Microfacies and Diagenetic Analysis of Lockhart Limestone, Shah Alla Ditta Area Islamabad, Pakistan
Figure 5. Showing the depositional environment of microfacies with respect to sea level rise and fall
er benthic foraminifers, gastropods, pelecypods, ostracods and rare dasycladacean algae. The benthic foraminifers, constitut- ing 20-45% of the skeletal constituents include, Miscellinae miscella, Lockhartia haimei, Lockhartia conditti, Ranikotalia trochodiformis, Quenquloclina sp., Idalina sinjarica sp., and Cibicide (Figure 4a). Dunham(1962) recognizes wackestone as a textural type in this microfacies, while Folk calls the same material poorly-washed biomicrite(1959).
Lockhart-Microfacies 2: Algal Foraminiferal Wackestone Microfacies.
The Algal-Foram Wackestone Microfacies is comprised of dark grey, thin bedded, nodular limestone with minor clay/ marl interbeds. It is characterized by larger and smaller ben- thic foraminifera mixed with dasycladacean algae, mollusks, gastropods and ostracods with rare echinoderms and planktic foraminifera. The dasycladacean algae vary from 10-15%. The benthic foraminifera constitute 20-25% of the skeletal constituents and include milliolids, Lockhartia sp., Rotalia sp., Textularia and Assilina sp. (Figure 4b)
Lockhart-Microfacies 3: Mixed Bioclastic Mudstone Microfacies.
The allochem constituents are exclusively skeletal frag- ments displaying mudstone depositional fabrics according to Dunham (1962), or biomicrite according to Folk (1959). Algae, Miscellanea miscella, and a very few smaller benthics are also
Figure 4a. Photomicrograph displaying (A) Assilina, (B) Rotalia trochidiformis (Lamarck) (RT), (C) Bioclast (bc), Textularia (T) and (L) Lockhartia sp. (D) Rotalia sp(E) Miscellanea sp.(Ms) and Bivalve (bi) in lime mud matrix in Foraminiferal Wackestone
Figure 4b. Photomicrograph displaying Lockhartia sp (A, B), Fossil replacement by calcite (C), Calcite vein (D), Quenquolocolina (E) , Assilina (F) in Algal Foraminiferal Wackstone.s
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