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1.
Eastward Andean orogenic growth since the late Oligocene led to variable crustal loading, flexural subsidence and foreland basin sedimentation in the Chaco basin. To understand the interaction between Andean tectonics and contemporaneous foreland development, we analyse stratigraphic, sedimentologic and seismic data from the Subandean Belt and the Chaco Basin. The structural features provide a mechanism for transferring zones of deposition, subsidence and uplift. These can be reconstructed based on regional distribution of clastic sequences. Isopach maps, combined with sedimentary architecture analysis, establish systematic thickness variations, facies changes and depositional styles. The foreland basin consists of five stratigraphic successions controlled by Andean orogenic episodes and climate: (1) the foreland basin sequence commences between ～27 and 14 Ma with the regionally unconformable, thin, easterly sourced fluvial Petaca strata. It represents a significant time interval of low sediment accumulation in a forebulge‐backbulge depocentre. (2) The overlying ～14–7 Ma‐old Yecua Formation, deposited in marine, fluvial and lacustrine settings, represents increased subsidence rates from thrust‐belt loading outpacing sedimentation rates. It marks the onset of active deformation and the underfilled stage of the foreland basin in a distal foredeep. (3) The overlying ～7–6 Ma‐old, westerly sourced Tariquia Formation indicates a relatively high accommodation and sediment supply concomitant with the onset of deposition of Andean‐derived sediment in the medial‐foredeep depocentre on a distal fluvial megafan. Progradation of syntectonic, wedge‐shaped, westerly sourced, thickening‐ and coarsening‐upward clastics of the (4) ～6–2.1 Ma‐old Guandacay and (5) ～2.1 Ma‐to‐Recent Emborozú Formations represent the propagation of the deformation front in the present Subandean Zone, thereby indicating selective trapping of coarse sediments in the proximal foredeep and wedge‐top depocentres, respectively. Overall, the late Cenozoic stratigraphic intervals record the easterly propagation of the deformation front and foreland depocentre in response to loading and flexure by the growing Intra‐ and Subandean fold‐and‐thrust belt. 相似文献
2.
Foreland basin systems 总被引：32，自引：1，他引：32
A foreland basin system is defined as: (a) an elongate region of potential sediment accommodation that forms on continental crust between a contractional orogenic belt and the adjacent craton, mainly in response to geodynamic processes related to subduction and the resulting peripheral or retroarc fold-thrust belt; (b) it consists of four discrete depozones, referred to as the wedge-top, foredeep, forebulge and back-bulge depozones – which of these depozones a sediment particle occupies depends on its location at the time of deposition, rather than its ultimate geometric relationship with the thrust belt; (c) the longitudinal dimension of the foreland basin system is roughly equal to the length of the fold-thrust belt, and does not include sediment that spills into remnant ocean basins or continental rifts (impactogens). The wedge-top depozone is the mass of sediment that accumulates on top of the frontal part of the orogenic wedge, including ‘piggyback’ and ‘thrust top’ basins. Wedge-top sediment tapers toward the hinterland and is characterized by extreme coarseness, numerous tectonic unconformities and progressive deformation. The foredeep depozone consists of the sediment deposited between the structural front of the thrust belt and the proximal flank of the forebulge. This sediment typically thickens rapidly toward the front of the thrust belt, where it joins the distal end of the wedge-top depozone. The forebulge depozone is the broad region of potential flexural uplift between the foredeep and the back-bulge depozones. The back-bulge depozone is the mass of sediment that accumulates in the shallow but broad zone of potential flexural subsidence cratonward of the forebulge. This more inclusive definition of a foreland basin system is more realistic than the popular conception of a foreland basin, which generally ignores large masses of sediment derived from the thrust belt that accumulate on top of the orogenic wedge and cratonward of the forebulge. The generally accepted definition of a foreland basin attributes sediment accommodation solely to flexural subsidence driven by the topographic load of the thrust belt and sediment loads in the foreland basin. Equally or more important in some foreland basin systems are the effects of subduction loads (in peripheral systems) and far-field subsidence in response to viscous coupling between subducted slabs and mantle–wedge material beneath the outboard part of the overlying continent (in retroarc systems). Wedge-top depozones accumulate under the competing influences of uplift due to forward propagation of the orogenic wedge and regional flexural subsidence under the load of the orogenic wedge and/or subsurface loads. Whereas most of the sediment accommodation in the foredeep depozone is a result of flexural subsidence due to topographic, sediment and subduction loads, many back-bulge depozones contain an order of magnitude thicker sediment fill than is predicted from flexure of reasonably rigid continental lithosphere. Sediment accommodation in back-bulge depozones may result mainly from aggradation up to an equilibrium drainage profile (in subaerial systems) or base level (in flooded systems). Forebulge depozones are commonly sites of unconformity development, condensation and stratal thinning, local fault-controlled depocentres, and, in marine systems, carbonate platform growth. Inclusion of the wedge-top depozone in the definition of a foreland basin system requires that stratigraphic models be geometrically parameterized as doubly tapered prisms in transverse cross-sections, rather than the typical ‘doorstop’ wedge shape that is used in most models. For the same reason, sequence stratigraphic models of foreland basin systems need to admit the possible development of type I unconformities on the proximal side of the system. The oft-ignored forebulge and back-bulge depozones contain abundant information about tectonic processes that occur on the scales of orogenic belt and subduction system. 相似文献
3.
