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1.
Sedimentary strata in the Lhasa terrane of southern Tibet record a long but poorly constrained history of basin formation and inversion. To investigate these events, we sampled Palaeozoic and Mesozoic sedimentary rocks in the Lhasa terrane for detrital zircon uranium–lead (U–Pb) analysis. The >700 detrital zircon U–Pb ages reported in this paper provide the first significant detrital zircon data set from the Lhasa terrane and shed new light on the tectonic and depositional history of the region. Collectively, the dominant detrital zircon age populations within these rocks are 100–150, 500–600 and 1000–1400 Ma. Sedimentary strata near Nam Co in central Lhasa are mapped as Lower Cretaceous but detrital zircons with ages younger than 400 Ma are conspicuously absent. The detrital zircon age distribution and other sedimentological evidence suggest that these strata are likely Carboniferous in age, which requires the existence of a previously unrecognized fault or unconformity. Lower Jurassic strata exposed within the Bangong suture between the Lhasa and Qiangtang terranes contain populations of detrital zircons with ages between 200 and 500 Ma and 1700 and 2000 Ma. These populations differ from the detrital zircon ages of samples collected in the Lhasa terrane and suggest a unique source area. The Upper Cretaceous Takena Formation contains zircon populations with ages between 100 and 160 Ma, 500 and 600 Ma and 1000 and 1400 Ma. Detrital zircon ages from these strata suggest that several distinct fluvial systems occupied the southern portion of the Lhasa terrane during the Late Cretaceous and that deposition in the basin ceased before 70 Ma. Carboniferous strata exposed within the Lhasa terrane likely served as source rocks for sediments deposited during Cretaceous time. Similarities between the lithologies and detrital zircon age‐probability plots of Carboniferous rocks in the Lhasa and Qiangtang terranes and Tethyan strata in the Himalaya suggest that these areas were located proximal to one another within Gondwanaland. U–Pb ages of detrital zircons from our samples and differences between the geographic distribution of igneous rocks within the Tibetan plateau suggest that it is possible to discriminate a southern vs. northern provenance signature using detrital zircon age populations. 相似文献
2.
The effectiveness of detrital zircon thermochronology as a means of linking hinterland evolution and continental basin sedimentation studies is assessed by using Mesozoic continental sediments from the poorly understood Khorat Plateau Basin in eastern Thailand. New uranium lead (U‐Pb) and fission‐track (FT) zircon data from the Phu Kradung Formation identify age modes at 141 ± 17 and 210 ± 24 Ma (FT) and 2456 ± 4, 2001 ± 4, 251 ± 3, and 168 ± 2 Ma (U‐Pb), which are closely similar to data from the overlying formations. The FT data record post‐metamorphic cooling, whereas the U‐Pb data record zircon growth events in the hinterland. Comparison is made between detrital zircon U‐Pb data from ancient and modern sources across Southeast Asia. The inherent stability of the zircon U‐Pb system means that 250 Myr of post‐orogenic sedimentary recycling fails to change the regional zircon U‐Pb age signature and this precludes use of the U‐Pb approach alone for providing unique provenance information. Although the U‐Pb zircon results are consistent with (but not uniquely diagnostic of) the Qinling Orogenic Belt as the original source terrane for the Khorat Plateau Basin sediments, the zircon FT cooling data are more useful as they provide the key temporal link between basin and hinterland. The youngest zircon FT modes from the Khorat sequence range between 114 ± 6 (Phra Wihan Formation) and 141 ± 17 Ma (Phu Kradung Formation) that correspond to a Late Jurassic/Early Cretaceous reactivation event, which affected the Qinling Belt and adjacent foreland basins. The mechanism for regional Early Cretaceous erosion is identified as Cretaceous collision between the Lhasa Block and Eurasia. Thus, the Khorat Plateau Basin sediments might have originated from a reactivation event that affected a mature hinterland and not an active orogenic belt as postulated in previous models. 相似文献
3.
