Late Quaternary stratigraphy and sedimentology of the inner part of southwest Joseph Bonaparte Gulf

Joseph Bonaparte Gulf is a large embayment on the northwestern continental margin of Australia. It is approximately 300 km east‐west and 120 km north‐south with a broad continental shelf to seaward. Maximum width from the southernmost shore of Joseph Bonaparte Gulf to the edge of the continental shelf is 560 km. Several large rivers enter the gulf along its shores. The climate is monsoonal, sub‐humid, and cyclone‐prone during the December‐March wet season. A bedrock high (Sahul Rise) rims the shelf margin. The sediments within the gulf are carbonates to seaward, grading into clastics inshore. A seaward‐thinning wedge of highstand muds dominates the sediments of the inner shelf of Joseph Bonaparte Gulf. Mud banks up to 15m thick have developed inshore. Coarse‐grained sand ridges up to 15 m high are found off the mouth of the Ord River. These overlie an Upper Pleistocene transgressive lag of mixed carbonate and gravelly siliciclastic sand. Four drowned strandlines are present on the inner shelf at depths of 20, 25, 28 and 30 m below datum. These are interpreted as having formed during stillstands in the Late Pleistocene transgression. Older strandlines at great depths are inferred as having formed during the fall in sea‐level following the last highstand. For the most part the Upper Pleistocene‐Holocene marine sediments overlie an erosion surface cut into older Pleistocene sediments. Incised valleys cut into this erosion surface are up to 5 km wide and have a relief of at least 20 m. The largest valley is that cut by the Ord River. Upper Pleistocene sediments deposited in the incised valleys include interpreted lowstand fluvial gravels, early transgressive channel sands and floodplain silts, and late transgressive estuarine sands and gravels. Older Pleistocene sediments are inferred to have been deposited before and during the 120 ka highstand (isotope stage 5). They consist of sandy calcarenites deposited in high‐energy tide‐dominated shelf environments. Still older shelf and valley‐fill sediments underlie these. The contrast between the Holocene muddy clastic sediments and the sandy carbonates deposited by the 120 ka highstand suggests that either the climate was more arid in the past, with less fluvial transport, or that mud was more effectively trapped in estuaries, allowing development of carbonate depositional environments inshore.     

The Quaternary Lancaster Sound trough‐mouth fan,NW Baffin Bay

The development of the Lancaster Sound Trough Mouth Fan (TMF) and glacial history in Arctic Canada were studied using a high‐resolution seismic profile across the entire fan and two piston cores. Stacked tills separated by erosion surfaces on the shelf pass seaward through till deltas into thick transparent glacigenic debris flow (GDF) deposits on the slope, separated by thin, well‐stratified glaciomarine layers. An age model was built by ties to the Ocean Drilling Program Site 645. The deepest GDF on the seismic profile was indicative of the onset of shelf‐crossing glaciation in the Early Pleistocene. The transition of the growth of Lancaster Sound TMF from an aggradational sequence (unit M) to an aggradational–progradational sequence (unit F) occurred at the Middle Pleistocene transition in glacial cyclicity. In the most recent glacial cycle, GDF sheets were deposited during Heinrich events 4 and 2 according to the correlation of the main detrital carbonate beds in two piston cores. The outmost till wedge reflects the maximum advance of the grounding glacier, far seaward of previously proposed Last Glacial Maximum ice extent. Copyright © 2011 John Wiley & Sons, Ltd.     

The geologic history of the passive margin off new england and the canadian maritime provinces

The geologic history of the passive continental margin off the east coast of North America from New England to Newfoundland is described using all available geological and geophysical information. “Rift” and “drift” phases of the margin's evolution are recognized, with rifting initiated in Late Triassic and completed by Early Jurassic. The plate decoupling process created a complex block-faulted terrain as a result of uplift and tensional fracturing. The approximate plane of continental separation is marked by a “hinge zone” characterized by a pronounced steepening of basement gradients. Since the Early Jurassic, the margin has undergone continual subsidence in response to cooling and sediment loading. This “drift” sequence attains its maximum thickness in the vicinity of the continental slope and thins both landward and seaward. On the shelf, this unit consists of Mesozoic evaporites, carbonates, and deltaic deposits. Overlying these sediments is a prograding wedge of Cenozoic elastics. On the rise, the Mesozoic sediments are evaporites, hemipelagic limestones and shales and carbonaceous clays. The Cenozoic is dominantly terrigenous material. Separating these two sedimentary provinces is the continental slope, a site of major facies changes and a Mesozoic reef complex.     