Linkage of Sevier thrusting episodes and Late Cretaceous foreland basin megasequences across southern Wyoming (USA) 总被引：2，自引：0，他引：2
Deposition and subsidence analysis, coupled with previous structural studies of the Sevier thrust belt, provide a means of reconstructing the detailed kinematic history of depositional response to episodic thrusting in the Cordilleran foreland basin of southern Wyoming, western interior USA. The Upper Cretaceous basin fill is divided into five megasequences bounded by unconformities. The Sevier thrust belt in northern Utah and southwestern Wyoming deformed in an eastward progression of episodic thrusting. Three major episodes of displacement on the Willard‐Meade, Crawford and ‘early’ Absaroka thrusts occurred from Aptian to early Campanian, and the thrust wedge gradually became supercritically tapered. The Frontier Formation conglomerate, Echo Canyon and Weber Canyon Conglomerates and Little Muddy Creek Conglomerate were deposited in response to these major thrusting events. Corresponding to these proximal conglomerates within the thrust belt, Megasequences 1, 2 and 3 were developed in the distal foreland of southern Wyoming. Two‐dimensional (2‐D) subsidence analyses show that the basin was divided into foredeep, forebulge and backbulge depozones. Foredeep subsidence in Megasequences 1, 2 and 3, resulting from Willard‐Meade, Crawford and ‘early’ Absaroka thrust loading, were confined to a narrow zone in the western part of the basin. Subsidence in the broad region east of the forebulge was dominantly controlled by sediment loading and inferred dynamic subsidence. Individual subsidence curves are characterized by three stages from rapid to slow. Controlled by relationships between accommodation and sediment supply, the basin was filled with retrogradational shales during periods of rapid subsidence, followed by progradational coarse clastic wedges during periods of slow subsidence. During middle Campanian time (ca. 78.5–73.4 Ma), the thrust wedge was stalled because of wedge‐top erosion and became subcritical, and the foredeep zone eroded and rebounded because of isostasy. The eroded sediments were transported far from the thrust belt, and constitute Megasequence 4 that was mostly composed of fluvial and coastal plain depositional systems. Subsidence rates were very slow, because of post‐thrusting rebound, and the resulting 2‐D subsidence was lenticular in an east–west direction. During late Campanian to early Maastrichtian time, widespread deposits of coarse sediment (the Hams Fork Conglomerate) aggraded the top of the thrust wedge after it stalled, prior to initiation of ‘late’ Absaroka thrusting. Meanwhile Megasequence 5 was deposited in the Wyoming foreland under the influence of both the intraforeland Wind River basement uplift and the Sevier thrust belt. 相似文献
4.
Detrital zircon geochronology of pre‐ and syncollisional strata,Acadian orogen,Maine Appalachians 
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下载免费PDF全文 The Central Maine Basin is the largest expanse of deep‐marine, Upper Ordovician to Devonian metasedimentary rocks in the New England Appalachians, and is a key to the tectonics of the Acadian Orogeny. Detrital zircon ages are reported from two groups of strata: (1) the Quimby, Rangeley, Perry Mountain and Smalls Falls Formations, which were derived from inboard, northwesterly sources and are supposedly older; and (2) the Madrid, Carrabassett and Littleton Formations, which were derived from outboard, easterly sources and are supposedly younger. Deep‐water deposition prevailed throughout, with the provenance shift inferred to mark the onset of foredeep deposition and orogeny. The detrital zircon age distribution of a composite of the inboard‐derived units shows maxima at 988 and 429 Ma; a composite from the outboard‐derived units shows maxima at 1324, 1141, 957, 628, and 437 Ma. The inboard‐derived units have a greater proportion of zircons between 450 and 400 Ma. Three samples from the inboard‐derived group have youngest age maxima that are significantly younger than the nominal depositional ages. The outboard‐derived group does not share this problem. These results are consistent with the hypothesised provenance shift, but they signal potential problems with the established stratigraphy, structure, and (or) regional mapping. Shallow‐marine deposits of the Silurian to Devonian Ripogenus Formation, from northwest of the Central Maine Basin, yielded detrital zircons featuring a single age maximum at 441 Ma. These zircons were likely derived from a nearby magmatic arc now concealed by younger strata. Detrital zircons from the Tarratine Formation, part of the Acadian foreland‐basin succession in this strike belt, shows age maxima at 1615, 980 and 429 Ma. These results are consistent with three episodes of zircon recycling beginning with the deposition of inboard‐derived strata of the Central Maine Basin, which were shed from post‐Taconic highlands located to the northwest. Next, southeasterly parts of this succession were deformed in the Acadian orogeny, shedding detritus towards the northwest into what remained of the basin. Finally, by Pragian time, all strata in the Central Maine Basin had been deformed and detritus from this new source accumulated as the Tarratine Formation in a new incarnation of the foreland basin. Silurian‐Devonian strata from the Central Maine Basin have similar detrital zircon age distributions to coeval rocks from the Arctic Alaska and Farewell terranes of Alaska and the Northwestern terrane of Svalbard. We suggest that these strata were derived from different segments of the 6500‐km‐long Appalachian‐Caledonide orogen. 相似文献
5.