ABSTRACT Zircon is the most widely used mineral in detrital dating studies because it is common to multiple rock types, is chemically and physically resistant, and can endure successive cycles of burial, metamorphism and erosion. Zircon also has the advantage that single grains may be dated by either the fission‐track (FT) or U–Pb method, which, because of their contrasting thermal sensitivities (total resetting occurs at temperatures > 320 °C for FT and > 700–900 °C for U–Pb), can provide unique information about both the age structure and the thermal evolution of a sediment source. However, single method‐based bias and difficulties associated with interpreting measured ages can influence both the quality and the level of useful provenance information. For example, the zircon FT system is sensitive to metamorphic overprinting and hence measured ages alone cannot be interpreted as unambiguously dating formation age of the source rock. In contrast, U–Pb zircon data have high resistance (700–900 °C) to thermal overprinting and therefore recorded formation ages may not relate to an immediate source but may instead reflect a polycyclical history. The focus of this paper is to examine, from a practical standpoint, the provenance potential of detrital zircon fission track data and to investigate the method's complementary role as an aide to the interpretation of high‐temperature detrital U–Pb zircon data by combining U–Pb and FT methods in a single study. 相似文献
4.
《Basin Research》2018,30(5):835-862
We used detrital zircon U/Pb geochronology and apatite (U–Th–Sm)/He thermochronology to better constrain depositional ages and sedimentation rates for the Pliocene Productive Series in Azerbaijan. U/Pb analysis of 1,379 detrital zircon grains and (U–Th–Sm)/He analysis of 57 apatite grains—from Kirmaky Valley and Yasamal Valley onshore sections, Absheron Peninsula—yielded two distinct sub‐populations: “young” Neogene grains and “old” Mesozoic, Palaeozoic and Proterozoic/Archean grains. The large numbers of Neogene age grains (around 10% of all grain ages) provided a new absolute age constraint on the maximum depositional age of the Lower Productive Series of 4.0 Myr. These “young” Neogene zircon grains most likely originated from volcanic ash falls sourced from the Lesser Caucasus or Talesh Mountains. In this paper we propose a timescale scenario using the maximum depositional age of the Productive Series from detrital zircon grain U/Pb constraints. Potential consequences and limitations of using apatite (U–Th–Sm)/He dating method in estimating maximum depositional ages are also discussed. These new age constraints for the Lower Productive Series gave much faster sedimentation rates than previously estimated: 1.3 km/Myr in the South Caspian Basin margin outcrops and up to 3.9 km/Myr in the basin centre. The sedimentation rates are one of the highest in comparison to other sedimentary basins and coeval to global increase in sedimentation rates 2–4 Myr. The older group of detrital zircon grains constitutes the majority of grains in all sample sets (~80%). These older ages are inferred to reflect the provenance of the Productive Series sediment. This sediment is interpreted to have been derived from the Proterozoic and Archean crystalline basement rocks and Phanerozoic cover of the East European Craton, Proterozoic/Palaeozoic rocks of the Ural Mountains and Mesozoic sedimentary rocks of the Greater Caucasus. This sediment was likely supplied from northerly sourced drainage that emptied into the South Caspian Basin. 相似文献
5.
Use of deep‐water sediments in submarine fans to reconstruct changing erosion onshore is based on the premise of relatively simple transport between source and sink. However, debate continues regarding the degree of sediment buffering and recycling in the sediment transport process. In this study, we investigate the origin of sediment in the Indus Submarine Canyon since the Last Glacial Maximum (LGM; ~20 ka) using zircon U‐Pb dates. Zircon grains in the submarine canyon are resolvably different from those at the river mouth, at least before 6.6 ka, implying a disconnection between the river mouth and the canyon up to that time. Sand may be stored near the river mouth as sea level rose, while finer‐grained sediment was directly transferred into deeper water. Since 1 ka the upper canyon has shown big and rapid provenance changes, most notably a sharp increase in erosion from Nanga Parbat, whose influence is minor in the modern river. Such rapid changes imply a lack of buffering in the recent past. The modern river contrasts with sediments in the canyon in terms of its zircon U‐Pb age populations and may be influenced by significant anthropogenic impact on the terrestrial drainage basin, especially damming. 相似文献
6.
