Tectonic Evolution Of Basin Research Articles

Earthquake-related Tectonic Deformation of Soft-sediments and Its Constraints on Basin Tectonic Evolution

: The authors introduced two kinds of newly found soft-sediment deformation-syn-sedimentary extension structure and syn-sedimentary compression structure, and discuss their origins and constraints on basin tectonic evolution. One representative of the syn-sedimentary extension structure is syn-sedimentary boudinage structure, while the typical example of the syn-sedimentary compression structure is compression sand pillows or compression wrinkles. The former shows NW-SE-trending contemporaneous extension events related to earthquakes in the rift basin near a famous Fe-Nb-REE deposit in northern China during the Early Paleozoic (or Mesoproterozoic as proposed by some researches), while the latter indicates NE-SW-trending contemporaneous compression activities related to earthquakes in the Middle Triassic in the Nanpanjiang remnant basin covering south Guizhou, northwestern Guangxi and eastern Yunnan in southwestern China. The syn-sedimentary boudinage structure was found in an earthquake slump block in the lower part of the Early Paleozoic Sailinhudong Group, 20 km to the southeast of Bayan Obo, Inner Mongolia, north of China. The slump block is composed of two kinds of very thin layers—pale-gray micrite (microcrystalline limestone) of 1–2 cm thick interbedded with gray muddy micrite layers with the similar thickness. Almost every thin muddy micrite layer was cut into imbricate blocks or boudins by abundant tiny contemporaneous faults, while the interbedded micrite remain in continuity. Boudins form as a response to layer-parallel extension (and/or layer-perpendicular flattening) of stiff layers enveloped top and bottom by mechanically soft layers. In this case, the imbricate blocks cut by the tiny contemporaneous faults are the result of abrupt horizontal extension of the crust in the SE-NW direction accompanied with earthquakes. Thus, the rock block is, in fact, a kind of seismites. The syn-sedimentary boudins indicate that there was at least a strong earthquake belt on the southeast side of the basin during the early stage of the Sailinhudong Group. This may be a good constraint on the tectonic evolution of the Bayan Obo area during the Early Paleozoic time. The syn-sedimentary compression structure was found in the Middle Triassic flysch in the Nanpanjiang Basin. The typical structures are compression sand pillows and compression wrinkles. Both of them were found on the bottoms of sand units and the top surface of the underlying mud units. In other words, the structures were found only in the interfaces between the graded sand layer and the underlying mud layer of the flysch. A deformation experiment with dough was conducted, showing that the tectonic deformation must have been instantaneous one accompanied by earthquakes. The compression sand pillows or wrinkles showed uniform directions along the bottoms of the sand layer in the flysch, revealing contemporaneous horizontal compression during the time between deposition and diagenesis of the related beds. The Nanpanjiang Basin was affected, in general, with SSW-NNE compression during the Middle Triassic, according to the syn-sedimentary compression structure. The two kinds of syn-sedimentary tectonic deformation also indicate that the related basins belong to a rift basin and a remnant basin, respectively, in the model of Wilson Cycle.

Magnetostratigraphy of Cenozoic sediments from the Xining Basin: Tectonic implications for the northeastern Tibetan Plateau

The Xining subbasin of the Longzhong basin holds the longest continuous Cenozoic stratigraphic record at the margin of the northeastern Tibetan Plateau. Despite a rich biostratigraphic content (including the Xiejia mammal fauna), the tectonic evolution of the basin is largely unconstrained. In this study we present stratigraphic, biostratigraphic, and magnetostratigraphic results that provide a basis for reconstructing the Cenozoic tectonic evolution of the Xining basin with respect to adjacent regions of the northeastern Tibetan Plateau. Magnetostratigraphic analysis from three red bed sections in the Xining basin indicates continuous deposition at low and nearly constant accumulation rates (average 2.2 cm/kyr) from 52.0 to 17.0 Ma. We interpret this result to indicate that no major regional tectonic event implying large sediment accumulation variations has affected the Xining basin deposition during this considerable time window. In detail, accumulation rate variations outline a three‐stage evolution with 1.8 cm/kyr from 52.0 Ma to 34.5 Ma, 4.1 cm/kyr from 34.5 to 31.0 Ma, and 2.3 cm/kyr from 31.0 to 17.0 Ma. The second‐order increase between 34.5 and 31.0 Ma can be interpreted to result from either a distal tectonic event or to be of climatic origin. Although the region was tectonically quiescent for much of the Cenozoic, tectonic activity occurred during basin initiation (or reactivation) at circa 55.0–52.5 Ma and during intense basin deformation after 17.0 Ma.