Ice sheet grounding and iceberg plow marks on the northern and central Yermak Plateau revealed by geophysical data

We present new evidence for a grounded ice sheet and subsequent erosion by large fields of coherent icebergs for the central and northern Yermak Plateau (80.6°N to 82.2°N). Sediment echosounder and swath bathymetry data were combined with seismic reflection profiles and reveal at least three different glacial events marked by erosional unconformities: (i) An erosional unconformity was observed at ～70–90 m below seafloor down to depths of more than 850 m present water depth, extending to ～82°N. The erosional unconformity is overlain by an acoustically chaotic layer of ～50 m thickness interpreted as a diamicton originating from a grounded ice sheet. The erosional unconformity and the overlying diamicton can be correlated to the overconsolidated sediments found at ODP Site 910 at a sediment depth between ～19 and 70–95 m. The oldest sediments just above the overconsolidated sediments are of late Early Pleistocene age (MIS19/20) and provide a minimum age for the grounding event. (ii) Parallel to sub-parallel mega-scale lineations are observed on large parts of the plateau west and northeast of the Sverdrup Bank at water depths between 725 and 850 m. These lineations are mainly oriented NNE-SSW and were quite likely formed by the keels of deep-draft, mega-scale tabular icebergs entrapped in a coherent mass of icebergs and sea ice. The lineations are of late Middle Pleistocene age. (iii) Smaller-scale curvilinear plow marks were found in the southernmost part of our study area at water depths between 640 and 775 m. These were possibly caused by single icebergs and are of Late Pleistocene age. Iceberg scours are also found on three basement heights on the Yermak Plateau. These, however, cannot be assigned to specific events; they might as well originate from additional glacial phases.The western (at >850 m water depth) and eastern (at >1000–1200 m water depth) flanks of the Yermak Plateau are relatively featureless, and indicate the maximum depth of a grounded ice sheet and of iceberg armadas probably entrapped in sea ice.     

障壁岛—潟湖沉积特征及模式:以美国普拉姆岛上更新统—全新统为例*

普拉姆岛(Plum island)是美国东北部缅因湾最大的障壁海岸,岛内向陆一侧为新英格兰地区最大潟湖和沼泽区,它们是晚第四纪末次冰期冰川作用和冰后期海岸作用的沉积响应。通过普拉姆岛研究区上更新统—全新统160个钻孔描述,识别出8种沉积物: 泥炭、冰川黏土、黏土、粉砂、细砂、中粗砂、砾、坠石。根据沉积物类型及其组合特征,结合沉积环境,共划分出8种沉积微相: 障壁沙丘、滨岸沙、水下临滨沙、河道、潮汐水道、潟湖、潮坪、沼泽。研究区在晚第四纪末次冰盛期(MIS2)被劳伦斯蒂德冰盖(Laurentide Ice Sheet)覆盖,发育冰川地貌,冰川泥覆盖在基岩之上,形成底层沉积; 冰后期(MIS1),冰盖消融,海平面发生变化,在冰川地貌鼓丘附近形成沙坝,最终沉积演化为障壁岛—潟湖环境,潟湖通过潮汐水道与广海相连通。     

Correlation of early quaternary events in the U.S. Gulf Coast

A reexamination of the sequences of planktonic foraminifers and calcareous nannoplankton in the Plio-Pleistocene sediments beneath the Louisiana continental shelf has been undertaken in order to modernize correlation schemes that were established 10–20 y.a. As a consequence, it can be shown that (1) a new correlation of marine micropaleontological and continental glacial events is necessary; (2) the Gulf Coast faunal events can be reliably correlated with those in the type Italian Pleistocene section and in the deep-sea cores; (3) it is becoming increasingly evident that it is invalid to correlate the Plio-Pleistocene boundary, as defined by paleontology, with a climatically defined boundary.     