Early Mesozoic Basins in the Yanshan Fold–Thrust Belt (YFTB), located along the northern margin of the North China Craton (NCC), record significant intraplate deformation of unknown age. In this article, we present evidence for the rapid exhumation of high‐grade basement rocks along the northern margin of the NCC in the Early Mesozoic. U–Pb geochronology of detrital zircons constrains the maximum depositional ages of syntectonic sedimentary units that formed during the unroofing of basement rocks and plutons in the Xiabancheng Basin. In the Early Mesozoic, the Xiabancheng Basin recorded a dramatic transformation in depositional environments, related to a significant change in the regional tectonic setting. In this study, the tectonic evolution of the YFTB is established from paleocurrent data and U–Pb zircon ages of sandstone and granitic gravels of the Xingshikou Formation, Xiabancheng Basin. The paleocurrent direction of meandering fluvial facies in the Triassic Liujiagou and Ermaying Formations are from east to west. In contrast, the overlying Xingshikou Formation consists of alluvial fan facies with paleocurrent directions from north‐northwest to south‐southeast. The lower and middle segments of the Xingshikou Formation record rapid exhumation of basement rocks along the northern margin of the NCC. U‐Pb ages of detrital zircons within the Xingshikou Formation are characterized by three major U–Pb age groups: 2.2–2.5 Ga, 1.7–1.8 Ga and 193–356 Ma. From 193 Ma to 356 Ma, a subsidiary peak occurs at 198 ± 5 Ma, constraining the sedimentation age of the Xingshikou Formation to the Early Jurassic. Zircon from the Wangtufang pluton in the northern portion of the Xiabancheng Basin yields U–Pb ages of 191 ± 1 Ma and 207 ± 1 Ma. Within error, these crystallization ages are identical to detrital zircon ages of 206 ± 1 Ma and 206 ± 2 Ma obtained for granitic gravel clasts in the Xingshikou Formation. Thus, the Wangtufang pluton and surrounding basement rocks must have experienced rapid uplift and exhumation during the Early Jurassic. The onset of exhumation along the northern margin of the NCC occurred at ca. 198–180 Ma. 相似文献
7.
《Basin Research》2018,30(Z1):401-423
The Lobo Formation of southwestern New Mexico consists of spatially variable continental successions attributed to the Laramide orogeny (80–40 Myr), although its age and provenance are virtually undocumented. This study combines sedimentological, magnetostratigraphical and geochronological data to infer the timing and origin of the Lobo Formation. Measured sections of Lobo strata at two locations, Capitol Dome in the Florida Mountains and in the Victorio Mountains, indicate significant differences in depositional environments and sediment provenance. At Capitol Dome, where Lobo strata were deposited above a syncline developed in Palaeozoic strata, deposition took place in fluvial, palustrine and marginal lacustrine settings, with alluvial‐fan deposits only at the top of the formation. Combined magnetostratigraphy and a young U–Pb detrital zircon age suggest deposition of the section at Capitol Dome from ~60 to 52 Ma. The Lobo Formation in the Victorio Mountains was deposited in alluvial‐fan and fluvial settings; the age of deposition is poorly bracketed between 66 ± 2 Ma, the weighted‐mean age of two young zircons, and middle Eocene (~40 Ma), the approximate age of overlying volcanic rocks. U–Pb zircon ages from sandstones at the Victorio and Capitol Dome localities indicate that different source rocks provided sediment to the Lobo Formation. Local Proterozoic basement (~1.47–1.45 Ga) dominated the source of the Lobo Formation in the Victorio Mountains, consistent with abundant granitic clasts that are present in the proximal facies there; a diverse range of grain ages suggest that recycled Lower Cretaceous strata provided the dominant source for Lobo Formation sediment at the Capitol Dome locality. The U–Pb data suggest that the depositional systems at the two sites were not connected. Contrasts in depositional setting and detrital zircon provenance indicate that the Palaeogene Lobo Formation in southwest New Mexico was deposited in an assemblage of local depositional settings, possibly in separate structural basins, as a consequence of Laramide tectonics in the region. 相似文献
8.
