evaluated former records and specimens. Forty-five specimens and living individuals were examined, and 189 records were gathered from local sources. Our data confirm that this cat is endemic to China, and occurs in montane forest edge, alpine shrubland and meadow habitats. At present it is confined to the provinces of eastern Qinghai and northern Sichuan. Its wild populations are facing a number of threats and environmental pressures such as poaching, use of chemical rodenticides, and environmental changes. We recommend moving this species to Category I of Chinese law, enforcement of its protection in reserves, and the establishment of new reserves, specifically for this species, in areas in which it is currently unprotected.

First Report of Heterobasidion parviporum (S Group of H. annosum sensu lato) on Tsuga spp. in Asia.

Members of the Heterobasidion annosum (Fr.) Bref. complex are among the most important pathogens in coniferous forests of Europe and North America. Three intersterile groups (P, S, and F) have been found in this complex from Europe (1) and were recently segregated into three species based on intersterility, host preferences, and morphology (4). In a survey of wood-rotting fungi in China in 2002, Heterobasidion spp. were found on Tsuga chinensis (Franch.) Pritz and T. dumosa (D. Don) Eichl. in natural forests from the northern Sichuan Province of southwestern China (32°43' to 33°11' N, 103°50' to 103°53' E.). Basidiocarps of the fungus were relatively common on decayed wood in roots of dead trees, stumps, and fallen trunks. We collected four basidiocarps (Dai 4045, 4051, 4214, and 4224 in the Institute of Applied Ecology, Chinese Academy of Sciences, IFP) from three stands of mixed coniferous forests and made 40 homokaryotic, single-basidiospore cultures (02046, 02047, 02050, and 02051 in the Finnish Forest Research Institute). Two homokaryons from each basidiocarp were paired with homokaryotic tester strains of European H. annosum (P group), H. parviporum Niemelä & Korhonen (S group), and H. abietinum Niemelä & Korhonen (F group). The pairings showed that the progeny from the four basidiocarps are H. parviporum. The Chinese isolates did not form clamp connections with H. annosum sensu stricto, and a strong demarcation line developed in all these pairings. In contrast, the Chinese isolates formed clamp connections in almost every pairing with European H. parviporum, the clamp connections developed in both sides of the pairings, and no distinct demarcation line was present in most of these pairings. The Chinese homokaryons were also compatible with European H. abietinum, but in most of these pairings, clamp connections were found in the isolate from China but not in the European tester, and a demarcation line was present in most of the pairings. In contrast to H. annosum sensu stricto, the Chinese basidiocarps had smaller pores (4.5 to 6 per mm versus 3 to 4.5 per mm), and a thin tomentum on the pileal surface in contrast to the basidiocarps of H. abietinum. Previously, H. parviporum was found in Asia on coniferous hosts such as Abies, Larix, Picea and Pinus spp. (2). The North American S group of H. annosum sensu lato attacks species of Tsuga spp. in western North America (3), but to our knowledge, this is the first report of H. parviporum on native species of Tsuga spp. outside North America.

COMMUNITY ASSEMBLY PATTERNS OF PARIDS ALONG AN ELEVATIONAL GRADIENT IN WESTERN CHINA

Abstract Eight species of parids commonly occur in the mountains of northern Sichuan Province, People's Republic of China. They represent four monophyletic groups regarded by some authorities as genera, but more traditionally as subgenera of the large genus Parus. To test the competition-based hypothesis that less closely related species are more likely to co-occur, we used specimens and observations obtained in October 1989 and May 1991 to delineate the morphology, elevational range, and habitat associations of each species in this rich assemblage. A morphometric cluster analysis did not support the assumption that phylogenetic similarity predicts morphological and hence ecological similarity. Up to five species commonly co-occurred in mixed flocks, as in Europe (where five subgenera are represented), but a randomization test showed that community assembly was random with respect to subgenus. On the other hand, for the entire data set (P = 0.05) and during spring (P = 0.07), species in the same morphomet...

