Pub Date : 2022-10-19DOI: 10.1017/s1755691022000184
María Ríos, E. Cantero, Darío Estraviz-López, N. Solounias, J. Morales
The recovery of a new partial cranium of Decennatherium rex Ríos et al. 2017 bearing two anterior and two posterior ossicones from the Late Miocene deposits of the site Batallones-10 (MN-10, Cerro de los Batallones, Madrid Basin) sheds light on the complex variability of the cranial appendages of these extinct giraffids. The special features of the anterior ossicones of BAT10’18-C6-40, each formed by two bosses and separated by a septum increase the range of morphological variability found in the anterior ossicones of giraffids. Posterior ossicone variability has already been described in several sivatherine taxa as Sivatherium maurusium (Harris, 1974) but anterior ossicone variability has never been discussed for four-ossicone taxa. This new specimen accounts for the third morphotype found in D. rex anterior ossicones. BAT10’18-C6-40 is identified as an adult D. rex male on the basis of the development of the posterior ossicones. These are large and already show the first large bump which in this taxon is always located on the middle of the dorsal surface at a similar height on the right and left ossicones which agrees with Solounias (1988) who stated that these small irregular protuberances have a somewhat fixed position, suggesting a genetic basis. This new specimen represents a new example of cranial variability in D. rex, and makes it the extinct giraffid with the largest anterior ossicone variability found so far.
rex Ríos等人2017年从巴塔龙-10遗址（MN-10，Cerro de los Batallones，马德里盆地）的中新世晚期沉积物中发现了一个新的部分颅骨，其上有两个前部和两个后部骨化锥，这揭示了这些已灭绝长颈鹿颅骨附属物的复杂变异性。BAT10'18-C6-40的前听骨锥的特殊特征，每个由两个凸台形成，并由隔膜分隔，增加了长颈鹿前听骨的形态变异范围。在几个小骨化石分类群中，小骨化石的后部变异性已经被描述为毛小骨化石（Harris，1974），但四个小骨化石类群的前部小骨化石变异性从未被讨论过。这个新标本是霸王龙前骨化骨中发现的第三个形态类型。BAT10'18-C6-40在后骨化锥发育的基础上被鉴定为成年霸王龙雄性。这些突起很大，并且已经显示出第一个大突起，在这个分类单元中，它总是位于背表面的中间，在左右听骨锥上的高度相似，这与Solounias（1988）的观点一致，他指出这些不规则的小突起有一个固定的位置，这表明了遗传基础。这一新标本代表了霸王龙头骨变异性的一个新例子，使其成为迄今为止发现的前骨化锥变异性最大的已灭绝长颈鹿。
{"title":"Anterior ossicone variability in Decennatherium rex Ríos, et al. 2017 (Late Miocene, Iberian Peninsula)","authors":"María Ríos, E. Cantero, Darío Estraviz-López, N. Solounias, J. Morales","doi":"10.1017/s1755691022000184","DOIUrl":"https://doi.org/10.1017/s1755691022000184","url":null,"abstract":"\u0000 The recovery of a new partial cranium of Decennatherium rex Ríos et al. 2017 bearing two anterior and two posterior ossicones from the Late Miocene deposits of the site Batallones-10 (MN-10, Cerro de los Batallones, Madrid Basin) sheds light on the complex variability of the cranial appendages of these extinct giraffids. The special features of the anterior ossicones of BAT10’18-C6-40, each formed by two bosses and separated by a septum increase the range of morphological variability found in the anterior ossicones of giraffids. Posterior ossicone variability has already been described in several sivatherine taxa as Sivatherium maurusium (Harris, 1974) but anterior ossicone variability has never been discussed for four-ossicone taxa. This new specimen accounts for the third morphotype found in D. rex anterior ossicones. BAT10’18-C6-40 is identified as an adult D. rex male on the basis of the development of the posterior ossicones. These are large and already show the first large bump which in this taxon is always located on the middle of the dorsal surface at a similar height on the right and left ossicones which agrees with Solounias (1988) who stated that these small irregular protuberances have a somewhat fixed position, suggesting a genetic basis. This new specimen represents a new example of cranial variability in D. rex, and makes it the extinct giraffid with the largest anterior ossicone variability found so far.","PeriodicalId":55171,"journal":{"name":"Earth and Environmental Science Transactions of the Royal Society of Edinburgh","volume":" ","pages":""},"PeriodicalIF":1.2,"publicationDate":"2022-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43118450","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-09-06DOI: 10.1017/s1755691022000172
Jacinta N. CHUKWUMA-ORJI