Li Liu Jie Xu Daniel F. Stockli Timothy F. Lawton Ronald C. Blakey 《Basin Research》2023,35(2):489-509
Detrital zircon (DZ) geochronology has become a popular tool in provenance studies during the past two decades. However, similar zircon crystallization ages from different source regions greatly hamper the interpretation of sediment dispersal and recycling processes. The Alleghenian–Ouachita–Marathon (AOM) foreland and vicinity in North America is a region where some dominant DZ age groups could come from both the southern Appalachians in the eastern United States and the Gondwanan terranes in Mexico. In this study, we present 1045 new DZ U–Pb ages and 81 DZ core–rim age pairs in lower Permian sandstone in the Permian Basin and Miocene sandstone in the eastern Gulf of Mexico (GOM). These new data were integrated with published DZ single U–Pb age and core–rim ages from syn- to post-orogenic strata in the Permian Basin, Marathon foldbelt, southern Appalachian foreland basin and eastern GOM to interpret the sediment-dispersal models in the AOM foreland and eastern GOM. Our models show that during the Leonardian Stage, sediments derived from the Appalachians were first delivered to the US midcontinent and then recycled to the Permian Basin; during the Miocene, sediment from the Appalachians fluxed to the eastern GOM, with no longshore mixing from the western GOM. These models based on the integration of single U–Pb and core–rim ages are consistent with published results that used other methods, including zircon single U–Pb age, zircon Hf isotopic data, zircon (U–Th)/He age, sedimentology and stratigraphy. Our results demonstrate that although some limitations exist, zircon core–rim age is a powerful tool, adding an extra constraint on the interpretation of sediment-dispersal systems. This tool is particularly applicable to the post-orogenic stage, during which the sediment pathways are more complicated because of the dominant input from distal sources. Insights gained in this study imply that this novel strategy of using core and rim ages could be integrated with other methods to better understand sediment dispersal. 相似文献
9.
《Basin Research》2018,30(3):395-425
The Centinela Mining District (CMD), Atacama Desert (northern Chile), includes several mid‐late Eocene porphyry Cu deposits that contains supergene mineralization and provides access to a record of gravel deposits that host syn‐sedimentary exotic Cu mineralized bodies. By studying these gravels, we reconstruct the unroofing history and constrain the geomorphological conditions that produced supergene and exotic Cu mineralization. We present an integrated study based on stratigraphic and sedimentological data, lithology clast counts, 40Ar/39Ar and U/Pb ages from interbedded tuff layers and U/Pb detrital zircon geochronology data. To relate the gravel deposition episodes to the timing of the supergene mineralization, we provide in‐situ and exotic supergene mineral ages (40Ar/39Ar and K‐Ar). Six gravel units were deposited between the mid‐Eocene and the mid‐Miocene. The Esperanza gravels were deposited concurrently with the emplacement of porphyry Cu deposits at depth. The subsequent Tesoro I, II and III and Atravesado gravels register the unroofing of these deposits, from the advanced argillic zone to the sericitic and prophylitic hypogene zones. The Arrieros gravels register landscape pediplanation, that is, denudational removal and wear of the landscape to base level on a relatively stable tectonic regime, occurring roughly contemporaneous with supergene activity. The supergene mineral ages of the CMD define a time span (ca. 25–12 Ma) during which most of the supergene ages cluster in northern Chile. This time span corresponds with a period of warm and humid climate conditions in the southern hemisphere. We conclude that landscape pediplanation favours supergene mineralization and helps preserve the former supergene mineralized zones from significant erosion. Low erosion rates during pediplanation may constitute a necessary condition for the efficiency of the supergene processes in such semi‐arid climate. 相似文献
10.