Glacial landforms on German Bank, Scotian Shelf: evidence for Late Wisconsinan ice-sheet dynamics and implications for the formation of De Geer moraines

The extent and behaviour of the southeast margin of the Laurentide Ice Sheet in Atlantic Canada is of significance in the study of Late Wisconsinan ice sheet-ocean interactions. Multibeam sonar imagery of subglacial, ice-marginal and glaciomarine landforms on German Bank, Scotian Shelf, provides evidence of the pattern of glacial-dynamic events in the eastern Gulf of Maine. Northwest-southeast trending drumlins and megaflutes dominate northern German Bank. On southern German Bank, megaflutes of thin glacial deposits create a distinct northwest-southeast grain. Lobate regional moraines (>10km long) are concave to the northwest, up-ice direction and strike southwest-northeast, normal to the direction of ice flow. Ubiquitous, overlying De Geer moraines (<10 km long) also strike southwest-northeast. The mapped pattern of moraines implies that, shortly after the last maximum glaciation, the tidewater ice sheet began to retreat north from German Bank, forming De Geer moraines at the grounding line with at least one glacial re-advance during the general retreat. The results indicate that the Laurentide Ice Sheet extended onto the continental shelf.     

Gondwanaland origin, dispersion, and accretion of East and Southeast Asian continental terranes

East and Southeast Asia is a complex assembly of allochthonous continental terranes, island arcs, accretionary complexes and small ocean basins. The boundaries between continental terranes are marked by major fault zones or by sutures recognized by the presence of ophiolites, mélanges and accretionary complexes. Stratigraphical, sedimentological, paleobiogeographical and paleomagnetic data suggest that all of the East and Southeast Asian continental terranes were derived directly or indirectly from the Iran-Himalaya-Australia margin of Gondwanaland. The evolution of the terranes is one of rifting from Gondwanaland, northwards drift and amalgamation/accretion to form present day East Asia. Three continental silvers were rifted from the northeast margin of Gondwanaland in the Silurian-Early Devonian (North China, South China, Indochina/East Malaya, Qamdo-Simao and Tarim terranes), Early-Middle Permian (Sibumasu, Lhasa and Qiangtang terranes) and Late Jurassic (West Burma terrane, Woyla terranes). The northwards drift of these terranes was effected by the opening and closing of three successive Tethys oceans, the Paleo-Tethys, Meso-Tethys and Ceno-Tethys. Terrane assembly took place between the Late Paleozoic and Cenozoic, but the precise timings of amalgamation and accretion are still contentious. Amalgamation of South China and Indochina/East Malaya occurred during the Early Carboniferous along the Song Ma Suture to form “Cathaysialand”. Cathaysialand, together with North China, formed a large continental region within the Paleotethys during the Late Carboniferous and Permian. Paleomagnetic data indicate that this continental region was in equatorial to low northern paleolatitudes which is consistent with the tropical Cathaysian flora developed on these terranes. The Tarim terrane (together with the Kunlun, Qaidam and Ala Shan terranes) accreted to Kazakhstan/Siberia in the Permian. This was followed by the suturing of Sibumasu and Qiangtang to Cathaysialand in the Late Permian-Early Triassic, largely closing the Paleo-Tethys. North and South China were amalgamated in the Late Triassic-Early Jurassic and finally welded to Laurasia around the same time. The Lhasa terrane accreted to the Sibumasu-Qiangtang terrane in the Late Jurassic and the Kurosegawa terrane of Japan, interpreted to be derived from Australian Gondwanaland, accreted to Japanese Eurasia, also in the Late Jurassic. The West Burma and Woyla terranes drifted northwards during the Late Jurassic and Early Cretaceous as the Ceno-Tethys opened and the Meso-Tethys was destroyed by subduction beneath Eurasia and were accreted to proto-Southeast Asia in the Early to Late Cretaceous. The Southwest Borneo and Semitau terranes amalgamated to each other and accreted to Indochina/East Malaya in the Late Cretaceous and the Hainanese terranes probably accreted to South China sometime in the Cretaceous.     

Geodynamic significance of the Raspas Metamorphic Complex (SW Ecuador): geochemical and isotopic constraints