Ditch cuttings (69 samples) from a section of Awaizombe-1well located in the Northern Depobelt of the eastern Niger Delta Basin were used for this study. The lithology of the studied interval 1373–1812 m (439 m thick) consists of fissile grey shale and mudstone units. The scid method of sample preparation for palynormorphs’ recovery was adopted. Analysis recorded a well-preserved and diverse assemblage of palynomorphs, rich in pollen, spores and dinoflagellate cysts (dinocysts). First and last occurrences of marker and age diagnostic species were used for palynostratigraphic interpretation. Four palynostratigraphic interval range zones were established: Psilatriporites sp.–Racemonocolpites hians Zone; early Oligocene (Rupelian age), Praedapollis africanus–Doualaidites laevigatus Zone; late Eocene (Priabonian age), middle Eocene (Lutetian and Bartonian ages), Doualaidites laevigatus–Praedapollis flexibilies Zone; and early Eocene (Ypresian age), Verrucatosporites usmensis–Retitricolpites ituensis Zone. The first downhole occurrence of D. laevigatus at the 1482 m marks the late Eocene/early Oligocene boundary. Established zones are useful for inter and intra basins correlation. Lithology and age of the studied section are suggestive of the lower Agbada Formation. Palaeoenvironmental interpretations using diagnostic species revealed two environments: brackish and inner neritic to upper bathyal (0–600 m) under relatively warm-water marine condition indicated by thermophilic dinocyst taxa, such as Lingulodinium machaerophorum, Polysphaeridium zoharyi and Homotryblium spp. The lithology and these types of environments are good sites for hydrocarbon generation.
{"title":"Palynostratigraphy, biochronology and palaeobathymetry of a section of Awaizombe-1 well, eastern Niger Delta, Nigeria","authors":"Jacinta N. CHUKWUMA-ORJI","doi":"10.1017/s1755691022000172","DOIUrl":"https://doi.org/10.1017/s1755691022000172","url":null,"abstract":"\u0000 Ditch cuttings (69 samples) from a section of Awaizombe-1well located in the Northern Depobelt of the eastern Niger Delta Basin were used for this study. The lithology of the studied interval 1373–1812 m (439 m thick) consists of fissile grey shale and mudstone units. The scid method of sample preparation for palynormorphs’ recovery was adopted. Analysis recorded a well-preserved and diverse assemblage of palynomorphs, rich in pollen, spores and dinoflagellate cysts (dinocysts). First and last occurrences of marker and age diagnostic species were used for palynostratigraphic interpretation. Four palynostratigraphic interval range zones were established: Psilatriporites sp.–Racemonocolpites hians Zone; early Oligocene (Rupelian age), Praedapollis africanus–Doualaidites laevigatus Zone; late Eocene (Priabonian age), middle Eocene (Lutetian and Bartonian ages), Doualaidites laevigatus–Praedapollis flexibilies Zone; and early Eocene (Ypresian age), Verrucatosporites usmensis–Retitricolpites ituensis Zone. The first downhole occurrence of D. laevigatus at the 1482 m marks the late Eocene/early Oligocene boundary. Established zones are useful for inter and intra basins correlation. Lithology and age of the studied section are suggestive of the lower Agbada Formation. Palaeoenvironmental interpretations using diagnostic species revealed two environments: brackish and inner neritic to upper bathyal (0–600 m) under relatively warm-water marine condition indicated by thermophilic dinocyst taxa, such as Lingulodinium machaerophorum, Polysphaeridium zoharyi and Homotryblium spp. The lithology and these types of environments are good sites for hydrocarbon generation.","PeriodicalId":55171,"journal":{"name":"Earth and Environmental Science Transactions of the Royal Society of Edinburgh","volume":" ","pages":""},"PeriodicalIF":1.2,"publicationDate":"2022-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44374220","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-09-01DOI: 10.1017/S1755691022000123
M. Stoker, S. Holford, J. Totterdell
ABSTRACT This study presents an appraisal of the Middle Eocene–Quaternary Dugong Supersequence of the Eucla Basin, offshore southern Australia. It combines details of the rock record with seismic-stratigraphical information, and the resulting stratigraphic framework provides constraints on the nature of the late post-breakup development of the southern Australian continental margin. It is well established that the onshore-to-mid-shelf succession comprises a predominantly aggrading-to-prograding unconformity-bounded succession of carbonate platform deposits; however, our analysis of the outer shelf–upper slope section challenges the widely held view that this shelf-margin wedge represents a distally steepened prograding carbonate ramp primarily modulated by global eustasy. Instead, our results show that the Middle Eocene–Quaternary succession is punctuated by a series of unconformities that reflect a persistent tectonic instability and differential vertical movements throughout the late post-breakup period, the genesis of which is most closely related to tectonic events. Moreover, the upper slope clinoform succession was constructed and shaped predominantly by alongslope processes, and four different contourite drift types are recognised based on their seismic-stratigraphic expression: elongate mounded