The duration and extent of sediment routing systems are intrinsically linked to crustal- to mantle-scale processes. Therefore, distinct changes in the geodynamic regime may be captured in the detrital record. This study attempts to reconstruct the sediment routing system of the Canning Basin (Western Australia) during the Early Cretaceous to decipher its depositional response to Mesozoic-Cenozoic supercontinent dispersal. Specifically, we reconstruct source-to-sink relationships for the Broome Sandstone (Dampier Peninsula) and proximal modern sediments through multi-proxy analysis of detrital zircon (U–Pb, Lu–Hf and trace elements) and detrital rutile (U–Pb and trace elements). Multi-proxy comparison of detrital signatures and potential sources reveals that the majority of the detrital zircon and rutile grains are ultimately sourced from crystalline basement in central Australia (Musgrave Province and Arunta region) and that proximal sediment supply (i.e., Kimberley region) is negligible. However, a significant proportion of detritus might be derived from intermediate sedimentary sources in central Australia (e.g., Amadeus Basin) rather than directly from erosion of crystalline basement. Broome Sandstone data are consistent with a large-scale drainage system with headwaters in central Australia. Contextualization with other broadly coeval drainage systems suggests that central Australia acted as a major drainage divide during the Early Cretaceous. Importantly, reorganization after supercontinent dispersal is characterized by the continuation of a sediment pathway remnant of an earlier transcontinental routing system originating in Antarctica that provided a template for Early Cretaceous drainage. Review of older Canning Basin strata implies a prolonged denudation history of central Australian lithologies. These observations are consistent with the long-lived intracontinental tectonic activity of central Australia governing punctuated sediment generation and dispersion more broadly across Australia and emphasize the impact of deep Earth processes on sediment routing systems. 相似文献
11.
Cretaceous evolution of the Andean margin between 36°S and 40°S latitude through a multi‐proxy provenance analysis of Neuquén Basin strata (Argentina) 
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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
12.
Sedimentology,provenance and geochronology of the upper Cretaceous–lower Eocene western Xigaze forearc basin,southern Tibet 下载免费PDF全文
下载免费PDF全文 Located on the southern margin of the Lhasa terrane in southern Tibet, the Xigaze forearc basin records Cretaceous to lower Eocene sedimentation along the southern margin of Asia, prior to and during the initial stages of continental collision with the Tethyan Himalaya in the Early Eocene. We present new measured stratigraphic sections, totalling 4.5 km stratigraphic thickness, from a 60 km E–W segment of the western portion of the Xigaze forearc basin, northeast of the Lopu Kangri Range (29.8007° N, 84.91827° E). In addition, we apply U–Pb detrital zircon geochronology to constrain the provenance and maximum depositional ages of investigated strata. Stratigraphic ages range between ca. 88 and ca. 54 Ma and sedimentary facies indicate a shoaling‐upward trend from deep‐marine turbidites to fluvial deposits. Depositional environments of coeval Cretaceous strata along strike include deep‐marine distal turbidites, slope‐apron debris‐flow deposits and marginal marine carbonates. This along‐strike variability in facies suggests an irregular paleogeography of the Asian margin prior to collision. Paleocene–Eocene strata are composed of shallow marine carbonates with abundant foraminifera such as Nummulites‐Discocyclina and Miscellanea‐Daviesina and transition into fluvial deposits dated at ca. 54 Ma. Sandstone modal analyses, conglomerate clast compositions and detrital zircon U–Pb geochronology indicate that forearc detritus in this region was derived solely from the Gangdese magmatic arc to the north. In addition, U–Pb detrital zircon age spectra within the upper Xigaze forearc stratigraphy are similar to those from Eocene foreland basin strata south of the Indus‐Yarlung suture near Sangdanlin, suggesting that the Xigaze forearc was a possible source of Sangdanlin detritus by ca. 55 Ma. We propose a model in which the Xigaze forearc prograded south over the accretionary prism and onto the advancing Tethyan Himalayan passive margin between 58 and 54 Ma, during late stage evolution of the forearc basin and the beginning of collision with the Tethyan Himalaya. The lack of documented forearc strata younger than ca. 51 Ma suggests that sedimentation in the forearc basin ceased at this time owing to uplift resulting from continued continental collision. 相似文献
13.