Basin evolution of Upper Cretaceous–Lower Cenozoic strata in the Malargüe fold‐and‐thrust belt: northern Neuquén Basin,Argentina 下载免费PDF全文
下载免费PDF全文 The Andean Orogen is the type‐example of an active Cordilleran style margin with a long‐lived retroarc fold‐and‐thrust belt and foreland basin. Timing of initial shortening and foreland basin development in Argentina is diachronous along‐strike, with ages varying by 20–30 Myr. The Neuquén Basin (32°S to 40°S) contains a thick sedimentary sequence ranging in age from late Triassic to Cenozoic, which preserves a record of rift, back arc and foreland basin environments. As much of the primary evidence for initial uplift has been overprinted or covered by younger shortening and volcanic activity, basin strata provide the most complete record of early mountain building. Detailed sedimentology and new maximum depositional ages obtained from detrital zircon U–Pb analyses from the Malargüe fold‐and‐thrust belt (35°S) record a facies change between the marine evaporites of the Huitrín Formation (ca. 122 Ma) and the fluvial sandstones and conglomerates of the Diamante Formation (ca. 95 Ma). A 25–30 Myr unconformity between the Huitrín and Diamante formations represents the transition from post‐rift thermal subsidence to forebulge erosion during initial flexural loading related to crustal shortening and uplift along the magmatic arc to the west by at least 97 ± 2 Ma. This change in basin style is not marked by any significant difference in provenance and detrital zircon signature. A distinct change in detrital zircons, sandstone composition and palaeocurrent direction from west‐directed to east‐directed occurs instead in the middle Diamante Formation and may reflect the Late Cretaceous transition from forebulge derived sediment in the distal foredeep to proximal foredeep material derived from the thrust belt to the west. This change in palaeoflow represents the migration of the forebulge, and therefore, of the foreland basin system between 80 and 90 Ma in the Malargüe area. 相似文献
6.
Facies distributions, stratal geometry and regional erosional bevelling surfaces in Upper Cretaceous (Cenomanian-Santonian) strata of the Alberta foreland basin are interpreted in terms of high-frequency (probably eustatic) relative changes in sea level, superimposed on longer-term basin-floor warping, related to episodic tectonic loading. Thick marine shales correspond to periods of rapid subsidence whereas thin but extensive strandplain sandstones record rapid progradation during slow subsidence. Westward-thickening wedges of coastal plain strata were deposited during initial downwarping of a near-horizontal strandplain, prior to marine transgression. Surfaces of erosional bevelling beneath which between 40 and >160m of strata have been removed extend at least 300 km from the present deformation front and are interpreted to reflect forebulge uplift in the east. Uplift appears to have lagged about 0.25-0.5 Myr behind the onset of accelerated loading. Thin marine sandstones which grade westward into mudstone are interpreted as material winnowed from the crest of the rising forebulge. Subsidence and/or westward migration of the forebulge allowed the sea to flood westward across the eastern flank of the eroded forebulge. The transgressive shoreface cut asymmetric notches which were later blanketed by marine shales which lap out from east to west. The two unconformities which embody the largest erosional vacuity are veneered locally with oolitic ironstone which accumulated in a shallow, sediment-starved setting on the crest of the forebulge. The consistent pattern of erosional bevelling and lap-out of transgressive shales might be interpreted as evidence that the forebulge migrated towards the thrust load over a period of <1 Myr. 相似文献
7.