drift (Quaternary); infill drift (Pliocene); plastered drift (Oligocene); and separated drift (Middle–Upper Eocene). The Quaternary drift – herein termed the ‘Eyre Terrace Drift’ – is a spectacular basin-scale deposit, over 500 m thick and traced for up to 200 km along the upper slope Eyre Terrace. Upslope-migrating sediment waves are associated with this drift. Key sedimentary attributes consistent with a contourite origin include fine-grained sediment, multi-scale gradational bed contacts and pervasive bioturbation. There is also evidence of episodic downslope mass-movement processes ranging from the large-scale Late Neogene Slide, which extends downslope for 15–20 km, to sporadic slumped beds and turbidites recovered in boreholes. The interaction of alongslope and downslope processes indicates a more dynamic sedimentary setting than previously assumed along the outer margin of the Eucla Basin.
{"title":"Stratigraphic architecture of the Cenozoic Dugong Supersequence: implications for the late post-breakup development of the Eucla Basin, southern Australian continental margin","authors":"M. Stoker, S. Holford, J. Totterdell","doi":"10.1017/S1755691022000123","DOIUrl":"https://doi.org/10.1017/S1755691022000123","url":null,"abstract":"ABSTRACT This study presents an appraisal of the Middle Eocene–Quaternary Dugong Supersequence of the Eucla Basin, offshore southern Australia. It combines details of the rock record with seismic-stratigraphical information, and the resulting stratigraphic framework provides constraints on the nature of the late post-breakup development of the southern Australian continental margin. It is well established that the onshore-to-mid-shelf succession comprises a predominantly aggrading-to-prograding unconformity-bounded succession of carbonate platform deposits; however, our analysis of the outer shelf–upper slope section challenges the widely held view that this shelf-margin wedge represents a distally steepened prograding carbonate ramp primarily modulated by global eustasy. Instead, our results show that the Middle Eocene–Quaternary succession is punctuated by a series of unconformities that reflect a persistent tectonic instability and differential vertical movements throughout the late post-breakup period, the genesis of which is most closely related to tectonic events. Moreover, the upper slope clinoform succession was constructed and shaped predominantly by alongslope processes, and four different contourite drift types are recognised based on their seismic-stratigraphic expression: elongate mounded drift (Quaternary); infill drift (Pliocene); plastered drift (Oligocene); and separated drift (Middle–Upper Eocene). The Quaternary drift – herein termed the ‘Eyre Terrace Drift’ – is a spectacular basin-scale deposit, over 500 m thick and traced for up to 200 km along the upper slope Eyre Terrace. Upslope-migrating sediment waves are associated with this drift. Key sedimentary attributes consistent with a contourite origin include fine-grained sediment, multi-scale gradational bed contacts and pervasive bioturbation. There is also evidence of episodic downslope mass-movement processes ranging from the large-scale Late Neogene Slide, which extends downslope for 15–20 km, to sporadic slumped beds and turbidites recovered in boreholes. The interaction of alongslope and downslope processes indicates a more dynamic sedimentary setting than previously assumed along the outer margin of the Eucla Basin.","PeriodicalId":55171,"journal":{"name":"Earth and Environmental Science Transactions of the Royal Society of Edinburgh","volume":"113 1","pages":"279 - 312"},"PeriodicalIF":1.2,"publicationDate":"2022-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43457121","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-09-01DOI: 10.1017/S175569102200010X
A. Dawson, P. Bishop, J. Hansom, D. Fabel
ABSTRACT New 10Be exposure age dating and geomorphological mapping of emerged shoreline features in W Jura and NE Islay throw new light on the regional pattern of ice sheet deglaciation and late-glacial relative sea level change. We conclude that the oldest and highest emerged shorelines in this area were produced ~15.7–16.3 ka, shortly after ice sheet deglaciation ~16.5 ka. It is envisaged that the first incursion of marine waters into coastal areas took place close to a former ice sheet margin that oscillated in position across this part of the Scottish Inner Hebrides. The first evidence of late-glacial marine sedimentation following deglaciation consists of emerged marine terrace fragments and unvegetated gravel beach ridges, the former represented by a prominent glacio-isostatically tilted shoreline that declines in altitude NE to SW, from ~40 m above