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We integrated our new data with a review of published work on the Indo-Myanmar Orogenic Belt (IMOB) of the eastern Neotethys in Myanmar, western Yunnan (China) and Naga Hills (India), in order to better understand subduction-accretion processes of the Neotethys Ocean in SE Asia, and interactive relationships between the Gondwana and Laurasia supercontinents. From east to west, the IMOB is divided into three geographic units, the Shan-Thai Plateau, Myanmar Central Basin and Indo-Burma Range; the Mogok Metamorphic and Slate Belt is within the Shan-Thai Plateau. The Shan-Thai Plateau and eastern Myanmar Central Basin contain Paleozoic sedimentary successions, low-grade to amphibolitic facies metamorphic rocks, and the Luxi ultramafic and Myitkyina-Mogok ultramafic-diorite belts. Unmetamorphosed and metamorphosed sediments have similar detrital zircon age peaks of 1000 Ma, and 700 Ma or 500 Ma, and they are separated by the Luxi ultramafic belt, whose eNd(0) and 87Sr/86Sr(i) values are similar to surrounding granite, diorite and migmatite and the γOs = −4.8 ~ −8.8 is indicative of old sub-continental lithospheric mantle, rather than an oceanic suture zone. These data and relations suggest that these regions belong to the Cimmerian continental sliver, derived from the Gondwana supercontinent. The Myitkyina-Mogok ultramafic-diorite belt, located along the eastern margin of the Myanmar Central Basin that was associated with the continental sliver, contains peridotite, andesite, hornblende gabbro, diorite, granodiorite and plagiogranite, all with arc geochemical signatures and ages of 177–166 Ma. The source region of some of these igneous rocks contains a component of EM1, which is close to low 87Sr/86Sr(i) ratio of a migmatite in the Cimmerian continental sliver as shown by Sr Nd isotopes values, suggesting this belt developed as a Jurassic continental margin arc. The Mogok Metamorphic and Slate Belt contains granodiorite, diorite, tonalite, granite and migmatite extending from the Gongshan, Tengchong and Luxi areas in western Yunnan (China) to Mandalay, Kalaw, Padatchaung and Moulmein in Myanmar. These rocks have arc geochemical character and yield ages of 185–170 Ma, 128–112 Ma, 91 Ma and 75–45 Ma, suggesting development of four episodes of arc magmatism. Along the central axis of the Myanmar Central Basin there are magmatic arc-related 106–94 Ma diorite, granodiorite and tonalite, as well as Eocene and Neogene-Present (38–0 Ma) andesite, dacite, trachyte and rhyolite. Accretion took place along the central axis of the Myanmar Central Basin towards the Indo-Burma Range, and westward to the present trench axis on the margin of the Indian Ocean, as shown by westward younging of accretionary complexes and trench-slope basins. A Jurassic accretionary complex, located in the Hpakan area in the north of the Myanmar Central Basin, contains 189–147 Ma high-pressure metamorphic rocks such as jadeitite, garnet-mica schist and glaucophane schist. In the eastern belt of the Indo-Burma Range Early Cretaceous (119–115 Ma) accretionary complexes consist of upper plate Triassic unmetamorphosed and low-grade metamorphic sediments, and lower plate amphibolites, high-pressure metamorphic rocks and Jurassic-Early Cretaceous oceanic plate stratigraphy containing MORB- and OIB-type basalts and thin-bedded radiolarian cherts. Late Early Cretaceous (~100 Ma) and Late Cretaceous to Middle Eocene (75–45 Ma) trench-slope basin deposits, containing abundant fossil plants and shallow-water sedimentary structures, cover most of the Indo-Burma Range, where sediments rest with an angular unconformity on older accretionary complexes. The presence of earlier magmatic arcs, accretionary complexes and trench-slope basins suggests that the present trench on the margin of the Indian Ocean has evolved by continuous eastward subduction since the Jurassic. The magmatic arc axis migrated eastward (landward) during some time periods (Jurassic to Early Cretaceous, and Late Cretaceous to Middle Eocene) and westward (seaward) migration during others (Early Cretaceous to late Early Cretaceous, and Middle Eocene to Present), during continuous east-dipping subduction.