Barbara Carrapa Sharon Bywater‐Reyes Peter G. DeCelles Estelle Mortimer George E. Gehrels 《Basin Research》2012,24(3):249-268
Important aspects of the Andean foreland basin in Argentina remain poorly constrained, such as the effect of deformation on deposition, in which foreland basin depozones Cenozoic sedimentary units were deposited, how sediment sources and drainages evolved in response to tectonics, and the thickness of sediment accumulation. Zircon U‐Pb geochronological data from Eocene–Pliocene sedimentary strata in the Eastern Cordillera of northwestern Argentina (Pucará–Angastaco and La Viña areas) provide an Eocene (ca. 38 Ma) maximum depositional age for the Quebrada de los Colorados Formation. Sedimentological and provenance data reveal a basin history that is best explained within the context of an evolving foreland basin system affected by inherited palaeotopography. The Quebrada de los Colorados Formation represents deposition in the distal to proximal foredeep depozone. Development of an angular unconformity at ca. 14 Ma and the coarse‐grained, proximal character of the overlying Angastaco Formation (lower to upper Miocene) suggest deposition in a wedge‐top depozone. Axial drainage during deposition of the Palo Pintado Formation (upper Miocene) suggests a fluvial‐lacustrine intramontane setting. By ca. 4 Ma, during deposition of the San Felipe Formation, the Angastaco area had become structurally isolated by the uplift of the Sierra de los Colorados Range to the east. Overall, the Eastern Cordillera sedimentary record is consistent with a continuous foreland basin system that migrated through the region from late Eocene through middle Miocene time. By middle Miocene time, the region lay within the topographically complex wedge‐top depozone, influenced by thick‐skinned deformation and re‐activation of Cretaceous rift structures. The association of the Eocene Quebrada del los Colorados Formation with a foredeep depozone implies that more distal foreland deposits should be represented by pre‐Eocene strata (Santa Barbara Subgroup) within the region. 相似文献
8.
Constraint on foreland basin migration in the Zagros mountain belt using Sr isotope stratigraphy 下载免费PDF全文
下载免费PDF全文 We have constrained the time‐space migration of the Zagros foredeep basin by performing Sr isotope stratigraphy on 31 samples of marine macrofossils from Neogene sediments now exposed in the Zagros mountain belt in southwest Iran. Our results show that these deposits (represented mainly by the Mishan Formation) are strongly diachronous, with ages ranging between 17.2 ± 0.2 and 1.1 ± 0.1 Ma. These deposits are older in the west (Dezful region) and become progressively younger towards the south and the south‐east (Fars region). Our results show that the marine foredeep was replaced by a fluvial sedimentary environment between ca. 14 and 12 Ma in the western sector, while this occurred between ca. 8 and 1 Ma in the eastern sector, becoming younger towards the south. These results enable us to show that the foreland basin migrated perpendicular to the orogen at rates of between 17.5 and 50 mm year?1 throughout the Neogene, exceeding migration rates in the Alps, Pyrenees, Apennines and Himalayan foreland basins. The sporadically elevated rates in the Zagros appear to be related to times when major widely spaced pre‐existing basement faults became reactivated. Finally, our results, when combined with published data, have enabled us to establish a new chronostratigraphic diagram for the Neogene portion of the Zagros foreland basin. Our study highlights that foreland basins are extremely dynamic settings where depocentres and palaeoenvironments may change rapidly in both time and space in relation to migrating deformation. 相似文献
9.
Detrital thermochronologic record of burial heating and sediment recycling in the Magallanes foreland basin,Patagonian Andes 下载免费PDF全文
下载免费PDF全文 Julie C. Fosdick Marty Grove Stephan A. Graham Jeremy K. Hourigan Oscar Lovera Brian W. Romans 《Basin Research》2015,27(4):546-572
The Patagonian Magallanes retroarc foreland basin affords an excellent case study of sediment burial recycling within a thrust belt setting. We report combined detrital zircon U–Pb geochronology and (U–Th)/He thermochronology data and thermal modelling results that confirm delivery of both rapidly cooled, first‐cycle volcanogenic sediments from the Patagonian magmatic arc and recycled sediment from deeply buried and exhumed Cretaceous foredeep strata to the Cenozoic depocentre of the Patagonian Magallanes basin. We have quantified the magnitude of Eocene heating with thermal models that simultaneously forward model detrital zircon (U–Th)/He dates for best‐fit thermal histories. Our results indicate that 54–45 Ma burial of the Maastrichtian Dorotea Formation produced 164–180 °C conditions and heating to within the zircon He partial retention zone. Such deep burial is unusual for Andean foreland basins and may have resulted from combined effects of high basal heat flow and high sediment accumulation within a rapidly subsiding foredeep that was floored by basement weakened by previous Late Jurassic rifting. In this interpretation, Cenozoic thrust‐related deformation deeply eroded the Dorotea Formation from ca. 5 km burial depths and may be responsible for the development of a basin‐wide Palaeogene unconformity. Results from the Cenozoic Río Turbio and Santa Cruz formations confirm that they contain both Cenozoic first‐cycle zircon from the Patagonian magmatic arc and highly outgassed zircon recycled from older basin strata that experienced burial histories similar to those of the Dorotea Formation. 相似文献
10.