ordnance datum (OD) in NW Jura to ~19 m OD in central Islay. In W Jura, north of Loch Tarbert, spectacular staircases of up to 55 unvegetated gravel beach ridges were formed shortly after regional deglaciation, possibly within 1 ka. A preliminary estimate of the average rate of relative sea level lowering across W Jura between deglaciation and the Younger Dryas is in the order of ~7 mmyr−1. Geomorphological evidence from Shian Bay, W Jura, indicates a truncation of the late-glacial beach ridge staircases by a large 480-m-long beach ridge (the Colonsay Ridge) at ~14.9 ka, when former relative sea level was at ~18 m OD. This ridge may represent the product of either a stillstand in the progressive lowering of relative sea level during the late-glacial or a reversal. This raises the intriguing possibility of an association between ridge formation and the timing of the well-established global meltwater pulse 1A between ~14.65 and ~14.8 ka.
新的10Be暴露年龄定年和北侏罗和北侏罗出现的海岸线特征地貌填图，为揭示冰盖消冰和晚冰期相对海平面变化的区域格局提供了新的思路。我们认为，该地区最古老和最高的海岸线形成于~15.7 ~ 16.3 ka，在冰盖消融~16.5 ka之后不久。据设想，海水第一次侵入沿海地区发生在靠近苏格兰内赫布里底群岛这部分地区的前冰盖边缘。退冰后晚冰期海洋沉积的第一个证据是出现的海相阶地碎片和无植被的砾石滩脊，前者以突出的冰川-均衡倾斜海岸线为代表，其高度从东北向西南下降，从西北侏罗的地形基准面以上~40 m下降到伊莱岛中部的~19 m OD。在塔伯特湖(Loch Tarbert)北部的西侏罗(wjura)，在区域冰川消退后不久，可能在1 ka内形成了多达55个未被植被覆盖的砾石海滩山脊，形成了壮观的阶梯。据初步估计，在消冰期和新仙女木期之间，整个西侏罗大陆的平均相对海平面下降速率约为~7 mmyr−1。来自西侏罗石安湾的地貌证据表明，在约14.9 ka，当以前的相对海平面约18 m OD时，一个480 m长的大海滩脊(Colonsay ridge)截断了晚冰期海滩脊阶梯。这个山脊可能代表了晚冰期相对海平面逐渐下降的静止状态或反转的产物。这提出了一种有趣的可能性，即脊的形成与公认的全球融水脉冲1A的时间在~14.65 ~ ~14.8 ka之间存在联系。
{"title":"10Be exposure age dating of Late Quaternary relative sea level changes and deglaciation of W Jura and NE Islay, Scottish Inner Hebrides","authors":"A. Dawson, P. Bishop, J. Hansom, D. Fabel","doi":"10.1017/S175569102200010X","DOIUrl":"https://doi.org/10.1017/S175569102200010X","url":null,"abstract":"ABSTRACT New 10Be exposure age dating and geomorphological mapping of emerged shoreline features in W Jura and NE Islay throw new light on the regional pattern of ice sheet deglaciation and late-glacial relative sea level change. We conclude that the oldest and highest emerged shorelines in this area were produced ~15.7–16.3 ka, shortly after ice sheet deglaciation ~16.5 ka. It is envisaged that the first incursion of marine waters into coastal areas took place close to a former ice sheet margin that oscillated in position across this part of the Scottish Inner Hebrides. The first evidence of late-glacial marine sedimentation following deglaciation consists of emerged marine terrace fragments and unvegetated gravel beach ridges, the former represented by a prominent glacio-isostatically tilted shoreline that declines in altitude NE to SW, from ~40 m above ordnance datum (OD) in NW Jura to ~19 m OD in central Islay. In W Jura, north of Loch Tarbert, spectacular staircases of up to 55 unvegetated gravel beach ridges were formed shortly after regional deglaciation, possibly within 1 ka. A preliminary estimate of the average rate of relative sea level lowering across W Jura between deglaciation and the Younger Dryas is in the order of ~7 mmyr−1. Geomorphological evidence from Shian Bay, W Jura, indicates a truncation of the late-glacial beach ridge staircases by a large 480-m-long beach ridge (the Colonsay Ridge) at ~14.9 ka, when former relative sea level was at ~18 m OD. This ridge may represent the product of either a stillstand in the progressive lowering of relative sea level during the late-glacial or a reversal. This raises the intriguing possibility of an association between ridge formation and the timing of the well-established global meltwater pulse 1A between ~14.65 and ~14.8 ka.","PeriodicalId":55171,"journal":{"name":"Earth and Environmental Science Transactions of the Royal Society of Edinburgh","volume":"113 1","pages":"253 - 266"},"PeriodicalIF":1.2,"publicationDate":"2022-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43083629","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-09-01DOI: 10.1017/S1755691022000160
Jozef Klembara, D. Berman, A. Henrici, T. Martens, M. Hain
ABSTRACT Presented for the first time is a reconstruction of the skull of Diadectes (Diadectomorpha) based on several specimens of a single species Diadectes absitus from the early Permian of central Germany. Since its first discovery at the end of the 19th century the only reconstructions of the skull of Diadectes were without specific designation, despite a rich Permo-Carboniferous fossil record. The skull of D. absitus is reconstructed in dorsal, lateral, posterior, and ventral views and includes exocranial and endocranial elements. The reconstructions of Diadectes presented here are compared with those of all other authors, and the differences are analysed and discussed. The comparisons recognised three features not recorded in other species of Diadectes: (1) anterior and posterior margins of the transverse process of the pterygoid parallel one another; (2) the angle between the posterior margin of the transverse process and the lateral margin of the quadrate ramus of the pterygoid is sharply defined; and (3) the anterior ventral margin of the transverse process of the pterygoid bears a distinct sharp ridge. These characters are discussed in the context of the skull anatomy of Diadectes and inaccuracies in previous cranial reconstructions of the genus are rectified.