Geotectonic evolution of the Great Basin

The crust of the Great Basin has occupied a range of tectonic settings through geologic time. Archean and Paleoproterozoic crustal genesis preceded residence of Laurentia within the Mesoproterozoic supercontinent Rodinia, which rifted in the late Neoproterozoic to delineate the Cordilleran flank of Laurentia. Successive stages of Phanerozoic evolution included (1) early to middle Paleozoic miogeoclinal sedimentation along a passive continental margin, (2) late Paleozoic to earliest Mesozoic thrusting of oceanic Antler and Sonoma allochthons over the continental margin in response to episodic slab rollback beneath an offshore Klamath-Sierran island-arc complex, (3) Mesozoic to mid-Cenozoic arc-rear and backarc thrusting, together with pulses of interior magmatism, associated with development of the Cordilleran magmatic arc to the west where subduction and arc accretion expanded the continental margin, and (4) middle to late Cenozoic crustal extension, which involved initial intra-arc to backarc deformation and later transtensional torsion of the continental block inland from the evolving San Andreas transform system. Potential metallogenic influences on Great Basin tectonic evolution included transfer of substance from mantle to crust by magmatism and associated metasomatism, and reworking of crustal materials by both magmatism and intracrustal fluid flow, the latter of which was induced both by thermal effects of magmatism and by reconfiguration of fluid-bearing rock masses during multiple episodes of Great Basin deformation.

Characteristics of Geo‐Temperature Gradient Distribution in the Kuqa Foreland Basin on the North Edge of the Tarim Basin, Western China

AbstractBased on the geo‐temperature data of 109 wells in the Kuqa foreland basin on the north edge of the Tarim basin, the characteristics of temperature field distribution are presented. The average geo‐temperature gradients of different structural units of Kuqa basin range from 18°C/km to 28°C/km, which are comparably lower than those of any other large and middle size basins in China. So the Kuqa foreland basin is globally a cold one with lower temperature. In detail, the distribution of geo‐temperature gradient of Kuqa foreland basin can be described as following. The mountain frontier belts including the Yiqikelike, Kelasu and Dawanqi areas have relatively high geo‐temperature gradients compared with other structural units of Kuqa. From the north to south of Kuqa, the geo‐temperature gradient decreases gradually. At the south of Kuqa, the geo‐temperature gradient is evidently different. In general, the geo‐temperature gradients decrease with the increasing of depth, tending to be identical at depth. But the rates of decrease are all different at different tectonic settings. The relationship between geo‐temperature gradient and formation and tectonic evolution of basin in relation to hydrocarbon exploration is also discussed.

Sandstone Petrology and Geochemistry of the Turpan Basin (NW China): Implications for the Tectonic Evolution of a Continental Basin

The evolution of the Turpan basin (NW China) from the Permian to the Tertiary was reconstructed from sandstone petrology and geochemistry, The sandstones are mostly feldspathic litharenite and litharenite, and were deposited mainly in fluvial and lacustrine environments. Sandstone samples show large variations in the contents of quartz and lithic fragments, A general increase in compositional maturity is observed from the Permian to the Tertiary. In particular, quartz content is only 11% in the Permian, increases to 27% in the Triassic, 35% in the Lower Jurassic, 36% in the Upper Jurassic, and more than 47% in the Cretaceous and Tertiary. The geochemistry of sandstones also varies with time. Late Permian sandstones have lower SiO2 (67,48%), and higher Fe2O3 (4.87%) and MgO (1.75%) values, whereas Triassic and Jurassic samples show high SiO2 (74,15%, 77.5% respectively) and low Fe2O3 (4,06%, 2.8%) and MgO (0,95%, 0.79%) contents. In the Cretaceous and Tertiary, Fe2O3 and MgO contents increased again. K2O, Na2O, and Al2O3 also vary considerably within the study site. The tectonic evolution of the basin can be subdivided into three stages from petrologic and geochemical data: the first stage covers the Permian; the second stage the Triassic and Jurassic, and the third stage the Cretaceous and Tertiary. There are two large discontinuities in sandstone composition among these three stages, These discontinuities signify the influence of collision and convergence of the Tarim block at the end of the Permian, and the Gangdise block between the Jurassic and the Cretaceous, with the Eurasian Plate. The source-rock regions of the basin varied with time. In Permian, Triassic, and Jurassic time, the paleo-Jueluotage Shan Mountains were the dominant source region for the Turpan basin, while in the Cretaceous and Tertiary, the paleo-Bogda Shan Mountains were an important source region. In the Tertiary and later, the Bogda Shan Mountains continued to be strongly uplifted during the collision of the Indian Plate with the Eurasian Plate and were the dominant source region. The trace-element ratios Eu/Eu*, Gd-n/Yb-n, La/Yb, and La/Th (subscript n refers to chandrite-normalized values) show that the source rocks of the sedimentary rocks were derived from upper continental crust, The data from the Turpan basin show that combined petrologic and geochemical analysis of sandstone suites can be used to track changes in the sediment supply from adjacent areas if (1) a long-term record of the basin fill is available; (2) the source signal is preserved by proximal depositional conditions; and (3) diagenetic alteration of sediments is limited. Provenance-derived variations in sandstone compositions are therefore a key in unraveling regional tectonic histories.