The Upper Devonian Rhinestreet black shale of the western New York state region of the Appalachian Basin has experienced multiple episodes of overpressure generation manifested by at least two sets of natural hydraulic fractures. These overpressure events were thermal in origin and induced by the generation of hydrocarbons during the Alleghanian orogeny close to or at the Rhinestreet's ～3.1 km maximum burial depth. Analysis of differential gravitational compaction strain of the organic‐rich shale around embedded carbonate concretions that formed within a metre or so of the seafloor indicates that the Rhinestreet shale was compacted ～58%. Compaction strain was recalculated to a palaeoporosity of 37.8%, in excess of that expected for burial >3 km. The palaeoporosity of the Rhinestreet shale suggests that porosity reduction caused by normal gravitational compaction of the low‐permeability carbonaceous sediment was arrested at some depth shy of its maximum burial depth by pore pressure in excess of hydrostatic. The depth at which the Rhinestreet shale became overpressured, the palaeo‐fluid retention depth, was estimated by use of published normal compaction curves and empirical porosity‐depth algorithms to fall between 850 and 1380 m. Early and relatively shallow overpressuring of the Rhinestreet shale likely originated by disequilibrium compaction induced by a marked increase in sedimentation rate in the latter half of the Famennian stage (Late Devonian) as the Catskill Delta Complex prograded westward across the Appalachian Basin in response to Acadian tectonics. The regional Upper Devonian stratigraphy of western New York state indicates that the onset of overpressure occurred at a depth of ～1100 m, well in advance of the Rhinestreet shale's entry into the oil window during the Alleghanian orogeny. 相似文献
11.
Forebulge migration in the Cretaceous Western Interior basin of the central United States 总被引：3，自引：0，他引：3
ABSTRACT This study combines stratigraphic evidence with geodynamic modelling to demonstrate that a forebulge played an identifiable role in Cenomanian–Turonian erosion and sediment accumulation in the North American Western Interior basin. The early to middle Turonian forebulge migrated progressively eastwards, and by the upper middle Turonian acted as a 'backstop' against which barrier islands formed in the axial basin.
This paper focuses on the progressive migration of an unconformity on the forebulge. The lengthwise orogen-parallel orientation and time-transgressive orogen-normal migration of the forebulge unconformity are characteristics that differentiate it from unconformities developed on reactivated basement structures. We present a conceptual model in which the unconformity formed as the seafloor was uplifted by forebulge-related flexure to a water depth at which submarine bypass and erosion occurred. A numerical model that describes forebulge migration in response to load dispersal by erosion of the orogenic front and sedimentation into the foredeep indicates that the distance from the thrust front to the forebulge is within reasonable bounds established using a flexural rigidity of 3×1024 Nm.
We identify architecturally similar, coeval unconformities from Montana to New Mexico, and interpret the similar distance from the thrust front to a point where each unconformity dissipates as indicative of a uniform lithospheric flexural response along the orogenic front. Here we ascribe cratonward (west-to-east) forebulge migration to erosional load redistribution, whereas orogen-parallel (north–south) stratigraphic climb of the forebulge unconformities developed in response to depocentre migration. Inherited lithospheric inhomogeneities may have allowed the forebulge in central Colorado to crest farther from the orogen than to the north and south. 相似文献
This paper focuses on the progressive migration of an unconformity on the forebulge. The lengthwise orogen-parallel orientation and time-transgressive orogen-normal migration of the forebulge unconformity are characteristics that differentiate it from unconformities developed on reactivated basement structures. We present a conceptual model in which the unconformity formed as the seafloor was uplifted by forebulge-related flexure to a water depth at which submarine bypass and erosion occurred. A numerical model that describes forebulge migration in response to load dispersal by erosion of the orogenic front and sedimentation into the foredeep indicates that the distance from the thrust front to the forebulge is within reasonable bounds established using a flexural rigidity of 3×10
We identify architecturally similar, coeval unconformities from Montana to New Mexico, and interpret the similar distance from the thrust front to a point where each unconformity dissipates as indicative of a uniform lithospheric flexural response along the orogenic front. Here we ascribe cratonward (west-to-east) forebulge migration to erosional load redistribution, whereas orogen-parallel (north–south) stratigraphic climb of the forebulge unconformities developed in response to depocentre migration. Inherited lithospheric inhomogeneities may have allowed the forebulge in central Colorado to crest farther from the orogen than to the north and south. 相似文献
12.
Jason S. Reed James A. Spotila Kenneth A. Eriksson Robert J. Bodnar 《Basin Research》2005,17(2):259-268
An inferred burial and exhumation history of Pennsylvanian strata in the central Appalachian foreland basin is constrained by integrating palaeothermometers, geochronometers and estimated palaeogeothermal gradients. Vitrinite reflectance data and fluid inclusion homogenization temperatures indicate that burial of Lower and Upper Pennsylvanian strata of the Appalachian Plateau in West Virginia exceeded ～4.4 km during the late Permian and occurred at a rate of ～100 m Myr?1. Exhumation rates of ～10 m Myr?1 from the late Permian to the early Cretaceous are constrained using maximum burial conditions and published apatite fission track (AFT) ages. AFT and radiogenic helium ages indicate exhumation rates of ～30–50 m Myr?1 from the early to late Cretaceous. Radiogenic helium dates and present day sampling depths indicate that exhumation rates from the late Cretaceous to present were ～25 m Myr?1. Exhumation rates for Upper and Lower Pennsylvanian strata within the Appalachian Plateau are remarkably similar. Early slow exhumation was possibly driven primarily by isostatic rebound associated with Triassic rifting. The later, more rapid exhumation can be attributed to thermal expansion followed by lithospheric flexure related to sediment loading along the passive margin. 相似文献
13.