{"title":"Reconstruction of the skull and description of new anatomical features of Diadectes absitus (Diadectidae, Diadectomorpha) from the early Permian of central Germany","authors":"Jozef Klembara, D. Berman, A. Henrici, T. Martens, M. Hain","doi":"10.1017/S1755691022000160","DOIUrl":"https://doi.org/10.1017/S1755691022000160","url":null,"abstract":"ABSTRACT Presented for the first time is a reconstruction of the skull of Diadectes (Diadectomorpha) based on several specimens of a single species Diadectes absitus from the early Permian of central Germany. Since its first discovery at the end of the 19th century the only reconstructions of the skull of Diadectes were without specific designation, despite a rich Permo-Carboniferous fossil record. The skull of D. absitus is reconstructed in dorsal, lateral, posterior, and ventral views and includes exocranial and endocranial elements. The reconstructions of Diadectes presented here are compared with those of all other authors, and the differences are analysed and discussed. The comparisons recognised three features not recorded in other species of Diadectes: (1) anterior and posterior margins of the transverse process of the pterygoid parallel one another; (2) the angle between the posterior margin of the transverse process and the lateral margin of the quadrate ramus of the pterygoid is sharply defined; and (3) the anterior ventral margin of the transverse process of the pterygoid bears a distinct sharp ridge. These characters are discussed in the context of the skull anatomy of Diadectes and inaccuracies in previous cranial reconstructions of the genus are rectified.","PeriodicalId":55171,"journal":{"name":"Earth and Environmental Science Transactions of the Royal Society of Edinburgh","volume":"113 1","pages":"267 - 278"},"PeriodicalIF":1.2,"publicationDate":"2022-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42838566","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-09-01DOI: 10.1017/s1755691022000275
{"title":"TRE volume 113 issue 3 Cover and Front matter","authors":"","doi":"10.1017/s1755691022000275","DOIUrl":"https://doi.org/10.1017/s1755691022000275","url":null,"abstract":"","PeriodicalId":55171,"journal":{"name":"Earth and Environmental Science Transactions of the Royal Society of Edinburgh","volume":" ","pages":"f1 - f2"},"PeriodicalIF":1.2,"publicationDate":"2022-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46610889","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-09-01DOI: 10.1017/s1755691022000287
{"title":"TRE volume 113 issue 3 Cover and Back matter","authors":"","doi":"10.1017/s1755691022000287","DOIUrl":"https://doi.org/10.1017/s1755691022000287","url":null,"abstract":"","PeriodicalId":55171,"journal":{"name":"Earth and Environmental Science Transactions of the Royal Society of Edinburgh","volume":"113 1","pages":"b1 - b2"},"PeriodicalIF":1.2,"publicationDate":"2022-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45847580","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-08-31DOI: 10.1017/S1755691022000135
R. Saber, A. Caglayan, V. Isik
ABSTRACT The geological and tectonic background of the Sabalan area in NW Iran and its present-day surface processes make it ideal for examining the effects of tectonic processes in shaping the Earth's crust. As a result of the intense distribution of pre-Quaternary and Quaternary structures (e.g., faults, joints and folds), most of the drainage basins in the southern and central parts of the study area have developed under tectonic-dominated conditions, whereas the effects of erosional processes are greater in the north and east. An evaluation of the geomorphic indices using the index of active tectonics (IAT) and analytical hierarchy process (AHP) methods shows that the AHP results are more reliable than the IAT results and are coherent with the geological and structural conditions of the study area. The geomorphic results are highly consistent with the intensity and distribution of fractures. The majority of fractures have developed in a NW–SE direction, indicating antithetic R′ Riedel fractures to the main NE-SW-trending faults. However, a significant number of the fractures in the study area are NNE–SSW- and NE–SW-oriented R and P fractures and NNW–SSE-oriented tension fractures. Palaeostress analysis of the fault data shows at least two faulting events in the pre-Quaternary and Quaternary, respectively. The pre-Quaternary NNW–SSE-striking dextral strike-slip faults experienced post-Eocene 25–30° clockwise rotation and re-activated as NE–SW-striking sinistral faults during the Quaternary. Although seismic activity is currently low, the consistency of our results with the regional stress data show that the study area is still tectonically active.