The Raspas Metamorphic Complex of southwestern Ecuador is regarded as the southernmost remnant of oceanic and continental terranes accreted in the latest Jurassic–Early Cretaceous. It consists of variably metamorphosed rock types. (1) Mafic and ultramafic rocks metamorphosed under high-pressure (HP) conditions (eclogite facies) show oceanic plateau affinities with flat REE chondrite-normalized patterns, Nd_{150 Ma} ranging from +4.6 to 9.8 and initial Pb isotopic ratios intermediate between MORB and OIB. (2) Sedimentary rocks metamorphosed under eclogitic conditions exhibit LREE enriched patterns, strong negative Eu anomalies, Rb, Nb, U, Th, Pb enrichments, low Nd_{150 Ma} values (from −6.4 to −9.5), and high initial ⁸⁷Sr/⁸⁶Sr and ^206,207,208Pb/²⁰⁴Pb isotopic ratios suggesting they were originally sediments derived from the erosion of an old continental crust. (3) Epidote-bearing amphibolites show N-MORB affinities with LREE depleted patterns, LILE, Zr, Hf and Th depletion, high Nd_{150 Ma} (>+10) and low initial Pb isotopic ratios.The present-day well defined internal structure of the Raspas Metamorphic Complex seems to be inconsistent with the formerly proposed interpretation of a “tectonic mélange”. The association of oceanic plateau rocks and continent-derived sediments both metamorphosed in HP conditions suggests that the thin edge of the oceanic plateau first entered the subduction zone and dragged sediments downward of the accretionary wedge along the Wadatti–Benioff zone. Subsequently, when its thickest part arrived into the subduction zone, the oceanic plateau jammed the subduction processes, due to its high buoyancy.In Ecuador and Colombia, the latest Jurassic–Early Cretaceous suture involves HP oceanic plateau rocks and N-MORB rocks metamorphosed under lower grades, suggesting a composite or polyphase nature for the latest Jurassic–Early Cretaceous accretionary event.     

Crustal structure across southern Mexico inferred from gravity data

We present a gravity model of the crustal structure in southern Mexico based on interpretation of a detailed marine gravity profile perpendicularly across the Middle America Trench offshore from Acapulco, and a regional gravity transect extending into continental Mexico across the Sierra Madre del Sur, the central sector of the Trans-Mexican Volcanic Belt, the Sierra Madre Oriental, the Coastal Plain, and into the Gulf of Mexico. The elastic thickness of the Cocos lithospheric plate was found to be 30 km. In agreement with a previous seismic refraction study, no major differences in crustal structure were observed on both sides of the O’Gorman Fracture Zone. The gravity high seaward of the trench is interpreted as due to the incipient flexure and crustal thinning. The gravity low at the axis of the trench is explained by the increase in water depth and the existence of low-density accreted or continental-derived sediments (2.25 and 2.40 g/cm³). A gravity high of 50 mGal extending about 100 km landward is interpreted as caused by local shoaling of the Moho. The crust attains a thickness of 42 km under the Trans-Mexican Volcanic Belt but thins beneath the Coastal Plain and the continental slope of the Gulf of Mexico. Gravity highs around the Sierra de Tamaulipas are interpreted in terms of relief of the lower–upper crustal interface, implying a shallow basement.     

黄河源区第四纪地质研究的新进展

通过对黄河源区的钻孔、自然露头的研究, 建立了黄河源区的第四纪地层层序。第四纪地层可划分为下更新统、中更新统、上更新统和全新统。下更新统为河湖相沉积; 中更新统主要有湖积物、冰碛物和冰水沉积物; 上更新统主要有湖积物、冰碛物、冰水沉积物、洪积物和河流沉积物; 全新统主要由河流沉积物、洪积物和湖积物构成。黄河源区的冰期可划分为3期, 即末次冰期、倒数第二次冰期、倒数第三次冰期, 末次冰期又可分为2个冰阶。黄河源区的湖泊演化可划分为早更新世、中更新世和晚更新世—全新世3个阶段: 早更新世的湖泊范围小; 中更新世的湖泊范围明显扩大, 在位置上也较早更新世的湖泊南移; 晚更新世的湖泊经历了两次的扩张—收缩变化, 到了全新世, 除现今还发育的几个湖泊外, 大多数地区的湖水已退出, 基本上转变为河流环境。在晚更新世末期到全新世初期, 封闭黄河源区的多石峡被切开, 湖水外泄, 现今的黄河形成了, 同时发生了袭夺长江水系的水流。     

The Quaternary evolution of the Gulf of Corinth, central Greece: coupling between surface processes and flow in the lower continental crust

