کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
4691051 | 1636185 | 2006 | 23 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Sedimentary facies and the context of dolocrete in the Lower Triassic Sherwood Sandstone group: Corrib Field west of Ireland
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موضوعات مرتبط
مهندسی و علوم پایه
علوم زمین و سیارات
فرآیندهای سطح زمین
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چکیده انگلیسی
The Lower Triassic Sherwood Sandstone Group (SSG) reservoir in the Corrib Field is predominantly fine- to medium-grained fluvial sandstone with minor aeolian and playa sediments that formed under semi-arid to arid conditions. There is no evidence of roots, burrows or organic-rich soils in the SSG suggesting an environment with sparse vegetation in the catchment and sedimentation from a predominantly braided sand-dominated river. Dolomite is the main porosity-occluding cement (<Â 25 vol.%) in the Sherwood Sandstone Group reservoir in the Corrib Gas Field, offshore west of Ireland. Dolomite is demonstrably early diagenetic since it is non-ferroan, brightly luminescent, occurs in rocks with high (uncompacted) intergranular volumes and grew before all burial diagenetic cements. Conversely, calcrete is the dominant early diagenetic cement in well 27/5-1 in the SSG, â¼50 km south of Corrib. Dolocrete and/or calcrete are represented throughout the entire SSG interval and typically form under conditions of very low sediment accumulation rates. Dolocrete occurs equally in all facies showing that it is not a result of depositional processes. Core goniometry data in the Corrib Field revealed that the general palaeoflow direction was from south to north. During progressive evaporation of river- and ground-water calcite formed first, followed by dolomite further downstream with gypsum formed last if evaporation continues. This well-established pattern indicates that well 27/5-1 has calcrete and Corrib has dolocrete since they both result from evaporative concentration of ground- and river-water during flow down the very shallow Triassic palaeogradient.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Sedimentary Geology - Volume 187, Issues 3â4, 1 June 2006, Pages 205-227
Journal: Sedimentary Geology - Volume 187, Issues 3â4, 1 June 2006, Pages 205-227
نویسندگان
Susanne Schmid, Richard H. Worden, Quentin J. Fisher,