{"title":"Landscape response to deformation in the Sabalan area, NW Iran: Inferred from quantitative morphological and structural analysis","authors":"R. Saber, A. Caglayan, V. Isik","doi":"10.1017/S1755691022000135","DOIUrl":"https://doi.org/10.1017/S1755691022000135","url":null,"abstract":"ABSTRACT The geological and tectonic background of the Sabalan area in NW Iran and its present-day surface processes make it ideal for examining the effects of tectonic processes in shaping the Earth's crust. As a result of the intense distribution of pre-Quaternary and Quaternary structures (e.g., faults, joints and folds), most of the drainage basins in the southern and central parts of the study area have developed under tectonic-dominated conditions, whereas the effects of erosional processes are greater in the north and east. An evaluation of the geomorphic indices using the index of active tectonics (IAT) and analytical hierarchy process (AHP) methods shows that the AHP results are more reliable than the IAT results and are coherent with the geological and structural conditions of the study area. The geomorphic results are highly consistent with the intensity and distribution of fractures. The majority of fractures have developed in a NW–SE direction, indicating antithetic R′ Riedel fractures to the main NE-SW-trending faults. However, a significant number of the fractures in the study area are NNE–SSW- and NE–SW-oriented R and P fractures and NNW–SSE-oriented tension fractures. Palaeostress analysis of the fault data shows at least two faulting events in the pre-Quaternary and Quaternary, respectively. The pre-Quaternary NNW–SSE-striking dextral strike-slip faults experienced post-Eocene 25–30° clockwise rotation and re-activated as NE–SW-striking sinistral faults during the Quaternary. Although seismic activity is currently low, the consistency of our results with the regional stress data show that the study area is still tectonically active.","PeriodicalId":55171,"journal":{"name":"Earth and Environmental Science Transactions of the Royal Society of Edinburgh","volume":"113 1","pages":"227 - 252"},"PeriodicalIF":1.2,"publicationDate":"2022-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42434141","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-07-28DOI: 10.1017/S1755691022000081
S. Ingrams, D. Jolley, S. Schneider
ABSTRACT The Jurassic to Cretaceous strata exposed in the Rollrock Section, Sverdrup Basin, Arctic Canada, represent one of the northernmost continuous outcrops spanning this poorly understood transition. The Oxfordian–Valanginian mudstones of the Rollrock Section were deposited in a shallow marine environment and, as such, provide the ideal lithology to investigate the response of high latitude dinoflagellate cyst populations to the frequent environmental perturbations of this time. Using a multivariate statistical approach, distinct palaeoecologically significant groups are identified and directly linked to time and palaeoenvironments, allowing for the reconstruction of underlying long term palaeoenvironmental trends. These palaeoenvironmental trends are identified to be driven by sequence stratigraphic cycles. For the first time, fourth order sequences are recorded from this pivotal period in the Sverdrup Basin and reveal an additional level of short term climatic events that complicate the identification of long term trends. The relationship existing between marine phytoplankton and climate is utilised to decipher the interplay of long-term and short-term climate fluctuations, distinguishing them from evolutionary trends. Two groups of dinoflagellate cysts, identified by process morphology, are recorded to act as environmental proxies. High percentages of proximochorate dinoflagellate cysts, such as Trichodinium erinaceoides, indicate more proximal, high energy, nutrient rich conditions and are dominant in fourth order transgressive systems tracts. High percentages of chorate dinoflagellate cysts, such as Oligosphaeridium complex, signify distal, low energy, nutrient depleted conditions and are dominant in fourth order highstand systems tracts.