The Gulf of Corinth in central Greece is an active normal fault zone with particularly clear evidence of isostatic footwall uplift, constrained by Quaternary marine terraces, and hanging-wall subsidence and sedimentation. It is bounded to the south by a Pliocene to Early Pleistocene sedimentary basin, which is now eroding into the Gulf. Previous work has suggested that the relief across this region has increased dramatically since the Early Pleistocene, due to the isostatic response to increased rates of footwall erosion and hanging-wall sedimentation. It is indeed assumed here that incision accompanying the draw-down of global sea-level at 0.9 Ma, during the first major Pleistocene glaciation, initiated the erosion of the basin south of the Gulf of Corinth and so abruptly increased the sedimentation rate in the Gulf. The resulting transient thermal and isostatic response to these changes is modelled, with the subsiding depocentre and eroding sediment source coupled by flow in the lower continental crust. The subsequent enhancement of relief, involving an increase in bathymetry from near zero to 900 m and 500 m of uplift of the eroding land surface in the sediment source, is shown to be a direct consequence of this change. The model is sensitive to the effective viscosity of the lower crust, and can thus resolve this parameter by matching observations. A value of 6×10¹⁹ Pa s is indicated, suggesting a viscosity at the Moho no greater than 10¹⁸ Pa s. Similar transient topographic effects caused by increased rates of sedimentation and erosion are likely to be widespread within the geological record, suggesting that this coupling process involving flow in the weak lower crust may be of major geological and geomorphological importance.     

Detrital zircon geochronology analysis of the Late Mesozoic deposition in the Turpan‐Hami basin: Implications for the uplift history of the Eastern Tian Shan,north‐western China

Analysing the provenance changes of synorogenic sediments in the Turpan‐Hami basin by detrital zircon geochronology is an efficient tool to examine the uplift and erosion history of the easternmost Tian Shan. We present detrital zircon U‐Pb analysis from nine samples that were collected within marginal lacustrine Middle‐Late Jurassic and aeolian‐fluvial Early Cretaceous strata in the basin. Middle‐Early Jurassic (159–172 Ma) zircons deriving from the southern Junggar dominated the Middle Jurassic sample from the western Turpan‐Hami basin, whereas Permian‐Carboniferous (270–330 Ma) zircons from the Bogda mountains were dominant in the Late Jurassic to Early Cretaceous samples. Devonian‐Silurian (400–420 Ma) and Triassic (235–259 Ma) zircons from the Jueluotage and Harlik mountains constituted the subordinate age groups in the Late Jurassic and Early Cretaceous samples from the eastern basin respectively. These provenance transitions provide evidence for uplift of the Bogda mountains in the Late Jurassic and the Harlik mountains since the Early Cretaceous.     

Detrital zircon age constraints on depositional history and provenance of the Murihiku Supergroup,Murihiku Terrane,North Island,New Zealand

In the Murihiku Terrane of New Zealand, U-Pb detrital zircon ages in Murihiku Supergroup sandstones of Late Triassic, Jurassic and possibly earliest Cretaceous age have a marked youngest age component that is close to, and sometimes coincident with, established biostratigraphic ages, thus reflecting contemporary volcanism. However, youngest Huriwai Group samples yield 137–142 Ma zircon age components (earliest Early Cretaceous) in conflict with palynofloras that suggest only a latest Jurassic age. This is resolved if the age of the Jurassic/Cretaceous boundary is lowered to ca. 140 Ma. Older, reworked zircons are mainly Early Jurassic, Late Triassic and Late Permian reflecting an enduring exhumed magmatic arc source nearby. This might be in the adjacent Median Batholith but as a Murihiku sediment source its Jurassic, Triassic and Permian elements are not well-matched in terms of extent, age and bulk compositions. A connection between the Murihiku (proximal forearc) and Waipapa Composite (distal accretionary wedge) terranes is probable, with a common magmatic arc, speculatively situated in the New England Orogen, eastern Australia.     

Chronology of upper Quaternary offshore successions from the southeastern Mediterranean Sea,Israel

Pleistocene and Holocene transgressions advancing over the shelf that was exposed during glacial maxima drowned any continental and shallow marine sediments deposited during low sea level stands. To complement records from sequences exposed on land, core material from the shallow continental shelf is needed to reconstruct climatic and sea level fluctuations. Two cores drilled offshore Ashqelon off the southern Mediterranean coast of Israel, in a water depth of 10 and 25 m, were analyzed. Sedimentary facies and faunal analyses indicate that most of the sediments were deposited in nearshore environments, with only short intervals of continental episodes. Luminescence dating of alkali feldspar and quartz, as well as ¹⁴C ages of mollusks, date the cores to marine oxygen isotopic stages 6–1, between ∼140 and 5 ka. Comparison between the dating methods shows that most alkali feldspar ages agree with independent sea level and sedimentological constraints while quartz ages are overestimated.     

