The Karakoram–Jiali Fault Zone (KJFZ) comprises a series of right-lateral shear zones that southerly bound the eastward extrusion of northern Tibet relative to India and stable Eurasia. Here we present new 40Ar/39Ar age data from the Puqu and Parlung faults, two easternmost branches of the Jiali fault zone, which indicate a main phase of the KJFZ shearing from ∼18 to 12 Ma. Thus, the Tibetan eastward extrusion bounded by principal strike-slip fault zones started and was probably most active around the middle Miocene, an interval marked also by active east–west extension in southern Tibet. The coincidence of these two tectonic events strongly suggests a common causal mechanism, which is best explained as oblique convergence between India and Asia. Under the framework of this mechanism, the extension in southern Tibet is not a proxy for the plateau uplift. The KJFZ activity was furthermore coincident with right-lateral displacements along the Gaoligong and Sagaing faults in southeast Asia. This defines a Miocene deformation record for the regional dextral accommodation zone that, in response to the continuing India–Asia collision, may have accounted for the initiation and prolonged history of clockwise rotation of the Tibetan extrusion around the eastern Himalayan Syntaxis.

Adakites are geochemically distinct intermediate to felsic lavas found exclusively in subduction zones. Here we report the first example of such magmas from southern Tibet in an active continental collision environment. The Tibetan adakites were emplaced from ca. 26 to 10 Ma, and their overall geochemical characteristics suggest an origin by melting of eclogites and/or garnet amphibolites in the lower part ( similar to50 km) of thickened Tibetan crust. This lower-crustal melting required a significantly elevated geotherm, which we attribute to removal of the tectonically thickened lithospheric mantle in late Oligocene time. The identification of collisiontype adakites from southern Tibet lends new constraints to not only the Himalayan-Tibetan orogenesis-how and when the Indian lithosphere started underthrusting Asia can be depicted-but also the growth of the early continental crust on Earth that consists dominantly of the tonal ite-trondhjemite-granodiorite suites marked by adalkitic geochemical affinities.

Abstract Mesozoic magmatism occurred extensively in the North China block (NCB) and the Dabie–Sulu orogen (DSO) post‐dating the North–South China collision, resulting in abundant intrusive and volcanic rocks ranging from basic to acidic compositions. The intermediate‐acidic intrusive rocks can be grouped into two types, namely high‐Ba–Sr granitoids and low‐Ba–Sr granitoids that both have distinct geochemical characteristics. The high‐Ba–Sr granitoids are similar in most of the incompatible trace element systematics to the associated basic rocks, which probably originated from melting of subcontinental lithospheric mantle, indicating significant mantle contributions to them. Geochemical similarities are observed between the basic rocks from the NCB and DSO, implying a regional‐scale magma‐generating mechanism and that mantle enrichment beneath the DSO was independent from the Triassic deep continental subduction in the region. We therefore interpret that the Mesozoic magmatism resulted from delamination of the ancient lithospheric mantle beneath the eastern part of North China.

The Permian–Triassic (P–T) mass extinction, the greatest biological mortality event in the Earth’s history, was probably caused by dramatic and global forcing mechanisms such as the Siberian flood volcanism. Here we present the first set of high-precision 40Ar/39Ar dating results of volcanic and intrusive rocks from the Emeishan Traps, South China, which define a main stage of the flood magmatism at ∼251–253 Ma and a subordinate precursory activity at ∼255 Ma. This time span is generally coeval with, or slightly older than, the age of the P–T boundary estimated by the ash beds in the Meishan stratotype section and the main eruption of the Siberian Traps. Our data reinforces the notion that the eruption of the Emeishan Traps, rather than eruption of the Siberian Traps, accounted for the formation of the P–T boundary ash beds in South China. The Emeishan flood magmatism, which occurred in the continental margin comprising thick marine limestone formations, moreover, may have triggered rapid release of large volumes of methane and carbon dioxide that could have been responsible for the global δ13C excursion and associated environmental crisis leading to the mass extinction at the P–T boundary.

Southeast Asia, or, in a more strict sense, the Indochinese continent, was previously considered to be composed entirely of Proterozoic to Phanerozoic rocks, and reliable evidence for Archean crust was lacking, Gneisses from the Cavinh Complex, south of the Red River shear zone, northern Vietnam, however, show Archean Nd model ages of 3.4-3.1 Ga, Zircon separates from the rocks yielded U-Pb dates of 2.8-2.5 Ga, the first convincing evidence for the presence of a Late Archean complex in Southeast Asia, Given that the Red River shear zone was propagating in the South China block with a left-lateral offset of similar to 600 km, the Cavinh Complex can be correlated with the Late Archean Kangding Complex in the western margin of the Yangtze craton, southwestern China. The Cavinh Complex therefore represents one of the oldest crustal nuclei of the South China block.