Geochemical and Geological Control on Filling History of Eocene Reservoirs, Maracaibo Basin, Venezuela: ABSTRACT

Crude oils of Eocene fluvio-deltaic reservoirs in {open_quotes}Bloque V{close_quotes} and {open_quotes}Centro Lago{close_quotes} fields in the center of the Maracaibo Lake show many differences in composition, which are due to stratigraphically and structurally controlled reservoir geometry and a low rate of in-reservoir mixing of at least two successive petroleum charges. Oils produced from the top of structural highs contain 18(H) oleanane, higher Pr/Ph and C{sub 23-3}/C{sub 24-4} ratios, a lower proportion of DBT/P compounds, and clearly different fingerprint patterns in the C{sub 6}-C{sub 15} range, than those observed in oils produced from the lower parts of the structures. These compositional differences suggest that two source rocks, or two distinctive organic facies within the same Cretaceous La Luna Formation, generated and filled vertically poorly connected Eocene reservoirs. On the other hand, saturate-biomarkers ratios, triaromatics (C{sub 21}/C{sub 21}+C{sub 28}), n-paraffins (n-C{sub 20}/n-C{sub 29}) and n-heptane index suggest that oils in upper reservoirs are slightly less mature than oils in lower reservoirs and, consequently filled the structure first. Additional evidence from formation water analysis and tectonic basin evolution allow us to interpret at least two petroleum pulses from Cretaceous source rocks during Upper Miocene to present day kitchens located in the Andes foredeep atmore » the southeast of the study area.« less

Tectonic Development of Baltimore Canyon Trough: ABSTRACT

New well data and a new gravity model across the southern end of Baltimore Canyon Trough provide a more complete history of the basin's tectonic evolution and deep crustal structure than was previously known. The basin, which formed during the separation of North America from Africa, narrows and shallows along strike, as basement depth decreases from about 18 km (59,000 ft) in the north near New York to about 4-6 km (13,123-19,685 ft) in the south near Cape Hatteras. Previous analysis of the Continental Offshore Stratigraphic Test (COST) B2 and B3 wells using backstripping techniques showed a seaward increase in the amount of stretching during the basin's formation. The new biostratigraphic and paleoenvironmental interpretations are from the USGS Island Beach well 1 jus landward of the hinge zone in the basin. This well, along with the COST B2 and B3 data, provides a sampling of the sedimentary sections overlying continental, transitional (rift-stage), and oceanic crust. The subsidence histories derived from these data give a cross-sectional view of the basin's evolution. A gravity model of the southern end of the basin, along USGS multi-channel seismic line 28, primarily analyzes a 60-mgal shelfedge anomaly. This anomaly reflects the change in bathymetry and more important a change toward the continent in underlying crustal thickness from typical oceanic to thinned continental crust. The crustal thinning is compared to the broad thinning zone to the north. Well-defined rift structures on the landward edge of the basin are modeled as rift grabens near the hinge zone. End_of_Article - Last_Page 533------------

Tectônica do alinhamento estrutural do Paranapanema

A structural line ESE-WNW oriented named Paranapanema had a strong influence during the Paraná sedimentary basin tectonic evolution from the Upper Carboniferous to the dose of Mesozoic. During this time onlap of stratigraphic units indicates this region as a marginal one dividing the basin in two sub-basins with different tectonic behaviour. Cenazoic reactivation of the ancient fault lines with sedimentation in isolated basins indicates that the same processes were acting until recent times.