The Guangxian Orogeny, as an important concept on geology of South China, was created 70 years ago. It is generally regarded as an orogenic movement caused by the convergence of the Cathaysian and Yangtze blocks at the end of Silurian. Based on the recent progress of the geological research on Guangxi and adjacent areas, western Guangxi and Liuzhou-Heshan area of central Guangxi may belong to a stable block of Early Paleozoic. The Guangxian Orogeny originated from the northward translation of the Yunkai Block on its south at the end of Cambrian, and formed the Damingshan-Dayaoshan fold belt between the two blocks. It was possibly related with the Late Pan-African Orogeny. The convergence of the Cathaysian and Yangtze blocks occurred in Late Ordovician to Early Silurian and mainly had effect on Hunan and Jiangxi provinces. The term “Chongyu Orogeny” may be suitable for it. At the end of Silurian orogenic movement did not occur in this area.

In order to better constrain the paleogeographic evolution of south China we measured Sm-Nd and Rb-Sr isotopic compositions for 23 Mesozoic granites that crop out throughout the area. Tightly grouped neodymium depleted mantle model ages (1.4 ± 0.3 Ga) suggest the region is underlain by relatively homogeneous Proterozoic crust and fail to define crustal provinces. Neither the isotopic nor geologic data suggest that a Mesozoic suture exists. However, granites possessing anomalously high Sm (>8 ppm) and Nd (>45 ppm) concentrations, relatively high initial epsilon neodymium (−4 to −8), and high but variable initial 87Sr/86Sr (0.759 to 0.713) form a northeast trending zone that coincides with two prominent Mesozoic basins. Southeast of the zone lie the majority of Mesozoic intrusives and Upper Triassic to Lower Cretaceous extensional basins found in south China. Mesozoic paleomagnetic poles are well clustered northwest of the zone. Pre-Cretaceous poles southeast of it are discordant with respect to those from the northwest. The only recognized tectonostratigraphic terrane in south China lies southeast of the zone. The terrane is bordered by a northeast trending sinistral fault that was active in the Mesozoic. Other faults in south China have similar attitudes, ages, and sense of shear. Together, the observations suggest that the Mesozoic tectonic regime in south China consisted of strike-slip activity plus concomitant rifting as terranes or fragments of similar crust were transported north along sinistral faults. The zone, defined by the granites enriched in Nd and Sm, demarcates displaced terranes to the southeast from relatively stable land to the northwest.

We report Early and Middle Triassic paleomagnetic data from the south Chinese provinces of Fujian and Guangxi. The characteristic magnetization of the rocks in each case is concluded to be a primary remanence that passes the fold test. The Triassic pole from western Guangxi and four other Triassic and Late Permian poles from three provinces that lie on undisputed parts of the Yangtze craton are well clustered. This suggests that Guangxi (except the southeast part) was also a part of the Yangtze craton, at least since the Triassic and probably since the Late Permian. With respect to the Yangtze craton, between the Early Triassic and the Late Cretaceous, Fujian may have been rotated 121 ± 9° counterclockwise and displaced 22 ± 9° north, or rotated 59 ± 9° clockwise and displaced 3 ± 9° south, depending on the hemisphere in which the magnetization was acquired. Based on consistency with other paleomagnetic results, and in accordance with the geologic data from the area, the former interpretation is preferred. A remarkable coincidence of Mesozoic poles for south China and south Korea is observed which, if true, implies that the South China Block (except for the displaced terranes in the coastal provinces) and Korea may have been part of the same continental landmass from the Triassic onwards. This is consistent with some geologic observations suggesting affinities between the two places. It also implies that the major fault zones in north China (e.g., the Tan-Lu fault) are unrelated to major fault zones in southeast China (e.g., the Changle-Nanao fault), with the former probably associated with the suturing of north and south China and the latter influenced by proto-Pacific plate motion.