Recent interpretation of seismic sections and free-air gravity anomalies in offshore northern Taiwan reveals that the southern Taiwan–Sinzi Folded Zone began to form in late Middle Miocene, though it was mainly constructed in the Late Pliocene with strong reverse faulting and folding. Two westward progradational sequences were deposited in the shelf basin with sediments supplied from the southern Taiwan–Sinzi Folded Zone and the southern Ryukyu Arc. These two structures are displaced by several northwest-striking dextral strike–slip faults that were active in the early Quaternary when the clockwise-rotated southern Ryukyu Arc and the folded southern Taiwan–Sinzi Folded Zone were broken. It is believed that recent extension in the southern Okinawa Trough started in the early Quaternary because uplift on the southern Taiwan–Sinzi Folded Zone continued to latest Pliocene–early Quaternary. Paleogene–Miocene sediments of the East China Sea Shelf in the western part of the southern Okinawa Trough Basin are interpreted to indicate that the East China Sea Shelf Basin extended to the east of the southern Taiwan–Sinzi Folded Zone.

Scleractinian coral reefs, when coexistent with siliciclastic sediments, usually occur in association with deltaic or coastal sands. Nevertheless, Pleistocene reef limestones in southwestern Taiwan are developed in association with thick claystones that were deposited in a deeper-water environment. These reef limestones are characterized by: (1) rapid transition from underlying claystones upward to reefal limestones, (2) lateral interfingering with open-shelf claystones, (3) being overlain by terrestrial deposits or exposed with no covering strata, and (4) being located in close association with anticlines. The authors propose that these reef limestones developed on anticlinal ridges raised above the adjacent sea floor by thrust-front migration in a foreland setting.

Left-lateral movement of the Ailao Shan-Red River shear zone lends support to the hypothesis of continental extrusion resulting from the collision of India with Asia, Our new observations from northwestern Yunnan, China, and northwestern Vietnam on different sides of the shear zone demonstrate that the sinistral offset was similar to 600 km according to correlations of Permian-Triassic flood basalt successions and late Paleogene highly potassic mafic magmas. We conclude that the shear was propagating on the South China continental margin and does not correspond to a suture between South China and Indochina Furthermore, the highly potassic magmas were emplaced from ca. 40 to 30 Ma, before the shear movement, which was caused by the late Oligocene to early Miocene (ca, 27-22 Ma) extrusion activity, This suggests that a late Eocene to early Oligocene intraplate extension, possibly induced by delamination of thickened continental lithosphere, took place in northwestern Yunnan (or eastern Tibet) as a response to the India-Asia collision, This extension, and sea-floor spreading of the South China Sea that began ca, 30 Ma, could have accounted for the initiation of the Ailao Shan-Red River shear zone.

The India-Eurasia collision alone set up a series of chain reactions and caused the formation and destruction of sedimentary basins within the domain of the collision belt. Changes in the rate and angle of convergence between the India and Eurasia plates reflect different stages of tectonic development in Southeast Asia. For example, extrusion of the Indochina block induced the consumption of the pre-existing proto-South China Sea along northeastern Kalimantan and led to the eventual opening of the South China Sea along the South China margin. Subsequent motions of the Sino-Burma-Thailand, Malay Peninsula, Sumatra, and Kalimantan blocks have produced a succession of basins stretching from north Sumatra to central Thailand and on to the Natuna area.We present reconstructions of the Southeast Asia region at 60 Ma, 50 Ma, 40 Ma, 30 Ma, 20 Ma, 15 Ma, 10 Ma, and 5 Ma. It is clear, from the reconstructions, that the impact between Greater India and Southeast Asia took place in the northwestern part of Southeast Asia. The duration for the impact was probably from the Middle Eocene to Early Miocene. This timing is in good agreement with the dating of the main Red River Fault motion (Wu et al., 1989; Scharer et al., 1990). Since the impact between Greater India and Southeast Asia was basically west of the Burma block, there is no reason to assume that the Sumatra, Malay Peninsula, and Kalimantan should extrude to the southeast first along the left-laterally displaced Mae Ping and Three Pagodas fault zones as suggested by Peltzer and Tapponnier (1988). If the opening of the central Thailand basins, the Gulf of Thailand, and the Malay Basin are taken into consideration, a dextral megashear zone is required to compensate the relative motion between Indochina and the Malay Peninsula. This dextral megashear zone might even extend into western Kalimantan and serve as a boundary between the Indochina block and Kalimantan.