An integrated provenance analysis of the Upper Cretaceous Magallanes retroarc foreland basin of southern Chile (50°30′–52°S) provides new constraints on source area evolution, regional patterns of sediment dispersal and depositional age. Over 450 new single‐grain detrital‐zircon U‐Pb ages, which are integrated with sandstone petrographic and mudstone geochemical data, provide a comprehensive detrital record of the northern Magallanes foreland basin‐filling succession (>4000‐m‐thick). Prominent peaks in detrital‐zircon age distribution among the Punta Barrosa, Cerro Toro, Tres Pasos and Dorotea Formations indicate that the incorporation and exhumation of Upper Jurassic igneous rocks (ca. 147–155 Ma) into the Andean fold‐thrust belt was established in the Santonian (ca. 85 Ma) and was a significant source of detritus to the basin by the Maastrichtian (ca. 70 Ma). Sandstone compositional trends indicate an increase in volcanic and volcaniclastic grains upward through the basin fill corroborating the interpretation of an unroofing sequence. Detrital‐zircon ages indicate that the Magallanes foredeep received young arc‐derived detritus throughout its ca. 20 m.y. filling history, constraining the timing of basin‐filling phases previously based only on biostratigraphy. Additionally, spatial patterns of detrital‐zircon ages in the Tres Pasos and Dorotea Formations support interpretations that they are genetically linked depositional systems, thus demonstrating the utility of provenance indicators for evaluating stratigraphic relationships of diachronous lithostratigraphic units. This integrated provenance dataset highlights how the sedimentary fill of the Magallanes basin is unique among other retroarc foreland basins and from the well‐studied Andean foreland basins farther north, which is attributed to nature of the predecessor rift and backarc basin. 相似文献
14.
Cretaceous evolution of the Andean margin between 36°S and 40°S latitude through a multi‐proxy provenance analysis of Neuquén Basin strata (Argentina) 下载免费PDF全文
下载免费PDF全文 Andrea Di Giulio Ausonio Ronchi Alessio Sanfilippo Elizabeth A. Balgord Barbara Carrapa Victor A. Ramos 《Basin Research》2017,29(3):284-304
During the Cretaceous, the Neuquén Basin transitioned from an extensional back‐arc to a retroarc foreland basin. We present a multi‐proxy provenance study of Aptian to Santonian (125–84 Ma) continental sedimentary rocks preserved in the Neuquén Basin used to resolve changes of sediment drainage pattern in response to the change in tectonic regime. Sandstone petrology and U–Pb detrital zircon geochronology constrain the source units delivering detritus to the basin; apatite U–Pb and fission track dating further resolve provenance and determine the age and patterns of exhumation of the source rocks. Sandstone provenance records a sharp change from a mixed orogenic source during Aptian time (ca. 125 Ma), to a magmatic arc provenance in the Cenomanian (ca. 100 Ma). We interpret this provenance change as the result of the drainage pattern reorganisation from divergent to convergent caused by tectonic basin inversion. During this inversion and early stages of contraction, a transient phase of uplift and basin erosion, possibly due to continental buckling, caused the pre‐Cenomanian unconformity dividing the Lower from Upper Cretaceous strata in the Neuquén Basin. This phase was followed by the development of a retroarc foreland basin characterised by a volcanic arc sediment provenance progressively shifting to a mixed continental basement provenance during Turonian‐Santonian (90–84). According to multi‐proxy provenance data and lag times derived from apatite fission track analysis, this trend is the result of a rapidly exhuming source within the Cordillera to the west, in response to active compressional tectonics along the western margin of South America, coupled with the increasing contribution of material from the stable craton to the east; this contribution is thought to be the result of the weak uplift and exhumation of the foreland due to eastward migration of the forebulge. 相似文献
15.