Matthias Bernet Peter van der Beek Raphaël Pik† Pascale Huyghe‡ Jean-Louis Mugnier‡ Erika Labrin‡ Adam Szulc§ 《Basin Research》2006,18(4):393-412
Fission‐track (FT) analysis of detrital zircon from synorogenic sediment is a well‐established tool to examine the cooling and exhumation history of convergent mountain belts, but has so far not been used to determine the long‐term evolution of the central Himalaya. This study presents FT analysis of detrital zircon from 22 sandstone and modern sediment samples that were collected along three stratigraphic sections within the Miocene to Pliocene Siwalik Group, and from modern rivers, in western and central Nepal. The results provide evidence for widespread cooling in the Nepalese Himalaya at about 16.0±1.4 Ma, and continuous exhumation at a rate of about 1.4±0.2 km Myr?1 thereafter. The ～16 Ma cooling is likely related to a combination of tectonic and erosional activity, including movement on the Main Central thrust and Southern Tibetan Detachment system, as well as emplacement of the Ramgarh thrust on Lesser Himalayan sedimentary and meta‐sedimentary units. The continuous exhumation signal following the ～16 Ma cooling event is seen in connection with ongoing tectonic uplift, river incision and erosion of lower Lesser Himalayan rocks exposed below the MCT and Higher Himalayan rocks in the hanging wall of the MCT, controlled by orographic precipitation and crustal extrusion. Provenance analysis, to distinguish between Higher Himalayan and Lesser Himalayan zircon sources, is based on double dating of individual zircons with the FT and U/Pb methods. Zircons with pre‐Himalayan FT cooling ages may be derived from either nonmetamorphic parts of the Tethyan sedimentary succession or Higher Himalayan protolith that formerly covered the Dadeldhura and Ramgarh thrust sheets, but that have been removed by erosion. Both the Higher and Lesser Himalaya appear to be sources for the zircons that record either ～16 Ma cooling or the continuous exhumation afterwards. 相似文献
14.
The Cenozoic geodynamics of the north‐eastern Mediterranean Basin have been dominated by the subduction of the African Plate under Eurasia. A trench‐parallel crustal‐scale thrust system (Misis–Kyrenia Thrust System) dissects the southern margin of the overriding plate and forms the structural grain and surface expression of northern Cyprus. Late Eocene to Miocene flysch of the Kythrea (De?irmenlik) Group is exposed throughout northern Cyprus, both at the hanging‐wall and foot‐wall of the thrust system, permitting access to an extensive Cenozoic sedimentary record of the basin. We report the results of a combined examination of detrital zircon and rutile U–Pb geochronology (572 concordant ages), coupled with Th/U ratios, Hf isotopic data and quantitative assessment of grain morphology of detrital zircon from four formations (5 samples) from the Kythrea flysch. These data provide a line of independent evidence for the existence of two different sediment transportation systems that discharged detritus into the basin between the late Eocene and late Miocene. Unique characteristics of each transport system are defined and a sediment unmixing calculation is demonstrated and explained. The first system transported almost exclusively North Gondwana‐type, Precambrian‐aged detrital zircon sourced from siliciclastic rock units in southern Anatolia. A different drainage system is revealed by the middle to late Miocene flysch sequence that is dominated by Late Cretaceous–Cenozoic‐aged detrital zircon, whose age range is consistent with the magmatic episodicity of southeast Anatolia, along the Arabia–Eurasia suture zone. Deposition of these late Miocene strata took place thereupon closure of the Tethyan Seaway and African–Eurasian faunal exchange, and overlap in time with a pronounced uplift of eastern Anatolia. Our analytical data indicate the onset of prominent suture‐parallel sediment transport from the collision zone of south‐eastern Anatolia into the Kyrenia Range of northern Cyprus, marking the drainage response to the continental collision between Arabia and Eurasia. 相似文献
15.
《Basin Research》2018,30(1):132-147
The development of fast and reliable instrumental methods for U‐Pb dating and Lu‐Hf isotope analysis of zircon has caused detrital zircon to become a popular provenance indicator for clastic sediments and an important tool in basin analysis. In parallel with the increasing ease of access to data, advanced methods of data interpretation have been developed. The downside of some techniques for visualization and comparison of detrital zircon distribution patterns is that the results are difficult to relate to what the zircon grains really record: The age and nature of geological processes in a protosource terrane. Some simple methods of data presentation and inter‐sample comparison that preserve a direct and intuitively understandable relationship between the data and the age of zircon‐forming processes in the protosource are proposed here: Comparison of confidence intervals around empirical, cumulative distribution curves combined with the use of a plot of upper vs. lower quartile values of cumulative zircon U‐Pb age or Lu‐Hf model age distributions. This approach allows a robust and transparent separation to be made between samples whose detrital zircon distributions are indistinguishable from each other, and those that are more or less similar. Furthermore, it allows simple comparison between detrital zircon distributions and the geological age record of potential protosource terranes, or the detrital zircon distributions of possible sedimentary precursors. 相似文献
16.