下刚果盆地重力滑脱构造发育特征及演化规律

论述了西非被动大陆边缘下刚果盆地重力滑脱构造的发育特征及演化规律。下刚果盆地早白垩世至今的被动大陆边缘阶段主要发育重力滑脱构造,可分为上陆坡的重力滑脱伸展构造、中陆坡和下陆坡的重力滑脱底辟构造、下陆坡-深海平原转换区的重力滑脱冲断构造。一期完整的重力滑脱构造演化模式为从早到晚由陆向海逐渐发育的前展式发育模式,即最早发育高部位的重力滑脱伸展构造、其次发育中部的重力滑脱底辟构造、最后发育低部位的重力滑脱冲断构造。下刚果盆地总共发育两期重力滑脱构造,分别是早白垩世阿尔布期(Albian)-渐新世的第一期(早期)重力滑脱构造,中新世至今的第二期(晚期)重力滑脱构造。这两期重力滑脱构造之间呈现出从早到晚由陆向海发育的前展式结构,即晚期的重力滑脱构造位于早期重力滑脱构造的向海一侧。     

Sediment failure and sedimentary framework of the wilmington geotechnical corridor,U.S. atlantic continental margin

Seaward of New Jersey and the Baltimore Canyon Trough, a 7500 km² corridor across the continental margin was studied in detail using geotechnical and geophysical techniques. The objective of the study was to identify the sedimentary pattern and bottom processes which have occurred and are active on the continental margin. Delineation of a mid-Pliocene unconformity, present throughout most of the corridor, permits an evaluation of the Quaternary sedimentation pattern and its variability. Sediment failure characterized by large slide blocks and thin layer slide deposits was found on the continental slope and rise within the Quaternary sediments. Spencer and Wilmington Submarine Canyons have been active in channeling large volumes of sediment to the lower slope and rise. An increase in sediment thickness near Wilmington Canyon indicates the importance and activity of the Delaware Bay drainage system during the Pleistocene. Although both Spencer and Wilmington are as old as late Tertiary the Wilmington Valley on the lower slope and rise is a recent topographic feature. Based on geophysical data the numerous valleys that dissect the continental slope and rise appear to be active periodically in the seaward transport of sediment to the deep sea.     

Significance of slope sediments layering on physical characteristics and interflow within the Critical Zone – Examples from the Colorado Front Range,USA

The subalpine to montane zones within the Critical Zone (CZ) of the Colorado Front Range, USA outside Pleistocene glaciation limits are characterized by the abundance of stratified and multilayered slope deposits exhibiting depths >1 m. Initial luminescence dating for the upper sediment layers in different profiles give last glacial ages ranging between 40 and 12 ka. A periglacial origin by solifluction is hypothesized for these slope deposits, which is corroborated by geomorphic and sedimentologic parameters. The stratified slope sediments have a strong influence on the physical and chemical properties as well as on soil forming processes in the CZ. Examples are provided for the sediment derived contribution of some elements and common clay minerals together and the great importance of slope sediments as barriers and pathways for the interflow that runs in sediment layers are shown.     

Variations in sediment yield over the advance and retreat of a calving glacier, Laguna San Rafael, North Patagonian Icefield

Bathymetric and sub-bottom acoustic data were collected in Laguna San Rafael, Chile, to determine sediment yields during the Little Ice Age advance and subsequent retreat of San Rafael Glacier. The sediment volumes and subaqueous landforms imaged are used to interpret the proglacial dynamics and estimate erosion rates from a temperate tidewater glacier over a complete advance-retreat cycle. Sediment yields from San Rafael Glacier averaged 2.7 × 10⁷ m³/a since the end of the Little Ice Age, circa AD 1898, corresponding to average basin-wide erosion rates of 23 ± 9 mm/a; the highest erosion rates, 68 ± 23 mm/a, occurred at the start of the retreat phase, and have since been steadily decreasing. Erosion rates were much lower during glacial advance, averaging at most 7 mm/a, than during retreat. Such large glacial sediment yields over two centuries of advance and retreat suggest that the contribution of sediments stored subglacially cannot account for much of the sediment being delivered to the terminus today. The detailed sub-bottom information of a proglacial lagoon yields important clues as to the timing of erosion, deposition and transfer of glacigenic sediments from orogens to the continental shelves, and the influence of glacier dynamics on this process.