In southwest China, the major Cathaysian-Gondwana divide (the Palaeo-Tethyan suture) is very well delineated by a narrow north-south zone of oceanic siliceous sedimentary rocks and dismembered ophiolite complexes including probable remains of reef-capped oceanic islands. The location of this zone, the Changning-Menglian suture, is not well appreciated in the English language literature, probably because of the failure to recognise the approximately 600 × 400 km Simao terrane which lies to the east of the suture. Many analyses mistakenly include the Simao element in the Sibumasu terrane thus placing a terrane of distinct Cathaysian affinities on the Gondwana side of the major palaeogeographic divide. A measure of the size and time span of Palaeo-Tethys is contained in the Changning-Menglian suture zone sedimentary rocks; deep marine cherts are dated between Early Devonian and Middle Permian, and limestones, interpreted as caps to seamounts, extend the age range of the ocean to Late Permian. These data agree with recent views of Cathaysian elements rifting from Gondwana in the Silurian or Devonian followed by a major rifting event on the north Gondwana margin early in the Permian. Subduction created an active continental margin on the western edge of the Simao terrane throughout much of the Triassic and the closure of this branch of Palaeo-Tethys is marked by the cessation of this activity in the early Late Triassic.

We have collected oriented cores in Jurassic redbeds from two areas in southern Guangxi Province. Stepwise thermal demagnetization of the samples and subsequent statistical analysis show that the stable magnetization from both areas is a near-primary chemical remanence that passes the fold test. Area 1 lies in a shear zone and is rotated 24° ± 12° counterclockwise and insignificantly displaced 4° ± 12° northward with respect to Area 2, which lies outside the shear zone, 80 km to the northwest of Area 1. After adjusting for a post-Jurassic tectonic rotation identified in a previous paleomagnetic study, the pole for Area 2 is indistinguishable from an averaged Early to Middle Jurassic reference pole for the Yangtze craton, suggesting that this area was joined to the Yangtze craton by that time, and confirming that considerable clockwise rotation of south China relative to north China remained to be accomplished before the present configuration of the two blocks was attained. In combination with geological observations, these data support a terrane model based on sinistral shear acting parallel to recognized structural trends in this part of southeast China during post-Triassic time.

We report Cretaceous and Tertiary paleomagnetic data from Fujian, Guangxi and Guangdong provinces in south China. In Guangxi Province we sampled Early Cretaceous redbeds of the Xinlong Formation at eight localities separated by up to 100 km. The high-temperature component obtained by thermal demagnetization is of dual polarity and passes the fold test, and implies 18° ± 8° counterclockwise rotation and insignificant poleward displacement with respect to cratonic localities in Sichuan Province. A Tertiary basin lying in a southeast-trending fault zone is also rotated counterclockwise by 40° ± 8°. Both results can be explained very well by a simple block rotation model for the Cenozoic tectonic evolution of western Guangxi Province that is driven by left-lateral shear on southeast-trending faults. The timing and sense of shear are the same as for India-Asia collision models involving the extrusion of Indochina along the Red River fault zone, which lies several hundred kilometers to the southwest, but the magnitude of fault displacement in Guangxi is much less. In the coastal provinces of Fujian and Guangdong we find Late Cretaceous directions that are rotated clockwise with respect to Sichuan Province. Combined with similar clockwise rotations found by two other studies of coeval rocks from the same region, the mean rotation for the coastal provinces is 12° ± 8°; this could indicate a coherent block rotation of the region driven by extrusion tectonics. However, the limited number of sampling localities also allows the possibility that the directions reflect local rotations due to dextral shearing driven by circum-Pacific tectonics.