{"title":"Sequence stratigraphy and microplankton palaeoenvironmental dynamics across the Jurassic–Cretaceous transition in the Canadian Arctic","authors":"S. Ingrams, D. Jolley, S. Schneider","doi":"10.1017/S1755691022000081","DOIUrl":"https://doi.org/10.1017/S1755691022000081","url":null,"abstract":"ABSTRACT The Jurassic to Cretaceous strata exposed in the Rollrock Section, Sverdrup Basin, Arctic Canada, represent one of the northernmost continuous outcrops spanning this poorly understood transition. The Oxfordian–Valanginian mudstones of the Rollrock Section were deposited in a shallow marine environment and, as such, provide the ideal lithology to investigate the response of high latitude dinoflagellate cyst populations to the frequent environmental perturbations of this time. Using a multivariate statistical approach, distinct palaeoecologically significant groups are identified and directly linked to time and palaeoenvironments, allowing for the reconstruction of underlying long term palaeoenvironmental trends. These palaeoenvironmental trends are identified to be driven by sequence stratigraphic cycles. For the first time, fourth order sequences are recorded from this pivotal period in the Sverdrup Basin and reveal an additional level of short term climatic events that complicate the identification of long term trends. The relationship existing between marine phytoplankton and climate is utilised to decipher the interplay of long-term and short-term climate fluctuations, distinguishing them from evolutionary trends. Two groups of dinoflagellate cysts, identified by process morphology, are recorded to act as environmental proxies. High percentages of proximochorate dinoflagellate cysts, such as Trichodinium erinaceoides, indicate more proximal, high energy, nutrient rich conditions and are dominant in fourth order transgressive systems tracts. High percentages of chorate dinoflagellate cysts, such as Oligosphaeridium complex, signify distal, low energy, nutrient depleted conditions and are dominant in fourth order highstand systems tracts.","PeriodicalId":55171,"journal":{"name":"Earth and Environmental Science Transactions of the Royal Society of Edinburgh","volume":"113 1","pages":"159 - 174"},"PeriodicalIF":1.2,"publicationDate":"2022-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43135136","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-07-28DOI: 10.1017/S1755691022000111
Marta RODRÍGUEZ-MARTÍNEZ, W. Buggisch, S. Menéndez, E. Moreno-Eiris, A. Perejón
ABSTRACT The presence of archaeocyath-bearing clasts from Cenozoic tills and Cambrian Mount Wegener Formation reveal erosion of a hidden Cambrian carbonate platform in Shackleton Range, Antarctica. We provide microfacies, paleontological, diagenetic and tectonically induced fabric data from carbonate clasts which, in addition to available geochemical and geochronological data from Shackleton Range, allow the paleoenvironmental reconstruction of a lost Cambrian Series 2 mixed siliciclastic–carbonate platform that was developed and eroded during the Ross orogeny. Carbonate production was dominated by non-skeletal grains in possibly restricted platform-interior and oolitic shoal complex settings, while open subtidal sub-environments (calcimicrobe carpets, calcimicrobe–archaeocyath patch reefs, muddy bottoms) were dominated by a diverse calcimicrobe assemblage and/or by secondary to accessory heterozoan assemblage (archaeocyaths and other sponges, chancelloriids, hyoliths, coralomorphs, trilobites, echinoderms). We describe a Botoman assemblage with 34 archaeocyathan species among 12 existing archaeocyathan genera. A new archaeocyath family Shackletoncyathidae is proposed. New species (Rotundocyathus glacius sp. nov., Buggischicyathus microporus gen. et sp. nov., Paragnaltacyathus hoeflei, Shackletoncyathus buggischi