We have attempted to quantify the relative motion history between southernmost South America (SSA) and the Antarctic Peninsula (AP) by calculating and comparing SSA‐Africa, AP‐Africa and SSA‐AP synthetic flow lines for 84–0 Ma. The flow lines were created using published poles of rotation and plate reconstruction software. The results indicate that since 84 Ma, SSA and AP have moved approximately westward relative to a fixed Africa; however, SSA's rate of westerly motion in that reference frame has been significantly more rapid than AP's rate. Approximately 1320 km of east‐west, left‐lateral strike‐slip displacement and 490 km of north‐south, divergent displacement have occurred between the southern tip of SSA and the northern tip of AP since 84 Ma. Increased rates of SSA‐AP interplate separation and a change in the angle of plate divergence at approximately 55–40 Ma marked the onset of accelerated continental separation that eventually led to seafloor spreading in the western Scotia Sea at 30 Ma and the development of the Scotia Arc. Increased separation rates between SSA and AP at 55–40 Ma may be related to a global Eocene plate reorganization event. The northeast‐southwest oriented western Scotia Sea spreading centers appear to have accommodated all of the SSA‐AP interplate motion between 30 and 9 Ma. We suggest that prior to 30 Ma and the opening of Drake Passage, components of interplate strike‐slip and divergent motion were accommodated by intracontinental deformation that included strike‐slip faulting, counterclockwise tectonic rotation, and continental extension in the southernmost Andes. The results indicate that the opening of the Scotia Sea was caused by plate‐scale motions as SSA and AP drifted away from Africa at different velocities along different, nonparallel trajectories. Subduction retreat along the South Scotia Ridge and South Sandwich arc and back arc spreading in the Scotia Sea contributed to the width of separation between SSA and AP across Drake Passage. The results place limits on how SSA‐AP relative motion has been temporally and spatially partitioned in the Scotia Arc region.

Reconstructions of the South China Sea region at 60 Ma, 40 Ma, 30 Ma, 20 Ma, 10 Ma and 5 Ma are presented. We have attempted to place the South China Sea Basin in a regional tectonic framework. The tectonic evolution of the major blocks surrounding the South China Sea were analyzed, as well as the relative motions of the Indian and Australian plates. We have tried to correct the tectonic models available in this region. A 3-D graphics terminal was used to derive rotation poles for the different tectonic blocks and our model was then tested to determine its self-consistency. When the model conflicted with previous interpretations the input data were evaluated for alternative explanations.At least two, and possibly three, stages of extension can be recognized in this region. The earliest one, active in the Late Cretaceous to Eocene, involved NW-SE extension. The second one, active from the Late Eocene to Early Miocene involved north-south extension. The third stage of extension, which probably trended NW-SE, can be dated as post-Oligocene. The first extensional event produced the NE-SW trending proto-South China Sea and a series of sedimentary basins along the South China margin. Following the southeastward extrusion of Indochina, the proto-South China Sea was mostly consumed at the Palawan Trough. Renewed north-south extension in the South China continental margin started the present-day South China Sea spreading in the Oligocene. The southeastward extrusion of Indochina, blocked by Sundaland, resulted in the NW-SE trending opening of the South China Sea Basin in the Early Miocene. Collision of the North Palawan microcontinental block with the West Philippines block stopped the opening of the South China Sea at the end of Early Miocene. Spreading activity switched to the Sulu Sea Basin in the Middle Miocene but collision between the Sulu Ridge and the West Philippines at Mindanao halted the opening of the Sulu Sea at the end of the Middle Miocene. In the Late Miocene, Greater India continued its northward path and seems to have ripped open the Andaman Sea. In the Pliocene, subduction along the northern Manila Trench placed the North Luzon Arc on a collision path with the East Asia continental margin at Taiwan.Our reconstructions, along with detailed geological and geophysical information, may be used as a predictive tool for basin evolution models and block interactions in this region. The development of the South China Sea Basin, the Gulf of Thailand, the Malay Basin and the central Thailand basins are the result of collision-induced extensional forces. The Sulu, Celebes and Sumatra basins were formed as a consequence of prolonged subduction. The opening of the Pearl River Mouth, West Natuna, South China Sea, Sulu, and possibly Celebes, basins were terminated by various plate collisions. During the course of plate reorganizations major boundary faults have changed their slip senses during different stages of evolution.