Lin Li Yani Najman Guillaume Dupont-Nivet Mauricio Parra Pierrick Roperch Mustafa Kaya Niels Meijer Paul O'Sullivan Gilby Jepson Jovid Aminov 《Basin Research》2023,35(2):530-550
Knowledge of the tectonic history of the Pamir contributes to our understanding of both the evolution of collisional orogenic belts as well as factors controlling Central Asian aridification. It is, however, not easy to decipher the Mesozoic–Cenozoic tectonics of the Pamir due to extensive Neogene deformation in an orogen that remains largely understudied. This study reports detrital apatite and zircon fission-track (FT) ages from both the eastern Tajik Basin sedimentary rocks and Pamir modern river sands. These FT data, supported by vitrinite reflectance and zircon and apatite U–Pb double dating, suggest that the majority of the FT ages are unreset and record exhumation stages of the Pamir, which has served as the source terrane of the Tajik Basin since the Cretaceous. Furthermore, we combine the new data with a compilation of published detrital apatite and zircon FT data from both the Tajik Basin sedimentary rocks and Pamir modern river sands, to explore the Mesozoic–Cenozoic tectonic history of Pamir. Deconvolved FT Peak Ages document two major Mesozoic exhumation events associated with the Late Triassic–Early Jurassic Cimmerian orogeny that reflects accretion of the Pamir terranes, as well as the Early–early Late Cretaceous deformation associated with the northward subduction of the Neo-Tethys Ocean beneath Pamir. The compiled data also show significant Late Eocene–Neogene exhumation associated with the ongoing formation of the Pamir, which peaks at ca. 36, 25, 14 and 7 Ma. 相似文献
17.
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
18.
Provenance of Palaeo‐Rhine sediments from zircon thermochronology,geochemistry, U/Pb dating and heavy mineral assemblages 下载免费PDF全文
下载免费PDF全文 Sediments deposited in the Late Cenozoic basins of the Central European Rift System, including the Upper Rhine Graben (URG) and the Lower Rhine Embayment (LRE), document the drastic extension of the Rhine's catchment towards the Central Alps in the Late Pliocene by distinct heavy mineral assemblages. This outstanding change in principal sediment sources should be accompanied by a change towards distinctly younger (i.e. Tertiary) detrital mineral cooling ages. Therefore, it provides a particularly well‐suited framework to explore the thermochronological provenance record in relation to heavy mineral assemblages. In this multi‐proxy approach we (i) exploit and elaborate detrital zircon (U–Th)/He thermochronology (ZHe) for sediment provenance surveys, (ii) document shortcomings if only a single geochronological method is employed, and (iii) obtain tighter constraints on the sources of Paleo‐Rhine sediments. Our results are based on Pliocene and Pleistocene sediment samples from the northern URG (drill core Ludwigshafen P36) and the LRE (lignite mine Hambach). In a Late Pliocene URG sample, Variscan and Permo‐Triassic cooling ages dominate the age spectra of the ZHe and Zircon fission track (ZFT) thermochronometers. The youngest ages are Late Cretaceous and these zircons show rare earth element signatures that suggest derivation from hydrothermally affected basement rocks of the URG margins. In contrast, a Lower Pleistocene URG sample contains significant Tertiary age components that unequivocally indicate Alpine sources. This cardinal difference coincides well with a significant change in the heavy mineral assemblage. The extension of the catchment of the Rhine towards the Central Alps is considered to occur no earlier than the latest Pliocene (i.e. after ~3.0 Ma). Despite strongly contrasting heavy mineral compositions, the Pliocene and Pleistocene samples from the LRE show largely similar ZHe and ZFT age distributions dominated by Permo‐Triassic and Variscan ages. Admixture of zircon‐dominated, but overall heavy mineral‐poor sediment derived from local drainages of the Rhenish Massif likely explains this apparent contradiction in sediment provenance proxies. Tertiary cooling ages occur in both Pliocene and Pleistocene LRE samples. Zircon Th/U ratios and U/Pb ages reveal that the young age component in Late Pliocene sediments from the LRE is not derived from the Alps but from Oligocene trachytic members of the Central European volcanic centres of the Vogelsberg, Westerwald, and/or Siebengebirge. The integration of ZHe and ZFT techniques with zircon geochemistry and U/Pb geochronology adds the respective advantages of each method and allows for a very detailed picture of detrital zircon provenance. 相似文献