gen. et. sp. nov., Santelmocyathus santelmoi gen. et sp. nov., Wegenercyathus sexangulae gen. et sp. nov.) and Tabulaconus kordae coralomorph are reported from Antarctica for the first time. Archaeocyathan fauna share few species with contemporary fauna of South Australia (9) and even fewer with the Antarctic platforms of the Shackleton Limestone (2) or the Schneider Hills limestone (1). Similarity is greater with Antarctic allochthonous assemblages of Permo-Carboniferous tillites from Ellsworth Mountains (2), Cenozoic deposits from King George Island (4) or Weddell Sea (1). The Shackleton Range lost/hidden platform shows a distinct entity related with its tectonosedimentary evolution, in a possible back-arc basin on the Mozambique seaway during the E and W Gondwana amalgamation, which distinguishes it from those developed on the palaeo-Pacific margin of the E Antarctic craton.
{"title":"Reconstruction of a Ross lost Cambrian Series 2 mixed siliciclastic–carbonate platform from carbonate clasts of the Shackleton Range, Antarctica","authors":"Marta RODRÍGUEZ-MARTÍNEZ, W. Buggisch, S. Menéndez, E. Moreno-Eiris, A. Perejón","doi":"10.1017/S1755691022000111","DOIUrl":"https://doi.org/10.1017/S1755691022000111","url":null,"abstract":"ABSTRACT The presence of archaeocyath-bearing clasts from Cenozoic tills and Cambrian Mount Wegener Formation reveal erosion of a hidden Cambrian carbonate platform in Shackleton Range, Antarctica. We provide microfacies, paleontological, diagenetic and tectonically induced fabric data from carbonate clasts which, in addition to available geochemical and geochronological data from Shackleton Range, allow the paleoenvironmental reconstruction of a lost Cambrian Series 2 mixed siliciclastic–carbonate platform that was developed and eroded during the Ross orogeny. Carbonate production was dominated by non-skeletal grains in possibly restricted platform-interior and oolitic shoal complex settings, while open subtidal sub-environments (calcimicrobe carpets, calcimicrobe–archaeocyath patch reefs, muddy bottoms) were dominated by a diverse calcimicrobe assemblage and/or by secondary to accessory heterozoan assemblage (archaeocyaths and other sponges, chancelloriids, hyoliths, coralomorphs, trilobites, echinoderms). We describe a Botoman assemblage with 34 archaeocyathan species among 12 existing archaeocyathan genera. A new archaeocyath family Shackletoncyathidae is proposed. New species (Rotundocyathus glacius sp. nov., Buggischicyathus microporus gen. et sp. nov., Paragnaltacyathus hoeflei, Shackletoncyathus buggischi gen. et. sp. nov., Santelmocyathus santelmoi gen. et sp. nov., Wegenercyathus sexangulae gen. et sp. nov.) and Tabulaconus kordae coralomorph are reported from Antarctica for the first time. Archaeocyathan fauna share few species with contemporary fauna of South Australia (9) and even fewer with the Antarctic platforms of the Shackleton Limestone (2) or the Schneider Hills limestone (1). Similarity is greater with Antarctic allochthonous assemblages of Permo-Carboniferous tillites from Ellsworth Mountains (2), Cenozoic deposits from King George Island (4) or Weddell Sea (1). The Shackleton Range lost/hidden platform shows a distinct entity related with its tectonosedimentary evolution, in a possible back-arc basin on the Mozambique seaway during the E and W Gondwana amalgamation, which distinguishes it from those developed on the palaeo-Pacific margin of the E Antarctic craton.","PeriodicalId":55171,"journal":{"name":"Earth and Environmental Science Transactions of the Royal Society of Edinburgh","volume":"113 1","pages":"175 - 226"},"PeriodicalIF":1.2,"publicationDate":"2022-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47867477","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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