New Late Jurassic palaeomagnetic data from the northern Sichuan basin: implications for the deformation of the Yangtze craton

SUMMARY Upper Jurassic red sandstones and red siltstones were collected from 67 layers at 12 localities in the Penglaizhen formation. This formation is in the north of Bazhong county (31.8°N, 106.7°E) in the Sichuan basin, which is located in the northern part of the Yangtze craton. Thermal demagnetization isolated a high-temperature magnetic component with a maximum unblocking temperature of about 690°C from 45 layers. The primary nature of the magnetization acquisition is ascertained through the presence of magnetostratigraphic sequences with normal and reversed polarities, as well as positive fold and reversal tests at the 95 per cent confidence level. The tilt-corrected mean direction of 36 layers is D=20.0°, I=28.8° with a 95 =5.8°. A Late Jurassic palaeomagentic pole at 64.7°N, 236.0°E with A 95 =7.0° is calculated from the palaeomagnetic directions of 11 localities. This pole position agrees with the two other Late Jurassic poles from the northern part of the Yangtze craton. A characteristic Late Jurassic pole is calculated from the three poles (68.6°N, 236.0°E with A 95 =8.0°) for the northern part of the Yangtze craton. This pole position is significantly diVerent from that for the southern part of the Yangtze craton. This suggests that the southern part of the Yangtze craton was subjected to southward extrusion by 1700±1000 km with respect to the northern part. Intracraton deformation occurred within the Yangtze craton.

Geochemical characteristics of the sandstone-type uranium deposits in Northern Sichuan Province

Described in detail in this paper are the geochemical characteristics of the sandstone-type uranium deposits in northern Sichuan Province. Favorable and unfavorable conditions for the enrichment of uranium are explored on the basis of the elemental abundances and ratios of U, Th and K determined by gamma-ray spectroscopy. Gammaray spectroscopic (U, Th and K) and XRF analyses (As, Ba) are helpful to distinguish U-bearing light-colored sandstones from U-barren light-colored ones and red sandstones (red claystone) from light-colored sandstones. Therefore, the favorable target area for prospecting the sandstone-type uranium deposits can be defined in northern Sichuan Province.

The Black-Necked CranesGrus NigricollisOf Ruoergai Marshes, Sichuan, China

SummaryThe marshes of the Hongyuan-Ruoergai Plateau in northern Sichuan were visited between 27 May and 10 June 1991 to determine the status there of Black-necked CranesGrus nigricollis, to investigate reports of threats to their habitat from peat-mining, and to consider options for a protected area for the cranes. Almost 80,000 ha of wetlands in Ruoergai County were surveyed, as well as some of the contiguous wetlands in northern Hongyuan County; 240 Black-necked Cranes and 24 active nests were located. Between 600 and 900 cranes were estimated to be present on the plateau, making this the most important breeding and summering area for the species hitherto known. Neither peatmining nor hunting was judged to pose a threat to the cranes. The principal threat is drainage of habitat for pastureland: overgrazing by domestic livestock is a serious problem on the grasslands, and some drainage of bogs has already occurred in an attempt to increase the area of grazing land. The establishment of a large “crane conservation area” has been proposed, in which there would be no restrictions on the traditional activities of the local tribespeople, but where large-scale drainage, peat-mining and other development activities likely to have a negative impact on the wetlands would be prohibited.

An indentation model for the North and South China collision and the development of the Tan‐Lu and Honam Fault Systems, eastern Asia

Passive continental margins are geometrically irregular as a consequence of either triple‐junction evolution or the development of transfer zones in detachment fault systems, whereas active continental margins are smoothly arc‐shaped due to subduction of plates on the Earth's spherical surface. We propose that this basic difference in boundary geometry has played an important role in the latest Paleozoic‐early Mesozoic collision of North and South China. In particular, we suggest that prior to collision, the active southern margin of the North China Block (NCB) was contiguous across the Qilian Shan, Qinling, Dabie Shan, Shandong peninsula of east central China to the Imjingang area of central Korea. The passive northern margin of the South China Block (SCB), in contrast, had a more irregular shape, such that its northeastern segment in northern Jiangsu and eastern Anhui provinces of China extended some 500 km farther north than its western counterparts in northern Sichuan, southern Shaanxi, and northern Hubei provinces. Collision of the NCB and the SCB began by indentation of the northeastern SCB into the eastern NCB in the late Early Permian and lasted until the Late Triassic‐Early Jurassic. The indentation produced the left‐slip Tan‐Lu fault in northeastern China and the right‐slip Honam shear zone in southeastern Korea and caused the northward displacement of the Shandong and the Imjingang metamorphic belts. This model predicts that collision along the Dabie and Qinling metamorphic belt occurred significantly later than along the Shandong belt, which is consistent with radiometric and depositional constraints on the time of collision. The proposed model accounts for the abrupt termination of the Tan‐Lu fault at its south end and the drastic decrease in slip along the Tan‐Lu fault north of the Shandong metamorphic belt. The model also predicts the distribution and ages of metamorphism along the suture and the observed local but intense Triassic deformation (=Indosinian orogeny) in northeastern China and northern Korea, which was previously an enigmatic feature in this region.