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Fluvial deposition during transition from flexural to dynamic subsidence in the Cordilleran foreland basin: Ericson Formation,Western Wyoming,USA 下载免费PDF全文
下载免费PDF全文 The Ericson Formation was deposited in the distal foredeep of the Cordilleran foreland basin during Campanian time. Isopach data show that it records early dynamic subsidence and the onset of basin partitioning by Laramide uplifts. The Ericson Formation is well exposed around the Rock Springs uplift, a Laramide structural dome in southwestern Wyoming; the formation is thin, regionally extensive, and does not display the wedge‐shaped geometry typical of foredeep deposits. Sedimentation in this area was controlled both by activity in the thrust belt and by intraforeland tectonics. The Ericson Formation is ideally situated both spatially and temporally to study the transition from Sevier to Laramide (thin‐ to thick‐skinned) deformation which corresponded to the shift from flexural to dynamic subsidence and the demise of the Cretaceous foreland basin system. We establish the depositional age of the Ericson Formation as ca. 74 Ma through detrital zircon U–Pb analysis. Palaeocurrent data show a generally southeastward transport direction, but northward indicators near Flaming Gorge Reservoir suggest that the intraforeland Uinta uplift was rising and shedding sediment northward by late Campanian time. Petrographic data and detrital zircon U–Pb ages indicate that Ericson sediment was derived from erosion of Proterozoic quartzites and Palaeozoic and Mesozoic quartzose sandstones in the Sevier thrust belt to the west. The new data place temporal and geographic constraints on attempts to produce geodynamic models linking flat‐slab subduction of the oceanic Farallon plate to the onset of the Laramide orogenic event. 相似文献
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Sediment provenance studies have proven to be an effective method to extract the sediment provenance and tectonic process information recorded by detrital minerals. In this contribution, we conducted detrital monazite and zircon U‐Pb geochronology and detrital Cr‐spinel major element chemistry analyses on samples from the Qaidam Basin to reconstruct the spatial and temporal evolution of the Altyn Tagh Range and the Qimen Tagh Range in the northern Tibetan Plateau. Based on the significant variation in [Th/U]N, [Gd/Lu]N and [Eu/Eu*]N and the U‐Pb ages of the monazite and zircon, the South Altyn Tagh subduction‐collision belt and the North Qimen Tagh Range were, respectively, the main provenances of the Ganchaigou section and the Dongchaishan‐Weitai section in the Qaidam Basin in the Cenozoic. Paleozoic peak metamorphism, retrograde granulite‐facies metamorphism and amphibolite‐facies metamorphism in the South Altyn Tagh subduction‐collision belt were well recorded by the detrital monazite. In comparison, the detrital zircon is a better indicator of igneous events than detrital monazite. Synthesizing the detrital monazite, zircon and Cr‐spinel data, we concluded that the South Altyn Tagh Ocean and Qimen Tagh Ocean existed in the early Paleozoic and that the Altyn Tagh terrane and Qimen Tagh terrane experienced different Paleozoic tectonothermal histories. The collision between the Qaidam terrane and the Azhong terrane occurred at ca. 500 Ma. The Middle Ordovician was the key period of transformation from the collision‐induced compressional environment to an extensional environment in the area of the South Altyn Tagh Range. In the early Paleozoic, the Qimen Tagh area was characterized by the subduction of oceanic crust. 相似文献