The Anticosti Basin, largely hidden beneath the Gulf of St. Lawrence, includes foreland basin successions that record multiple tectonic events associated with the Ordovician to Devonian evolution of the northern Appalachian orogen. Due to the lack of well ties and minimal onshore exposure, geophysical data must be used in mapping the offshore stratigraphy. Outcropping geologic boundaries are tied to magnetic lineaments that parallel stratigraphy. These lineaments are correlated with reflections on seismic profiles in order to interpret the subsurface. Seismic isochron maps for successive basin development episodes display differences in geometry, implying that orogenic loading varied through time. The geometry and subsidence rates recorded by the Middle Ordovician Goose Tickle Group imply that it formed in a pro-arc setting associated with loading during arc-continent collision that was most intense in the northern Newfoundland Appalachians. The geometry and subsidence recorded by the overlying Long Point Group imply pro-arc loading by Taconian allochthons in the Québec segment of the orogen. Diachronous subduction polarity reversal along the margin placed the Long Point Group in a combined retro-arc and pro-arc setting, comparable to that experienced by parts of the north Australian margin at the present day. The uppermost Silurian to Lower Devonian Clam Bank Formation and Lower Devonian Red Island Road Formation represent foreland basin successions associated with the later Salinian and Acadian orogenies. Their consistent thickness implies a broad, shallow basin, suggesting that the lithosphere was cooler and stronger than during earlier subsidence, and are consistent with a retro-arc setting. 相似文献
16.
Andreu Vinyoles Miguel Lpez‐Blanco Miguel Garcs Pau Arbus Luis Valero Elisabet Beamud Beln Oliva‐Urcia Patricia Cabello 《Basin Research》2021,33(1):447-477
The propagation of the deformation front in foreland systems is typically accompanied by the incorporation of parts of the basin into wedge‐top piggy‐back basins, this process is likely producing considerable changes to sedimentation rates (SR). Here we investigate the spatial‐temporal evolution of SR for the Tremp–Jaca Basin in the Southern Pyrenees during its evolution from a wedge‐top, foreredeep, forebulge configuration to a wedge‐top stage. SR were controlled by a series of tectonic structures that influenced subsidence distribution and modified the sediment dispersal patterns. We compare the decompacted SR calculated from 12 magnetostratigraphic sections located throughout the Tremp–Jaca Basin represent the full range of depositional environment and times. While the derived long‐term SR range between 9.0 and 84.5 cm/kyr, compiled data at the scale of magnetozones (0.1–2.5 Myr) yield SR that range from 3.0 to 170 cm/kyr. From this analysis, three main types of depocenter are recognized: a regional depocenter in the foredeep depozone; depocenters related to both regional subsidence and salt tectonics in the wedge‐top depozone; and a depocenter related to clastic shelf building showing transgressive and regressive trends with graded and non‐graded episodes. From the evolution of SR we distinguish two stages. The Lutetian Stage (from 49.1–41.2 Ma) portrays a compartmentalized basin characterized by variable SR in dominantly underfilled accommodation areas. The markedly different advance of the deformation front between the Central and Western Pyrenees resulted in a complex distribution of the foreland depozones during this stage. The Bartonian–Priabonian Stage (41.2–36.9 Ma) represents the integration of the whole basin into the wedge‐top, showing a generalized reduction of SR in a mostly overfilled relatively uniform basin. The stacking of basement units in the hinterland during the whole period produced unusually high SR in the wedge‐top depozone. 相似文献
17.
Joel E. Saylor Brian K. Horton Junsheng Nie Jaime Corredor Andrés Mora 《Basin Research》2011,23(4):377-402
This paper addresses foreland basin fragmentation through integrated detrital zircon U–Pb geochronology, sandstone petrography, facies analysis and palaeocurrent measurements from a Mesozoic–Cenozoic clastic succession preserved in the northern Andean retroarc fold‐thrust belt. Situated along the axis of the Eastern Cordillera of Colombia, the Floresta basin first received sediment from the eastern craton (Guyana shield) in the Cretaceous–early Palaeocene and then from the western magmatic arc (Central Cordillera) starting in the mid‐Palaeocene. The upper‐crustal magmatic arc was replaced by a metamorphic basement source in the middle Eocene. This, in turn, was replaced by an upper‐crustal fold‐thrust belt source in the late Eocene which persisted until Oligocene truncation of the Cenozoic section by the eastward advancing thrust front. Sedimentary facies analysis indicates minimal changes in depositional environments from shallow marine to low‐gradient fluvial and estuarine deposits. These same environments are recorded in coeval strata across the Eastern Cordillera. Throughout the Palaeogene, palaeocurrent and sediment provenance data point to a uniform western or southwestern sediment source. These data show that the Floresta basin existed as part of a laterally extensive, unbroken foreland basin connected with the proximal western (Magdalena Valley) basin from mid‐Paleocene to late Eocene time when it was isolated by uplift of the western flank of the Eastern Cordillera. The Floresta basin was also connected with the distal eastern (Llanos) basin from the Cretaceous until its late Oligocene truncation by the advancing thrust front. 相似文献
18.
Foreland basin strata provide an opportunity to review the depositional response of alluvial systems to unsteady tectonic load variations at convergent plate margins. The lower Breathitt Group of the Pocahontas Basin, a sub‐basin of the Central Appalachian Basin, in Virginia preserves an Early Pennsylvanian record of sedimentation during initial foreland basin subsidence of the Alleghanian orogeny. Utilizing fluvial facies distributions and long‐term stacking patterns within the context of an ancient, marginal‐marine foreland basin provides stratigraphic evidence to disentangle a recurring, low‐frequency residual tectonic signature from high‐frequency glacioeustatic events. Results from basin‐wide facies analysis, corroborated with petrography and detrital zircon geochronology, support a two end‐member depositional system of coexisting transverse and longitudinal alluvial systems infilling the foredeep during eustatic lowstands. Provenance data suggest that sediment was derived from low‐grade metamorphic Grenvillian‐Avalonian terranes and recycling of older Palaeozoic sedimentary rocks uplifted as part of the Alleghanian orogen and Archean‐Superior‐Province. Immature sediments, including lithic sandstone bodies, were deposited within a SE‐NW oriented transverse drainage system. Quartzarenites were deposited within a strike‐parallel NE‐SW oriented axial drainage, forming elongate belts along the western basin margin. These mature quartzarenites were deposited within a braided fluvial system that originated from a northerly cratonic source area. Integrating subsurface and sandstone provenance data indicates significant, repeated palaeogeographical shifts in alluvial facies distribution. Distinct wedges comprising composite sequences are bounded by successive shifts in alluvial facies and define three low‐frequency tectonic accommodation cycles. The proposed tectonic accommodation cycles provide an explanation for the recognized low‐frequency composite sequences, defining short‐term episodes of unsteady westward migration of the flexural Appalachian Basin and constrain the relative timing of deformation events during cratonward progression of the Alleghanian orogenic wedge. 相似文献
19.
Mauricio Parra Andrés Mora Carlos Jaramillo Vladimir Torres Gerold Zeilinger Manfred R. Strecker 《Basin Research》2010,22(6):874-903
In order to evaluate the relationship between thrust loading and sedimentary facies evolution, we analyse the progradation of fluvial coarse‐grained deposits in the retroarc foreland basin system of the northern Andes of Colombia. We compare the observed sedimentary facies distribution with the calculated one‐dimensional (1D) Eocene to Quaternary sediment‐accumulation rates in the Medina wedge‐top basin and with a three‐dimensional (3D) sedimentary budget based on the interpretation of ～1800 km of industry‐style seismic reflection profiles and borehole data. Age constraints are derived from a new chronostratigraphic framework based on extensive fossil palynological assemblages. The sedimentological data from the Medina Basin reveal rapid accumulation of fluvial and lacustrine sediments at rates of up to ～500 m my?1 during the Miocene. Provenance data based on gravel petrography and paleocurrents reveal that these Miocene fluvial systems were sourced from Upper Cretaceous and Paleocene sedimentary units exposed to the west in the Eastern Cordillera. Peak sediment‐accumulation rates in the upper Carbonera Formation and the Guayabo Group occur during episodes of coarse‐grained facies progradation in the early and late Miocene proximal foredeep. We interpret this positive correlation between sediment accumulation and gravel deposition as the direct consequence of thrust activity along the Servitá–Lengupá faults. This contrasts with one class of models relating gravel progradation in more distal portions of foreland basin systems to episodes of tectonic quiescence. 相似文献
20.
Reactivation of intraplate structures and weak zones within the foreland lithosphere disrupt the modelled geometry and pattern of migration of the flexural wave in foreland basins. In the southern Appalachians (USA), the Middle Ordovician unconformity, irregular Middle Ordovician distal foreland deposition and backstepping of Middle–lower Upper Ordovician carbonate strata have been related to migration of the flexural wave. However, integration of stratigraphy, tectonic subsidence history and composition of palinspastically restored distal foreland strata, using a map of subsurface basement structures as reference, allows us to distinguish an early event of inversion from two events of flexural migration. Sections restoring at very short distances outside the boundaries of a former basement graben have the youngest passive‐margin strata preserved beneath Middle Ordovician (～466 Ma) peritidal to deep lagoonal carbonates with gravel‐size chert clasts. In contrast, sections restoring inside the graben record >470 m of truncation of pre‐Middle Ordovician passive‐margin strata, late onset of deposition (～456 Ma), and subaerial features in carbonate and siliciclastic strata. The lacuna geometry and early patterns of distal foreland uplift and carbonate deposition indicate that inversion of a basement graben in response to Middle Ordovician convergence, rather than a migrating or semi‐fixed forebulge, was the primary control on the early evolution of the distal foreland. Drowning of the carbonate platform in more proximal settings, northeastward onset of deposition on upthrown blocks, and thick accumulation of carbonates in downthrown blocks record northwestward and northeastward flexural wave migration at the Middle–Late Ordovician boundary. In early Late Ordovician, the overall shoaling of carbonate and siliciclastic depocentres and the rise of tectonic subsidence curves indicate hinterlandward migration of flexural uplift. Both events of flexural migration were accompanied by influx of volcanic ash and synorogenic sediments. 相似文献